The researchers used the classic imiquimod model of psoriasis, in which daily application of an immune-stimulating cream to shaved mouse skin triggers scaly, red, thickened lesions that closely mirror human disease. Imiquimod works by activating toll-like receptors 7 and 8, unleashing a cascade of inflammatory cytokines, and it also acts directly on itch-sensing nerve channels. Fifty-six mice were divided into seven groups: a healthy control, an untreated disease model, a plain gel base, the corticosteroid clobetasol propionate as a benchmark, and three experimental groups receiving celecoxib emulgel, diallyl trisulfide emulgel, or a combination of both. Treatment began on day eight and continued for a week, with all assessments performed by blinded observers in line with ARRIVE guidelines.

The results were striking. Mice treated with imiquimod alone developed severe lesions, with cumulative Psoriasis Area and Severity Index scores climbing to 4.6 while controls stayed at zero. The plain gel base helped somewhat — an expected emollient effect — but the active treatments cut scores far more deeply: celecoxib brought the score down to 1.75, diallyl trisulfide to 1.4, and the combination to 1.9, all statistically indistinguishable from the gold-standard corticosteroid. Histological examination told the same story. Where imiquimod-treated skin showed thickened epidermis, parakeratosis, Munro microabscesses, and dense lymphocytic infiltration, treated skin retained near-normal architecture, with epidermal thickness reduced by more than half in all three active groups.

Perhaps the most patient-relevant finding concerned itch. Scratching is not merely a nuisance in psoriasis — it can trigger the Koebner phenomenon, in which new lesions appear at sites of skin trauma, creating a vicious cycle. Imiquimod-treated mice scratched nearly four times more often than controls over a thirty-minute observation window. Celecoxib cut scratch bouts by 66 percent, diallyl trisulfide by 77 percent, and the combination by 70 percent, matching the corticosteroid. Skin serotonin, a key itch mediator that also drives keratinocyte proliferation and lymphocyte activation, fell by up to 56 percent — and the combination actually outperformed the steroid on this measure, reducing serotonin 23 percent more than clobetasol did.

Underneath these visible improvements, the team mapped a coherent molecular mechanism. Imiquimod inflated the interleukin-23/interleukin-22/interleukin-19/interleukin-17 axis — the canonical psoriasis pathway — raising skin IL-23 nearly twofold, IL-22 more than threefold, and serum IL-17 almost fourfold. Both compounds, alone and together, suppressed every node of this axis, with the combination reducing IL-17 by 68 percent. A Bliss independence analysis revealed that the combination acted synergistically on IL-23, the master cytokine that sustains Th17 cells, the immune population widely blamed for driving psoriatic inflammation.

The drugs also converged on the interleukin-6/JAK2/STAT3 signaling cascade, a pathway targeted by several approved psoriasis drugs. Imiquimod raised serum IL-6 nearly fivefold and ear JAK2 and STAT3 protein levels five- to sevenfold. The combination therapy knocked these back by 68, 64, and 71 percent respectively — beating the corticosteroid by 26 to 40 percent on each measure. This matters because JAK/STAT signaling has been directly linked to cytokine-induced itch, and JAK inhibitors relieve pruritus in psoriasis patients. The authors note a limitation: they measured total protein rather than the phosphorylated, active forms of JAK2 and STAT3, so follow-up work with phospho-specific assays is planned.

Inflammation beyond the cytokine axis also subsided. Interferon-gamma and tumor necrosis factor-alpha, both elevated by imiquimod, fell by up to 51 and 64 percent respectively under combination treatment, and myeloperoxidase — an enzyme marker of neutrophil infiltration that correlates with disease severity — dropped by half. Immunohistochemistry confirmed that CD4-positive and CD8-positive T-cell infiltration into skin, which surged after imiquimod exposure, was significantly reduced by all three treatments. Pearson correlation analysis strengthened the biological story: every inflammatory marker measured correlated strongly and positively with both PASI scores and scratch counts, reinforcing their potential as biomarkers of disease activity.

One of the more intriguing findings concerned the spleen. Imiquimod increased absolute spleen weight by 88 percent, reflecting extramedullary hematopoiesis and systemic immune activation — evidence that even a skin-limited trigger reverberates through the whole body. Celecoxib, diallyl trisulfide, and their combination all reduced spleen weight by roughly a third, and histology showed the combination preserved near-normal splenic architecture, with only minimal expansion of lymphoid follicles. Notably, the corticosteroid group showed the least splenic recovery, alongside the well-documented skin-thinning and hair-follicle atrophy that steroids cause — adverse effects the experimental emulgels did not produce.

The rationale for pairing these two particular molecules is elegant. Celecoxib, a selective COX-2 inhibitor, suppresses prostaglandin E2, a mediator elevated in psoriatic blister fluid that fuels both inflammation and itch; it also independently dampens IL-6-driven STAT3 activation. Diallyl trisulfide is a slow-releasing hydrogen sulfide donor derived from garlic, and serum hydrogen sulfide is known to be depleted in psoriasis patients in proportion to disease severity. Slow-release donors mimic the body’s natural sustained hydrogen sulfide production better than inorganic salts, and related donors have already eased psoriasis-like disease in mice by curbing neutrophil recruitment and pruritus. Hydrogen sulfide–NSAID hybrid molecules are an active research frontier precisely because pairing the two mechanisms lowers toxicity while boosting anti-inflammatory effect.

