Regulatory B cells: origin, phenotype, and function

Mixed cryoglobulinemia decelerates hepatocellular carcinoma development in hepatitis C patients with SVR by downregulating regulatory B cells: a 12-year prospective cohort study

How mixed cryoglobulinemia (MC) affects cancer risk in chronic hepatitis C patients with sustained virologic response (SVR) remains unclear. In a 12-year prospective study, post-SVR MC was assessed every 3‒6 months. Among the 891 SVR patients, 265 (29.7%) had baseline (24 weeks after completing anti-HCV therapy) MC, and the 12-year cancer cumulative incidence was 19.7%. Among the 73 patients who developed cancer, 37 (50.7%) had hepatocellular carcinoma (HCC), with the following associated baseline variables: for cancer, male sex, age and alanine aminotransferase (ALT) levels; for HCC, male sex, age, and cirrhosis; and for non-HCC cancer, rheumatoid factor levels. Among patients with post-SVR HCC, the mean time to HCC was longer in those with than in those without baseline MC (1545.4 ± 276.5 vs. 856.9 ± 115.2 days, p = 0.014). Patients with baseline MC had decreased circulating interleukin-10 (IL-10)-positive B cell (CD19+IL-10+cells/CD19+cells) (31.24 ± 16.14 vs. 40.08 ± 15.42%, p = 0.031), regulatory B cell (Breg) (CD19+CD24hi CD27+cells/CD19+cells) (10.45 ± 7.10 vs. 15.76 ± 9.14%, p = 0.035), IL-10-positive Breg (CD19+CD24hiCD27+IL-10+cells/CD19+cells) (5.06 ± 4.68 vs. 8.83 ± 5.46%, p = 0.015) and HCC-infiltrating Breg (18.6 ± 10 vs. 33.51 ± 6.8%, p = 0.022) ratios but comparable circulating and HCC-infiltrating regulatory T cell ratios relative to patients without baseline MC. In conclusion, old male SVR patients with elevated ALT levels or cirrhosis require intensive monitoring for cancer development, especially HCC. Tailored HCC follow-up is needed for SVR patients according to their baseline MC, which might downregulate Bregs to decelerate HCC development for almost 2 years.

The remodeling of B-cell subsets was correlated with the clearance of hepatitis B antigen during pegylated IFN α-2a therapy in CHB patients

BACKGROUND

B-cell may participate in the cellular immune process of hepatitis B antigen clearance. However, the function and specific mechanism of B-cell during interferon-pegylated interferon α-2a (Peg-IFN-α) treatment in chronic hepatitis B (CHB) patients have not yet been described.

METHODS

A total of 150 CHB patients enrolled in this study, who received 48 weeks of Peg-IFN α treatment. The differentiation clusters CD19, CD24, CD27, CD38, CD40, and CD80 of B cell surface markers in CHB patients were detected by flow cytometry. Spearman correlation and Logistic regression analysis were performed for the analysis.

RESULTS

The clearance rate of HBsAg increased significantly with the duration of Peg-IFN-α treatment, reaching 32.2% by 48 weeks. During the Peg-IFN-α therapy, the frequency of B-cell and its subsets increased significantly. However, we did not observe any significant difference in the frequency of the B-cell and its subsets in patients with or without HBsAg clearance after 48 weeks Peg-IFN-α treatment. The change in HBsAg value was negatively related to the change in plasmablasts (CD19+CD38+) level before and after 48 weeks treatment (r = -0.326, p = 0.006). Moreover, the results showed that HBsAg <288.70 IU/mL at baseline and HBsAg <58.05 IU/mL at 12 weeks were strong predictors of HBsAg clearance in patients with 48 weeks Peg-IFN-α treatment.

CONCLUSION

The remodeling of B cell subsets, especially plasmablasts (CD19+CD38+), during Peg-IFN-α treatment was closed associated with the clearance of hepatitis B antigen.

Tumor immune microenvironment remodeling after neoadjuvant therapy in gastric cancer: Update and new challenges

Gastric cancer (GC) is a malignant tumor with one of the highest morbidity and death rates in the world. Neoadjuvant therapy, including neoadjuvant chemotherapy (NAC) and NAC combined with immunotherapy, can improve the resection and long-term survival rates. However, not all patients respond well to neoadjuvant therapy. It has been confirmed that immune cells in the tumor immune microenvironment, including T cells, B cells, and natural killer cells, can affect the efficacy of neoadjuvant therapy. This paper summarizes current preclinical and clinical evidence to more fully describe the effects of neoadjuvant therapy on the immune microenvironment of GC, to provide the impetus to identify biomarkers to predict the potency of neoadjuvant therapy, and to identify the mechanisms of drug resistance, which should promote the development of individualized and accurate treatments for GC patients.

Expanding Human Breg for Cellular Therapy in Transplantation: Time for Translation

Regulatory B cells (Breg) are instrumental in protecting allografts in transplantation. Breg signatures are identified in operationally tolerant human kidney transplant recipients and can predict organ survival and acute rejection. Animal models of transplantation and autoimmunity support the use of Breg as an adoptive cellular therapy. Detailed mechanistic studies have identified multiple signaling pathways utilized by Breg in their induction, expansion, and downstream function. These preclinical studies provide the guiding principles, which will inform protocols by which to expand this crucial immunoregulatory population before clinical use. There is an urgent need for novel therapies to improve long-term transplant outcomes and to minimize immunosuppression-related morbidity including life-threatening infection and cancer. Systematic evaluation of the signals, which drive Breg expansion, will be key to transforming the as of yet unharnessed potential of this potent immunoregulatory cell. In this review, we explore the potential avenues of translating Breg subsets from cell culture at the laboratory bench to cell therapy at the patient's bedside. We will discuss the standardization of Breg phenotypes to aid in precursor population selection and quality control of a Breg-cell therapy product. We will evaluate avenues by which to optimize protocols to drive human Breg expansion to levels sufficient for cellular therapy. Finally, we will examine the steps required in process development including scalable culture systems and quality control measures to deliver a viable Breg-cell therapy product for administration to a transplant recipient.

Immunosenescence in autoimmune diseases

Autoimmune diseases (AIDs) are a group of disorders in which the immune system mistakenly attacks the body's own tissues, characterized by the loss of tolerance to self-antigens and destruction of tissues. Aging is a natural process of physiological decline that also alters the immune system, a condition known as immunosenescence. During immunosenescence, the immune system undergoes various changes, including modifications and antigenicity of self-antigens, abnormalities in the quantity, phenotype, and function of lymphocytes and antibodies, as well as a narrowing of the B and T cell receptor repertoire, changes that may increase susceptibility to AIDs. Additionally, senescent immune cells and the senescence-associated secretory phenotype (SASP) contribute to target organ involvement in AIDs, exacerbating chronic inflammation and tissue damage. Mitochondrial dysfunction and metabolic imbalances in AIDs lead to the accumulation of senescent cells, which act as upstream drivers of immunosenescence. In this review, we summarize the bidirectional relationship between AIDs and immunosenescence, as well as its potential mechanisms. Therapeutic approaches targeting immunosenescence in AIDs remain at an early stage. Strategies aimed at resetting or reversing the aging immune system are expected to become a novel direction in the future.

