Expression profiling of immune cells in systemic lupuserythematosus by single-cell RNA sequencing

Systemic lupus erythematosus(SLE)is a systemic autoimmune disease characterized by abnormal cellular and humoral immune responses and excessive autoantibody production.The precise pathologic mechanism of SLE remains elusive.The advent of single-cell RNA sequencing(scRNA-seq)enables unbiased analysis of the molecular differences of cell populations at the single-cell level.We used scRNA-seq to profile the transcriptomes of peripheral blood mononuclear cells from an SLE patient compared with a healthy control(HC).A total of 16,021 cells were analyzed and partitioned into 12 distinct clusters.The marker genes of each cluster and the four major immune cell types(B cells,CD4+T cells,CD8+T cells,myeloid cells,and NK cells)were determined.Moreover,several genes involved in antigen processing and presentation through MHCII were highly enriched.GO enrichment analyses revealed abnormal gene expression patterns and signaling pathways in SLE.Of note,pseudotime analysis revealed that there was a different lineage hierarchy in the peripheral blood mononuclear cells(PBMCs)of the SLE patient,indicating that the cell states were substantially altered under disease conditions.Our analysis provides a comprehensive map of the cell types and states of the PBMCs of SLE patients at the single-cell level for a better understanding of the pathogenesis,diagnosis,and treatment of SLE.

循环射流混合槽内湍流强化传热数值模拟及射流层优化

循环射流混合槽(CJT)作为一种过程强化设备可以提高湍流的混合效率及反应选择性。为进一步提高其工业应用价值,对循环射流混合槽流场的传热能力进行分析并对其射流层数进行结构优化。在恒壁温的条件下,采用SST k-ω模型分析循环射流混合槽流场区域的非稳态流动传热特性。在充分湍流状态下研究了Re=3260~16303,射流层数M=5~9对循环射流混合槽壁面对流传热特性及流场传热特性的影响。结果表明,M=9时对流换热系数的变异系数C_(h)随Re增加而减少,壁面传热均匀性提高2.8%~19.3%;流场与温度场协同性随Re增加而增加,Re=16 303时的协同角为75.5o比Re=3260时减小约0.5°。Re=9782时C_(h)随M增加而降低,壁面传热均匀性提高2.7%~16.3%;速度矢量与温度梯度协同性随M增加而减小,M=9时全局协同性相较于M=5时降低了6.1%。当M=7时中心混合区与射流混合区的场协同角均在73°~74°之间,两区域流场间热量传递能力匹配程度较好;当M<7时中心混合区的协同性优于射流混合区,当M>7时射流混合区协同性优于中心混合区。研究Re及射流层数M对循环射流混合槽热量吸收和传递性能的影响,发现Re的变化对循环射流混合槽吸热量的影响大于射流层数M的变化。

IL-10-producing regulatory B cells restrain the T follicular helper cell response in primary Sjögren’s syndrome

Increased numbers of T follicular helper(Tfh)cells have been implicated in the development of autoimmune diseases including primary Sjögren’s syndrome(pSS),but how the Tfh cell response is regulated during autoimmune pathogenesis remains largely unclear.Here,we first found negative correlations between IL-10^(+)regulatory B(Breg)cell numbers and Tfh cell responses and disease activity in patients with pSS and mice with experimental Sjögren’s syndrome(ESS).Moreover,we detected high expression of IL-10 receptor on Tfh cells and their precursors in both humans and mice.In culture,IL-10 suppressed human and murine Tfh cell differentiation by promoting STAT5 phosphorylation.By using an adoptive transfer approach and two-photon live imaging,we found significantly increased numbers of Tfh cells with enhanced T cell homing into B cell follicles in the draining cervical lymph nodes of RAG-2−/−mice transferred with IL-10-deficient B cells during ESS development compared with those of RAG-2−/−mice transferred with wild-type B cells.In ESS mice,CD19^(+)CD1d^(hi)CD5^(+)Breg cells with decreased IL-10 production exhibited severely impaired suppressive effects on T cell proliferation.Consistently,CD19^(+)CD24^(+)CD38^(hi) Breg cells from pSS patients showed significantly reduced IL-10 production with defective inhibitory function in the suppression of autologous Tfh cell expansion.Furthermore,the adoptive transfer of IL-10-producing Breg cells markedly suppressed the Tfh cell response and ameliorated ESS progression in ESS mice.Together,these findings demonstrate a critical role for IL-10-producing Breg cells in restraining the effector Tfh cell response during pSS development.

IL-17 sustains the plasma cell response via p38-mediated Bcl-xL RNA stability in lupus pathogenesis

Recent studies have demonstrated a central role for plasma cells in the development of autoimmune diseases,such as systemic lupus erythematosus(SLE).Currently,both the phenotypic features and functional regulation of autoreactive plasma cells during SLE pathogenesis remain largely unclear.In this study,we first found that a major subset of IL-17 receptor-expressing plasma cells potently produced anti-dsDNA IgG upon IL-17A(IL-17)stimulation in SLE patients and lupus mice.Using a humanized lupus mouse model,we showed that the transfer of Th17 cell-depleted PBMCs from lupus patients resulted in a significantly reduced plasma cell response and attenuated renal damage in recipient mice compared to the transfer of total SLE PBMCs.Moreover,long-term BrdU incorporation in lupus mice detected highly enriched long-lived BrdU+subsets among IL-17 receptor-expressing plasma cells.Lupus mice deficient in IL-17 or IL-17 receptor C(IL-17RC)exhibited a diminished plasma cell response and reduced autoantibody production with attenuated renal damage,while the adoptive transfer of Th17 cells triggered the plasma cell response and renal damage in IL-17-deficient lupus mice.In reconstituted chimeric mice,IL-17RC deficiency resulted in severely impaired plasma cell generation but showed no obvious effect on germinal center B cells.Further mechanistic studies revealed that IL-17 significantly promoted plasma cell survival via p38-mediated Bcl-xL transcript stabilization.Together,our findings identified a novel function of IL-17 in enhancing plasma cell survival for autoantibody production in lupus pathogenesis,which may provide new therapeutic strategies for the treatment of SLE.