The authors are careful about scope. This was a single-dose screening study in an animal model, with no pharmacokinetic, skin-deposition, or long-term safety data yet, and no solvent-matched vehicle control for the dimethylformamide carrier. Equivalence to corticosteroid therapy cannot be claimed from this design. But the convergence of evidence — PASI relief, itch suppression, histological normalization, spleen protection, and coordinated damping of the IL-23/IL-17 and IL-6/JAK2/STAT3 cascades, all achieved with topically applied, inexpensive, orally familiar compounds — makes a compelling case for the next step: head-to-head clinical comparison against clobetasol in patients with early psoriasis. If the mouse results translate, relief for the 60 to 90 percent of patients who itch might come not from a new biologic, but from a garlic extract and an old painkiller rubbed into the skin.

Subject of Research: Topical celecoxib and diallyl trisulfide emulgels against imiquimod-induced psoriasis in BALB/c mice

Article Title: Celecoxib or diallyl trisulfide topical emulgels, alone or in combination, reduce pruritus and inflammatory cascades in a BALB/c mouse model of imiquimod-induced psoriasis

Article References: Kamel, M. M., Zaki, H. F., Saleh, R. A., Henry, S. R., Ibrahim, M. K., Mofreh Bakr, M., Abouhussein, D. M. N., & Rabie, M. A. (2026). Celecoxib or diallyl trisulfide topical emulgels, alone or in combination, reduce pruritus and inflammatory cascades in a BALB/c mouse model of imiquimod-induced psoriasis. Pharmacia, 73, Article e205623. https://doi.org/10.3897/pharmacia.73.e205623

Image Credits: AI Generated

DOI: 10.3897/pharmacia.73.e205623

Keywords: psoriasis, celecoxib, diallyl trisulfide, imiquimod mouse model, IL-23/IL-17 axis, JAK2/STAT3, pruritus, hydrogen sulfide donor, emulgel, BALB/c mice, inflammation, clobetasol

Docetaxel is a cornerstone taxane chemotherapy drug used to treat early-stage breast cancer around the world, appearing in numerous landmark adjuvant and neoadjuvant regimens. Yet despite its proven ability to improve survival, docetaxel carries a heavy dermatological burden. Patients frequently develop rashes, intense itching known as pruritus, and hand-foot syndrome, a condition marked by redness, swelling, and tenderness on the palms and soles that can make walking or gripping objects excruciating. In severe cases, docetaxel has even been linked to life-threatening skin reactions such as toxic epidermal necrolysis, historically called Lyell’s syndrome. Standard supportive care, typically built around dexamethasone premedication, blunts some of these effects but leaves many patients suffering, and until now no established adjunctive primary prophylaxis for docetaxel-induced skin toxicity has existed.

The new study, led by pharmacist Katsuya Makihara and colleagues at Yodogawa Christian Hospital in Osaka, examined whether desloratadine could fill that gap. The drug is a peripheral H1-receptor antagonist, meaning it blocks histamine signaling outside the brain without causing the drowsiness associated with older antihistamines. Importantly, desloratadine also possesses documented anti-inflammatory properties: laboratory work has shown that it suppresses nuclear factor-kappaB activity, a central molecular switch driving inflammatory responses, consistent with inverse agonism at the H1 receptor. That dual profile made it an intriguing candidate for skin toxicity, which is thought to involve a mix of hypersensitivity and inflammatory mechanisms rather than a purely allergic process.

The researchers conducted a single-center retrospective cohort study involving 143 patients with stage I to III breast cancer who received perioperative docetaxel-based chemotherapy at a dose of 75 milligrams per square meter of body surface area every three weeks, all with standard dexamethasone premedication. Desloratadine was not assigned randomly. Instead, it was prescribed nonrandomly to 49 patients, about 34 percent of the cohort, who took 5 milligrams daily from the morning after their first docetaxel infusion through the completion of treatment. The remaining 94 patients received no prophylactic antihistamine at all. The primary outcome was any patient-reported skin toxicity, encompassing rash, pruritus, or hand-foot syndrome.

Because the treatment assignment was not random, the team had to contend with confounding, the ever-present danger in observational research that patients given the antihistamine differed systematically from those who were not. To address this, the investigators used a sophisticated statistical technique called inverse probability of treatment weighting, or IPTW, with Hájek-normalized stabilized weights. In essence, the method builds a propensity score, a model estimating each patient’s probability of receiving desloratadine based on their measured characteristics, and then reweights the cohort so that treated and untreated patients become statistically comparable as if the treatment had been assigned by chance. Confidence intervals were derived from 2,000 patient-level bootstrap resamples with propensity-score refitting, a robust approach that accounts for the uncertainty introduced by estimating the weights themselves. The researchers also assessed calendar-time confounding, the possibility that practice patterns changed over the study period, by restricting the analysis to the post-implementation era.