Rapamycin-modified CD169low/-tolDC promotes skin graft survival in mice via IL-10+Breg

Skin allografts are prone to rejection because of their high immunogenicity. By achieving immune tolerance, the long-term survival of skin allografts can be extended without the need for immunosuppressants or with only short-term low-dose dependency. Tolerogenic dendritic cells (tolDCs) show a strong potential for graft tolerance. We explored the mechanism whereby rapamycin-modified CD169low/-tolDCs regulate interleukin-10 (IL-10) B regulatory (IL-10+ Breg) cell production and mediate the long-term survival of skin allografts in mice. CD169low/-tolDCs were obtained through flow cytometry sorting after treating the mesenchymal stem cell (MSC)-derived dendritic cells with a low dose of GM-CSF. A treatment regimen combining preoperative stimulation and postoperative adoptive infusion of CD169low/-tolDCs was used to treat an acute rejection (AR) mouse skin transplantation model-the adoptive infusion group. An equivalent dose of saline was administered to the control group. Survival and graft rejection rates were assessed. Mixed lymphocyte culture, flow cytometry, immunohistochemistry (IHC), and western blotting (WB) were used to elucidate the expression of different IL-10+ Breg subsets in mice treated with adoptive infusion therapy and the molecular mechanisms whereby CD169low/-tolDCs induce IL-10+ Breg production to mediate tolerance. Adoptive infusion of CD169low/-tol DCs markedly prolonged the rejection time after skin transplantation in mice and promoted graft survival. A significant increase was observed in local blood flow signals in the transplanted skin, along with mild local inflammation. Flow cytometric analysis revealed a positive correlation between high expression of IL-10+ Breg and the changes in Foxp3+ Tregs in vivo, primarily enriched in the CD19 + CD24 + CD27+ mBreg and CD19 + CD23 + CD27-CD24+ Breg subsets, with higher levels of IgM expression. Significant differences were observed compared with control mice. CD79b/NF-κB pathway was found to be involved in Breg production. CD24, CD23, CD79, BTK, NF-κB p50/p65, CD40, and IKKα levels in the adoptive infusion group were significantly increased compared with those in the control group. Adoptive infusion of CD169low/-MSCs/tolDCs may activate the NF-κB pathway through CD79/BTK-dependent and CD40/IKKα-independent pathways, inducing high expression of IL-10 + Breg and promoting graft survival of mouse skin transplantation.

Maternal probiotic supplementation and effects on the fetal placenta

Increasing number of pregnant women are consumi ng probiotics to promote their own health and that of their unborn fetuses. Such supplements are presumed to be safe for pregnant mothers and their unborn offspring. For pregnant mothers, such bioactive compounds might lower the risk of constipation, diarrhea, other gastrointestinal conditions, and pre-term birth, and prevent adverse pregnancy outcomes, including gestational diabetes mellitus and depression/anxiety. More research is needed to examine potential safety of probiotic consumption during pregnancy and long-term health consequences to offspring. The conceptus can also be indirectly affected by maternal probiotic supplementation through microorganism production of bioactive compounds. The placenta is in direct communication with the underlying uterine tissue. Thus, compounds in the maternal blood can easily transfer across the placenta and impact this hormonally sensitive organ. Select studies suggest that disruptions to the maternal microbiome dramatically affect the placenta. In the current review, we will therefore consider the evidence to date of how maternal probiotic supplementation affects the placenta. Three potential mechanisms we will explore include the possibility that maternal probiotic supplementation might impact the putative placenta microbiome. The second potential mechanism we will consider is that maternal probiotic consumption alters bacterial-derived metabolites, including short-chained fatty acids, polyamines, Vitamin B9, and Vitamin B12. The third potential mechanism to be discussed is that such supplements affect maternal and placental immune responses. Before probiotics are promoted for healthy pregnant women and those with gestational disorders, more studies, including those examining the effects on the placenta, are essential.

B cells modulate lung antiviral inflammatory responses via the neurotransmitter acetylcholine

The rapid onset of innate immune defenses is critical for early control of viral replication in an infected host and yet it can also lead to irreversible tissue damage, especially in the respiratory tract. Sensitive regulators must exist that modulate inflammation, while controlling the infection. In the present study, we identified acetylcholine (ACh)-producing B cells as such early regulators. B cells are the most prevalent ACh-producing leukocyte population in the respiratory tract demonstrated with choline acetyltransferase (ChAT)-green fluorescent protein (GFP) reporter mice, both before and after infection with influenza A virus. Mice lacking ChAT in B cells, disabling their ability to generate ACh (ChatBKO), but not those lacking ChAT in T cells, significantly, selectively and directly suppressed α7-nicotinic-ACh receptor-expressing interstitial, but not alveolar, macrophage activation and their ability to secrete tumor necrosis factor (TNF), while better controlling virus replication at 1 d postinfection. Conversely, TNF blockade via monoclonal antibody treatment increased viral loads at that time. By day 10 of infection, ChatBKO mice showed increased local and systemic inflammation and reduced signs of lung epithelial repair despite similar viral loads and viral clearance. Thus, B cells are key participants of an immediate early regulatory cascade that controls lung tissue damage after viral infection, shifting the balance toward reduced inflammation at the cost of enhanced early viral replication.

Immunomodulatory mechanisms driving tumor escape in glioblastoma: The central role of IDO and tryptophan metabolism in local and systemic immunotolerance

BACKGROUND

Glioblastoma (GBM) is the most aggressive primary brain tumor exhibiting extensive immune evasion mechanisms that hinder effective therapeutic interventions. This narrative review explores the immunomodulatory pathways contributing to tumor escape in GBM, specifically focusing on the role of Tryptophan (TRP) metabolism and its downstream mediators Tryptophan metabolism through the kynurenine pathway (KP) is initiated by indoleamine 2,3-dioxygenase (IDO) and tryptophan-2,3-dioxygenase (TDO2) enzymes and serves as a crucial mechanism for promoting an immunosuppressive microenvironments and systemic immunotolerance. Emerging evidence also indicates a non-enzymatic role for IDO1 signaling in these processes. The downstream effectors interact with immune cells, inducing local immunosuppression within the tumor microenvironment and altering peripheral immune responses.

METHODS

We systematically reviewed databases (MEDLINE via PubMed, Science Direct, and Embase) through October 2024 to highlight the interplay between local immune escape mechanisms and circulating immunotolerance, emphasizing the role of TRP metabolic enzymes in supporting GBM progression.

RESULTS

The literature review identified 99 records. TRP-related mechanisms play a central role in fostering immunotolerance in GBM. These phenomena involve intricate interactions between the infiltrating and circulating myeloid and lymphoid compartments, ultimately shaping a tolerant, pro-tumoral environment and the peripheral immunophenotype.

CONCLUSIONS

The biological activity of IDO1 and TRP metabolites positions these compounds as potential markers of disease activity and promising molecular targets for future therapeutic approaches.

The Critical Role of Regulatory T Cells in Immune Tolerance and Rejection Following Liver Transplantation: Interactions With the Gut Microbiome

Liver transplantation (LT) is the ultimate treatment for patients with end-stage liver disease or early hepatocellular carcinoma. In the context of LT, because of the unique immunological characteristics of human liver allograft, 5%-20% of selected LT recipients can achieve operational tolerance. Nonetheless, there remains a risk of rejection in LT patients. Maintaining immune homeostasis is thus crucial for improving clinical outcomes in these patients. In mechanism, several immune cells, including dendritic cells, Kupffer cells, myeloid-derived suppressor cells, hepatic stellate cells, regulatory B cells, and CD4 + regulatory T cells (Treg), contribute to achieving tolerance following LT. In terms of Treg, it plays a role in successfully minimizing immunosuppression or achieving tolerance post-LT while also reducing the risk of rejection. Furthermore, the gut microbiome modulates systemic immune functions along the gut-liver axis. Recent studies have explored changes in the microbiome and its metabolites under various conditions, including post-LT, acute rejection, and tolerance. Certain functional microbiomes and metabolites exhibit immunomodulatory functions, such as the augmentation of Treg, influencing immune homeostasis. Therefore, understanding the mechanisms of tolerance in LT, the role of Treg in tolerance and rejection, as well as their interactions with gut microbiome, is vital for the management of LT patients.

Tumor-infiltrating and circulating B cells mediate local and systemic immunomodulatory mechanisms in Glioblastoma

BACKGROUND

Glioblastoma (GBM) demonstrates extensive immunomodulatory mechanisms that challenge effective therapeutic interventions. These phenomena extend well beyond the tumor microenvironment (TME) and are reflected in the circulating immunophenotype. B lymphocytes (B cells) have received limited attention in GBM studies despite their emerging importance in mediating both local and systemic immune responses. Recent findings highlight the complex regulatory interactions between B cells and other immune cell populations, including tumor-infiltrating macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), and other infiltrating lymphocytes (TILs). B cells are believed to hinder the efficacy of modern immunotherapy strategies focusing on T cells.

METHODS

This is a focused review of available evidence regarding B cells in GBM through January 2025.

