LAG-3 Inhibitory Receptor Expression Identifies Immunosuppressive Natural Regulatory Plasma Cells.

B lymphocytes can suppress immunity through interleukin (IL)-10 production in infectious, autoimmune, and malignant diseases. Here, we have identified a natural plasma cell subset that distinctively expresses the inhibitory receptor LAG-3 and mediates this function in vivo. These plasma cells also express the inhibitory receptors CD200, PD-L1, and PD-L2. They develop from various B cell subsets in a B cell receptor (BCR)-dependent manner independently of microbiota in naive mice. After challenge they upregulate IL-10 expression via a Toll-like receptor-driven mechanism within hours and without proliferating. This function is associated with a unique transcriptome and epigenome, including the lowest amount of DNA methylation at the Il10 locus compared to other B cell subsets. Their augmented accumulation in naive mutant mice with increased BCR signaling correlates with the inhibition of memory T cell formation and vaccine efficacy after challenge. These natural regulatory plasma cells may be of broad relevance for disease intervention.

Role of inhibitory B cell co-receptors in B cell self-tolerance to non-protein antigens.

Antibodies to non-protein antigens such as nucleic acids, polysaccharides, and glycolipids play important roles in both host defense against microbes and development of autoimmune diseases. Although non-protein antigens are not recognized by T cells, antibody production to non-protein antigens involve T cell-independent mechanisms such as signaling through TLR7 and TLR9 in antibody production to nucleic acids. Although self-reactive B cells are tolerized by various mechanisms including deletion, anergy, and receptor editing, T cell tolerance is also crucial in self-tolerance of B cells to protein self-antigen because self-reactive T cells induce autoantibody production to these self-antigens. However, presence of T cell-independent mechanism suggests that T cell tolerance is not able to maintain B cell tolerance to non-protein self-antigens. Lines of evidence suggest that B cell response to non-protein self-antigens such as nucleic acids and gangliosides, sialic acid-containing glycolipids, are suppressed by inhibitory B cell co-receptors CD72 and Siglec-G, respectively. These inhibitory co-receptors recognize non-protein self-antigens and suppress BCR signaling induced by these antigens, thereby inhibiting B cell response to these self-antigens. Inhibitory B cell co-receptors appear to be involved in B cell self-tolerance to non-protein self-antigens that can activate B cells by T cell-independent mechanisms.

CD72 is an inhibitory pattern recognition receptor that recognizes ribosomes and suppresses production of anti-ribosome autoantibody.

B cell responses to nucleic acid-containing self-antigens that involve intracellular nucleic acid sensors play a crucial role in autoantibody production in SLE. CD72 is an inhibitory B cell co-receptor that down-regulates BCR signaling, and prevents the development of SLE. We previously showed that CD72 recognizes the RNA-containing self-antigen Sm/RNP, a target of SLE-specific autoantibodies, and induces B cell tolerance to Sm/RNP by specifically inhibiting B cell response to this self-antigen. Here, we address whether CD72 inhibits B cell response to ribosomes because the ribosome is an RNA-containing self-antigen and is a target of SLE-specific autoantibodies as well as Sm/RNP. We demonstrate that CD72 recognizes ribosomes as a ligand, and specifically inhibits BCR signaling induced by ribosomes. Although conventional protein antigens by themselves do not induce proliferation of specific B cells, ribosomes induce proliferation of B cells reactive to ribosomes in a manner dependent on RNA. This proliferative response is down-regulated by CD72. These results suggest that ribosomes activate B cells by inducing dual signaling through BCR and intracellular RNA sensors and that CD72 inhibits B cell response to ribosomes. Moreover, CD72-/- but not CD72+/+ mice spontaneously produce anti-ribosome autoantibodies. Taken together, CD72 induces B cell self-tolerance to ribosomes by recognizing ribosomes and inhibiting RNA-dependent B cell response to this self-antigen. CD72 appears to prevent development of SLE by inhibiting autoimmune B cell responses to multiple RNA-containing self-antigens. Because these self-antigens but not protein self-antigens induce RNA-dependent B cell activation, self-tolerance to RNA-containing self-antigens may require a distinct tolerance mechanism mediated by CD72.

CD72-semaphorin3A axis: A new regulatory pathway in systemic lupus erythematosus.

