Biology subjects

Nichols, C. M.

Publications and source records attributed to Nichols, C. M..

5 recordsLinked to original sources

bioRxiv2026

SAP loss limits anti-insulin atypical B cell activation and pro-inflammatory CD8 T cells despite preserved Tfh responses to protect against type 1 diabetes

SLAM-associated protein (SAP) is required for T follicular helper (Tfh)-B cell interactions that underlie germinal center formation, but it is unclear if SAP governs islet-reactive CD4+ T cell-B cell interactions and downstream pro-inflammatory CD8+ T cell destruction of islets in type 1 diabetes (T1D). To address this question, we utilized the VH125SD.NOD mouse model, whereby 1-3% of all B cells bind insulin. Germline SAP loss in this model led to reduced T1D incidence and impaired germinal center B cell formation, yet did not alter T follicular helper cell formation or phenotype. SAP loss reduced pro-inflammatory and activated insulin-autoreactive B-T interactions and limited anti-insulin B cell proliferation, activation, and upregulation of co-stimulatory molecules otherwise enhanced in the pancreas. Anti-insulin extrafollicular antibody and memory responses following immunization were preserved in VH125SD.SAP-/-.NOD mice, but activated atypical anti-insulin B cell responses were reduced. Ultimately, SAP loss led to reduced pro-inflammatory CD8+ T cell formation and islet-reactive progenitor exhausted CD8+ T cells in pancreata. These data highlight the essential role of SAP in mediating proinflammatory, anti-insulin B-T interactions to support T1D. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=161 SRC="FIGDIR/small/741363v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@1971e3borg.highwire.dtl.DTLVardef@41d72eorg.highwire.dtl.DTLVardef@963004org.highwire.dtl.DTLVardef@2a76b5_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2026

Critical illness expands a transcriptionally distinct hypometabolic CD8+ T effector program associated with respiratory failure and mortality

Immune dysfunction is a major driver of morbidity and mortality in critical illness syndromes including sepsis. Specifically, CD8+ T cell dysfunction has been linked to organ failure and death. To characterize the immune substructure of circulating CD8+ T cells in critical illness at high dimension, we used single-cell RNA sequencing of peripheral blood CD8+ T cells from 38 critically ill patients and 9 healthy controls. We annotated seven CD8+ T cell clusters, which included a CD8+ effector subset, termed T effector state 2 (TEff-2), that was only present in critically ill patients and associated with more severe respiratory failure and higher mortality. TEff-2 showed effector activation and inflammatory stress conditioning yet had markedly reduced metabolic transcripts without canonical features of exhaustion. Trajectory analyses positioned TEff-2 as a terminal CD8+ T effector cell fate driven in part by DDIT4 and DUSP1, which negatively regulate mTOR and MAPK signaling, respectively. Interestingly, this transcriptional program was indistinguishable by classical protein cytometry methods. These results, including the mortality association, were validated in a larger (n=91) independent external cohort of critically ill patients with sepsis. In summary, TEff-2 represents a latent transcriptional program that delineates a clinically high-risk CD8+ T cell state in critical illness.

immunology↗

bioRxiv2026

Maternal Inflammation in Late Gestation Alters Vaccine-Induced Immune Responses in Adult Murine Offspring

BackgroundIntrauterine inflammation, commonly presenting as chorioamnionitis, is variably linked to preterm birth, neonatal infections and postnatal chronic inflammatory disorders. However, the effects of systemic maternal inflammation on exposed fetuses and offspring are less clear. We previously reported inflammatory responses in murine pups born after brief gestational exposure to experimental maternal inflammation. These findings led us to hypothesize that fetal exposure to maternal inflammation could lead to persistent alterations in postnatal immunity. ObjectiveTo test our hypothesis, we examined immune responses to vaccination, a useful measure of immune status, in young adult offspring with late gestational exposure to maternal LPS. Design/MethodsLate-gestation pregnant dams were treated with LPS or saline. Offspring (LPS-exposed or saline controls) were either immunized with the Tdap vaccine or remained unimmunized (naive mice), and were subsequently infected with Bordetella pertussis. Lung and spleen immune responses were assessed by multi-parameter flow cytometry, protein microarray and RT-PCR. ResultsWe observed that young adult (7 week old) mice exposed to maternal LPS during gestation, vaccinated with TDaP, and subsequently infected with pertussis exhibited lower lung neutrophil but higher CD4+ lymphocyte proportions relative to unexposed controls. In splenic studies, LPS-exposed mice had lower frequencies of CD4+IFN{psi}+ (Th1) and CD4+IL-17+ (Th17) cell populations. In vitro studies of post-vaccination responses to heat-killed B. pertussis showed variable levels of IL-2 and IL-4 in splenic cultures from LPS-exposed vs. control mice. Vaccinated, LPS-exposed mice showed variable splenic Stat3 and NFkb gene expression levels relative to those of naive LPS-exposed mice. ConclusionOur present murine studies show that experimental maternal inflammation during late gestation can alter immune response patterns to secondary challenge in young adult offspring. However, whether such intrauterine inflammatory exposure might also influence protective immune function remains to be determined. Our findings lead us to speculate that fetal exposure to systemic maternal inflammation in humans could have long-term implications for protective immunity.