RESULTS

Peripheral blood reflects a systemically dampened immune response, with sustained lymphopenia, increased plasma cells, and dysfunctional memory B cells. The tumor immune landscape is enriched in cells of B-lineage. Subsets of poorly characterized B regulatory cells (Bregs) populate the TME, developing their phenotype due to their proximity to MDSCs, TAMs, and tumoral cells. The Bregs inhibit CD8+ T activity and may have potential prognostic significance.

CONCLUSION

Understanding the role of B cells, how they are recruited, and their differentiation shifted towards an immunomodulatory role could inform better therapeutic strategies and unleash their full antitumoral potential in GBM.

Heterogeneity of the tumor immune cell microenvironment revealed by single-cell sequencing in head and neck cancer

Head and neck cancer (HNC) is the sixth most common disease in the world. The recurrence rate of patients is relatively high, and the heterogeneity of tumor immune microenvironment (TIME) cells may be an important reason for this. Single-cell sequencing (SCS) is currently the most promising and mature application in cancer research. It can identify unique genes expressed in cells and study tumor heterogeneity. According to current research, the heterogeneity of immune cells has become an important factor affecting the occurrence and development of HNC. SCSs can provide effective therapeutic targets and prognostic factors for HNC patients through analyses of gene expression levels and cell heterogeneity. Therefore, this study analyzes the basic theory of HNC and the development of SCS technology, elaborating on the application of SCS technology in HNC and its potential value in identifying HNC therapeutic targets and biomarkers.

The immune tolerance role of Bregs in inhibiting human inflammatory diseases, with a focus on diabetes mellitus

Regulatory B cells (Bregs) are pivotal modulators of immune tolerance, suppressing inflammation through cytokine secretion and cellular interactions. Their role is particularly significant in inflammatory diseases such as type 1 and type 2 diabetes mellitus (T1DM and T2DM), where immune dysregulation contributes to disease progression. In T1DM, Bregs mitigate β-cell autoimmunity via IL-10 production and FOXP3-mediated pathways, but genetic mutations and dysfunctions in these mechanisms exacerbate autoimmunity. In T2DM, chronic inflammation and metabolic stress impair Breg numbers and function, further fueling insulin resistance. While Bregs play a central role in T1DM by directly preventing β-cell destruction, their role in T2DM is more supportive, modulating inflammation in metabolically stressed tissues. Emerging therapeutic strategies aim to enhance Breg function through IL-10 induction, ex vivo expansion, or targeting Breg-specific pathways using gene-editing and small molecules. Future research should explore Breg heterogeneity, novel markers, and personalized therapies to unlock their full potential. Understanding and leveraging the immune tolerance role of Bregs may offer transformative strategies to inhibit inflammatory diseases like diabetes mellitus.

The influence of the gut microbiota on B cells in autoimmune diseases

Mounting evidence shows that gut microbiota communities and the human immune system coexist and influence each other, and there are a number of reports of a correlation between specific changes in gut microbiota and the occurrence of autoimmune diseases. B lymphocytes play a central role in the regulation of both gut microbiota communities and in autoimmune diseases. Here, we summarize evidence of the influence of gut microbiota-B cell pathways on autoimmune diseases and how B cells regulate microorganisms, which provides mechanistic insights with relevance for identification of potential therapeutic targets and related fields.

Immunological Avalanches in Renal Immune Diseases

The complex nature of immune system behavior in both autoimmune diseases and transplant rejection can be understood through the lens of avalanche dynamics in critical-point systems. This paper introduces the concept of the "immunological avalanche" as a framework for understanding unpredictable patterns of immune activity in both contexts. Just as avalanches represent sudden releases of accumulated potential energy, immune responses exhibit periods of apparent stability followed by explosive flares triggered by seemingly minor stimuli. The model presented here draws parallels between immune system behavior and other complex systems such as earthquakes, forest fires, and neuronal activity, where localized events can propagate into large-scale disruptions. In autoimmune conditions like systemic lupus erythematosus (SLE), which affects multiple organ systems including the kidneys in approximately 50% of patients, these dynamics manifest as alternating periods of remission and flares. Similarly, in transplant recipients, the immune system exhibits metastable behavior under constant allograft stimulation. This critical-point dynamics framework is characterized by threshold-dependent activation, positive feedback loops, and dynamic non-linearity. In autoimmune diseases, triggers such as UV light exposure, infections, or stress can initiate cascading immune responses. In transplant patients, longitudinal analysis reveals how monitoring oscillatory patterns in blood parameters and biological age markers can predict rejection risk. In a preliminary study on kidney transplant, all measured variables showed temporal instability. Proteinuria exhibited precise log-log linearity in power law analysis, confirming near-critical-point system behavior. Two distinct dynamic patterns emerged: large oscillations in eGFR, proteinuria, or biological age predicted declining function, while small oscillations indicated stability. During avalanche events, biological age increased dramatically, with partial reversal leaving persistent elevation after acute episodes. Understanding these dynamics has important implications for therapeutic approaches in both contexts. Key findings suggest that monitoring parameter oscillations, rather than absolute values, better indicates system instability and potential avalanche events. Additionally, biological age calculations provide valuable prognostic information, while proteinuria measurements offer efficient sampling for system dynamics assessment. This conceptual model provides a unifying framework for understanding the pathogenesis of both autoimmune and transplant-related immune responses, potentially leading to new perspectives in disease management and rejection prediction.

Phenotypic Diversity of Immunosuppressive B Cells Associated in Urothelial Carcinoma of the Bladder

BACKGROUND

Urothelial carcinoma of the bladder presents a complex tumor microenvironment, with tumor-infiltrating B cells (TIL-Bs) playing a significant role in disease progression. Although their presence is acknowledged, the phenotypic diversity of regulatory TIL-Bs in bladder cancer remain underexplored.

MATERIALS AND METHODS

In this study, we evaluated core B cell subsets and their immunosuppressive phenotypes in both peripheral blood (n=40) and bladder tumor tissues (n=40) to evaluate their relationship with disease severity.

RESULTS

Our findings revealed that high-grade bladder tumors are enriched with B cells and their subsets, particularly transitional B cells and plasmacytes (plasmablasts and plasma cells). However, total memory B cells were reduced in the tumor microenvironment compared to non-tumor tissues. It was further revealed that the high-grade tumors demonstrated significant infiltration of regulatory B cells (Breg), with elevated levels of IL10+ and TGFβ+ Breg cells as well as IL-10+TGF-β+ dual-cytokine-secreting Breg cells, suggesting their role in fostering an immunosuppressive microenvironment. Memory B cells demonstrated the highest frequency of Breg phenotypes among the B cell subsets. Additionally, Tertiary Lymphoid Structure formation and frequency were associated with disease severity, the differentiated B cells and IL10+ Breg cell counts, emphasizing the importance of these structures in bladder cancer progression and the potential involvement in Breg cells formation.

CONCLUSION

This study demonstrates the enrichment of the bladder cancer tumor microenvironment with diverse B cell subsets, including functional Breg cells, which correlates with disease severity.

Indoleamine 2,3-dioxygenase 1 alters the proportions of B cell subpopulations in the microenvironment of acute myeloid leukemia

Acute myeloid leukemia (AML), the most common leukemia in adults, exhibits immune escape characteristics like solid tumors. The expression of indoleamine 2,3-dioxygenase 1 (IDO1), a well-recognized immune checkpoint, has been detected in AML blast cells and is associated with poor clinical outcome. Although an imbalance of B cell subpopulations exists in AML patients' bone marrow microenvironment, the role of B cells and their interaction with IDO1 in AML have yet to be elucidated. Herein, with bioinformatic analysis, we found the close correlations between IDO1 expression and survival and B cell subpopulation proportions in AML patients. Further, our investigation into IDO1 expression and activity, B cell subpopulation proportions and immunosuppressive interleukin-10 (IL-10) level in AML cells and clinical samples revealed significant findings. Using a co-culture system of healthy human PBMCs and AML cell lines, we demonstrated that high IDO1 expression in AML cells could alter the proportions of total B, regulatory B and memory B cells, and increased the level of IL-10. Finally, with the IDO1 inhibitor RY103 designed by our laboratory, we found that IDO1 inhibition had good anti-leukemic effect and restored the abnormal proportions of B cell subpopulations in AML mice. Our study is the first to reveal the modulation of IDO1 on B cell subpopulations in AML, making a significant breakthrough in understanding the immune escape mechanisms of AML. Application of IDO1 inhibitor, such as RY103, targeting the imbalance of B cell subpopulations can lead to innovative treatments for AML.