CD72 is a regulatory co-receptor on B cells, with a role in the pathogenesis of systemic lupus erythematosus (SLE) in both human and animal models. Semaphorin3A (sema3A) is a secreted member of the semaphorin family that can reconstruct B cells' regulatory functions by upregulating IL-10 expression and inhibiting the pro-inflammatory activity of B and T cells in autoimmune diseases. The aim of our present study was to identify a new ligand for CD72, namely sema3A, and exploring the signal transduction pathways following its ligation in B cells. We established that CD72 functions as sema3A binding and signal-transducing receptor. These functions of CD72 are independent of neuropilin-1 (NRP-1) (the known sema3A receptor). We discovered that sema3A induces the phosphorylation of CD72 on tyrosine residues and the association of CD72 with SHP-1 and SHP-2. In addition, the binding of sema3A to CD72 on B cells inhibits the phosphorylation of STAT-4 and HDAC-1 and induces the phosphorylation of p38-MAPK and PKC-theta in B-cells derived B-lymphoblastoid (BLCL) cells, and in primary B-cells isolated from either healthy donors or SLE patients. We concluded that sema3A is a functional regulatory ligand for CD72 on B cells. The sema3A-CD72 axis is a crucial regulatory pathway in the pathogenesis of autoimmune and inflammatory diseases namely SLE, and modulation of this pathway may have a potential therapeutic value for autoimmune diseases.

Naturally selected CD7 CAR-T therapy without genetic editing demonstrates significant antitumour efficacy against relapsed and refractory acute myeloid leukaemia (R/R-AML).

BACKGROUND: The survival rate for patients with relapsed and refractory acute myeloid leukaemia (R/R-AML) remains poor, and treatment is challenging. Chimeric antigen receptor T cells (CAR-T cells) have been widely used for haematologic malignancies. Current CAR-T therapies for acute myeloid leukaemia mostly target myeloid-lineage antigens, such as CD123 and CD33, which may be associated with potential haematopoietic toxicity. As a lineage-specific receptor, CD7 is expressed in acute myeloid leukaemia cells and T cells but is not expressed in myeloid cells. Therefore, the use of CD7 CAR-T cells for R/R-AML needs to be further explored. METHODS: In this report, immunohistochemistry and flow cytometry were used to analyse CD7 expression in clinical samples from R/R-AML patients and healthy donors (HDs). We designed naturally selected CD7 CAR-T cells to analyse various functions and in vitro antileukaemic efficacy based on flow cytometry, and xenograft models were used to validate in vivo tumour dynamics. RESULTS: We calculated the percentage of cells with CD7 expression in R/R-AML patients with minimal residual disease (MRD) (5/16, 31.25%) from our institution and assessed CD7 expression in myeloid and lymphoid lineage cells of R/R-AML patients, concluding that CD7 is expressed in T cells but not in myeloid cells. Subsequently, we designed and constructed naturally selected CD7 CAR-T cells (CD7 CAR). We did not perform CD7 antigen knockdown on CD7 CAR-T cells because CD7 molecule expression is naturally eliminated at Day 12 post transduction. We then evaluated the ability to target and kill CD7+ acute myeloid leukaemia cells in vitro and in vivo. Naturally selected CD7 CAR-T cells efficiently killed CD7+ acute myeloid leukaemia cells and CD7+ primary blasts of R/R-AML patients in vitro and significantly inhibited leukaemia cell growth in a xenograft mouse model. CONCLUSION: Naturally selected CD7 CAR-T cells represent an effective treatment strategy for relapsed and refractory acute myeloid leukaemia patients in preclinical studies.

A regulatory role for CD72 expression on B cells and increased soluble CD72 in primary Sjogren's syndrome.