The results were striking. After stabilized IPTW adjustment, skin toxicity of any kind occurred in 46.2 percent of patients taking prophylactic desloratadine compared with 70.7 percent of those who took none. That translates to a risk difference of 24.6 percentage points, with a 95 percent confidence interval spanning from 43.0 to 5.3 percentage points below the untreated group, and a risk ratio of 0.65, meaning the treated patients faced roughly a 35 percent lower risk overall. When the toxicities were broken down by type, the picture became more nuanced. Pruritus showed the clearest benefit, with a descriptive risk ratio of 0.36, indicating itching was dramatically less common among antihistamine users. Rash appeared lower as well, with a risk ratio of 0.70, but the confidence interval of 0.43 to 1.03 just barely crossed the threshold of no effect, making that estimate imprecise. Hand-foot syndrome showed no benefit whatsoever, occurring at nearly identical rates in both groups, 5.9 percent versus 5.4 percent.

The team built in several safeguards against false positives. A negative-control analysis examined peripheral neuropathy, a nerve-damage side effect of docetaxel that desloratadine should not plausibly prevent. As expected, neuropathy rates were not lower in the treated group, with a risk ratio of 1.19, which strengthens the argument that the skin findings reflect a genuine pharmacological effect rather than some unmeasured difference between the groups. The post-implementation restricted analysis yielded similar results, with a risk ratio of 0.61, suggesting that shifts in prescribing habits over time did not manufacture the association.

Why might an antihistamine protect the skin but not the palms and soles? The answer likely lies in the differing biology of these toxicities. Pruritus and many rashes involve histamine signaling and H1-receptor-mediated inflammatory pathways, precisely the targets desloratadine was designed to hit. Hand-foot syndrome, by contrast, is generally attributed to direct toxic injury to the basal layers of the epidermis and to small blood vessels in high-friction areas, mechanisms that histamine blockade would not be expected to influence. The selective pattern of protection observed in the study is therefore biologically coherent, and it is exactly the kind of signal that lends credibility to observational findings.

The authors themselves are careful to frame the work as hypothesis-generating rather than practice-changing. Retrospective designs, even those bolstered by propensity-score methods, cannot rule out residual confounding from factors that were never recorded in the charts. The single-center setting raises questions about generalizability, and the modest sample size of 143 patients leaves several estimates, particularly for rash, statistically imprecise. Patient-reported outcomes, while valuable for capturing the subjective burden of itching and pain, introduce their own potential for reporting differences between groups. The researchers explicitly call for validation in a prospective randomized trial, the gold standard that would definitively establish whether desloratadine should join dexamethasone in the standard premedication toolkit.

Even with those caveats, the implications are considerable. Docetaxel is administered to hundreds of thousands of cancer patients worldwide each year, and dermatological adverse events are among the most common reasons patients dread their chemotherapy cycles. ESMO clinical practice guidelines on the prevention and management of anticancer-agent skin toxicities currently offer limited options for primary prevention. If a randomized trial confirms these results, the intervention would be remarkably accessible: desloratadine costs pennies per dose, is available without prescription in many countries, has a long track record of safety in allergic rhinitis and chronic urticaria, and requires nothing more than a daily tablet started the morning after the first infusion. In an era when cancer drug costs routinely soar into six figures, the prospect of a dollar-a-day antihistamine easing one of chemotherapy’s most visible burdens is a reminder that sometimes the most powerful advances in supportive care come not from new molecules, but from new uses for the medicines already sitting in the pharmacy.

Subject of Research: Prophylactic desloratadine use and docetaxel-induced skin toxicities in early-stage breast cancer

Article Title: Association between prophylactic desloratadine use and docetaxel-induced skin toxicities in patients with early-stage breast cancer: an inverse probability-weighted retrospective cohort study

Article References: Makihara, K., Kongo, K., Motomura, K., Kimoto, D., Abe, R., Matsumura, T., & Kawai, Y. (2026). Association between prophylactic desloratadine use and docetaxel-induced skin toxicities in patients with early-stage breast cancer: an inverse probability-weighted retrospective cohort study. Supportive Care in Cancer, 34(11), Article 1121. https://doi.org/10.1007/s00520-026-11387-2

Image Credits: AI Generated

DOI: 10.1007/s00520-026-11387-2

Keywords: docetaxel, desloratadine, breast cancer, skin toxicity, pruritus, hand-foot syndrome, antihistamine, chemotherapy, supportive care, IPTW, retrospective cohort study, pharmacology

The review’s central thesis is that atopic dermatitis itch emerges from a dynamic, bidirectional conversation between keratinocytes, the dominant cells of the epidermis, and the sensory neurons that innervate the skin. When the epithelial barrier breaks down, whether through genetic vulnerability, environmental insult, or the mechanical trauma of scratching, stressed keratinocytes release a cocktail of damage-induced mediators known as alarmins. Chief among these are thymic stromal lymphopoietin (TSLP), interleukin-33 (IL-33), and interleukin-25 (IL-25). These signals do not merely recruit immune cells; they act directly on cutaneous nerve fibers, activating or sensitizing them and thereby amplifying itch transmission. The result is a self-reinforcing itch-scratch-injury cycle in which each bout of scratching further damages the barrier, releases more pruritogens, and entrenches neural hypersensitivity.