immunology↗

bioRxiv2025

BCL6 in T cells promotes type 1 diabetes by redirecting fates of insulin-autoreactive B lymphocytes

Currently approved type 1 diabetes (T1D) immunotherapies broadly target T cells and delay but do not fully prevent diabetes development, highlighting the need for more selective targets. Anti-insulin germinal center B cells are uniquely able to present pathogenic insulin epitopes and drive anti-insulin T cells to adopt a T follicular helper fate. T cell expression of BCL6, a key transcriptional repressor in the germinal center response, is essential for spontaneous diabetes in non-obese diabetic (NOD) mice. However, the impact of T cells on pro-pathogenic anti-insulin B cell activity is still poorly understood. Here, we show that VH125SD.NOD mice with T cell loss of BCL6 still produce peripheral anti-insulin B cells yet are protected against diabetes (relative to Bcl6-sufficient controls). This protection was associated with reduced activation, proliferation, germinal center differentiation, and pancreatic infiltration of insulin-binding B cells. Minimally supervised analysis revealed insulin-binding B cells skew towards atypical memory B cell subsets specifically in pancreas and pancreatic lymph nodes, which was reduced by Bcl6{Delta}CD4 loss. Overall, this work suggests BCL6-expressing T cells are pivotal to license pathogenic insulin-binding B cells. Our findings support BCL6 inhibition as a promising T1D immunotherapy, even after insulin autoimmunity is established in the B cell repertoire. Article Highlights- Loss of floxed Bcl6 via Cd4-Cre protects against type 1 diabetes even when an insulin-skewed B cell repertoire is present - BCL6 loss in T cells reduces anti-insulin B cell upregulation of T cell co-stimulatory molecules, proliferation, and IgG class switching in pancreas and pancreatic lymph nodes in VH125SD.NOD mice - Anti-insulin B cells skew towards atypical and atypical memory B cell phenotypes compared to non-insulin binding B cells in pancreas and pancreatic lymph nodes, only some of which are reduced by T cell loss of Bcl6 - This study highlights the translational potential of targeting BCL6, even after the establishment of insulin-reactive B cells, in line with typical intervention points for at-risk individuals Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/671997v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@bf0daforg.highwire.dtl.DTLVardef@11b95fdorg.highwire.dtl.DTLVardef@141ccaorg.highwire.dtl.DTLVardef@6e4100_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

Metabolic Adaptations Rewire CD4 T Cells in a Subset-Specific Manner in Human Critical Illness with and without Sepsis

Host immunity in sepsis has features of hyperinflammation together with progressive immunosuppression, particularly among CD4 T cells, that can predispose to secondary infections and ineffectual organ recovery. Metabolic and immunologic dysfunction are archetypal findings in critically ill patients with sepsis, but whether these factors are mechanistically linked remains incompletely defined. We characterized functional metabolic properties of human CD4 T cells from critically ill patients with and without sepsis and healthy adults. CD4 T cells in critical illness showed increased subset-specific metabolic plasticity, with regulatory T cells (Tregs) acquiring glycolytic capacity that stabilized suppressive markers FOXP3 and TIGIT and correlated with clinical illness severity. Single-cell transcriptomics identified differential kynurenine metabolism in Tregs, which was validated ex vivo as a mechanism of Treg glycolytic adaptation and suppressive rewiring. These findings underscore immunometabolic dysfunction as a driver of CD4 T cell remodeling in sepsis and suggest therapeutic avenues to restore an effective immune response.

immunology↗