BACKGROUND: CD72, a co-receptor of B cell receptor (BCR), has been reported to have both positive and negative effects on B cell functions in several immunological diseases. The B cell plays an important role in the pathogenesis of primary Sjogren's syndrome (pSS). However, whether CD72 is involved in the process remains unknown. This study aimed to observe the possible role of CD72 in the pathogenesis of pSS. RESULTS: A total of 60 cases who fulfilled the American-European Consensus Group (AECG) criteria for the diagnosis of pSS and 61 gender and age-matched healthy controls were recruited in this study. The percentage of CD72+ B cells was 85.31 ± 8.37% in pSS patients and 76.91 ± 8.50% in healthy controls(p < 0.001). The percentage of CD72+ B cells was correlated to serum IgG levels in patients [ß = 0.018(0.001-0.036), p = 0.034]. The level of serum soluble CD72 was significantly higher in pSS patients than the one in healthy controls (0.41 (0.29) vs 0.07 (0.08) ng/mL, p < 0.001). CONCLUSIONS: The percentage of CD72+ B cells was upregulated in pSS patients and was correlated to the serum IgG level, which revealed the hyperactivity of B cells in this disease. The serum soluble CD72 level was also increased in pSS patients. These results indicated a potential role of CD72 in the pathogenesis of pSS.

CD40 and CD72 expression and prognostic values among children with systemic lupus erythematosus: a case-control study.

Systemic lupus erythematosus (SLE) is a chronic disease with proven interactions between immune system components, including both humoral- and cell-mediated immunity, as well as co-stimulatory and inhibitory molecules such as CD40 and CD72. Here, we investigated CD40 and CD72 expression on B cells of SLE children and assessed their prognostic values. We conducted a preliminary case-control study in Mansoura University Children's Hospital, Egypt from September 2018 to January 2020 including 27 SLE children and 27 healthy controls. We assessed cases during initial flare and after remission. Flow cytometry analysis was carried out for all participants for CD40 and CD72 expression of B cells. During flare, SLE cases had statistically significant higher CD40 and lower CD72 expression in comparison with controls (p < 0.001). After remission, the number of CD40+ B cells significantly decreased (p < 0.001), while the number of CD72+ B cells significantly increased (p < 0.001) in comparison with flare. We reported non-significant positive correlations between CD40 expression and SLE Disease Activity Index (SLEDAI; p = 0.347 during flare and p = 0.653 after remission) and negative correlations between CD72 expression and SLEDAI (p = 0.34 during flare and p = 0.044 after remission). No significant differences were detected between renal histopathology classes with regard to CDs expression on B cells (p = 0.45 for CD40 and p = 0.63 for CD72). In conclusion, CD40+ B cells and CD72+ B cells could be considered as markers of paediatric SLE flare and remission, respectively.

Low levels of the immunoregulator Semaphorin 4D (CD100) in sera of HIV patients.

INTRODUCTION: Semaphorin-4D (CD100), generated by CD4/CD8 T-cells and its receptor on B cells - CD72, play a role in immune regulation. Both have soluble forms - sCD100/sCD72. METHODS: sCD100 and sCD72 levels were determined by ELISA (MyBioSource, USA). RESULTS: 28 chronic HIV patients and 50 matched healthy volunteers participated in our study. Before treatment, CD4 T-cells counts were 267 ±â€¯216 cells/mcl and viral load (VL) was 586,675 ±â€¯1897,431 copies/ml. Two years following HAART, CD4 T-cells counts rose to 475 ±â€¯264 cells/mcl and VL dropped to 2050 ±â€¯10,539 copies/ml. CD8 T-cells counts were stable. sCD72 levels prior (4.13 ±â€¯2.03 ng/ml) and following HAART (3.53 ±â€¯2.01 ng/ml) were similar to control levels (4.51 ±â€¯2.66 ng/ml). sCD100 levels before (40.47 ±â€¯31.4 ng/ml) and following HAART (37.68 ±â€¯29.44 ng/ml) were significantly lower compared to controls (99.67 ±â€¯36.72 ng/ml) despite the significant increase in CD4 T-cells counts. CONCLUSIONS: The permanent low levels of the immunoregulator sCD100 suggest a role for CD100 in the immune dysfunction and T cells exhaustion of HIV.

Negative regulation of B cell responses and self-tolerance to RNA-related lupus self-antigen.

The antibody response to RNA-related antigens such as Sm/RNP requires the endosomal RNA sensor TLR7, and this process is crucial in the development of systemic lupus erythematosus at least in animal models. The inhibitory B cell receptor CD72 is unique because it recognizes Sm/RNP and specifically inhibits the activation of Sm/RNP-reactive B cells by activating SH2-containing protein tyrosine phosphatase 1 (SHP-1). In the normal immune system, Sm/RNP-reactive B cells are tolerized by a unique mechanism that probably involves SHP-1. These self-reactive B cells appear in the peripheral lymphoid organs, differentiate into marginal zone B cells, and then undergo apoptosis without further maturation into plasma cells. Thus, CD72 is involved in the suppression of TLR7-mediated response to RNA in complexes with nuclear proteins that are resistant to nucleases, whereas free RNAs are degraded by nucleases before they encounter the endosomal RNA sensor.