TSLP has emerged as perhaps the clearest example of epithelial-to-neural signaling. This keratinocyte-derived cytokine signals through a receptor complex comprising the TSLP receptor and the IL-7 receptor alpha subunit, potently activating dendritic cells and skewing immunity toward a type 2 profile dominated by Th2 cells, mast cells, and natural killer T cells. Serum TSLP is significantly elevated in patients with atopic dermatitis and correlates with disease severity. Crucially, work by Wilson and colleagues showed that calcium-dependent ORAI1/NFAT signaling in keratinocytes regulates TSLP release, and that TSLP in turn directly activates TRPA1-positive sensory neurons to induce itch. The same epithelial-neuronal crosstalk operates in airway epithelial cells, suggesting a mechanistic bridge that may help explain the atopic march, the progression from eczema to asthma and allergic rhinitis.

IL-33 presents a more complicated picture. It induces type 2 cytokines including IL-4, IL-5, and IL-13, synergizes with IL-4 to drive production of IL-31, a key pruritogen, and enhances histamine-induced itch through mast cell activation and IL-13 release. Its receptor, ST2, is expressed on dorsal root ganglion neurons in both humans and mice, and IL-33 can sensitize these neurons to IL-4- and IL-13-mediated signaling. In the spinal cord, IL-33/ST2 signaling activates an astrocytic JAK2-STAT3 pathway that engages the gastrin-releasing peptide (GRP) axis, a canonical spinal itch circuit whose serum levels correlate with disease severity and itch intensity in patients. Yet the review is candid about the limits of the evidence: some studies found no correlation between circulating IL-33 and pruritus severity, and neuronal-restricted IL-33 receptor signaling proved dispensable for itch in an AD-like mouse model. Genetic variants in the IL33 gene have been linked to itch severity, hinting that predisposition modulates the pathway, but a direct causal role in human AD itch remains unproven.

The strongest clinical case belongs to the type 2 cytokines IL-4 and IL-13. Both can directly activate mouse and human sensory neurons, and IL-4 additionally sensitizes neurons to a broad range of pruritogens. Mechanistically, chronic itch requires neuronal IL-4Ralpha-JAK1 signaling: deleting IL-4Ralpha or JAK1 specifically in sensory neurons markedly reduces scratching in mice, and JAK inhibition relieves recalcitrant chronic itch in patients unresponsive to conventional immunosuppressants. Recent work with human dorsal root ganglion neurons showed that IL-4, IL-13, and IL-33 sensitize neurons to both histaminergic and non-histaminergic pruritogens within just two hours of exposure, with IL-4 and IL-13 inducing a shared, cytokine-specific transcriptional program distinct from that triggered by other inflammatory stimuli. Type 2 immunity, in other words, has been co-opted by the nervous system itself.

Interleukin-31 stands out as the most thoroughly validated cytokine linking immune activation to neuronal itch signaling. Produced mainly by Th2 cells but also by basophils, macrophages, and, as recent evidence shows, M2-polarized macrophages in lesional skin, IL-31 signals through a receptor complex of IL-31 receptor A and the oncostatin M receptor. In a restricted population of IL-31RA-positive, TRPV1-positive, TRPA1-positive sensory neurons, IL-31 triggers intracellular calcium release and ERK activation. It also induces rapid STAT3 activation in these neurons, and STAT3 transcriptionally upregulates the IL-31 receptor itself, creating a feed-forward loop that amplifies sensitivity. Beyond the periphery, IL-31 induces expression of B-type natriuretic peptide (BNP), encoded by the NPPB gene, which transmits itch signals through natriuretic peptide receptor A in the spinal cord, and promotes axonal elongation and branching in small-diameter sensory neurons, providing a mechanistic explanation for the increased cutaneous nerve fiber density seen in chronic disease. The clinically approved antibody nemolizumab targets this axis.

The review also highlights periostin, a matrix protein secreted by dermal fibroblasts downstream of type 2 inflammation, as a conserved pruritogen that induces itch across mice, dogs, and non-human primates. Periostin binds integrin alphavbeta3 on sensory neurons, triggering extracellular calcium influx and spontaneous firing in an itch-related, TRPV1- and TRPA1-dependent manner, with BNP as a key neuropeptide effector. Remarkably, periostin also reciprocally induces keratinocyte-derived TSLP through the JAK2-STAT3 pathway, closing a feed-forward epithelial-neuronal loop. Serum periostin levels are elevated in patients and correlate with disease severity, positioning it as an emerging therapeutic target.

