Hepatocellular carcinoma is one of the deadliest cancers worldwide, and its rise is closely tied to chronic liver injury, cirrhosis, and persistent oxidative damage. Because diagnosis often comes late and treatment options are limited, scientists have long been interested in chemoprevention, the idea that compounds taken before disease develops can interrupt the earliest steps of tumor formation. Curcumin has attracted decades of attention for its anti-inflammatory and antioxidant behavior, but it suffers from notoriously poor absorption in the gut. Piperine has a well-documented ability to boost the bioavailability of curcumin, which is why the two are so frequently paired in both traditional cuisine and modern experimental design. The new study set out to test whether that pairing could do more than improve uptake, and whether it could measurably alter the biology of a developing liver tumor.

To model the disease, the researchers induced hepatocellular carcinoma in rats using a two-hit protocol that mirrors how human liver cancer often arises from accumulated toxic insults. Animals first received diethylnitrosamine, or DEN, a potent carcinogen that damages DNA and initiates malignant transformation in hepatocytes. This was followed by thioacetamide, or TAA, a compound that produces repeated cycles of liver injury, fibrosis, and regeneration, creating the inflamed, scarred environment in which initiated cells can proliferate into full tumors. The regimen ran for twenty weeks, a period long enough for tumor burden to become established and measurable. Alongside this carcinogenic exposure, separate groups of rats received oral pretreatment with curcumin alone, piperine alone, or the two compounds in combination, given throughout the entire experimental period.

The damage in the untreated carcinogen group was exactly what the model predicts. Rats exposed to DEN and TAA showed increased tumor burden, sharply elevated liver enzymes in the serum, and a biochemical signature of a liver under siege. Lipid peroxidation, the oxidative degradation of cell membranes, climbed as reactive oxygen species overwhelmed the tissue. The liver’s own antioxidant defenses, the enzymatic systems that normally neutralize free radicals, were depleted. Alpha-fetoprotein, a classic tumor marker for hepatocellular carcinoma, rose in the bloodstream, and interleukin-6, a pro-inflammatory signaling molecule implicated in cancer-promoting chronic inflammation, was elevated as well. Under the microscope, the liver architecture was severely distorted, with the organized lobular structure of healthy tissue replaced by the disarray of injury and nodular transformation.

The treatment groups told a strikingly different story. Rats that received curcumin, and to a greater extent those that received curcumin and piperine together, showed improved levels of the key serum biomarkers, better antioxidant status, and reduced lipid peroxidation. Histopathological examination revealed that the normal tissue structure was substantially restored rather than progressively destroyed. In practical terms, the compounds did not merely mask the damage in blood tests; the livers themselves looked measurably healthier. The combination regimen emerged as the most effective intervention, consistent with the idea that piperine’s enhancement of curcumin’s bioavailability translates into a stronger biological effect when the two are administered together.

The mechanistic heart of the paper lies in what the team found when they probed the TBP2–ASK1–JNK–caspase-3 axis in liver tissue. This signaling cascade begins with TBP2, a thioredoxin-binding protein that responds to oxidative stress, and passes through ASK1, a mitogen-activated protein kinase kinase kinase also known as MAP3K5, which becomes activated when its inhibitory thioredoxin partner is oxidized and released. Activated ASK1 phosphorylates downstream JNK, the c-Jun N-terminal kinase, which in turn influences the mitochondrial pathway of apoptosis, ultimately engaging caspase-3, the executioner enzyme that dismantles the cell. In the carcinogen-exposed rats, this axis was dysregulated, a disruption that matters because the balance of this pathway determines whether damaged cells are eliminated by programmed cell death or allowed to survive and accumulate the mutations that drive cancer.

Preventive treatment with curcumin and piperine normalized the expression of the proteins in this cascade, restoring a pattern of cellular signaling and apoptosis closer to that of healthy liver tissue. The authors interpret this as evidence that the chemopreventive effect of the compounds is not a vague antioxidant blanket but a targeted modulation of a defined stress-response pathway. By damping the oxidative stress that activates ASK1 and rebalancing the apoptotic machinery downstream, the treatment appears to preserve the liver’s ability to clear damaged cells while reducing the inflammatory and peroxidative conditions that fuel tumor growth. Immunohistochemistry and Western blotting provided complementary confirmation, mapping where in the tissue the protein changes occurred and quantifying their abundance.