Upregulation of CD72 expression on CD19+ CD27+ memory B cells by CD40L in primary immune thrombocytopenia.

CD72 is a co-receptor of B cells and regulates B cell activation. Although aberrant expression of CD72 has been reported in primary immune thrombocytopenia (ITP), it is uncertain whether this aberrant expression is restricted to specific B cell subsets. Furthermore, the mechanisms that regulate CD72 expression are unknown. In this study, we found higher frequency of CD19+ B cells, CD19+ CD27+ memory B cells and lower frequency of CD19+ CD27- naive B cells in active ITP patients compared with controls and patients in remission. CD72 expression on CD19+ CD27+ cells was upregulated in active ITP patients and correlated with platelet count and anti-platelet autoantibodies. In vitro, CD40L could specifically induce CD72 upregulation on CD19+ CD27+ B cells. In combination with CD40L, interleukin (IL) 10 and BAFF (also termed TNFSF13B) further enhanced CD72 expression on CD19+ CD27+ B cells, whereas IL21 reduced CD72 upregulation. CD72mRNA expression after CD40L stimulation was increased in ITP patients and controls. Significant increase of CD40L on CD4+ T cells was correlated with CD72 expression on CD19+ CD27+ B cells in ITP patients. In conclusion, upregulation of CD72 expression on CD27+ memory B cells might take part in the pathogenesis of ITP. Elevated CD40L on CD4+ cells combined with cytokines might contribute to the upregulation of CD72 expression on CD27+ memory B cells.

Increased soluble CD72 in systemic lupus erythematosus is in association with disease activity and lupus nephritis.

INTRODUCTION: B cell receptor (BCR) -mediated signals are enhanced when CD72 expression is deficient on B cells in autoimmune diseases. The significance of soluble CD72 (sCD72) has not been elucidated. METHODS: Soluble CD72 was analyzed in the serum of 159 SLE patients, 40 rheumatoid arthritis (RA) patients, and 100 healthy individuals. Correlations between sCD72 and SLE disease activity (SLEDAI) were assessed. RESULTS: Soluble CD72 was found increased in SLE patients, when compared to both RA patients and healthy individuals (20.2 ± 1.2 ng/ml; 10.6 ± 4.6 ng/ml and 7.2 ± 3.3 ng/ml; p < 0.001). Soluble CD72 level was significantly higher in SLE patients with renal involvement than in patients without (31.8 ± 2.3 ng/ml vs 13.9 ± 0.9 ng/ml; p < 0.001) and also with the presence of auto-antibodies. CONCLUSION: Soluble CD72 is significantly increased in SLE patients mainly in those with renal involvement. Increased sCD72 may become a potential biomarker for renal involvement in SLE.

CD72 negatively regulates mouse mast cell functions and down-regulates the expression of KIT and FcεRIα.

CD72 is a transmembrane protein belonging to the C-type lectin family that is expressed by various hematopoietic cells. When bound to its natural ligand, CD100 (semaphorin 4D), CD72 inhibits the KIT-mediated responses of human mast cells, but not IgE/FcεRI-mediated mast cell degranulation. We extended these findings to examine the role of CD72 in mouse mast cells. CD72 expression was detected in mouse bone marrow-derived mast cells (mBMMCs). As for human mast cells, an agonistic antibody against CD72 (K10.6) suppressed the KIT-mediated cell growth of, IL-6 production by and chemotaxis of mBMMCs. However, in contrast to human mast cells, the IgE-triggered degranulation of mBMMCs was suppressed by K10.6. K10.6 did not affect the phosphorylation of SHP-1 in mBMMCs, although SHP-1 mediated the inhibitory effects of CD72 in human mast cells. Administration of K10.6 induced phosphorylation of the ubiquitin ligase Cbl-b and decreased the expression of KIT and FcεRIα on the surface of murine mast cells. We also observed expression of CD72 in a mouse neoplastic cell line, P815, harboring gain-of-function mutations in KIT genes. In addition, we found that K10.6 activated Cbl-b, down-regulated KIT expression and suppressed the mutated KIT-driven growth of these cells. Thus, the mechanism by which CD72 mediates inhibitory effects in mast cells is species-dependent.

