Biology subjects

Patil, S. U.

Publications and source records attributed to Patil, S. U..

5 recordsLinked to original sources

bioRxiv2025

GPR15 and CD38 define a subset of peripheral blood pathogenic effector Th2 cells associated with active eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic disease driven by exposure to culprit antigens. Due to the local nature of the inflammation, diagnosis and assessment are limited to invasive procedures. Based on prior single-cell RNA sequencing (scRNA-seq) data linking peripheral GPR15+ pathogenic effector Th2 (peTh2) cells to esophageal tissue peTh2s, we hypothesized the direct involvement of GPR15+ peTh2 cells in EoE pathogenesis and aimed to further evaluate their association with EoE disease status. We subjected samples from subjects with or without EoE to flow cytometry (n = 74 peripheral blood, 17 biopsy) and scRNA-seq (n = 27 peripheral blood, 10 biopsy). Expression of GPR15 by peripheral peTh2 cells was increased in EoE, and these cells expressed increased CD38 in active EoE--findings recapitulated in esophageal biopsies. We also identified a peTh2-associated, CD38-containing gene expression program that peripheral GPR15+ peTh2 cells upregulated in active EoE. The level of upregulation was distinct from other circulating peTh2 cells and was more similar to that seen in esophageal peTh2 cells. An association between expression of GPR15 by peripheral peTh2 cells, the aryl hydrocarbon receptor was strongest in subjects with EoE, suggesting an environmental exposure or susceptibility. The magnitude of GPR15 expression by peripheral peTh2 cells could effectively in discriminate active EoE from no EoE in our study population (AUC 0.93). Our data suggest that EoE-related peTh2 cells are identifiable and accessible in the peripheral blood, and could be exploited in both clinical practice as a non-invasive biomarker and continued investigation into mechanisms driving EoE. One sentence summaryGPR15 marks a subset of peripheral blood pathogenic effector Th2 cells associated with eosinophilic esophagitis (EoE) that upregulate CD38 during active disease - an observation that has potential to be used for non-invasive diagnosis and monitoring of EoE and that has suggests new mechanisms driving this increasingly prevalent allergic disease.

immunology↗

bioRxiv2025

Microbial metabolism of food allergens determines the severity of IgE-mediated anaphylaxis

Anaphylaxis is an acute, potentially life-threatening reaction, often triggered by foods and largely mediated by IgE. Critically important to anaphylaxis are the factors that modulate its severity. The human microbiota is known to influence oral tolerance, but the microbial mechanisms directly involved in IgE-mediated anaphylaxis remain unknown. Here, we demonstrate that human saliva and jejunum harbor peanut-degrading bacteria that metabolize immunodominant allergens (Ara h 1 and 2) and alter IgE-binding. Additionally, we provide in vivo evidence that oral bacteria metabolize peanut allergens, influencing systemic allergen exposure and anaphylaxis severity. Finally, in clinical studies, we observe that common peanut-degrading bacteria, such as Rothia, from the oral cavity, are more abundant in peanut-allergic patients who exhibit better tolerance to allergen exposure. Altogether, these results demonstrate that human microbiota modulates IgE-mediated reactions through allergen metabolism. We reveal a novel microbial mechanism with potential to prevent, or reduce, the severity of IgE-mediated anaphylaxis.

immunology↗

bioRxiv2024

Origins and diversity of pan-isotype human bone marrow plasma cells

Bone marrow plasma cells (BMPCs) produce durable, protective IgM, IgG, and IgA antibodies, and in some cases, pro-allergic IgE antibodies, but their properties and sources are unclear. We charted single BMPC transcriptional and clonal heterogeneity in food-allergic and non-allergic individuals across CD19 protein expression given its inverse correlation to BMPC longevity. Transcriptional and clonal diversity revealed distinct functional profiles. Additionally, distribution of somatic hypermutation and intraclonal antibody sequence variance suggest that CD19low and CD19high BMPCs arise from recalled memory and germinal center B cells, respectively. Most IgE BMPCs were from peanut-allergic individuals; two out of 32 from independent donors bound peanut antigens in vitro and in vivo. These findings shed light on BMPC origins and highlight the bone marrow as a source of pathogenic IgE in peanut allergy.

immunology↗

bioRxiv2023

Full-length single-cell BCR sequencing paired with RNA sequencing reveals convergent responses to vaccination

Single-cell RNA sequencing can to resolve transcriptional features from large numbers of individual immune cells, but techniques capable of resolving the variable regions of B cell receptors (BCR) - defining features that confer antigen specificity to B cells - remain limited, especially from widely-used 3'-barcoded libraries. Here, we report a method that for recovering paired, full-length variable region sequences of the BCRs from 3'-barcoded single-cell whole transcriptome libraries. We first verified this method could produce accurate, full-length BCR sequences. We then applied this method to profile antigen-specific B cell responses elicited against the capsular polysaccharide of Streptococcus pneumoniae serotype 3 (ST3) by glycoconjugate vaccines in infant rhesus macaques. Using our method, we defined features of the BCR associated with specificity for the ST3 antigen and showed that these sequence characteristics are present in multiple vaccinated monkeys, indicating a convergent response to vaccination. These results demonstrate the utility of our method to resolve key features of the B cell repertoire and for profiling antigen-specific responses elicited by vaccination.

immunology↗

bioRxiv2019

BCR analysis of single-sorted, putative IgE+ memory B cells in food allergy: an ephemeral existence?

Immunoglobulin (Ig) E is the critical effector molecule in allergic reactions. Consequently, research efforts to understand the biology of IgE-expressing cells is of paramount importance. In particular, the role of IgE+ memory B cells (MBCs) in the perpetuation of allergic reactivity has been the subject of intense research. Studies in mice have convincingly established that IgE+ B cells are rare and transient and, therefore, an unlikely candidate to maintain allergic disease. In contrast, IgE+ MBCs have been detected by flow cytometry in the sputum and peripheral blood of humans and have been proposed as a clinical marker of allergic disease. We established a method to genetically validate, at the single-cell level, the putative IgE+ MBCs identified by flow cytometry from humans. We, then used this information to develop an enhanced flow cytometry protocol that more accurately identifies bona fide IgE+ MBCs. We found that IgE+ MBCs were detected in some patients with atopic dermatitis, but at a frequency that was ~100 times lower than previously reported. We also found that IgE+ MBCs were undetectable in PBMCs from peanut allergic patients. These findings provide tools to identify bona fide IgE+ MBCs, demonstrate their extreme rarity in circulation and are consistent with the lack of a central role for IgE+ MBCs in the maintenance of allergic sensitivity.\n\nOne Sentence SummaryThe frequency of IgE+ MBCs in the peripheral circulation of humans is orders of magnitude lower than previously reported and comparable between allergic and healthy donors, which cautions about the clinical utility of their assessment.

immunology↗