Regulatory B cells, the key regulator to induce immune tolerance in organ transplantation

In solid organ transplantation, especially renal transplantation, for the induction of immune tolerance, accumulating evidence has revealed that Regulatory B cells (Breg) play a crucial role in stimulating immune tolerance, alleviating immune responses, and improving graft survival. We describe the heterogeneous nature of Bregs, focusing on their defining surface markers and regulatory functions. Meanwhile, the major cytokine secretion function and the correlation between Breg and Treg or other immune checkpoints to balance the immune responses are addressed. Furthermore, we summarized the intrinsic and extrinsic pathways or costimulatory stimuli for the differentiation from naïve B cells. More importantly, we summarized the progression of the immune tolerance induction role of Breg in solid organ (kidney, liver, heart, lung, and islet) transplantation. This is an up-to-date review from the origin of Breg to the function of Breg in solid organ transplantation and how it induces immune tolerance in both murine models and human solid organ transplantation.

Immune cell traits and causal relationships with cholecystitis: a mendelian randomization analysis

Cholecystitis, characterized by inflammation of the gallbladder, is intricately linked to immune cells and the cytokines they produce. Despite this association, the specific contributions of immune cells to the onset and progression of cholecystitis remain to be fully understood. To delineate this relationship, we utilized the Mendelian randomization (MR) method to scrutinize the causal connections between 731 immune cell phenotypes and cholecystitis. By conducting MR analysis on 731 immune cell markers from public datasets, this study seeks to understand their potential impact on the risk of cholecystitis. It aims to elucidate the interactions between immune phenotypes and the disease, aiming to lay the groundwork for advancing precision medicine and developing effective treatment strategies for cholecystitis. Taking immune cell phenotypes as the exposure factor and cholecystitis as the outcome event, this study used single nucleotide polymorphisms (SNPs) closely associated with both immune cell phenotypes and cholecystitis as genetic instrumental variables. We conducted a two-sample MR analysis on genome-wide association studies (GWAS) data. Our research thoroughly examined 731 immune cell markers, to determine potential causal relationships with susceptibility to cholecystitis. Sensitivity analyses were performed to ensure the robustness of our findings, excluding the potential impacts of heterogeneity and pleiotropy. To avoid reverse causality, we conducted reverse MR analyses with cholecystitis as the exposure factor and immune cell phenotypes as the outcome event. Among the 731 immune phenotypes, our study identified 21 phenotypes with a causal relationship to cholecystitis (P < 0.05). Of these, eight immune phenotypes exhibited a protective effect against cholecystitis (odds ratio (OR) < 1), while the other 13 immune phenotypes were associated with an increased risk of developing cholecystitis (OR > 1). Additionally, employing the false discovery rate (FDR) method at a significance level of 0.2, no significant causal relationship was found between cholecystitis and immune phenotypes. Our research has uncovered a significant causal relationship between immune cell phenotypes and cholecystitis. This discovery not only enhances our understanding of the role of immune cells in the onset and progression of cholecystitis but also establishes a foundation for developing more precise biomarkers and targeted therapeutic strategies. It provides a scientific basis for more effective and personalized treatments in the future. These findings are expected to substantially improve the quality of life for patients with cholecystitis and mitigate the impact of the disease on patients and their families.

Therapeutic efficacy of rituximab combined with cyclosporin A on B-cell dysregulation in chronic graft-versus-host disease

OBJECTIVE

Chronic graft-versus-host disease (cGVHD) is a significant complication following allogenic hematopoietic stem cell transplantation, often necessitating therapeutic interventions such as rituximab (RTX) and cyclosporin A (CsA). This study aims to elucidate the mechanisms by which RTX and CsA jointly address B-cell dysregulation in cGVHD, providing a theoretical foundation and scientific rationale for the treatment and prognostic evaluation of this condition.

METHODS

A total of 30 cGVHD mouse models were established by subjecting recipient mice to total body irradiation followed by injection of a mixed suspension of bone marrow cells and splenocytes from donor mice. From Day 2 to Day 29 post-model establishment, the mice received subcutaneous administration of RTX and CsA. Throughout the study, body weight, clinical cGVHD scores, and survival rates were monitored. Blood samples were collected via the orbital venous plexus. Serum levels of B-cell activating factor (BAFF) and pro-inflammatory factors were measured using enzyme-linked immunosorbent assay (ELISA), and the ratio of regulatory B cells (Bregs) in the blood sample was assessed via flow cytometry.

RESULTS

Mice with cGVHD exhibited a 14.5% decrease in body weight, elevated clinical scores, and more severe symptoms compared to the control group. Notably, all mice in both the cGVHD and control groups survived until the conclusion of the study. Induction of cGVHD resulted in B-cell dysregulation, evidenced by elevated serum BAFF levels and a decreased proportion of Bregs. However, treatment with RTX combined with CsA ameliorated B-cell dysregulation and significantly reduced serum levels of pro-inflammatory factors in cGVHD mice, with decreases of 39.78% in TNF-α and 37.89% in IL-6.

CONCLUSION

The combination of RTX and CsA effectively mitigates B-cell dysregulation in cGVHD, thereby reducing the severity and progression of the disease.

Aberrations in peripheral B lymphocytes and B lymphocyte subsets levels in Parkinson disease: a systematic review

Objective

The association of B lymphocytes and B lymphocyte subsets and Parkinson's disease (PD) is increasingly acknowledged. However, there is inconsistence in the alterations of B lymphocytes or B lymphocyte subsets in peripheral blood of PD patients. To comprehensively understand its changes in PD patients,it is necessary to conduct a systematic review on this subject.

Methods

PubMed, Cochrane Library, and MEDLINE databases were searched until 3rd February 2024.

Results

We included 20 studies (n=2658) to conduct this systematic review. We conducted a qualitative analysis to assess the alterations of B lymphocytes and B lymphocyte subsets in the peripheral blood of individuals with PD. And studies reviewed demonstrated a significant decrease in the number of B cells, as well as immune dysregulation in the B lymphocyte subsets of these patients' peripheral blood.

Conclusion

Studies reviewed demonstrated that PD is linked to abnormalities in B lymphocytes and/or B lymphocytes subsets in peripheral blood. This study provides a novel perspective into the pathogenesis of PD, and future investigations into the B lymphocytes and/or B lymphocyte subsets as biomarkers and therapeutic targets for PD is warranted.

PD-L1+ plasma cells suppress T lymphocyte responses in patients with sepsis and mouse sepsis models

Sepsis, a leading cause of death in intensive care units, is associated with immune alterations that increase the patients' risk of secondary infections and mortality, so better understandings of the pathophysiology of sepsis-induced immunosuppression is essential for the development of therapeutic strategies. In a murine model of sepsis that recapitulates immune alterations observed in patients, here we demonstrate that PD-L1+CD44+B220LowCD138+IgM+ regulatory plasma cells are induced in spleen and regulate ex vivo proliferation and IFNɣ secretion induced by stimulation of T splenocytes. This effect is mediated both by cell-cell contact through increased PD-L1 expression on plasma cells and by production of a soluble factor. These observations are recapitulated in three cohorts of critically ill patients with bacterial and viral sepsis in association with increased mortality. Our findings thus reveal the function of regulatory plasma cells in the pathophysiology of sepsis-induced immune alterations, and present a potential therapeutic target for improving immune cell function impaired by sepsis.

