Biology subjects

Michalik, J.

Publications and source records attributed to Michalik, J..

8 recordsLinked to original sources

bioRxiv2026

Distinct activation programs in naive and memory CD8 T cells govern stemness and effector persistence of their progeny

Infection- and vaccination-induced memory CD8+ T cells provide protection upon subsequent exposure to cognate antigen through their increased abundance and robust per-cell responses. However, how prior antigen experience alters T-cell activation programs remains poorly understood. We longitudinally profiled gene expression in naive, central memory, and effector memory CD8+ T cells in response to cognate antigen across multiple models of acute infection. Naive T cells engaged TOX- and TCF7-centered programs and generated early stem-like central memory precursors. Their initially slow proliferation was followed by rapid expansion and the production of large numbers of short-lived effector cells. Central memory T cells rapidly triggered effector and proliferation programs while maintaining a smaller self-renewing population. Effector memory T cells expanded poorly and generated almost exclusively effector progeny. Effector progeny derived from both memory subsets survived contraction more efficiently than naive T-cell-derived progeny and established persistent effector memory populations. These data show that prior antigen experience does not simply accelerate CD8+ T-cell activation but redirects cell-intrinsic programs that shape progeny fate and persistence. These distinct programs may reflect adaptation to primary versus repeated antigen exposure and suggest that infection and vaccination history can shape the balance between stem-like memory and persistent effector populations.

immunology↗

bioRxiv2026

T cells restrain inflammation driven by TNF-induced cell death

TNF is a potent proinflammatory cytokine that can induce cell death by activating the kinase RIPK1. The adaptor proteins TANK and AZI2 protect against cell death by recruiting TBK1 to the TNF receptor signaling complex, thereby inhibiting RIPK1. While deficiency of either adaptor alone is well tolerated, combined loss of TANK and AZI2 results in partial embryonic lethality and severe TNF- and RIPK1-driven autoinflammation. Here, we show that TANK/AZI2-deficient mice exhibit a striking expansion of regulatory T cells (Tregs), most of which display an effector phenotype with high expression of immunosuppressive genes. Although thymic Treg generation is modestly increased, Tregs arise predominantly in the periphery through a largely cell-intrinsic mechanism. The marked accumulation of effector Tregs suggested that the T-cell compartment may limit TNF-driven pathology in this model. Supporting this, T cell ablation in TANK/AZI2-deficient mice markedly exacerbates disease progression and enhances TNF-driven, RIPK1-mediated inflammation. Similarly, T cells protect against acute TNF-induced systemic inflammatory response syndrome by limiting RIPK1-mediated cell death. Together, our findings identify TANK and AZI2 as negative regulators of Treg formation, demonstrate that T cells restrain TNF-driven inflammation by limiting RIPK1-dependent cell death, and suggest that this protective effect is mediated primarily by Tregs.

immunology↗

bioRxiv2025

LCK deficiency in CD8 T cells leads to reduced proliferation and increased effector T-cell formation in mice

LCK is an SRC-family kinase that mediates the initial steps in T-cell antigen receptor signaling and governs positive and negative selection during thymocyte development. While its developmental role is well established, its functions in peripheral T-cell responses remain poorly defined. Here, we investigated the responses of wild-type and LCK-deficient TCR-transgenic OT-I T cells across two infection models and an autoimmune diabetes model. LCK-deficient T cells exhibited reduced antigen-induced proliferation but, paradoxically, displayed enhanced effector differentiation in vivo. This phenotype likely reflects dysregulation of specific TCR signaling pathways, as LCK was more critical for ERK and NFAT activation than for NF{kappa}B, AP-1, or AKT/mTOR signaling. T cells deficient in a related kinase FYN also showed a slight increase in effector cell formation, suggesting that effector differentiation is regulated by their combined activity rather than distinct non-redundant roles. Our results reveal that LCK has two intrinsic roles in T-cell responses - promoting proliferation while restraining effector differentiation. These findings provide new insight into the molecular mechanisms of T-cell activation in vivo with implications for understanding the pathophysiology of LCK deficiency in humans and optimizing adoptive T-cell therapies.

immunology↗

bioRxiv2025

IFNG-producing self-reactive CD4+ T cells drive autoimmune adrenalitis in a mouse model of Addison's disease

Autoimmune Addisons disease (AD) is a rare but life-threatening disorder caused by immune-mediated destruction of the adrenal cortex, and progress in therapy has been limited by insufficient mechanistic insight. Here, we establish a model of Experimental Autoimmune Adrenalitis (EAA) that recapitulates key features of AD and reveals sex-dependent differences in disease manifestation within the model. Immunization with peptides derived from the adrenal self-antigen CYP11A1 induces corticosterone insufficiency. We show that autoimmune adrenalitis is driven by IFNG produced by self-reactive CD4 T cells, promoting granulomatous inflammation in the adrenal cortex. Together, these findings identify IFNG as a central effector of autoimmune adrenalitis and suggest that targeting the IFNG pathway may represent a potential therapeutic strategy for AD. SignificanceAddisons disease (AD) is a rare autoimmune disorder that destroys the adrenal cortex, yet its underlying mechanisms remain unknown. We developed a mouse model of Experimental Autoimmune Adrenalitis (EAA) that mirrors the hormonal and immunological features of AD. Our study reveals that IFNG-producing CD4 T cells drive adrenal inflammation and dysfunction, identifying IFNG as a key pathogenic factor and a potential therapeutic target.