The study was conducted with formal ethical oversight, approved by the Institutional Animal Ethics Committee of Jamia Hamdard under the guidelines of India’s Committee for the Purpose of Control and Supervision of Experiments on Animals, and the work followed ARRIVE reporting standards for animal research. Data were analyzed by one-way analysis of variance followed by Tukey’s post hoc test, with results considered statistically significant at a threshold of p less than 0.05. The authors received no external funding for the study, and the first author was supported by a Junior Research Fellowship from the University Grants Commission. The article was published open access on 9 October 2026, making the full dataset and methods available to researchers anywhere without a subscription.

As with any animal study, the usual caveats apply. A rat model of chemically induced liver cancer, however well constructed, does not reproduce every feature of human hepatocellular carcinoma, which typically develops over decades against a backdrop of viral hepatitis, alcohol-related injury, or metabolic dysfunction. Doses used in laboratory animals often exceed what a person could reasonably obtain from diet alone, and curcumin’s low bioavailability remains a genuine obstacle to clinical translation even when piperine is present. The authors are careful to frame the findings as chemopreventive and hepatoprotective effects observed in an experimental model, associated with modulation of the TBP2–ASK1–JNK–caspase-3 axis, rather than as a demonstrated therapy for established human tumors.

Nevertheless, the study adds a meaningful piece to a growing body of evidence that dietary bioactive compounds can act on specific, measurable molecular targets rather than exerting only diffuse antioxidant effects. If the TBP2–ASK1–JNK–caspase-3 axis proves to be similarly dysregulated in human liver disease, the curcumin–piperine combination, or optimized derivatives of it, could become candidates for controlled trials aimed at preventing the progression of chronic liver injury toward cancer. For now, the image is an appealing one: two molecules that have traveled together through human kitchens for centuries, shown under the strict lens of modern molecular biology to coordinate a defense of the liver’s most vulnerable signaling machinery. The next step will be determining whether that defense survives the journey from the rat liver to the clinic.

Subject of Research: Chemoprevention of hepatocellular carcinoma by curcumin and piperine through modulation of the TBP2–ASK1–JNK–caspase-3 axis in rats

Article Title: Curcumin and piperine modulate the TBP2-ASK1-JNK-caspase-3 axis associated with prevention of DEN and TAA-induced hepatocellular carcinoma in rats

Article References: Afroz, N., Vafa, A., Ghosh, R., Rahaman, P. F., Wajid, S., & Ahmad, A. (2026). Curcumin and piperine modulate the TBP2-ASK1-JNK-caspase-3 axis associated with prevention of DEN and TAA-induced hepatocellular carcinoma in rats. BMC Cancer. https://doi.org/10.1186/s12885-026-17037-4

Image Credits: AI Generated

DOI: 10.1186/s12885-026-17037-4

Keywords: curcumin, piperine, hepatocellular carcinoma, chemoprevention, liver cancer, oxidative stress, ASK1, JNK, caspase-3, apoptosis, diethylnitrosamine, thioacetamide

Mitogen-activated protein kinases, or MAPKs, are a family of signaling enzymes that operate inside virtually every cell of the body. When a cell receives an external cue, such as a stress signal, a cytokine, or an antigen encounter, these kinases relay the message from the cell surface to the nucleus by a chain reaction of phosphorylation events. The family includes three major branches: p38, which is strongly associated with inflammation and cellular stress responses; extracellular signal-regulated kinase (ERK), which typically drives proliferation and differentiation; and c-Jun N-terminal kinase (JNK), which responds to stress and can trigger programmed cell death. Because immune cells rely heavily on these cascades to orchestrate their activation and effector functions, researchers have long suspected that MAPK signaling might be disturbed in autoimmune diseases, including those affecting the peripheral nerves.

The Belgrade team, led by Marina Stamenkovic and Irena Vukovic as co-first authors under the supervision of Vladimir Trajkovic and Verica Paunovic, went beyond the MAPK family to examine a broader metabolic network. They also measured the activity of AMP-activated protein kinase (AMPK), an intracellular energy sensor that switches cells into conservation mode when fuel is scarce, and mechanistic target of rapamycin complex 1 (mTORC1), the master growth regulator that AMPK antagonizes. Together, these pathways govern autophagy, the cellular recycling process by which cells digest their own damaged components. Autophagy has emerged in recent years as a critical regulator of immune cell behavior, and earlier work by some of the same investigators had linked reduced AMPK signaling in blood mononuclear cells to the severity of Guillain-Barré syndrome, another immune-mediated neuropathy.

