The role of autophagy in b cell tolerance

The National Institute of Allergy and Infectious Diseases awarded The Feinstein Institutes for Medical Research $209,375 on April 23, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to investigate the role of autophagy in B cell tolerance and its relationship to systemic lupus erythematosus.

The research examines how autophagy defects contribute to loss of B cell tolerance in autoimmune disease, specifically exploring crosstalk between autophagy pathways and endosomal Toll-like receptors (TLR7 and TLR9) that recognize nucleic acids. The study builds on prior findings that complete loss of autophagy pathways in B cells prevents SLE in mouse models and that selective deficiencies in specific autophagy components (ATG14 and RUBICON) protect lupus-prone mice from autoantibody production and nephritis-related mortality without significantly impairing responses to protein antigens. The work will investigate mechanisms by which autophagy dysfunction leads to autoantibody production and identify potential therapeutic targets.

Performance occurs in Manhasset, New York, with a period of performance from April 23, 2026 through March 31, 2028. The assistance type is a Project Grant.

Abstract

Autophagy is a crucial cellular process that maintains homeostasis by recycling or degrading unwanted cellular components. Canonical autophagy involves the formation of double membrane autophagosomes, which fuse with lysosomes for degradation. Non-canonical autophagy utilizes part of the autophagy machinery to generate single-membrane vesicles for lysosomal fusion. Recent findings reveal significant interactions between autophagy and other cellular degradative pathways. Importantly, autophagy defects have been linked to b cell tolerance loss in autoimmune diseases, notably systemic lupus erythematosus (SLE). The proposal seeks to investigate how autophagy contributes to the loss of b cell tolerance, particularly in relation to crosstalk with endosomal toll-like receptors (tlrs) that recognize nucleic acids. While these tlrs play a vital role in immune responses to infectious pathogens, their hyperactivation can lead to autoimmunity. Specifically, TLR7 and TLR9, which detect single-stranded (SS)RNA and double-stranded (DS)DNA, respectively, are critical in autoantibody responses in SLE. TLR7 overexpression has been shown to exacerbate SLE in animal models, with human polymorphisms enhancing TLR7 function also linked to the disease. TLR7 activation promotes b cell proliferation and plasma cell formation and is essential for spontaneous germinal center formation in SLE models. By contrast, although TLR9 is required for anti-dsdna autoantibody production, its loss can worsen SLE by enhancing TLR7 signaling. Complete loss of all autophagy pathways in b cells can prevent SLE in mouse models. We generated SLE- prone mice with b cell deficiency of ATG14 (canonical autophagy only) and of rubicon (involved in both autophagy pathways) and found that they both protect lupus-prone mice from autoantibody production and nephritis-related mortality, without significantly impacting responses to protein antigens. We hypothesize that the mechanism for this protection is via interference with vesicular trafficking and downregulation of endosomal TLR signals. In our first aim we will determine whether deficiencies in ATG14 or rubicon affect immune responses to RNA or DNA viruses. In our second aim we will investigate how these deficiencies influence autoreactive b cell selection by utilizing flow cytometry to identify at which b cell stage autoreactivity is censored and b cell subset repertoire analysis to identify selection mechanisms known to be influenced by tlrs. In our third aim we will assess whether deficiencies in ATG14 or rubicon reduce TLR signaling in activated b cells due to altered autophagosome and endolysosome traffic. This will involve analyzing endosomal traffic using confocal microscopy and measuring downstream signaling events and effector functions in b cells, along with investigating the function of newly identified rubicon isoforms. Overall, our studies will elucidate the role of autophagy in b cell tolerance and inform new therapeutic strategies that maintain immune tolerance without excessive immunosuppression.