Interaction of CD5 and CD72 is involved in regulatory T and B cell homeostasis.

Regulatory IL-10-producing CD1d(high)CD5(+)CD19(+) B cells and CD4(+)CD25(+)Foxp3(+) T cells have been found to modulate immune responses in autoimmunity, infection, and cancer, but the interaction between these two cell subsets remains unclear. Through cell culture and flow cytometry (FACS), we analyzed the interaction of regulatory T cells (Tregs) and regulatory B cells (Bregs). A neutralizing antibody was used to determine the role of CD5 and CD72 in maintaining regulatory T and B cell homeostasis. We found that CD19(+)CD5(+)CD1d(hi) Bregs induced expansion of CD4(+)Foxp3(+) Tregs, and CD4(+)CD25(+) Tregs also induced expansion of IL-10-expressing Bregs. Once CD72 or CD5 was blocked, both IL-10-expressing Bregs and CD4(+)Foxp3(+)Tregs were reduced in the different cultures. Finally, FACS analysis demonstrated that Foxp3(+)CD4(+)Treg cells were reduced in CD19(Cre) mice defective of CD5 on the surface of B cells. The study suggests that the interaction of CD5 and CD72 plays a critical role in maintaining regulatory T and B cell homeostasis.

Soluble CD72, is a T-cell activator probably via binding to CD6 in homeostasis and autoimmunity.

Background: CD72 is a highly required regulatory molecule in B cells. Its sufficient expression is crucial for maintaining self-tolerance. In contrast, soluble CD72 (sCD72) is reported to be increased in the serum of autoimmune diseases such as systemic lupus erythematosus and primary Sjogren's syndrome (pSS). Objective: We wanted to assess the biological effect of sCD72 on CD4+T cells. Methods: We performed mass spectrometry and co-immunoprecipitation experiments to look for a sCD72 receptor on activated CD4+T cells. Afterward, to explore the biological functions of sCD72, we used flow cytometry for the cytokine secretion profile, a phosphorylation assay for the signaling pathway, and a CFSE dye-based assay for cell proliferation. Results: We found and validated the sCD72 and CD6 interaction as a possible ligand-receptor interaction. We also demonstrated that sCD72 significantly increases the expression of pro-inflammatory cytokines, namely IL-17A and IFN-γ, in activated CD4+T cells and increases the proliferation of CD4+T cells, possibly through its activation of the SLP-76-AKT-mTOR pathway. Conclusion: The sCD72-CD6 axis on activated CD4+T cells is probably a new signaling pathway in the induction of immune-mediated diseases. Therefore, targeting sCD72 may become a valuable therapeutic tool in some autoimmune disorders.

Integrative transcriptomic analysis reveals Cd72 as a novel pro-inflammatory factor in microglia following experimental ischemic stroke.

Ischemic stroke remains a leading cause of global mortality and disability, with neuroinflammation playing a critical role in determining patient outcomes. Microglia, the brain's resident immune cells, can both exacerbate neuroinflammation and neuronal damage by releasing neurotoxic mediators and engaging in excessive phagocytosis, while also aiding recovery through the production of anti-inflammatory cytokines and debris clearance. However, the molecular mechanisms governing microglial activation and polarization after ischemic stroke are not well elucidated. In this study, we combined integrative transcriptomic analyses with experimental validation in a murine model of middle cerebral artery occlusion/reperfusion (MCAO/R) to explore microglial heterogeneity and identify key regulatory factors in ischemic stroke. Bioinformatics analysis identified Cd72 as a novel pro-inflammatory modulator within ischemia-associated microglial phenotypes. We observed significant upregulation of Cd72 in microglia following MCAO/R, and selective knockdown of Cd72 using CX3CR1Cre/ERT2 mice and Cre recombinase-dependent adeno-associated virus reduced MCAO/R-induced infarct volume, neuronal apoptosis, and neurological deficits. Furthermore, Cd72 expression in microglia was positively correlated with pro-inflammatory pathways and cytokines, including TNF-α, IL-1ß, and IL-6. Knockdown of Cd72 significantly reduced these pro-inflammatory factors, highlighting its potential as a therapeutic target for mitigating inflammation in ischemic stroke. In conclusion, this study identifies Cd72 as a critical pro-inflammatory regulator in microglia following ischemic stroke, with its knockdown effectively reducing neuroinflammation and associated brain injury, highlighting Cd72 as a promising therapeutic target.

