Summary Systemic Lupus Erythematosus (SLE) is characterized by B-cells lacking IgD and CD27 (double negative; DN). We show that DN cell expansions reflected a subset of CXCR5−CD11c+ cells (DN2) representing pre-plasma cells (PC). DN2 cells predominated in African-American patients with active disease and nephritis, anti-Smith and anti-RNA autoantibodies. They expressed a T-bet transcriptional network; increased toll-like receptor-7 (TLR7); lacked the negative TLR regulator TRAF5; and were hyper-responsive to TLR7. DN2 cells shared with activated naïve cells (aNAV), phenotypic and functional features, and similar transcriptomes. Their PC differentiation and autoantibody production was driven by TLR7 in an interleukin-21 (IL-21)-mediated fashion. An in vivo developmental link between aNAV, DN2 cells and PC was demonstrated by clonal sharing. This study defines a distinct differentiation fate of autoreactive naïve B cells into PC precursors with hyper-responsiveness to innate stimuli, as well as establishes prominence of extra-follicular B-cell activation in SLE, and identifies therapeutic targets.

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Although B cells expressing the IFNγR or the IFNγ-inducible transcription factor T-bet promote autoimmunity in Systemic Lupus Erythematosus (SLE)-prone mouse models, the role for IFNγ signaling in human antibody responses is unknown. We show that elevated levels of IFNγ in SLE patients correlate with expansion of the T-bet expressing IgDnegCD27negCD11c+CXCR5neg (DN2) pre-antibody secreting cell (pre-ASC) subset. We demonstrate that naïve B cells form T-bethi pre-ASCs following stimulation with either Th1 cells or with IFNγ, IL-2, anti-Ig and TLR7/8 ligand and that IL-21 dependent ASC formation is significantly enhanced by IFNγ or IFNγ-producing T cells. IFNγ promotes ASC development by synergizing with IL-2 and TLR7/8 ligands to induce genome-wide epigenetic reprogramming of B cells, which results in increased chromatin accessibility surrounding IRF4 and BLIMP1 binding motifs and epigenetic remodeling of IL21R and PRDM1 loci. Finally, we show that IFNγ signals poise B cells to differentiate by increasing their responsiveness to IL-21.

Background We aim to generate a line of “universal donor” human induced pluripotent stem cells (hi PSC s) that are nonimmunogenic and, therefore, can be used to derive cell products suitable for allogeneic transplantation. Methods and Results hi PSC s carrying knockout mutations for 2 key components (β2 microglobulin and class II major histocompatibility class transactivator) of major histocompatibility complexes I and II (ie, human leukocyte antigen [HLA] I/ II knockout hi PSC s) were generated using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR associated protein 9 (Cas9) gene‐editing system and differentiated into cardiomyocytes. Pluripotency‐gene expression and telomerase activity in wild‐type ( WT ) and HLAI / II knockout hi PSC s, cardiomyocyte marker expression in WT and HLAI / II knockout hi PSC ‐derived cardiomyocytes, and assessments of electrophysiological properties (eg, conduction velocity, action‐potential and calcium transient half‐decay times, and calcium transient increase times) in spheroid‐fusions composed of WT and HLAI / II knockout cardiomyocytes, were similar. However, the rates of T‐cell activation before (≈21%) and after (≈24%) exposure to HLAI / II knockout hi PSC ‐derived cardiomyocytes were nearly indistinguishable and dramatically lower than after exposure to WT hi PSC ‐derived cardiomyocytes (≈75%), and when WT and HLAI / II knockout hi PSC ‐derived cardiomyocyte spheroids were cultured with human peripheral blood mononuclear cells, the WT hi PSC ‐derived cardiomyocyte spheroids were smaller and displayed contractile irregularities. Finally, expression of HLA ‐E and HLA ‐F was inhibited in HLAI / II knockout cardiomyocyte spheroids after coculture with human peripheral blood mononuclear cells, although HLA ‐G was not inhibited; these results are consistent with the essential role of class II major histocompatibility class transactivator in transcriptional activation of the HLA ‐E and HLA‐F genes, but not the HLA ‐G gene. Expression of HLA ‐G is known ...