Neurotrophic factors and neuropeptides add a structural dimension to the story. Nerve growth factor (NGF) is markedly elevated in the stratum corneum of lesional skin, correlating with itch severity, erythema, xerosis, eosinophil counts, and serum lactate dehydrogenase, and blocking NGF signaling ameliorates dermatitis and scratching in the NC/Nga mouse model. Substance P, classically acting through the neurokinin-1 receptor, drives neurogenic inflammation and correlates with itch intensity and even depression scores, but recent work shows it can also evoke non-histaminergic itch by activating MRGPRX2 on mast cells and MRGPRA1 on sensory neurons, and it has displayed paradoxically protective, barrier-restoring effects in some experimental settings. Calcitonin gene-related peptide (CGRP) promotes keratinocyte proliferation and epidermal thickening, with atopic keratinocytes showing heightened CGRP responsiveness and exaggerated hyperplasia. Artemin, a glial cell line-derived neurotrophic factor, is upregulated in lesional skin downstream of both the aryl hydrocarbon receptor, activated by organic components of air pollution, and toll-like receptor signaling triggered by house dust mite, linking environmental exposures directly to sensory nerve sprouting and warmth-provoked itch.

Woven through all of these pathways is the JAK-STAT signaling cascade, which the authors identify as the most clinically validated convergence point between immune cytokines and pruritus. Lesional skin from patients shows broad activation of phosphorylated JAK1-3 and STAT2/3 across epidermal and dermal compartments, and a spontaneous mouse model with an epidermal JAK1 gain-of-function mutation demonstrated that keratinocyte-intrinsic JAK1 hyperactivation alone is sufficient to drive barrier dysfunction, chronic inflammation, and pruritus. JAK1 is also enriched in pruriceptive neurons, where it mediates IL-4, IL-13, and IL-31 signaling, and electrophysiological studies suggest that JAK1-selective inhibitors such as upadacitinib can directly modulate cortical neuronal activity, hinting at central neuromodulatory effects beyond immune suppression.

The conceptual payoff of the review is a continuum model of chronic itch. It begins as peripherally driven, epithelial-mediated signaling, but repeated stimulation progressively sensitizes sensory neurons and broadens their responsiveness until itch becomes partially decoupled from peripheral cues and increasingly reflects structural and functional remodeling within itch-processing circuits. The finding that even non-lesional skin of patients exhibits heightened cowhage-induced itch underscores that altered sensory responsiveness is an intrinsic feature of the disease, not merely a byproduct of visible inflammation. The authors argue that early intervention to interrupt repetitive itch-scratch cycles, before central sensitization and neuronal remodeling become entrenched, may be essential to prevent long-term chronicity, treatment resistance, and the psychological comorbidities that so often shadow this disease.

Subject of Research: Neuroimmune mechanisms of chronic itch in atopic dermatitis

Article Title: Pruritogenic mediators in atopic dermatitis: mechanisms of neurogenic crosstalk

Article References: Wong, L.-S., Yang, J.-H., Yen, Y.-T., & Yang, J.-L. (2026). Pruritogenic mediators in atopic dermatitis: mechanisms of neurogenic crosstalk. Journal of Cutaneous Immunology and Allergy, 9, Article 16460. https://doi.org/10.3389/jcia.2026.16460

Image Credits: AI Generated

DOI: 10.3389/jcia.2026.16460

Keywords: atopic dermatitis, chronic itch, pruritus, keratinocytes, sensory neurons, TSLP, IL-31, IL-4, IL-13, JAK-STAT signaling, neuropeptides, neuroimmune crosstalk

The research, led by Carollina Mariga and colleagues at the Federal University of Santa Maria in Rio Grande do Sul, Brazil, set out to answer two questions at once: whether adjunctive Cannabis oil could improve control of recurrent clinical signs in dogs whose oclacitinib treatment had been unsatisfactory, and whether the cannabinoid supplement could allow a structured reduction of the conventional drug without clinical relapse. Sixteen dogs with a confirmed diagnosis of atopic dermatitis were enrolled, each previously treated with oclacitinib without satisfactory improvement. Food allergy had been excluded through an 8-to-12-week hypoallergenic elimination diet, and flea bite dermatitis was ruled out, following established diagnostic criteria.

The study design was a prospective, placebo-controlled, repeated-measures protocol in which every dog moved through the same fixed sequence of four stages. At T0, the animals received oclacitinib alone at individualized doses ranging from 0.2 to 1.1 mg/kg once daily, deliberately adjusted to leave a clinically detectable level of pruritus so that owners could perceive any treatment-related change. During the next 30 days, T30, the dogs received an oral placebo of mineral oil — tinted with artificial yellow food coloring to mimic the appearance of Cannabis oil — alongside full-dose oclacitinib. At T60, the placebo was replaced by Cannabis oil delivering 2.0 mg/kg of cannabidiol twice daily, still combined with full-dose oclacitinib. Finally, at T90, the cannabinoid oil was maintained while the oclacitinib dose was reduced by 50 percent. Because each animal served as its own control across all phases, the design reduced the interindividual biological variability that plagues cannabinoid research, where endocannabinoid tone differs markedly between individuals and tissues.