CD72, a new immune checkpoint molecule, is a novel prognostic biomarker for kidney renal clear cell carcinoma.

BACKGROUND: The incidence and mortality of clear cell carcinoma of the kidney increases yearly. There are limited screening methods and advances in treating kidney renal clear cell carcinoma (KIRC). It is important to find new biomarkers to screen, diagnose and predict the prognosis of KIRC. Some studies have shown that CD72 influences the development and progression of colorectal cancer, nasopharyngeal cancer, and acute lymphoid leukemia. However, there is a lack of research on the role of CD72 in the pathogenesis of KIRC. This study aimed to determine whether CD72 is associated with the prognosis and immune infiltration of KIRC, providing an essential molecular basis for the early non-invasive diagnosis and immunotherapy of KIRC. METHODS: Using TCGA, GTE, GEO, and ImmPort databases, we obtained the differentially expressed mRNA (DEmRNA) associated with the prognosis and immunity of KIRC patients. We used the Kruskal-Wallis test to identify clinicopathological parameters associated with target gene expression. We performed univariate and multivariate COX regression analyses to determine the effect of target gene expression and clinicopathological parameters on survival. We analyzed the target genes' relevant functions and signaling pathways through enrichment analysis. Finally, the correlation of target genes with tumor immune infiltration was explored by ssGSEA and Spearman correlation analysis. RESULTS: The results revealed that patients with KIRC with higher expression of CD72 have a poorer prognosis. CD72 was associated with the Pathologic T stage, Pathologic stage, Pathologic M stage, Pathologic N stage, Histologic grade in KIRC patients, Laterality, and OS event. It was an independent predictor of the overall survival of KIRC patients. Functional enrichment analysis showed that CD72 was significantly enriched in oncogenic and immune-related pathways. According to ssGSEA and Spearman correlation analysis, CD72 expression was significantly associated with tumor immune cells and immune checkpoints. CONCLUSION: Our study suggests that CD72 is associated with tumor immunity and may be a biomarker relevant to the diagnosis and prognosis of KIRC patients.

Blockage of CD72 reduces B cell proliferation in immune thrombocytopenic purpura, involving interleukin 1 and macrophage migration inhibitory factor secretion.

AIM: This study aims to explore the expression and role of CD72 in B lymphocytes in immune thrombocytopenic purpura (ITP). METHODS: The expression level of CD72 in B lymphocytes was detected by flow cytometry in 18 ITP patients and 19 controls of healthy donor or iron-deficiency anemia patients. B cell proliferation was determined by 5-bromo-2'-deoxyuridine incorporation (BrdU) in the culture of 17 ITP patients' and 11 controls' peripheral mononuclear cells (PMNCs). The secretion levels of antibodies against human platelet antigens (HPA), as well as B cell proliferation-related cytokine interleukin 1(IL-1) and macrophage migration inhibitory factor (MIF) in culture supernatants were measured by ELISA. RESULTS: CD72 was significantly increased in B cells of newly diagnosed or persistent ITP compared with ITP in remission. B cell proliferation in culture with CD72 antibody addition was significantly decreased both in ITP patients and in controls compared with isotype antibody addition. CD72 antibody did not significantly alter HPA antibody level in ITP patients. CD72 antibody increased IL-1 and MIF levels in ITP patients' cell culture supernatant but not in controls. CONCLUSION: CD72 expression elevation accompanies the active status of ITP. In vitro addition of CD72 antibody has a negative impact on B cell proliferation. The function of CD72 in B cell proliferation in ITP may be related to IL-1 and MIF secretion.

Single-cell transcriptomic analyses of cardiac immune cells reveal that Rel-driven CD72-positive macrophages induce cardiomyocyte injury.