Identification and validation of biomarkers related to ferroptosis in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a kind of interstitial lung disease (ILD). It has a high incidence rate and mortality. Its pathogenesis remains unclear. So far, no effective methods have been found for the early diagnosis of IPF. Ferroptosis has been reported to be critical in the initiation and progression of IPF. Therefore, our aim was to identify the hub gene related to ferroptosis co-expressed in the peripheral blood and pulmonary tissue of patients with IPF. Sequencing data were obtained from the Gene Expression Omnibus database. A comprehensive analysis was conducted on the differentially expressed genes (DEGs) to extract ferroptosis-related differentially expressed genes (FRDEGs). The results showed that ferroptosis-related signal paths were highly enriched in IPF, and 10 FRDEGs were identified.The hub gene was predicted through protein-protein interactions (PPI) and Cytoscape. The diagnostic utility of the hub gene was proven by enzyme-linked immunosorbent assay (ELISA) in serum and by immunohistochemistry (IHC) in pulmonary tissues. The results of ELISA indicated that the levels of ATM in the serum of patients with IPF were significantly lower than the normal levels. In contrast, the results of IHC showed that the expression of ATM in the pulmonary tissues of IPF patients exhibited a notably elevated trend. The immune status was assessed by the CIBERSORT method and so was the relevance between ATM and immune cells. These findings unveiled significant differences in various immune cell types in peripheral blood and pulmonary tissue between the IPF group and the control group. Furthermore, ATM was associated with various immune cells. This study suggests that as a ferroptosis-related gene, ATM assumes a pivotal role in the diagnosis and treatment of IPF. This discovery presents a novel approach for the clinical diagnosis and therapy of IPF.

The effect of TIM1+ Breg cells in liver ischemia-reperfusion injury

Liver transplantation is the only effective method for end-stage liver disease; however, liver ischemia reperfusion injury (IRI) seriously affects donor liver function after liver transplantation. IRI is a pathophysiological process in which organ damage is aggravated after the blood flow and oxygen supply of ischemic organ tissues are restored. It combines the two stages of hypoxic cell stress triggered by ischemia and inflammation-mediated reperfusion injury. Herein, we studied the protective effect and mechanism of the anti-T cell Ig and mucin domain (TIM1) monoclonal antibody, RMT1-10, on hepatic cell injury induced by IRI. First, a liver IRI model was established in vivo. HE, TEM, and Tunel were used to detect liver tissue injury, changes in the liver ultrastructure and liver cell apoptosis, respectively. ELISA were performed to determine the levels of ALT, AST, MDA, GSH, and related inflammatory factors. We found that RMT1-10 could significantly reduce liver injury. Flow cytometry results showed that the number of TIM1+ regulatory B cells (Bregs) in the IRI liver increased briefly, while pretreatment with RMT1-10 could increase the number of TIM1+ Bregs and interleukin-10 (IL-10) secretion in liver IRI model mice, thus playing a protective role in liver reperfusion. When Anti-CD20 was used to remove B cells, RMT1-10 had a reduced effect on liver IRI. Previous data showed that the number of T helper 1 cells (Th1:CD4+; CD8+) increased significantly after IRI. RMT1-10 inhibited Th1 cells; however, it significantly activated regulatory T cells. Sequencing analysis showed that RMT1-10 could significantly downregulate the expression of nuclear factor-kappa B (NF-κB) pathway-related genes induced by IRI. These results suggested that RMT1-10 could promote the maturation of B cells through an atypical NF-κB pathway, thereby increasing the number of TIM1+ Bregs and associated IL-10 secretion to regulate the inflammatory response, thereby protecting against liver IRI.

Impact of immune cell metabolism on membranous nephropathy and prospective therapy

Membranous nephropathy (MN) is a primary glomerular disease commonly causing adult nephrotic syndrome. Characterized by thickened glomerular capillary walls due to immune complex deposition, MN is a complex autoimmune disorder. Its pathogenesis involves immune deposit formation, complement activation, and a heightened risk of renal failure. Central to MN is immune system dysfunction, particularly the dysregulation of B and T cell responses. B cells contribute to renal injury through the production of autoantibodies, particularly IgG targeting the phospholipase A2 receptor (PLA2R) on podocytes, while T cells modulate immune responses that influence disease progression. Metabolic reprogramming alters lymphocyte survival, differentiation, proliferation, and function, potentially triggering autoimmune processes. Although the link between immune cell metabolism and MN remains underexplored, this review highlights recent advances in understanding immune metabolism and its role in MN. These insights may provide novel biomarkers and therapeutic strategies for MN treatment.

Cross-Talk Between Cancer and Its Cellular Environment-A Role in Cancer Progression

The tumor microenvironment is a dynamic and complex three-dimensional network comprising the extracellular matrix and diverse non-cancerous cells, including fibroblasts, adipocytes, endothelial cells and various immune cells (lymphocytes T and B, NK cells, dendritic cells, monocytes/macrophages, myeloid-derived suppressor cells, and innate lymphoid cells). A constantly and rapidly growing number of studies highlight the critical role of these cells in shaping cancer survival, metastatic potential and therapy resistance. This review provides a synthesis of current knowledge on the modulating role of the cellular microenvironment in cancer progression and response to treatment.

M2 macrophages promote IL-10+B-cell production and alleviate asthma in mice

Introduction

B cells have a central regulatory role in various diseases. While macrophages are found in the disease microenvironment and interact with tissue and diverse immune cells, their relationship with B cells remains poorly explored.

Methods

This study used an asthma animal model and macrophage depletion and demonstrated a significant exacerbation of asthma symptoms upon macrophage removal, coupled with a marked reduction in IL-10+ B-cell expression.

Results

Further analysis revealed that the macrophages interacting with IL-10+ B cells in the asthma microenvironment were of the M2 subtype. Furthermore, our sequencing data indicated a potential mechanism wherein M2 macrophages promote IL-10+ B-cell activity through the TGF-β pathway and oxidative phosphorylation pathways.

Conclusion

These findings suggest that M2 macrophages modulate IL-10+ B cells, ultimately mitigating asthma symptoms in mouse models.

IL-6/IL-12 superfamily of cytokines and regulatory lymphocytes play critical roles in the etiology and suppression of CNS autoimmune diseases

Cytokines influence cell-fate decisions of naïve lymphocytes and determine outcome of immune responses by transducing signals that regulate the initiation, intensity and duration of immune responses. However, aberrant regulation of physiological levels of cytokines contribute to the development of autoimmune and other inflammatory diseases. The Interleukin 6 (IL-6)/IL-12 superfamily of cytokines have a profound influence on all aspects of host immunity and our focus in this review is on the signaling pathways that mediate their functions, with emphasis on how this enigmatic family of cytokines promote or suppress inflammation depending on the physiological context. We also describe regulatory lymphocyte populations that suppress neuroinflammatory diseases by producing cytokines, such as IL-27 (i27-Breg) or IL-35 (i35-Breg and iTR35). We conclude with emerging immunotherapies like STAT-specific Nanobodies, Exosomes and Breg therapy that ameliorate CNS autoimmune diseases in preclinical studies.

The Role of NADPH Oxidase 2 in Leukocytes

NADPH oxidase (NOX) family members are major resources of intracellular reactive oxygen species (ROS). In the immune system, ROS derived from phagocytic NOX (NOX2) participate in both pathogen clearance and signaling transduction. The role of NOX2 in neutrophils and macrophages has been well studied as mutations in NOX2 subunits cause chronic granulomas disease (CGD). NOX2 is expressed across a wide range of immune cells and recent reports have demonstrated that NOX2-derived ROS play important roles in other immune cells during an immune response. In this review, we summarize current knowledge of functions of NADPH oxidase 2 in each subset of leukocytes, as well as associations of NOX2 deficiency with diseases associated specifically with autoimmunity and immune deficiency. We also discuss important knowledge gaps as well as potential future directions for NOX2 research.