Assessment relied on two blinded instruments. A veterinary dermatologist scored skin lesions using the Canine Atopic Dermatitis Extent and Severity Index, CADESI-4, adapted to include the ventral cervical region, while owners rated itching on a simple zero-to-five behavioral scale at every visit. Crucially, both the dermatologist and the owners were unaware of whether the animal was receiving placebo or Cannabis oil at any given phase, and the dermatologist was not informed of the study design or treatment sequence. Fourteen of the sixteen dogs completed all stages through T90; two were withdrawn before the final month because of deep secondary skin infections requiring systemic therapy, diagnosed clinically and by cytology.

The statistical picture was nuanced. CADESI-4 scores, analyzed with generalized linear mixed models, showed no statistically significant effect of time, with estimated marginal means of 4.65 at baseline, 5.13 during placebo, 2.74 during Cannabis treatment, and 3.59 after the oclacitinib reduction. The primary planned contrast between the placebo and Cannabis phases did not reach significance, and after Holm adjustment no pairwise comparison was significant. Pruritus, however, told a different story. A cumulative link mixed model accounting for the ordinal nature of the itch scale and the repeated measurements found a significant effect of time, with mean scores falling from 3.44 at baseline to 3.00 during placebo, 2.31 during Cannabis treatment, and 2.42 after the dose reduction. The direct placebo-versus-Cannabis comparison again fell short of significance, but the comparisons against baseline were striking: itch odds were significantly lower at T60 (p = 0.0013) and at T90 (p = 0.0065) than at T0, indicating lower cumulative odds of being in higher pruritus categories once cannabinoid therapy began.

Perhaps the most clinically intriguing finding emerged at the end of the protocol. When Cannabis oil was interrupted after T90 while the dogs remained on half their original oclacitinib dose, nine of the fourteen animals resumed scratching within a week — four on the second day, two on the third, one on the fourth, and two on the seventh. The remaining five dogs stayed stable for the full seven days without cannabinoid supplementation. Nine owners, or 56.25 percent, chose to continue Cannabis treatment after the study concluded. Together with the maintained pruritus scores during the 50 percent oclacitinib taper, these observations support the hypothesis that adjunctive cannabinoids may exert a drug-sparing effect, allowing meaningful dose reductions of an expensive targeted therapy without loss of itch control.

The biological plausibility of an antipruritic effect rests on the endocannabinoid system, a homeostatic regulator expressed throughout the layers of the skin and in immune cells. Cannabinoid receptor type 1 and type 2 expression is increased in the skin cells of atopic dogs, and experimental work in genetically modified mice shows that deleting CB1 receptors in primary sensory neurons exacerbates inflammation and pruritus, promoting substance P production and mast cell accumulation in the dermis, while CB2 deletion worsens psoriasiform dermatitis and itch. Cannabidiol itself demonstrates broad immunosuppressive potential by downregulating the Janus kinase/signal transducer and activator of transcription pathway — the very pathway oclacitinib targets — and inhibiting key activating cytokines including interleukin-6, interleukin-2, interferon-gamma, and tumor necrosis factor, while also disrupting interconnected cascades such as PI3K-Akt and MAPK.

The formulation used was a full-spectrum, CBD-rich oil containing 73.7 percent CBD by relative proportion of total cannabinoid mass, along with 2.11 percent delta-9-tetrahydrocannabinol, 2.05 percent cannabichromene, 1.85 percent cannabigerol, and smaller amounts of cannabidivarin, cannabigerolic acid, and cannabinol, plus terpenes such as caryophyllene, humulene, nerolidol, guaiol, and bisabolol. The authors argue that this chemical complexity — the so-called entourage effect — may enable multitarget action on inflammatory pathways including MAPK, NF-kB, the NLRP3 inflammasome, and JAK1/STAT6 signaling in skin cells. In vitro studies suggest that cannabichromene downregulates master inflammatory signaling by inhibiting NF-kB and MAPK and suppressing TNF-alpha, interleukin-1 beta, and inducible nitric oxide synthase, while cannabigerol provides immunomodulation through CB2 receptor engagement, PPAR-gamma and Nrf2 activation, and direct inhibition of COX-1, COX-2, and iNOS. The oil underwent laboratory analysis confirming its cannabinoid and terpene profile and the absence of contaminants such as heavy metals, mycotoxins, pesticides, and solvent residues.

The results align closely with a prior prospective, randomized, double-blinded, placebo-controlled study by Loewinger and colleagues, in which 32 atopic dogs treated with a CBD/CBDA mixture showed a significant reduction in pruritus that nonetheless failed to reach significance against placebo, and no improvement in CADESI-4 lesion scores. A retrospective report by Mogi and colleagues, in contrast, described improvements in both itch and lesions in eight dogs treated with CBD-rich oil, though without a control group and with gradually escalating doses. The authors also note that their cohort presented with considerably lower baseline lesion scores than in their own earlier pre-study, reflecting a deliberate choice to include dogs across the full clinical spectrum seen in routine practice — a decision that may have reduced the sensitivity of CADESI-4 to detect treatment-related improvement, since several animals had low or null baseline scores.