immunology↗

bioRxiv2024

An imbalance of naive and effector T-cell phenotypes in early type 1 diabetes across conventional and regulatory subsets

Type 1 diabetes (T1D) is an autoimmune disease caused by the loss of self-tolerance toward insulin-producing pancreatic {beta}-cells. Although the etiology of T1D is not fully understood, it is linked to dysregulation of the T-cell compartment. To identify T-cell signatures associated with T1D, we performed single-cell transcriptomic analysis of peripheral blood T-cells from newly diagnosed children, the same children after one year, and healthy donors. We observed reduced expression of genes related to effector and cytotoxic T-cell functions across conventional, unconventional, and regulatory T-cell subsets in diabetic children, particularly at the time of diagnosis. These findings were supported by flow cytometry analysis of the same cohort and by reanalysis of publicly available data. Overall, our results suggest that T1D is associated with impaired T-cell effector differentiation, which may contribute to immune dysregulation and loss of self-tolerance.

immunology↗

bioRxiv2023

ABIN1 is a negative regulator of effector functions in cytotoxic T cells

T cells are pivotal in the adaptive immune defense, necessitating a delicate balance between robust response against infections and self-tolerance. Their activation involves intricate cross-talk among signaling pathways triggered by the T-cell antigen receptors (TCR) and co-stimulatory or inhibitory receptors. The molecular regulation of these complex signaling networks is still incompletely understood. We identified an adaptor protein, ABIN1 as a component of the signaling complexes of GITR and OX40 co-stimulation receptors. T cells lacking ABIN1 are hyper-responsive ex vivo, and exhibit enhanced responses to cognate infections, and superior ability to induce experimental autoimmune diabetes in mice. We observed that ABIN1 negatively regulates NF-{kappa}B and p38 pathways. The latter was at least partially responsible for the upregulation of key effector proteins, IFNG and GZMB in ABIN1-deficient T cells after TCR stimulation. Our findings reveal the intricate role of ABIN1 in T-cell regulation and its potential as a target for therapeutic fine-tuning of T-cell responses.

immunology↗

bioRxiv2021

Regulatory T cells suppress the formation of super-effector CD8 T cells by limiting IL-2

Regulatory T cells (Tregs) are indispensable for maintaining self-tolerance by suppressing conventional T cells. On the other hand, Tregs promote tumor growth by inhibiting anti-cancer immunity. In this study, we identified that Tregs increase the quorum of self-reactive CD8+ T cells required for the induction of experimental autoimmune diabetes. Their major suppression mechanism is limiting available IL-2, an essential T-cell cytokine. Specifically, Tregs inhibit the formation of a previously uncharacterized subset of antigen-stimulated KLRK1+ IL7R+ (KILR) CD8+ effector T cells, which are distinct from conventional effector CD8+ T cells. KILR CD8+ T cells show a superior cell killing abilities in vivo. The administration of agonistic IL-2 immunocomplexes phenocopies the absence of Tregs, i.e., it induces KILR CD8+ T cells, promotes autoimmunity, and enhances anti-tumor responses. Counterparts of KILR CD8+ T cells were found in the human blood, revealing them as a potential target for immunotherapy.

immunology↗

bioRxiv2020

Phenotypic and clonal stability of antigen-inexperienced memory-like T cells across the genetic background, hygienic status, and aging

Antigen-inexperienced memory-like T (AIMT) cells are functionally unique T cells representing one of the two largest subsets of murine CD8+ T cells. However, differences between laboratory inbred strains, insufficient data from germ-free mice, a complete lack of data from feral mice, and unclear relationship between AIMT cells formation during aging represent major barriers for better understanding of their biology. We performed a thorough characterization of AIMT cells from mice of different genetic background, age, and hygienic status by flow cytometry and multi-omics approaches including analyses of gene expression, TCR repertoire, and microbial colonization. Our data showed that AIMT cells are steadily present in mice independently of their genetic background and hygienic status. Despite differences in their gene expression profiles, young and aged AIMT cells originate from identical clones. We identified that CD122 discriminates two major subsets of AIMT cells in a strain-independent manner. Whereas thymic CD122LOW AIMT cells (innate memory) prevail only in young animals with high thymic IL-4 production, peripheral CD122HIGH AIMT cells (virtual memory) dominate in aged mice. Co-housing with feral mice changed the bacterial colonization of laboratory strains, but had only minimal effects on the CD8+ T-cell compartment including AIMT cells.

immunology↗