The coronavirus disease 2019 (COVID-19) pandemic has highlighted the urgent need for effective prophylactic vaccination to prevent the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Intranasal vaccination is an attractive strategy to prevent COVID-19 as the nasal mucosa represents the first-line barrier to SARS-CoV-2 entry. The current intramuscular vaccines elicit systemic immunity but not necessarily high-level mucosal immunity. Here, we tested a single intranasal dose of our candidate adenovirus type 5-vectored vaccine encoding the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein (AdCOVID) in inbred, outbred, and transgenic mice. A single intranasal vaccination with AdCOVID elicited a strong and focused immune response against RBD through the induction of mucosal IgA in the respiratory tract, serum neutralizing antibodies, and CD4+ and CD8+ T cells with a Th1-like cytokine expression profile. A single AdCOVID dose resulted in immunity that was sustained for over six months. Moreover, a single intranasal dose completely protected K18-hACE2 mice from lethal SARS-CoV-2 challenge, preventing weight loss and mortality. These data show that AdCOVID promotes concomitant systemic and mucosal immunity and represents a promising vaccine candidate.

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34Although B cells expressing the IFNgR or the IFNg-inducible transcription factor T-bet drive autoimmunity 35 in Systemic Lupus Erythematosus (SLE)-prone mouse models, the role for IFNg signaling in human 36 antibody responses is unknown. We show that elevated levels of IFNg in SLE patients correlate with 37 expansion of the T-bet expressing IgD neg CD27 neg CD11c + CXCR5 neg (DN2) pre-antibody secreting cell 38 (pre-ASC) subset. We demonstrate that naïve B cells form T-bet hi pre-ASCs following stimulation with 39 either Th1 cells or with IFNg, IL-2, anti-Ig and TLR7/8 ligand and that IL-21 dependent ASC formation is 40 significantly enhanced by IFNg or IFNg-producing T cells. IFNg promotes ASC development by 41 synergizing with IL-2 and TLR7/8 ligands to induce genome-wide epigenetic reprogramming of B cells, 42 which results in increased chromatin accessibility surrounding IRF4 and BLIMP1 binding motifs and 43 epigenetic remodeling of IL21R and PRDM1 loci. Finally, we show that IFNg signals poise B cells to 44 differentiate by increasing their responsiveness to 45 46 50 adaptive arms of the immune system, which ultimately leads to loss of immune tolerance in B and T 51 lymphocytes and the production of autoantibodies (Abs) by Ab-secreting B cells (ASCs) (1). The hallmark 52 SLE autoAbs recognize nuclear proteins and nucleic acids (2), which are also ligands for TLR7 and TLR9 53 that are expressed by innate immune cells and B cells (3). SLE autoAbs bound to their autoAgs form 54 immune complexes, which are responsible for many of the clinical manifestations of SLE, particularly 55 those associated with organ damage (2). Consistent with the important role for B cells and ASCs in SLE 56 pathogenesis (4), the only new drug approved to treat SLE in decades, Belimumab, targets B cells. 58Inflammatory cytokines and chemokines also contribute to SLE pathogenesis (5). SLE patient PBMCs 59 often exhibit a type I interferon (IFN) transcriptional signature and systemic IFNa is elevated in many 60 patients (6). It is less well appreciated that IFNg is also increased in some SLE patients (7-9) and that a 61 distinct IFNg transcription signature can be detected in PBMCs from a portion of SLE patients (10, 11). 62Interestingly, elevated serum IFNg can be observed years before IFNa or autoAbs are detected in SLE 63 patients and much earlier than clinical disease (12, 13). Consistent with these observations, B cells from 64 SLE patients can exhibit signs of prior IFNg exposure. For example, CXCR3 and T-bet, two IFNg-inducible 65 proteins (14), are more highly expressed by circulating B cells from SLE patients compared to healthy 66 controls (8,(15)(16)(17)(18)(19). Moreover, data from mouse SLE models show that clinical disease is dependent on 67 B cell-specific expression of the IFNgR and the IFNg-induced transcription factors and T-68 bet in some (23, 24) but not all (21, 25) models. Taken together, these data suggest that IFNg-driven 69 inflammation may contribute to SLE B cell-driven pathophysiology. 71Two populations of...

Differential TLR4 ⁄ 2 gene expressions on psoriatic peripheral blood mononuclear cells and correlations with regulatory and ⁄ or proinflammatory cytokines and ⁄ or damage-associated molecular pattern molecule S100A9 emphasize innate immune response role in psoriasis.