Compromised anti-osteoclastogenic and immunomodulatory functions of regulatory B cells (Bregs) aggravate inflammatory bone loss in post-menopausal osteoporosis

Regulatory-B-cells (Bregs) modulate immune-homeostasis. Variations in the number and function of Bregs have been associated with various immune-related ailments, highlighting the importance of Bregs under inflammatory-conditions. Previously, we discovered the anti-osteoclastogenic-potential of Bregs. However, the crucial role of Bregs in the onset and progression of post-menopausal osteoporosis (PMO) has never been explored. Interestingly, our temporal-kinetic study demonstrated that Bregs have a compromised dynamics and functionality which further contributes to inception and the progression of the inflammatory bone loss condition in the PMO. Our ex-vivo findings further elucidate a significant reduction in the immunomodulatory and anti-osteoclastogenic functions of Bregs under the estrogen deficient post-menopausal osteoporotic conditions. The current study for the first time reports the crucial role of dysregulated-Bregs (both functionally and numerically), in the development of PMO. Our findings thereby provide a novel concept for immuno-therapeutically targeting "Bregs", for effective management and treatment of post-menopausal osteoporosis in the long run.

Aluminum promotes B1 cells to produce IL-10 and impairs adaptive immune system

Aluminum (Al) is a metal existing in the human body, yet the immunotoxicity of Al remains elusive. To investigate the immunotoxicity of Al, C57BL/6 mice were treated with 200 or 800 ppm Al via drinking water for 3 months, and thereafter the adaptive immune system was evaluated. In addition, mouse splenocytes and human peripheral blood mononuclear cells (PBMC) were treated with Al in vitro to assess the impact of Al in vitro. Treatment with Al reduced the production of IgM and IgG in the serum, and the activation of B cells, CD4 T cells and CD8 T cells in the spleen of mice; treatment with Al in vitro suppressed the production of IgM and IgG, and the activation of B cells, CD4 T cells and CD8 T cells in mouse splenocytes and human PBMC. In vitro co-culture assays suggested that the suppressed adaptive immunity was due to B cells modified by Al. In terms of mechanism, a direct action of Al on B1 cells induced the B1 cells to be IL-10-producing cells and thereby suppressed the adaptive immune system, which was critically dependent on the Jak1/3-STAT signaling. This study reveals that Al suppresses the adaptive immunity via induction of IL-10-producing B1 cells.

Interactions and communications in the prostate tumour microenvironment: evolving towards effective cancer therapy

Prostate cancer is one of the most common malignancies in men. The tumour microenvironment (TME) has a critical role in the initiation, progression, and metastasis of prostate cancer. TME contains various cell types, including cancer-associated fibroblasts (CAFs), endothelial cells, immune cells such as macrophages, lymphocytes B and T, natural killer (NK) cells, and other proteins such as extracellular matrix (ECM) components. The interactions and communications between these cells within the TME are crucial for the growth and response of various solid tumours, such as prostate cancer to different anticancer modalities. In this review article, we exemplify the various mechanisms by which the TME influences prostate cancer progression. The roles of different cells, cytokines, chemokines, and growth factors in modulating the immune response and prostate tumour growth will be discussed. The impact of these cells and factors and other ECM components on tumour cell invasion and metastasis will also be discussed. We explain how these interactions in TME can affect the response of prostate cancer to therapy. We also highlight the importance of understanding these interactions to develop novel therapeutic approaches for prostate cancer.

B cell immunometabolism in health and disease

B cells have crucial roles in the initiation and progression of many pathological conditions, and several therapeutic strategies have targeted the function of these cells. The advent of immunometabolism has provided compelling evidence that the metabolic reprogramming of immune cells can dramatically alter physiopathological immune activities. A better knowledge of the metabolic profiles of B cells can provide valuable means for developing therapies tuning defined cell pathways. Here we review the cellular and molecular mechanisms by which immunometabolism controls the physiology and pathophysiology of B cells and discuss the experimental evidence linking B cell metabolism to health, autoimmunity, and cancer. Considering that several metabolic pathways in B cells are involved differently, or even in opposite ways, in health and disease, we discuss how targeted modulation of B cell immunometabolism could be exploited mechanistically to rebalance abnormal B cell functions that have become altered in disease states.

Revealing the role of regulatory b cells in cancer: development, function and treatment significance

B cells are essential components of the immune response, primarily recognized for their ability to produce antibodies. However, emerging research reveals their important roles in regulating immune responses and influencing tumor development, independent of antibodies. The connection between tumor progression and alterations in the tumor microenvironment is well-established, as immune infiltrating cells can enhance the survival of tumor cells by modifying their surroundings. Despite this, the majority of studies have focused on T cells and macrophages, creating a gap in our understanding of B cells. Regulatory B cells (Bregs) represent a crucial subpopulation that plays a significant role in maintaining immune balance. They may have a substantial impact on tumor immunity by negatively regulating tumor-infiltrating immune cells. This paper reviews the existing literature on Bregs, examining their development, phenotypes, functions, and the mechanisms through which they exert their regulatory effects. Furthermore, we highlight their potential interventional roles and prognostic significance in cancer therapy. By addressing the current gaps in knowledge regarding Bregs within tumors, we hope to inspire further research that could lead to innovative cancer treatments and improved outcomes for patients.

Tumor-derived lactic acid promotes acetylation of histone H3K27 and differentiation of IL-10-producing regulatory B cells through direct and indirect signaling pathways

Tumor cells are known to enhance glycolysis, even under normoxic conditions, via the Warburg effect, producing excess lactic acid in the tumor microenvironment. Lactic acid enhances the IL-23/IL-17 pathway and induces chronic inflammation. The acidic microenvironment formed by lactic acid suppresses immune cell proliferation and activation. In the present study, we clarified that lactic acid had two novel activities for immune cells. First, lactic acid specifically enhanced acetylation at lysine 27 of histone H3 (H3K27ac) in splenic B cells and monocytes/macrophages, and this epigenetically up-regulates the expression of genes. Acetylation and methylation of other residues of histone H3 were rarely induced. Second, lactic acid induced a particularly-marked enhancement of Il10 gene expression in B cells, leading to an increase in IL-10-producing regulatory B (Breg) cells. Furthermore, two pathways should be involved in both the enhancement of H3K27ac and the induction of Breg cells by lactic acid: a direct pathway that enhances the CD40 signal in B cells, and an indirect pathway that affects B cells by activating the exchange protein directly activated by cAMP (EPAC) 1/2 in non-B cells. In tumor-bearing mice, the levels of H3K27ac of tumor-infiltrating B cells were significantly higher than splenic B cells and were suppressed by intraperitoneal injection of the EPAC1/2 inhibitor. In conclusion, tumor-derived lactic acid increases H3K27ac and IL-10-producing Breg cells, causing the suppression of anti-tumor immunity.

Immunoglobulin therapy for infertility and the role of immune cells in pregnancy success: An extensive investigation and update

In the United States, roughly one out of every eight couples, or 7.5 million women, experience challenges related to conceiving or maintaining a pregnancy. The body's immune response is vital during pregnancy. T cells, natural killer (NK) cells, B cells, and macrophages (MQ) are immune cells in the female reproductive tract. They are in charge of maintaining tissue homeostasis and regulating the immune system's response to invasive pathogens. Failure to regulate these immune cells might result in inflammation, which reduces fertility. The immune system modulation of pregnancy loss has been studied with intralipid, intravenous immunoglobulin (IVIG), and paternal leukocyte vaccination. A concentrated antibody called intravenous immunoglobulin (IVIG) is utilized as a biological agent to treat autoimmune, viral, and inflammatory diseases and some immunodeficiencies. The main objective of this treatment is to restore a damaged immune system. IgGs, through binding to specific antigens, promote the innate immunity's cellular and humoral immune response by activating complements and binding to Fc receptors of several immune cells. Contrariwise, IVIG regulates pathogenic autoimmunity in animal models, including skin-blister diseases, nephrotoxic nephritis, and K/BxN arthritis. IVIG has, therefore, been of great interest as an immune modulator in several immune disorders. This review aims to investigate the immunological reasons of reproductive failure, focusing on the immunomodulatory effects of IVIG in its treatment.

Tumor secretome shapes the immune landscape during cancer progression

The focus of cancer immunotherapy has traditionally been on immune cells and tumor cells themselves, often overlooking the tumor secretome. This review provides a comprehensive overview of the intricate relationship between tumor cells and the immune response in cancer progression. It highlights the pivotal role of the tumor secretome - a diverse set of molecules secreted by tumor cells - in significantly influencing immune modulation, promoting immunosuppression, and facilitating tumor survival. In addition to elucidating these complex interactions, this review discusses current clinical trials targeting the tumor secretome and highlights their potential to advance personalized medicine strategies. These trials aim to overcome the challenges of the tumor microenvironment by designing therapies tailored to the secretome profiles of individual cancer patients. In addition, advances in proteomic techniques are highlighted as essential tools for unraveling the complexity of the tumor secretome, paving the way for improved cancer treatment outcomes.