Proteasome inhibition suppresses Th17 cell generation and ameliorates autoimmune development in experimental Sjögren’s syndrome

Immunoproteasome activation in immune cells is involved in the modulation of immune responses.Increasing evidence indicates that proteasome inhibitors show beneficial effects in treating autoimmune diseases,but it remains unclear whether proteasome inhibition is an effective approach for suppressing autoimmune development in Sjögren’s syndrome(SS).Our previous work has demonstrated a critical role for Th17 cells in the development of experimental SS(ESS)in mice.In this study,we detected high levels of low-molecular-weight protein 7(LMP7),a key subunit of the immunoproteasome,in Th17 cells from ESS mice.Moreover,treatment with bortezomib(BTZ),a proteasome inhibitor,markedly suppressed Th17 differentiation in both murine and human naive T cells in culture.Furthermore,ESS mice treated with BTZ displayed significantly higher saliva flow rates and a reduction in tissue destruction in the salivary glands compared with vehicle-treated ESS mice.Notably,BTZ-treated ESS mice showed markedly decreased Th17 cells,germinal center B cells and plasma cells in the peripheral lymphoid organs.In addition,adoptively transferred wild type naive CD4+T cells rapidly differentiated into Th17 cells and induced salivary dysfunction in IL-17-deficient mice immunized for ESS induction.However,BTZ treatment profoundly suppressed the donor T-cell-derived Th17 response and ameliorated the reduction in salivary secretion in IL-17-deficient recipient mice.Taken together,our findings demonstrate that proteasome inhibition can effectively ameliorate ESS by suppressing the Th17 response,which may contribute to the development of a novel therapeutic strategy for the treatment of SS.

B1-cell-produced anti-phosphatidylserine antibodies contribute to lupus nephritis development via TLR-mediated Syk activation

Autoantibodies produced by B cells play a pivotal role in the pathogenesis of systemic lupus erythematosus (SLE). However, both the cellular source of antiphospholipid antibodies and their contributions to the development of lupus nephritis (LN) remain largely unclear. Here, we report a pathogenic role of anti-phosphatidylserine (PS) autoantibodies in the development of LN. Elevated serum PS-specific IgG levels were measured in model mice and SLE patients, especially in those with LN. PS-specific IgG accumulation was found in the kidney biopsies of LN patients. Both transfer of SLE PS-specific IgG and PS immunization triggered lupus-like glomerular immune complex deposition in recipient mice. ELISPOT analysis identified B1a cells as the main cell type that secretes PS-specific IgG in both lupus model mice and patients. Adoptive transfer of PS-specific B1a cells accelerated the PS-specific autoimmune response and renal damage in recipient lupus model mice, whereas depletion of B1a cells attenuated lupus progression. In culture, PS-specific B1a cells were significantly expanded upon treatment with chromatin components, while blockade of TLR signal cascades by DNase I digestion and inhibitory ODN 2088 or R406 treatment profoundly abrogated chromatin-induced PS-specific IgG secretion by lupus B1a cells. Thus, our study has demonstrated that the anti-PS autoantibodies produced by B1 cells contribute to lupus nephritis development. Our findings that blockade of the TLR/Syk signaling cascade inhibits PS-specific B1-cell expansion provide new insights into lupus pathogenesis and may facilitate the development of novel therapeutic targets for the treatment of LN in SLE.

Ecto-mesenchymal stem cells: a new player for immune regulation and cell therapy

Extensive studies have demonstrated that mesenchymal stem cells(MSCs)are multipotent mesoderm-derived stromal cells that can differentiate into a variety of cell types,including adipocytes,osteoblasts,chondrocytes,myocytes and neuronal cells.1 MSCs are found in numerous organs and tissues,including bone marrow,heart,lung,muscle,peripheral blood,adipose tissue,cartilage,synovium,dental pulp,tonsil,umbilical cord,placenta,thymus and olfactory mucosa.1 MSCs have been shown to possess potent immunosuppressive functions and tissue repair capacities,which have facilitated the clinical applications of MSCs in treating a diverse range of disorders involving angiogenesis and fibrosis,including rheumatic diseases and graft-versus-host diseases.2,3 Here,we provide a brief commentary on newly emerging evidence of the immunoregulatory function and potential application of ecto-mesenchymal stem cells.

The expanding functional diversity of plasma cells in immunity and inflammation

The generation and function of plasma cells have been well recognized as the central events in humoral immunity.In particular,long-lived plasma cells,characterized by a long lifespan and the lack of cell division,persistently secrete high-affinity antibodies to maintain serum antibody titers in the immune response and autoimmune inflammation.Although the significant expansion of plasma cells is observed during the aging process,autoimmune diseases and chronic infections,the expanding functional diversity and underlying mechanisms of plasma cells remain incompletely understood.Here,we describe recent advances in revealing new functional subsets and phenotypic features of plasma cells in aging and autoimmunity.