The research, published in Frontiers in Molecular Medicine, focused on a subset of patients who carry visible regions of inflammation and ulceration on the bladder wall known as Hunner lesions. This form, called Hunner type interstitial cystitis, follows a more severe clinical course than the more common non-Hunner type, and the two forms rarely, if ever, interconvert. Using high-resolution sequencing of the human leukocyte antigen, or HLA, genes, the investigators identified two alleles that are significantly enriched in patients with Hunner lesions compared with healthy populations.

HLA association has long been considered the gold standard of evidence that a disease is autoimmune. These genes encode proteins that display fragments of antigens on the surface of immune cells, allowing T cells to survey the body for threats. When specific HLA variants recur in patients with a disorder far more often than in the general population, it strongly suggests that the adaptive immune system is responding to a particular antigen, whether that antigen is a self-protein or an external invader. In this study, half of the twelve patients with Hunner lesions carried a rare allele called HLA-DQB1*02:02, an allele so uncommon that it has no recorded frequency in the European population and is absent from the National Marrow Donor Program database.

Compared with reported healthy control genotype frequency, the HLA-DQB102:02 allele showed a significant association with Hunner type disease, with an odds ratio of 6.29 and a P-value of 0.0065. The researchers also found that the HLA-DRB107:01:01 allele had a significantly higher allele frequency in the Hunner cohort than in reference databases, with an odds ratio of 4.6 and a P-value of 0.0004. Notably, none of the seven patients with non-Hunner type disease carried HLA-DQB1*02:02, hinting that the two clinically defined forms of the syndrome may be biologically distinct entities rather than variations of a single disease.

The significance of these particular alleles extends beyond statistics. HLA-DQB1*02:02 has previously been associated with celiac disease, systemic lupus erythematosus, and type 1 diabetes mellitus, all conditions with well-established autoimmune mechanisms. In celiac disease, this allele forms part of an MHC class II heterodimer called HLA-DQ2.2 that presents gluten epitopes to the immune system. The structural details of how antigens bind within the pocket formed by the DQB1 protein are well characterized, and the researchers suggest that a similar antigen-presentation event may be occurring in the bladder lesions of affected patients.

Previous work by the same laboratory had already identified clonal proliferation of B cells within Hunner lesions, with different B cell clones from multiple patients sharing the same B cell receptor. That observation indicated the cells were responding to a specific, unidentified antigen in that location. The new HLA findings complement this picture, as the DQB1 and DQA genes encode a heterodimer expressed on antigen-presenting cells that presents antigens to immune cells, with the B1 allele specifically forming the binding pocket that complexes with the antigen. Together, the cellular and genetic evidence points toward a targeted adaptive immune response within the lesions.

The study has important limitations that the authors acknowledge. The cohort was small, reflecting the rarity of Hunner type disease, which represented approximately 25 percent of all cases seen at the clinic over two years. The sample size was determined by patient availability rather than a formal power calculation, consistent with exploratory genetic association studies of rare disorders. All patients analyzed were Americans of European descent, and the authors emphasize that the results must be reproduced in people of different origins to determine whether the HLA association is local or global. Autoimmune diseases can be associated with different HLA alleles in different populations, as demonstrated by neuromyelitis optica spectrum disorders, which show varying associations depending on geographic region.

If the autoimmune hypothesis is confirmed, the therapeutic implications could be substantial. Current treatments for the condition, including surgical fulguration of lesions, corticosteroids, and bladder hydrodistention, frequently offer limited efficacy. Targeted biologic therapies used to manage autoimmunity, such as anti-interleukin agents and TNF-alpha blockers, could potentially be delivered directly into the bladder. Prior randomized controlled trials with TNF-alpha blockers demonstrated statistically significant reductions in bladder pain and urinary frequency, though patients were not stratified by lesion type and a significant placebo effect was reported. Monoclonal antibodies against BAFF, which regulate clonal B-cell expansion, should also be considered given the evidence of B-cell proliferation within the lesions.

Beyond treatment, identifying the specific HLA alleles involved opens the door to locating the antigen that drives the immune response. Animal models of autoimmune cystitis, including those that induce immunity against bladder proteins called uroplakins, are available to explore disease mechanisms and test new therapies. A natural model also exists in domestic cats, which develop a disorder histologically similar to the non-Hunner form. As researchers work to confirm these genetic associations in larger and more diverse cohorts, the prospect of finally understanding the etiology of this debilitating syndrome moves from speculation toward testable science.

Subject of Research: Immunology

Article Title: Association of specific HLA alleles in patients with interstitial cystitis suggesting autoimmunity

Article References: Tabansky Stern, I., Wang, J., Moldwin, R. M., Kim, J. M., Singh, J. H., Tran, D. C., Najjar, S., Akinci, M., Howard, A., Duke-Cohan, J. E., Belhaj, M., Stevens, J., Lane, W. J., Birder, L. A., Jackson, E. K., Keskin, D. B., Zhang, G., & Stern, J. N. H. (2025). Association of specific HLA alleles in patients with interstitial cystitis suggesting autoimmunity. Frontiers in Molecular Medicine, 5, Article 1712660. https://doi.org/10.3389/fmmed.2025.1712660

Image Credits: AI Generated

DOI: 10.3389/fmmed.2025.1712660

Keywords: interstitial cystitis, bladder pain syndrome, HLA, autoimmunity, Hunner lesions, immunogenetics, Association, specific, alleles, patients, interstitial, cystitis

The research team, led by Alino Demean Loghin and Brandon Noyon, co-primary authors, together with Jocelyn Gravel and Caroline Quach of the CHU Sainte-Justine research centre, set out to measure the appropriateness of empiric antibiotic prescriptions. Empiric therapy is the treatment started before laboratory results identify the exact bacterium and its antibiotic susceptibilities, so it must be selected based on clinical presentation, local resistance patterns, and institutional guidelines. When clinicians reach for the wrong drug or the wrong dose at this stage, children may receive unnecessary broad-spectrum exposure, and the selective pressure that drives antimicrobial resistance intensifies.