Mechanisms of T-cell Depletion in Tumors and Advances in Clinical Research

T lymphocytes (T cells) are essential components of the adaptive immune system that play a vital role in identifying and eliminating infected and tumor cells. In tumor immunotherapy, T cells have emerged as a promising therapeutic strategy due to their high specificity, potent cytotoxic capability, long-lasting immune memory, and adaptability within immunotherapeutic approaches. However, tumors can evade the immune system by depleting T cells through various mechanisms, such as inhibitory receptor signaling, metabolic exhaustion, and physical barriers within the tumor microenvironment. This review provided an overview of the mechanisms underlying T-cell depletion in tumors and discussed recent advances in clinical research related to T-cell immunotherapy for tumors. It highlighted the need for in-depth studies on key issues such as indications, dosage, and sequencing of combined therapeutic strategies tailored to different patients and tumor types, providing practical guidance for individualized treatment. Future research on T-cell depletion would be necessary to uncover the fundamental mechanisms and laws of T-cell depletion, offering both theoretical insights and practical guidance for the selection and optimization of tumor immunotherapy. Furthermore, interdisciplinary, cross-disciplinary, and international collaborative innovations are necessary for developing more effective and safer treatments for tumor patients.

Causal Relationship Between Immune Cells and Hypopituitarism: Bidirectional Mendelian Randomization Study

BACKGROUND

Hypopituitarism, one or more pituitary hormones inefficiently produced by the anterior pituitary or released from the posterior pituitary to adapt to the needs of the organism. Existing epidemiological data show that immune-mediated diffuse infiltration of the anterior pituitary is important in the development of hypopituitarism. However, the precise connection between immune cells and hypopituitarism remains unclear. This study aimed to elucidate the potential causal links between the 731 immune cell types and hypopituitarism risk.

METHODS

Based on data from a genome-wide association study, a bidirectional two-sample Mendelian randomization analysis was performed using 5 methods to explore the potential influence of immune cell phenotypes on hypopituitarism. Sensitivity analyses were conducted to examine the robustness of these findings.

RESULTS

Our findings support that B cells, T cells, Tregs, dendritic cells, monocytes, and myeloid cells each have a bidirectional influence on hypopituitarism. One B-cell phenotype was associated with increased hypopituitarism risk, while 2 B-cell phenotypes play a protective role in hypopituitarism. Moreover, 7 T-cell phenotypes demonstrate significant protective properties on hypopituitarism. Seven Tregs were associated with increased hypopituitarism risk. Furthermore, one monocyte was identified to be significantly associated with hypopituitarism risk. In addition, reverse Mendelian randomization analysis revealed that hypopituitarism was positively associated with 30 additional immune cell phenotypes and negatively associated with 17 immune cells.

CONCLUSIONS

Our investigation shed light on the intricate potential relationship between immune cells and hypopituitarism via genetic methods, underscoring the immune-mediated pathway in hypopituitarism pathogenesis, thereby offering valuable insights for future clinical investigations.

Regulatory B-Cells Are Associated Negatively With Regulatory T-Cells and Positively With Cytokines in Peripheral Blood of Pregnant Women

PROBLEM

Regulatory B-cells (Bregs, CD19+CD24hiCD38hi) are a specialized B-cell subset that suppresses immune responses and potentially contribute to the maintenance of an immune-privileged environment for fetal development during pregnancy. However, little is known about the surrounding immunological environment of Bregs in gestational physiology. The relationship of regulatory T-cells (Tregs, CD4+CD25hiCD127loFoxP3+) to Bregs in coordinating immunoregulation during pregnancy is unknown. We aimed to determine whether peripheral concentrations of Bregs and/or PD-L1-expressing Bregs correlated with Tregs and cytokines during pregnancy.

METHOD

Peripheral blood samples were obtained from 29 pregnant women at mean 12 weeks' gestation. Participants were age ≥ 18, self-identified as Latina/Hispanic, and N = 12 primigravid. Peripheral blood mononuclear cells were isolated, stained, and analyzed by flow cytometry to determine percentages of Tregs from CD4+ T-cells and five Treg subsets defined by immune checkpoint markers, and Bregs and PD-L1+ Bregs from total B-cells. Levels of 13 cytokines were measured on a Meso Scale Discovery multiplex platform.

RESULTS

Bregs positively correlated with pro-inflammatory cytokine interleukin (IL)-6. PD-L1+ Bregs positively correlated with T-cell suppressive cytokine IL-10. PD-L1+ Bregs negatively correlated with Tregs and Helios+, CTLA-4+, PD-1+, TIGIT+, and TIM3+ Tregs. For primigravida, PD-L1+ Bregs correlated positively with IL-10 and negatively with Helios+ and TIGIT+ Tregs. For multigravida, PD-L1+ Bregs correlated positively with IL-8 and negatively with Helios+, CTLA-4+, PD-1+, and TIGIT+ Tregs.

CONCLUSIONS

This study provides insight into the immunosuppressive role of Bregs and PD-L1+ Bregs during human pregnancy. Our results suggest that PD-L1+ Bregs can employ suppressive mechanisms to limit pro-inflammatory responses in primigravida.

Hspa13 Deficiency Impaired Marginal Zone B Cells Regulatory Function and Contributed to Lupus Pathogenesis

Dysregulated IL-10 producing regulatory B cells (Bregs) are associated with the progression of systemic lupus erythematosus. An immunomodulatory role of heat shock proteins (HSPs) is implicated in autoimmune diseases. However, the molecular basis underlying the role of Hspa13 in regulating Bregs function and lupus pathogenesis remains unclear. In this study, Bregs display higher Hspa13 expression than IL-10- B cells. Induction of IL-10 production is weakened in B cells with Hspa13 knockdown or knockout. Hspa13 binds to the IL-10 promoter via the TATA or CAAT box and activates IL-10 transcription in the nucleus. Furthermore, Hspa13 positive cells are enriched in marginal zone (MZ) B cells to regulate IL-10 production. Stimulated B220+ B or MZ B cells from CD19creHspa13fl/fl mice for Breg induction show an impaired capacity to promote CD4+Foxp3+ regulatory T cells (Treg) differentiation. In lupus MRL/lpr mice, a decline in Treg differentiation is accompanied by decreased Hspa13 expression in both Bregs and MZ B cells. Moreover, adoptive transfusion of Bregs and MZ B cells from CD19creHspa13fl/fl mice fails to increase the frequency of Tregs, attenuate renal pathology, or decrease anti-dsDNA antibody levels. These results explain the unique role of Hspa13 in determining MZ regulatory function and affecting lupus pathogenesis.

Peripheral Blood Lymphocyte Subsets and Heterogeneity of B Cell Subsets in Patients of Idiopathic Inflammatory Myositis with Different Myositis-specific Autoantibodies

Idiopathic inflammatory myopathies (IIM) are a group of myopathies that present with muscle weakness and multiple extra-muscular manifestations, in which lymphocytes play central roles in myositis pathogenesis. This study aimed to explore the clinical characteristics of lymphocyte subsets, especially B cell subsets, in patients with IIM. Our study included 176 patients with active IIM and 210 gender/age-matched healthy controls (HCs). Compared to HCs, patients have reduced counts of T cells, B cells, and natural killer cells. In addition, B cell subsets from 153 patients with IIM and 92 HCs were characterized. Patients had a lower percentage of memory B cells and translational memory B cells, while those patients were with an elevated percentage of CD19+ B cells, plasmablast and naïve B cells compared with HCs. Moreover, to further explore the heterogeneity of B cells in IIM, patients were categorized into three clusters based on clustering analysis. Cluster 1 was dominated by CD19+ B cells, Bregs and naïve B cells, cluster 3 was dominated by memory B cells and plasmablast, and cluster 2 had the highest proportion of translational memory B cells. Notably, patients in cluster 1 presented with higher CK levels, indicating muscle damage, whereas patients in cluster 3 showed a higher incidence of chest tightness. Our study indicated that lymphopenia is a common manifestation in patients with IIM. B cell subsets are abnormally expressed and showed high heterogeneity in patients with IIM. The patients with IIM were divided into three different clusters with different percentages of chest tightness and distinct CK levels.