AIMS: The goal of our study was to investigate the heterogeneity of cardiac macrophages (CMφs) in mice with transverse aortic constriction (TAC) via single-cell sequencing and identify a subset of macrophages associated with heart injury. METHODS AND RESULTS: We selected all CMφs from CD45+ cells using single-cell mRNA sequencing data. Through dimension reduction, clustering, and enrichment analyses, CD72hi CMφs were identified as a subset of pro-inflammatory macrophages. The pseudo-time trajectory and ChIP-Seq analyses identified Rel as the key transcription factor that induces CD72hi CMφ differentiation. Rel KD and Rel-/- bone marrow chimaera mice subjected to TAC showed features of mitigated cardiac injury, including decreased levels of cytokines and ROS, which prohibited cardiomyocyte death. The transfer of adoptive Rel-overexpressing monocytes and CD72hi CMφ injection directly aggravated heart injury in the TAC model. The CD72hi macrophages also exerted pro-inflammatory and cardiac injury effects associated with myocardial infarction. In humans, patients with heart failure exhibit increased CD72hi CMφ levels following dilated cardiomyopathy and ischaemic cardiomyopathy. CONCLUSION: Bone marrow-derived, Rel-mediated CD72hi macrophages play a pro-inflammatory role, induce cardiac injury and, thus, may serve as a therapeutic target for multiple cardiovascular diseases.

Truncated-semaphorin3A is a potential regulatory molecule to restore immune homeostasis in immune-mediated diseases.

Regulatory molecules have recently been recognized for their beneficial effects in the treatment of immune-mediated diseases, rather than using cytotoxic immune-suppressing drugs, which are associated with many unwanted side effects. Semaphorin3A (sema3A), a unique regulatory master of the immune system, was shown to be decreased in the serum of systemic lupus erythematosus (SLE) patients, in association with disease severity. Later, we were able to show its extremely beneficial effect in treating lupus nephritis in the NZB/W mice model. The mechanisms by which sema3A maintains its regulatory effect is by binding the regulatory receptor CD72 on B cells, thereby reducing the threshold of BCR signaling on B cells and reducing the production of pro-inflammatory cytokines. The aim of this study was to generate a stable sema3A molecule, easy to produce with a higher binding capacity to CD72 receptor rather than to Neuropilin-1 (NRP-1) receptor, which is expressed in many cell types. Using the crystallographic structure of parental sema3A, we synthesized a new secreted (shorter) sema3A derivative, which we called truncated sema3A (T-sema3A). The new molecule lacked the NRP-1 binding domain (the C-terminal site) and has an artificial dimerization site at position 257 (serine residue was exchanged with a cysteine residue). To facilitate the purification of this molecule we added Histidine epitope tag in frame upstream to a stop codon. This construct was transfected using a viral vector to 293HEK cells to generate cells stably expressing T-sema3A. T-sema3A is shown to be with a higher binding ability to CD72 than to NRP-1 as demonstrated by a homemade ELISA. In addition, T-sema3A was shown to be a regulatory agent which can induce the expression of IL-10 and TGF-ß and reduce the secretion of pro-inflammatory cytokines such as IL-6, IFN-γ, and IL-17A from human T and B-lymphocytes. Keeping this in mind, T-sema3A is highly effective in maintaining immune homeostasis, therefore, becoming a potential agent in restoring the regulatory status of the immune system in immune-mediated diseases.

[Relapsing-remitting multiple sclerosis: clinical and immunological aspects of the pathology on the example of molecules Sema4D and CD72]. / Remittiruyushchii rasseyannyi skleroz: kliniko-immunologicheskie aspekty patologii na primere molekul Sema4D i CD72.

OBJECTIVE: To study the expression of Sema4D (CD100), receptor CD72 and a role of Sema4D-CD72-dependent signal in the control of the functions of immunocompetent cells in relapsing-remitting multiple sclerosis (RRMS). MATERIAL AND METHODS: We studied 76 patients, including 52 with RRMS (41 in remission and 11 in exacerbation), 35 women (67.3%) and 17 men (32.7%) aged 18-55 years, who did not receive disease-modifying drugs, and 24 healthy donors. A controlled clinical and immunological examination of patients with RRMS was carried out proving the involvement of the Sema4D molecule and its CD72 receptor in pathological reactions in this autoimmune disease. RESULTS AND CONCLUSION: The use of SemaD as a target in the treatment of RRMS is scientifically substantiated. In case of a positive decision on the use of anti-Sema4D drugs, it will be necessary to take into account the effects of semaphorin not only in the central nervous system, but also in the immune system of patients with RRMS.