Safety findings were reassuring but instructive. During the placebo month, 62.5 percent of dogs experienced at least one adverse clinical sign, including drowsiness, soft stools, and vomiting; during the Cannabis introduction month, 68.75 percent did, with drowsiness the most frequent complaint; and during the final maintenance month, 35.71 percent. All episodes were mild, transient, and self-limiting. Notably, roughly one in five animals reported drowsiness, vomiting, or soft stools even while receiving only mineral oil and food coloring — a pattern the authors attribute at least partly to the caregiver placebo effect, in which owners attribute expected adverse effects to treatment after being informed of study procedures, though spontaneous gastrointestinal signs or effects of the placebo formulation itself remain possible. No relevant behavioral alterations were identified during cannabinoid therapy, consistent with previous work showing that CBD administration does not affect daily voluntary activity in healthy dogs.

The authors are candid about the limitations. The sequential design confounds treatment with time, so observed changes cannot be cleanly separated from natural disease fluctuations, regression to the mean, or observer expectation bias. Pruritus was measured with a simple owner-reported scale rather than the validated Pruritus Visual Analog Scale, the sample was small, and seasonal variation in pruritus was not formally investigated. The CBD-rich formulation, constrained by Brazilian regulations limiting THC content in marketed products to 0.3 percent, prevents evaluation of the potential contribution of higher THC levels and other minor cannabinoids. Still, the study is, to the authors’ knowledge, the first to report the combination of Cannabis oil and oclacitinib in dogs with atopic dermatitis and to provide preliminary observations of a potential oclacitinib-sparing effect. The findings do not support recommending Cannabis as a first-line treatment, but they raise an exploratory hypothesis that earlier introduction of cannabinoid therapy may offer clinical benefits before chronic inflammatory changes become fully established — a question that now demands randomized controlled trials to establish the specific contribution of Cannabis oil to clinical improvement and to consolidate its place in multimodal therapy for this lifelong disease.

Subject of Research: Clinical observations during adjunctive Cannabis treatment and subsequent oclacitinib dose reduction in dogs with atopic dermatitis

Article Title: Clinical observations during adjunctive Cannabis treatment and subsequent oclacitinib dose reduction in dogs with atopic dermatitis

Article References: Mariga, C., Silva, F. C. D., Schiefler, O. H. D. M., Amazonas, E., Mateus, A. L. S. S., Schmidt, C., & Filho, S. T. L. P. (2026). Clinical observations during adjunctive Cannabis treatment and subsequent oclacitinib dose reduction in dogs with atopic dermatitis. Frontiers in Allergy, 7, Article 1852631. https://doi.org/10.3389/falgy.2026.1852631

Image Credits: AI Generated

DOI: 10.3389/falgy.2026.1852631

Keywords: canine atopic dermatitis, cannabidiol, oclacitinib, endocannabinoid system, veterinary dermatology, pruritus, cannabis oil, multimodal therapy, CADESI-4, drug-sparing effect, Clinical, observations

The study, conducted by dermatologist Yesim Akpinar Kara of Ankara Training and Research Hospital and psychiatrist Bilge Bilgin Kapucu, enrolled a modest sample: nineteen patients with lichen simplex chronicus and seventeen with chronic idiopathic pruritus, all recruited from a dermatology outpatient clinic. The diagnosis of chronic idiopathic pruritus was made only after excluding systemic illness and identifiable skin disease, while lichen simplex chronicus was diagnosed on clinical grounds and confirmed by skin biopsy of lesional tissue. That biopsy confirmation matters, because it anchors the psychiatric findings to a dermatologically verified condition rather than a loose clinical impression.

To measure the sensation that dominates these patients’ lives, the researchers used the visual analog scale, a simple instrument in which patients rate itch intensity on a continuum. To probe the psychological landscape, they administered two well-established psychiatric instruments: the Brief Psychiatric Rating Scale, a clinician-rated measure of general psychiatric symptomatology developed originally in 1962, and the Automatic Thoughts Questionnaire, a self-report tool rooted in Aaron Beck’s cognitive model of emotional disorders. The questionnaire, developed by Hollon and Kendall in 1980 and validated in Turkish by Şahin and Şahin in 1992, quantifies the frequency of negative automatic thoughts — the self-critical, pessimistic, and catastrophic cognitions that cognitive theory holds to be central in depression and anxiety.

The headline finding is striking precisely because the itch itself was not the differentiator. On the visual analog scale, the two groups were statistically indistinguishable: mean scores were 6.53 for the lichen simplex chronicus group and 6.58 for the chronic idiopathic pruritus group, a difference that failed to reach significance in Kruskal–Wallis testing (p = 0.746). In other words, both groups were suffering from itch of comparable, and considerable, severity — well above the midpoint of the scale. Yet when the researchers turned to the Automatic Thoughts Questionnaire, the groups diverged sharply. Total scores were significantly higher in the lichen simplex chronicus group than in the idiopathic pruritus group (p = 0.011).