Improving bench-to-bedside translation for acute graft-versus-host disease models

The transplantation of allogeneic hematopoietic stem cells is a potentially curative treatment for hematological malignancies, inherited blood disorders and immune deficiencies. Unfortunately, 30-50% of patients receiving allogeneic hematopoietic stem cells will develop a potentially life-threatening inflammatory disease called acute graft-versus-host disease (aGVHD). In patients with aGVHD, graft-associated T cells, which typically target the skin, intestinal tract and liver, can also damage the lungs and lymphoid tissue. Damage to lymphoid tissue creates prolonged immunodeficiency that markedly increases the risk of infections and bleeding, resulting in considerable morbidity and mortality. Although mouse models of aGVHD have been instrumental to our understanding of this condition's pathogenesis, translation of preclinical data into new and more effective treatments for human disease has been limited for reasons that remain to be fully understood. However, evidence suggests that factors associated with mouse models of aGVHD likely contribute to these unsatisfactory results. In this Review, we identify and discuss the specific factors inherent to mouse models of aGVHD that may limit the translation of preclinical data to patient treatment, and suggest how to improve the translatability of these models.

Dynamic roles of tumor-infiltrating B lymphocytes in cancer immunotherapy

The amazing diversity of B cells within the tumor microenvironment is the basis for the diverse development of B cell-based immunotherapies. Here, we focus on elucidating the mechanisms of tumor intervention mediated by four tumor-infiltrating B lymphocytes. Naive B cells present the initial antigen, germinal center B cell subsets enhance antibody affinity, and immunoglobulin subtypes exert multiple immune effects, while regulatory B cells establish immune tolerance. Together they reflect the complexity of the changing dynamics of cancer immunity. Additionally, we have investigated the dynamic effects of tumor-infiltrating B lymphocytes in immunotherapy and their relationship to prognosis, providing new insights into potential treatment strategies for patients.

Targeting gut microbiota to regulate the adaptive immune response in atherosclerosis

Atherosclerosis, the leading cause of death worldwide, is a chronic inflammatory disease leading to the accumulation of lipid-rich plaques in the intima of large and medium-sized arteries. Accumulating evidence indicates the important regulatory role of the adaptive immune system in atherosclerosis during all stages of the disease. The gut microbiome has also become a key regulator of atherosclerosis and immunomodulation. Whilst existing research extensively explores the impact of the microbiome on the innate immune system, only a handful of studies have explored the regulatory capacity of the microbiome on the adaptive immune system to modulate atherogenesis. Building on these concepts and the pitfalls on the gut microbiota and adaptive immune response interaction, this review explores potential strategies to therapeutically target the microbiome, including the use of prebiotics and vaccinations, which could influence the adaptive immune response and consequently plaque composition and development.

Multi-dimensional analysis of B cells reveals the expansion of memory and regulatory B-cell clusters in humans living in rural tropical areas

B-cells play a critical role in the formation of immune responses against pathogens by acting as antigen-presenting cells, by modulating immune responses, and by generating immune memory and antibody responses. Here, we studied B-cell subset distributions between regions with higher and lower microbial exposure, i.e. by comparing peripheral blood B-cells from people living in Indonesia or Ghana to those from healthy Dutch residents using a 36-marker mass cytometry panel. By applying an unbiased multidimensional approach, we observed differences in the balance between the naïve and memory compartments, with higher CD11c+ and double negative (DN-IgDnegCD27neg) memory (M)B-cells in individuals from rural tropical areas, and conversely lower naïve B-cells compared to residents from an area with less pathogen exposure. Furthermore, characterization of total B-cell populations, CD11c+, DN, and Breg cells showed the emergence of specific memory clusters in individuals living in rural tropical areas. Some of these differences were more pronounced in children compared to adults and suggest that a higher microbial exposure accelerates memory B-cell formation, which "normalizes" with age.

Emerging roles of checkpoint molecules on B cells

Immune checkpoint molecules, including both co-inhibitory molecules and co-stimulatory molecules, are known to play critical roles in regulating T-cell responses. During the last decades, immunotherapies targeting these molecules (such as programmed cell death 1 (PD-1), and lymphocyte activation gene 3 (LAG-3)) have provided clinical benefits in many cancers. It is becoming apparent that not only T cells, but also B cells have a capacity to express some checkpoint molecules. These were originally thought to be only the markers for regulatory B cells which produce IL-10, but recent studies suggest that these molecules (especially T-cell immunoglobulin and mucin domain 1 (TIM-1), T cell immunoreceptor with Ig and ITIM domains (TIGIT), and PD-1) can regulate intrinsic B-cell activation and functions. Here, we focus on these molecules and summarize their characteristics, ligands, and functions on B cells.

Elusive modes of Foxp3 activity in versatile regulatory T cells

Foxp3-expressing CD4 regulatory T (Treg) cells play a crucial role in suppressing autoimmunity, tolerating food antigens and commensal microbiota, and maintaining tissue integrity. These multifaceted functions are guided by environmental cues through interconnected signaling pathways. Traditionally, Treg fate and function were believed to be statically determined by the forkhead box protein Foxp3 that directly binds to DNA. However, this model has not been rigorously tested in physiological and pathological conditions where Treg cells adapt their function in response to environmental cues, raising questions about the contribution of Foxp3-dependent gene regulation to their versatility. Recent research indicates that Foxp3 primarily functions as a transcriptional cofactor, whose chromatin interaction is influenced by other DNA-binding proteins that respond to cell activation, stimulation, or differentiation. This new perspective offers an opportunity to reevaluate Foxp3's activity modes in diverse biological contexts. By exploring this paradigm, we aim to unravel the fundamental principles of Treg cell biology.

Regulatory B cells in parasitic infections: roles and therapeutic potential

Parasitic infection is a complex process involving interactions among various immune cells. Regulatory B cells (Breg cells), a subset of B lymphocytes with immunosuppressive functions, play a role in modulating immune responses during infection to prevent excessive immune activation. This article reviews the origin, phenotype, and immunoregulatory mechanisms of Breg cells. We summarize the immunomodulatory roles of Breg cells in various parasitic infections. We also discuss the potential applications of activating Breg cells through parasitic infections and their derived molecules in the treatment of certain allergic, autoimmune, and inflammatory diseases. The aim is to provide new perspectives for the future treatment of parasitic diseases and other related conditions.

β-Glucan induced plasma B cells differentiation to enhance antitumor immune responses by Dectin-1

BACKGROUND

B lymphocytes, essential in cellular immunity as antigen-presenting cells and in humoral immunity as major effector cells, play a crucial role in the antitumor response. Our previous work has shown β-glucan enhanced immunoglobulins (Ig) secretion. But the specific mechanisms of B-cell activation with β-glucan are poorly understood. Here, we took advantage of β-glucan to improve the antitumor immune response of B cells.

RESULTS

In vitro experiments demonstrate that β-glucan enhance the differentiation of B220lo CD138+ B cells, up-regulate co-stimulatory molecules, and increase the production of cytokines and Ig in response to various antigens. Using the Dectin-1 knockout mice, we revealed that β-glucan modulate B cell immune responses dependent on Dectin-1 receptor. In mouse models of Lewis lung cancer (LLC) tumors, combining β-glucan with programmed death-1(PD-1) blocking antibodies led to increase recruitment of CD19+ B cells in the tumor microenvironment (TME), higher numbers of germinal centers B cells (GC B) in the spleen and draining lymph node (DLN), elevate Ig production, and delay tumor progression.

CONCLUSIONS

These findings reveal that β-glucan can serve as a potent adjuvant to modulate B cell immune responses in a Dectin-1 dependent manner and improve immune checkpoint blockade (ICB) therapy in antitumor.

CLINICAL TRIAL NUMBER

Not applicable.