For tetramer generation, RBD proteins were biotinylated with the BirA500 kit (Avidity), tetramerized with streptavidin-phycoerythrin (SA-PE) (Agilent, PJRS301-1), and stored in 50% glycerol at C20C as previously described (45). cytotoxic T lymphocyte antigen 4CIg therapy abatacept experienced reduced levels of SARS-CoV-2Cneutralizing antibodies after vaccination. At the cellular level, these patients showed reduced activation and class switching of SARS-CoV-2Cspecific B cells, as well as reduced figures and impaired helper cytokine production by SARS-CoV-2Cspecific CD4+ T cells. Individuals on methotrexate showed similar but less severe defects in vaccine response, whereas individuals around the B cellCdepleting therapy rituximab experienced a near-total loss of antibody production after vaccination. U-93631 U-93631 These data define a specific cellular phenotype associated with impaired response to SARS-CoV-2 vaccination in patients with RA on different immune-modifying therapies and help inform efforts to improve vaccination strategies in this vulnerable populace. Keywords: Autoimmunity, Vaccines Keywords: Adaptive immunity, Costimulation Introduction The COVID-19 pandemic, caused by SARS-CoV-2, has resulted in over U-93631 6 million deaths and worldwide economic and interpersonal disruption. Vaccines targeting the SARS-CoV-2 spike (S) protein are essential tools in combating this pandemic and have proved highly efficacious in preventing severe disease, hospitalization, and death. In the United States, the 2 2 most common SARS-CoV-2 vaccines are Pfizers BNT162b2 and Modernas mRNA-1273 vaccines, which use altered mRNA platforms that induce potent cellular and humoral responses to the S protein (1, 2). However, for patients with a compromised immune system, such as those with autoimmune disease taking immunosuppressive therapies, vaccination can often be less effective (3). Although both vaccines showed approximately 95% efficacy at preventing COVID-19 in initial clinical trials, immunocompromised patients were excluded from those trials (4), and a better understanding of the response to COVID-19 vaccination in this patient population is usually urgently needed. This is especially true given the emergence of viral variants that partially evade antibody-mediated protective immunity because of structural mutations in the S protein. The response to SARS-CoV-2 mRNA vaccines is usually characterized by quick production of S proteinCspecific antibodies, in the beginning from short-lived plasmablasts and later from a smaller pool of long-lived plasma cells (5, 6). The CXCL5 majority of vaccine-induced neutralizing antibodies target the S protein receptor binding domain (RBD) and contribute to protection by preventing conversation with the angiotensin-converting enzyme 2 (ACE2) receptor on human epithelial cells, thus blocking infection. Serum levels of anti-S antibodies decline slowly over several months but rebound quickly upon administration of subsequent booster vaccine doses or reinfection as S-specific memory B cells generated by the initial vaccination rapidly activate and differentiate into antibody-secreting plasmablasts (5). Vaccination also induces strong CD4+ and CD8+ T cell responses, as measured by expression of activation markers such as CD69 and CD137 by these cells after activation with S protein peptides. Among CD4+ T cells, effector and memory T cells generating important antiviral cytokines such as IL-2, IFN-, and IL-21 dominate the response, and an expanded populace of S-specific T cells persists for at least several months after vaccination (5, 7). Patients with autoimmune diseases such as rheumatoid arthritis (RA) are treated with drugs that target important immune pathways important for disease pathology but that can impair effective vaccine responses. Indeed, even though American College of Rheumatology has recognized the potential of these therapies to impact SARS-CoV-2 vaccination, there is limited consensus on whether to recommend brief cessation of treatment for patients with RA receiving the SARS-CoV-2 vaccines (8). Standard disease-modifying antirheumatic drugs are antiinflammatory and immunosuppressive small molecule drugs, the most common of which is usually methotrexate (MTX), which has become the standard of care for RA. The mechanism of action of MTX in RA has not been fully defined, although it is usually thought to take action U-93631 via adenosine signaling and blocking folate metabolism in disease-causing lymphocytes (9, 10). Patients whose disease is usually difficult to control with MTX and other first-line treatments are also treated with recombinant biologic drugs, among which is the cytotoxic T lymphocyte antigen 4CIg therapy abatacept. Abatacept functions by binding to CD80 and CD86 on antigen-presenting cells, effectively blocking their ability to provide costimulation to pathogenic autoreactive T cells. We as well as others exhibited that abatacept treatment reduces the number and activity of circulating T follicular helper (Tfh) cells (11C13), a specialized CD4+ T cell populace that produces IL-21 and provides help to promote the proliferation, isotype class.