To test whether these pathways are altered in chronic immune neuropathies, the researchers collected peripheral blood mononuclear cells, the mixed population of lymphocytes and monocytes that circulates in the bloodstream, from 17 patients with CIDP who had not yet received any immunotherapy, and from 7 patients with MMN who were already on chronic maintenance therapy with intravenous immunoglobulin (IVIg). They compared these samples with cells from age- and sex-matched healthy controls, using immunoblotting, a laboratory technique that separates proteins by molecular weight and detects them with specific antibodies, to quantify the phosphorylated, active forms of the signaling enzymes as well as markers of autophagy flux.

The results were strikingly selective. In both CIDP and MMN patients, the levels of phosphorylated, active p38 MAPK in circulating mononuclear cells were significantly higher than in healthy controls. In contrast, the activity of ERK and JNK, the other two MAPK branches, was not significantly altered, and neither were the AMPK/mTORC1 metabolic axis nor the autophagy markers. This specificity matters because it suggests that p38 activation is not a nonspecific consequence of chronic illness or inflammation but a distinctive feature shared by these two related yet clinically distinct neuropathies. The finding also aligns with earlier animal studies in which p38 and other MAPKs were found to be activated in the sciatic nerves of rats with experimental autoimmune neuritis, the laboratory model of human immune-mediated demyelinating neuropathy.

Perhaps the most intriguing clinical correlation emerged from the MMN group. The amount of p38 MAPK protein in patients’ blood cells was negatively correlated with their muscle strength, meaning that patients with more of this kinase in their leukocytes tended to have weaker muscles. Notably, this correlation was absent in CIDP, hinting that p38 may track disease activity differently in the two conditions. MMN is characterized by purely motor deficits, often beginning in the hands, and muscle strength is the principal measure by which clinicians judge disease progression and treatment response. A blood-based molecular correlate of strength, if confirmed, could eventually complement the clinical scales and electrophysiological tests currently used to monitor these patients.

The therapeutic dimension of the study came from comparing patients before and after IVIg treatment. Intravenous immunoglobulin is a pooled preparation of antibodies harvested from thousands of healthy donors, and it is a mainstay of therapy for both CIDP and MMN, though the two diseases differ in their longer-term management. Among nine CIDP patients who received IVIg, the treatment did not change the phosphorylation status of AMPK, any of the MAPKs, or the autophagy markers in their blood cells. Among six MMN patients, however, IVIg produced a measurable biochemical effect: it reduced the phosphorylation of p38 MAPK, ERK, and AMPK in their mononuclear cells. Crucially, the magnitude of the drop in phospho-p38 levels correlated with the improvement in hand grip strength, directly linking a molecular change in circulating immune cells to a functional clinical outcome.

These divergent responses raise fascinating questions about how IVIg works and why the same therapy might engage different mechanisms in different diseases. Previous research has shown that IVIg can suppress inflammatory signaling in monocytes, including NF-κB and p38 MAPK activation driven by tumor necrosis factor-alpha, and can induce autophagy in peripheral blood mononuclear cells. The new findings are consistent with the idea that in MMN, IVIg dampens a p38-centered inflammatory program in leukocytes, and that this immunological cooling accompanies, and may contribute to, the recovery of motor function. In CIDP, by contrast, the lack of detectable signaling change suggests either that IVIg acts through mechanisms not captured by these particular readouts, or that the relevant immune events occur in tissue-resident cells rather than in the circulating pool sampled by the researchers.

The authors are careful to frame the study as exploratory, and the limitations are real. The patient cohorts are small, particularly the MMN group, and the CIDP patients were treatment-naïve while the MMN patients were already on therapy, an asymmetry that complicates direct comparison between the diseases. Immunoblotting of bulk mononuclear cells also averages signals across heterogeneous cell populations, so the p38 elevation could reflect changes in a specific subset of lymphocytes or monocytes rather than a uniform shift. Nevertheless, the correlation between phospho-p38 reduction and grip strength improvement in MMN provides a concrete, testable hypothesis for future studies with larger cohorts and longitudinal sampling.

The findings also carry translational promise. Pharmacological inhibitors of p38 MAPK have been developed for decades, and one such inhibitor, losmapimod, recently showed encouraging results in a phase 2b trial for facioscapulohumeral muscular dystrophy, demonstrating that p38 blockade can be pursued safely in neuromuscular disease. The safety concerns that have historically shadowed p38 inhibitors, including effects on liver function and stress responses, remain relevant, but a circulating biomarker that identifies which patients are most likely to benefit could transform trial design. For now, the study’s central message is that a single stress-activated kinase in blood cells may serve as both a window into disease activity and a readout of therapeutic response in multifocal motor neuropathy, offering researchers a molecular thread to follow in the search for more precise treatments for these rare, disabling conditions.

