Biology subjects

Parham, K. A.

Publications and source records attributed to Parham, K. A..

4 recordsLinked to original sources

bioRxiv2022

Pre-Germinal Center Interactions with T Cells are Natural Checkpoints to Limit Autoimmune B Cell Responses

Interactions with antigen-specific T cells drive B cells activation and fate choices that ultimately determine the quality of high-affinity antibody responses. As such, thse interactions, and especially the long-lived interactions that occur prior to germinal center formation, may be important checkpoints to regulate undesirable responses. We directly observed interactions between T and B cells responding to the self-antigen Myelin Oligodendrocyte Glycoprotein (MOG) and found that they are of lower quality compared to interactions between cells responding to the model foreign antigen NP-ovalbumin (NP-OVA). This was associated with reduced expression of molecules that facilitate these interactions on the B cells but not on T cells. B cell expression of these molecules was not dictated by the T cell partner, nor could the relative lack of expression on MOG-sp. B cells be reversed by a multivalent antigen. Instead, MOG-sp. B cells were inherently less responsive to B cell Receptor stimulation than MOG-non-sp. cells. However, the phenotype of MOG-sp. B cells was not consistent with previous descriptions of autoimmune B cells that had been tolerized via regular exposure to systemically-expressed self-antigen. This suggests that alternate anergy pathways may exist to limit B cell responses to tissue-restricted self-antigens.

immunology↗

bioRxiv2022

Monovalent and trivalent VSV-based COVID-19 vaccines elicit potent neutralizing antibodies and immunodominant CD8+ T cells against diverse SARS-CoV-2 variants

Recombinant vesicular stomatitis virus (rVSV) vaccines expressing Spike proteins of Wuhan, Beta and/or Delta variants of SARS-CoV-2 were generated and tested for induction of antibody and T cell immune responses in mice. rVSV-Wuhan and rVSV-Delta vaccines and a rVSV-Trivalent (mixed rVSV-Wuhan, -Beta, -Delta) vaccine elicited potent neutralizing antibodies (nAbs) against live SARS-CoV-2 Wuhan (USAWA1), Beta (B.1.351), Delta (B.1.617.2) and Omicron (B.1.1.529) viruses. Prime-boost vaccination with rVSV-Beta was less effective in this capacity. Heterologous boosting of rVSV-Wuhan with rVSV-Delta induced strong nAb responses against Delta and Omicron viruses, with rVSV-Trivalent vaccine consistently effective in inducing nAbs against all the SARS-CoV-2 variants tested. All vaccines, including rVSV-Beta, elicited a spike-specific immunodominant CD8+ T cell response. Collectively, rVSV vaccines targeting SARS-CoV-2 variants of concern may be considered in the global fight against COVID-19.

immunology↗

bioRxiv2021

Systemic administration of anti-CD20 indirectly reduces B cells in the inflamed meninges in a chronic model of central nervous system autoimmunity

Anti-CD20 B cell depleting therapies have demonstrated that B cells are important drivers of disease progress in Multiple Sclerosis, although the pathogenic mechanisms are not well understood. A population of B cells accumulates in the inflamed meninges in MS and also some chronic animal models of disease, typically adjacent to demyelinating lesions. The role of these meningeal B cells in disease is not known, nor is their susceptibility to anti-CD20 therapy. Here, we administered anti-CD20 to 2D2 IgHMOG spontaneous experimental autoimmune encephalomyelitis mice in the chronic phase of disease, after the establishment of meningeal B cell clusters. Compared to the circulation, lymph nodes, and spleen, B cell depletion from the CNS was delayed and not evident until 7d post administration of anti-CD20. Further, we did not find evidence that anti-CD20 accessed meningeal B cells directly, but rather that depletion was indirect and the result of ongoing turnover of the meningeal population and elimination of the peripheral pool from which it is sustained. The reduction of B cell numbers in the CNS coincided with less demyelination of the spinal cord white matter and also, surprisingly, an increase in the number of T cells recruited to the meninges but not parenchyma.

immunology↗

bioRxiv2018

Autoreactive T cells preferentially drive differentiation of non-responsive memory B cells at the expense of germinal center maintenance.

B cell fate decisions within a germinal center (GC) are critical to determining the outcome of the immune response to a given antigen. Here, we characterize GC kinetics and B cell fate choices in a response to the autoantigen myelin oligodendrocyte glycoprotein (MOG), and compare them the response to a standard model foreign antigen (NP-haptenated ovalbumin, NPOVA). Both antigens generated productive primary responses, as evidenced by GC development, circulating antigen-specific antibodies, and differentiation of memory B cells. However, in the MOG response the status of the cognate T cell partner drove preferential B cell differentiation to a memory phenotype at the expense of GC maintenance, resulting in a truncated GC. Reduced plasma cell differentiation was largely independent of T cell influence. Interestingly, memory B cells formed in the MOG GC were unresponsive to secondary challenge and this could not be overcome with T cell help.

immunology↗