That asymmetry — identical itch, different minds — is what makes the study conceptually interesting. Lichen simplex chronicus is, at its core, a scratch-itch cycle made flesh: repeated mechanical trauma to the skin triggers lichenification, the thickened, leathery change that in turn lowers the threshold for further itching and scratching. If patients with this condition carry a heavier load of negative automatic thoughts than patients whose itch has no visible target, it raises the possibility that certain cognitive patterns — rumination, catastrophizing, obsessive attention to bodily sensations — may fuel the compulsive scratching that creates and maintains the lesions. The authors suggest that incorporating psychiatric assessment, particularly evaluation of negative automatic thoughts with the Automatic Thoughts Questionnaire, may be beneficial in clinical management, especially for patients with lichen simplex chronicus.

The psychiatric symptom profiles added further texture. Clinically relevant anxiety and depressive symptoms were observed in both groups, confirming that chronic itch of either type travels in the company of meaningful psychological burden. Previous literature has long hinted at this: studies have documented obsessive-compulsive features and reduced quality of life in lichen simplex chronicus patients, elevated stress and neurotrophin levels in the same population, and heightened anxiety and depression across allergic and non-allergic skin disorders. Population-based work from Norway has linked itch with stress and diminished self-efficacy in adolescents, while studies in psoriasis have tied itch frequency to coping strategies and quality of life. The new findings fit squarely into this tradition but add a specific cognitive variable that most earlier studies did not measure.

Equally notable is what the study did not find. No significant correlation emerged between visual analog scale itch scores and psychiatric symptoms, meaning that how badly a patient itched did not predict how anxious or depressed they were, nor how severe their automatic thoughts were. This decoupling of sensation intensity from psychological distress echoes a recurring theme in psychodermatology: the subjective intensity of a symptom and its psychological consequences are related but separable dimensions. A patient scratching a 6.5 out of 10 itch may be coping well or may be trapped in a spiral of negative thinking, and the itch score alone cannot tell a clinician which.

The study’s limitations are real and the authors are candid in framing the work as preliminary. Thirty-six patients is a small sample, and the statistical comparisons relied on non-parametric testing appropriate to that size, but small samples limit generalizability and statistical power. The cross-sectional design cannot establish direction: do negative automatic thoughts drive scratching and lichenification, or does the visible, disfiguring plaque of lichen simplex chronicus generate shame, rumination, and negative self-talk? Both pathways are plausible, and they are not mutually exclusive — a feedback loop in which cognition and skin reinforce each other would be consistent with everything known about the condition. The absence of a healthy control group also means the study can compare the two itch disorders to each other but cannot say whether either group’s automatic thought burden exceeds that of the general population, although prior work on personality differences in lichen simplex chronicus patients suggests it plausibly does.

Why should the broader scientific readership care? Because chronic itch is a global problem with an enormous unmet therapeutic need. Uremic pruritus in dialysis patients, for example, remains a major burden in end-stage renal disease despite decades of attention, and the International Forum for the Study of Itch has had to construct an entire clinical classification system simply to organize the many forms chronic itch takes. Antihistamines, the lay public’s default remedy, work poorly for most chronic itch, and the pipeline of targeted neuromodulatory therapies is still maturing. If cognitive variables such as automatic thoughts meaningfully stratify patients — identifying, say, the lichen simplex chronicus patient whose scratching is cognitively driven — that opens the door to targeted adjunctive treatments. Cognitive behavioral therapy, which directly targets automatic thoughts, has already shown benefit in conditions as varied as irritable bowel syndrome and rheumatoid arthritis, where negative cognitions amplify symptom burden; itch could plausibly join that list.

The practical message for clinicians is deceptively simple. A dermatologist seeing thickened, scratched skin should consider that the patient’s mental life may be part of the pathology, and a brief questionnaire — thirty items, a few minutes of a patient’s time — may reveal a treatable dimension that a prescription cream will never touch. Conversely, the study reminds psychiatrists that somatic complaints like chronic itch can be the presenting face of anxiety and depression. The authors’ preliminary report does not settle the question of causality, and its sample size forbids sweeping conclusions. But it does something valuable: it takes a familiar clinical observation — that the worst itch often belongs to patients who scratch hardest and think darkest — and gives it a number, a scale, and a p-value. In a field where the skin and the mind have long been treated as separate territories, that is a small but genuine step toward medicine that treats the patient as a single, connected system.

Subject of Research: The relationship between itch severity, negative automatic thoughts, and psychiatric symptoms in lichen simplex chronicus and chronic idiopathic pruritus

Article Title: Evaluation of Itch severity and automatic thoughts in patients with Lichen Simplex Chronicus and Chronic Idiopathic Pruritus: a preliminary report

Article References: Kara, Y. A., & Kapucu, B. B. (2026). Evaluation of Itch severity and automatic thoughts in patients with Lichen Simplex Chronicus and Chronic Idiopathic Pruritus: a preliminary report. Archives of Dermatological Research, 318(1), Article 439. https://doi.org/10.1007/s00403-026-04892-1

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04892-1

Keywords: chronic itch, pruritus, lichen simplex chronicus, chronic idiopathic pruritus, automatic thoughts, psychodermatology, anxiety, depression, visual analog scale, cognitive behavioral therapy, dermatology, psychiatry