Subject of Research: The role of leukocyte p38 MAP kinase signaling in immune-mediated peripheral polyneuropathies and its modulation by intravenous immunoglobulin therapy

Article Title: The role of leukocyte p38 MAP kinase in immune-mediated peripheral polyneuropathies: distinct modulation by intravenous immunoglobulins

Article References: Stamenkovic, M., Vukovic, I., Milosevic, E., Peric, S., Paunic, A., Anicin, A., Basta, I., Bozovic, I., Palibrk, A., Ivanovic, V., Trajkovic, V., & Paunovic, V. (2026). The role of leukocyte p38 MAP kinase in immune-mediated peripheral polyneuropathies: distinct modulation by intravenous immunoglobulins. Journal of Neurology, 273(10), Article 627. https://doi.org/10.1007/s00415-026-14106-3

Image Credits: AI Generated

DOI: 10.1007/s00415-026-14106-3

Keywords: p38 MAPK, CIDP, multifocal motor neuropathy, intravenous immunoglobulin, peripheral neuropathy, immune cell signaling, AMPK, mTORC1, autophagy, ERK, JNK, biomarker

The compound in question is tetramethylpyrazine, or TMP, the principal active component of Ligusticum chuanxiong, an herb long used in Chinese medicine. TMP is a small, highly symmetric pyrazine ring decorated with four methyl groups, giving it a molecular weight of just 136.20 grams per mole and a moderate lipophilicity that theoretically favors membrane permeability. Crucially, it can cross the blood-brain barrier, in part by downregulating a microRNA called miR-297c-5p, which stabilizes the tight junction protein occludin and improves barrier integrity. Its oral bioavailability, however, is limited by first-pass metabolism and rapid clearance, a hurdle that any clinical translation will need to address through new formulations.

The review, conducted under PRISMA guidelines with searches of PubMed, Web of Science, and Google Scholar through December 2025, screened 132 articles and ultimately included 69. Its central thesis is that TMP acts as what the authors call a pathway crosstalk modulator, activating the Nrf2/ARE antioxidant axis while suppressing the JNK/AP-1 inflammatory axis. Because these two pathways are physically connected through shared molecular nodes, a single compound that tilts both in the right direction could, in principle, interrupt the ferroptosis-inflammation feedback loop that drives permanent neurological deficits.

Ferroptosis itself is a relatively recent addition to the cell death lexicon. Unlike apoptosis, it is iron-dependent and non-apoptotic, characterized by the runaway accumulation of lipid peroxides and the inactivation of glutathione peroxidase 4, or GPX4. After spinal cord injury, hemorrhage floods the lesion with free iron, which catalyzes the Fenton reaction and generates hydroxyl radicals that attack the polyunsaturated fatty acids in neuronal and oligodendrocyte membranes. As cells rupture, they release damage-associated molecular patterns such as HMGB1 and ATP, which activate microglia and infiltrating macrophages. These immune cells then pump out tumor necrosis factor-alpha and interleukin-1 beta, along with reactive oxygen species that further fuel lipid peroxidation, closing the loop.

The Nrf2 pathway is the cell’s first line of defense against exactly this kind of oxidative catastrophe. Under resting conditions, the adaptor protein Keap1 escorts Nrf2 to the proteasome for degradation, keeping the transcription factor scarce. When oxidative stress modifies key cysteine residues on Keap1, Nrf2 escapes destruction, translocates to the nucleus, binds antioxidant response elements, and switches on a battery of protective genes. The review emphasizes that Nrf2 is not merely a general antioxidant switch; it directly regulates the ferroptosis machinery itself, upregulating xCT to import cystine for glutathione synthesis, GPX4 to clear lipid peroxides, ferritin heavy chain 1 to sequester free iron, and simultaneously suppressing the pro-ferroptotic enzyme ACSL4. Genetic evidence underscores the point: Nrf2 knockout mice suffer larger lesions and worse neurological deficits after spinal cord injury.

The JNK pathway, by contrast, is the villain of the piece. A member of the MAPK kinase family, JNK is activated by dual phosphorylation from MKK4 and MKK7, which are themselves triggered by oxidative stress through the kinase ASK1 or by inflammatory cytokines. Once active, JNK phosphorylates c-Jun, energizing the AP-1 transcription factor complex, which drives expression of TNF-alpha, IL-1 beta, IL-6, COX-2, and inducible nitric oxide synthase. This pushes microglia toward the pro-inflammatory M1 phenotype and amplifies the inflammatory cascade. JNK also promotes apoptosis by activating Bax and upregulating Fas ligand, and emerging evidence suggests it worsens ferroptosis by inducing mitochondrial dysfunction and suppressing antioxidant enzymes, creating the ROS-rich environment in which lipid peroxidation thrives.

