Tumor Necrosis Factor Alpha inhibits humoral immunity by regulating the antibody secreting cell bone marrow niche

Abstract

Abstract Humoral immunity is a critical component of the immune memory, and its longevity is partly dependent on the survival of antibody-secreting cells (ASC). Previous studies have shown that several types of infections can deplete pre-existing antibody titers, but the exact mechanism of this process is unclear. Most, if not all, forms of infection induce inflammation including Tumor Necrosis Factor Alpha (TNFa). Here we show that TNFa-mediated inflammation depletes pre-existing antibody titers by limiting ASC retention in the bone marrow (BM) survival niche. Acute recombinant TNFa (rTNFa) treatment induces ASC egress from the BM into the blood and limits engraftment of adoptively transferred ASCs into the BM of recipient mice. To determine if the TNFa-mediated ASC egress from the BM was cell-intrinsic or –extrinsic, we generated BM chimeras with wild-type and TNFa receptor knockout mice. We found that TNFa signaling through TNFa receptor 1 in non-hematopoietic cells induces ASC egress from the BM in a cell-extrinsic manner. Treatment with rTNFa did not induce ASC death in the BM, but it increased glucose uptake and expression of CXCR4, a receptor involved in ASC retention in the BM. In contrast, mobilized ASCs in the blood had reduced glucose uptake, CD98 expression, and CD93 expression suggesting that ASC metabolism is highly dependent on the BM niche. Our findings demonstrate that inflammation alters ASC physiology in both cell-intrinsic and extrinsic manners, leading to reduced antibody titers and long-term immune memory.