Antimicrobial resistance, often abbreviated AMR, is recognized by the World Health Organization as one of the most serious threats to global public health. Every inappropriate prescription contributes to the problem by killing susceptible bacteria while leaving resistant strains to flourish. Pediatric emergency departments represent a particularly important setting for stewardship efforts because they handle enormous volumes of common infections, and urinary tract infections in children are a frequent trigger for antibiotic prescribing. The Montreal team viewed this as an ideal opportunity to audit real-world practice against a data-driven local guideline.

The study design was straightforward but rigorous. The investigators reviewed charts of children aged 18 years or younger who presented to the emergency department between January and December 2022 with a presumptive diagnosis of urinary tract infection and who had a urine sample collected for urinalysis and culture. Children with concurrent infections were excluded to keep the analysis focused. From a total of 1,029 children diagnosed with a urinary tract infection during the study year, the team randomly sampled 449 charts for detailed evaluation, of which 358, or 79.8 percent, proved eligible for the final analysis.

The cohort reflected the typical epidemiology of pediatric urinary infections. The median age was 34 months, meaning half the children were younger than roughly three years old, and 253 of the 358 participants, or 70.7 percent, were female, consistent with the shorter female urethra facilitating bacterial ascent into the bladder. About a quarter of the children, 96 cases or 26.8 percent, were diagnosed with cystitis, an infection confined to the bladder, while the remainder had pyelonephritis, the more serious upper urinary tract infection involving the kidneys. This distinction matters clinically because the two conditions call for different antibiotic strategies and different durations of therapy.

The primary outcome was defined as the appropriateness of the empiric prescription, judged by whether both the antibiotic choice and the dose matched the hospital’s local guidelines. The researchers also collected a rich set of independent variables, including age, sex, past medical history such as urinary tract abnormalities, prior infections, and vesicoureteral reflux, documented allergies, presenting temperature, the method used to collect the urine sample, urinalysis results, and the bacteria ultimately identified on culture. Inter-rater reliability was assessed on a five percent sample of chart reviews to ensure the evaluations were consistent, a methodological safeguard that strengthens confidence in the reported proportions.

The headline result was that 75 of the 358 prescriptions, or 20.9 percent, were deemed inappropriate, with a 95 percent confidence interval of 16.9 to 25.5 percent. In other words, roughly one in five children received an empiric antibiotic regimen that did not conform to the hospital’s own recommendations. But the aggregate figure concealed a dramatic asymmetry between infection types. For cystitis, 61.5 percent of prescriptions were inappropriate, with a confidence interval spanning 51.0 to 71.2 percent, whereas for pyelonephritis the inappropriate rate was only 6.1 percent, with a confidence interval of 3.5 to 9.7 percent.

Delving into the reasons behind these failures, the researchers found that the choice of antibiotic itself was the culprit in 61 of the 75 inappropriate cases, accounting for 83 percent of the deviations. Dosing errors made up the remainder. This pattern suggests that the problem is not careless arithmetic but a systematic mismatch between what prescribers reach for and what the local guideline recommends for lower urinary tract infections. For cystitis, oral agents such as trimethoprim-sulfamethoxazole are typically favored when local susceptibility profiles permit, and the high inappropriateness rate hints that clinicians may be defaulting to broader or otherwise non-recommended agents for bladder infections.

Why would guideline adherence be so much worse for cystitis than for pyelonephritis? The authors point to an opportunity for improved antibiotic stewardship rather than offering a definitive explanation, but several plausible mechanisms fit the data. Bladder infections are perceived as mild and self-limited, which may lower the perceived stakes of antibiotic selection and encourage habitual prescribing. Pyelonephritis, by contrast, carries visible stakes, with febrile children at risk of renal scarring and sepsis, prompting closer attention to guidelines. Emergency department workflow, familiarity with specific drugs, and ambiguity about which children have upper versus lower disease at the moment of prescribing may all contribute to the gap.

The implications extend well beyond a single Montreal hospital. The study demonstrates that even within an institution equipped with local guidelines and susceptibility data, adherence can vary enormously by diagnosis, and that targeted interventions should focus where the failures cluster. Stewardship programs that combine electronic decision support, prescriber feedback, and regular audits of empiric prescribing could plausibly close much of the cystitis gap, reducing unnecessary broad-spectrum exposure in thousands of children each year. As resistance profiles of common uropathogens such as Escherichia coli continue to evolve, the study serves as a reminder that the routine prescriptions, not just the dramatic cases, determine the long-term effectiveness of the antibiotic arsenal.

Subject of Research: Guideline adherence of antibiotic prescriptions for pediatric urinary tract infections in an emergency department

Article Title: Guideline adherence of antibiotic prescriptions for urinary tract infections in a pediatric emergency department: a retrospective cohort study

Article References: Demean Loghin, A., Noyon, B., Gravel, J., & Quach, C. (2026). Guideline adherence of antibiotic prescriptions for urinary tract infections in a pediatric emergency department: a retrospective cohort study. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07757-8

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07757-8

Keywords: urinary tract infection, antibiotics, pediatrics, emergency department, antimicrobial resistance, antibiotic stewardship, cystitis, pyelonephritis, clinical guidelines, retrospective cohort study, prescription appropriateness, Escherichia coli