The review proposes that TMP intervenes on both arms through several mechanisms. On the Nrf2 side, its electron-rich pyrazine ring may mimic alpha,beta-unsaturated ketones and undergo Michael addition reactions with cysteine residues such as Cys151 and Cys273 on Keap1, destabilizing the Keap1-Cullin3 ubiquitin ligase complex and freeing Nrf2. TMP may also activate upstream kinases like PI3K/Akt and PKC, and it upregulates the autophagy adaptor p62, which competitively binds Keap1. On the JNK side, TMP’s direct radical-scavenging capacity prevents reactive oxygen species from prying thioredoxin away from ASK1, keeping the JNK cascade in check. Because Nrf2 transcriptionally upregulates thioredoxin-1, which itself inhibits ASK1, activating Nrf2 creates a positive feedback loop that further suppresses JNK, a molecular ratchet that favors protection over inflammation.

What distinguishes this review from earlier work is its spatiotemporal framing. Ferroptosis peaks rapidly, within roughly six hours of injury, while neuroinflammation rises later, beginning around 12 to 24 hours and peaking between days three and seven. The authors therefore propose a time-sequential dual regulation strategy: in the acute phase, TMP’s Nrf2 activation should dominate, blocking lipid peroxidation and preserving vulnerable neurons and oligodendrocytes; in the subacute to chronic phase, JNK inhibition should take precedence, curbing cytokine release, limiting M1 microglial polarization, and softening glial scar formation. In this framing, TMP transforms the injury microenvironment from a cytotoxic battlefield into a niche permissive for axonal sparing, remyelination, and eventual motor recovery, a shift from antioxidant damage control toward active regenerative repair.

The evidence base is not purely theoretical. A systematic review and meta-analysis has confirmed that TMP improves motor function recovery in rat models of spinal cord injury, and animal studies show reduced glial scar formation and preserved residual white matter tracts even in incomplete injuries. TMP has also demonstrated anti-ferroptotic effects in sepsis-induced liver injury and chronic kidney disease models, and TMP nitrone derivatives have shown safety and some functional benefits in clinical trials for amyotrophic lateral sclerosis. Yet the authors are candid about the gaps: most mechanistic studies remain at the level of phosphorylation measurements and phenotypic description, lacking gene knockout validation, direct target identification, ChIP-seq or co-immunoprecipitation evidence for pathway crosstalk, and systematic pharmacokinetic or clinical time-window studies.

The path forward, the review argues, runs through modern tools. Single-cell sequencing could resolve how neurons, microglia, astrocytes, and oligodendrocytes respond differently to TMP; proteomics could identify its direct molecular targets; and gene-edited mouse models could confirm pathway dependence. On the translational side, nanoparticle formulations, sustained-release hydrogels, and exosome-based delivery could overcome the bioavailability bottleneck, while combination strategies pairing TMP with stem cell transplantation, biomaterial scaffolds, or rehabilitation training could amplify its effects. If those efforts succeed, a compound extracted from an ancient medicinal root could become a template for a new generation of multi-target neuroprotective therapies, ones that do not merely mop up damage after spinal cord injury but actively reshape the injured cord for repair.

Subject of Research: Tetramethylpyrazine modulation of the Nrf2/JNK axis to inhibit ferroptosis and neuroinflammation after spinal cord injury

Article Title: Tetramethylpyrazine modulates the Nrf2/JNK axis to intervene in ferroptosis and neuroinflammation after spinal cord injury: an integrated perspective from antioxidant to regenerative therapy

Article References: Jiahao, D., Zirui, Z., & Tao, C. (2026). Tetramethylpyrazine modulates the Nrf2/JNK axis to intervene in ferroptosis and neuroinflammation after spinal cord injury: an integrated perspective from antioxidant to regenerative therapy. Molecular Biology Reports, 53(1), Article 1621. https://doi.org/10.1007/s11033-026-12641-w

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12641-w

Keywords: tetramethylpyrazine, spinal cord injury, ferroptosis, neuroinflammation, Nrf2, JNK, Keap1, GPX4, microglia, Ligusticum chuanxiong, oxidative stress, neuroprotection