CD4+CXCR5+ T cells activate CD27+IgG+ B cells via IL-21 in patients with hepatitis C virus infection

BACKGROUND: Chronic hepatitis C virus (HCV) infection causes the skewing and activation of B cell subsets, but the characteristics of IgG+ B cells in patients with chronic hepa-titis C (CHC) infection have not been thoroughly elucidated. CD4+CXCR5+ follicularhelperT(Tfh)cells,viainterleukin (IL)-21 secretion, activate B cells. However, the role of CD4+CXCR5+T cellsintheactivationof IgG+ BcellsinCHCpatientsis not clear.
METHODS: The frequency of IgG+ B cells, including CD27?IgG+B and CD27+IgG+ B cells,the expression of the activation markers (CD86 and CD95) in IgG+ B cells, and the percentage of circu-lating CD4+CXCR5+ T cells were detected by flow cytometry in CHC patients (n=70) and healthy controls (n=25). The con-centrations of serum IL-21 were analyzed using ELISA. The role of CD4+CXCR5+ T cells in the activation of IgG+ B cells was investigated using a co-culture system.
RESULTS: A significantly lower proportion of CD27+IgG+ B cells with increased expression of CD86 and CD95 was observed in CHC patients.The expression of CD95 was negatively correlated with the percentage of CD27+IgG+ B cells, and it contributed to CD27+IgG+ B cell apoptosis. Circulating CD4+CXCR5+ T cells and serum IL-21 were significantly increased in CHC patients. Moreover, circulating CD4+CXCR5+ T cells from CHC patients induced higher expressions of CD86 and CD95 in CD27+IgG+B cells in a co-culture system; the blockade of the IL-21 decreased the expression levels of CD86 and CD95 in CD27+IgG+ B cells.
CONCLUSIONS: HCV infection increased the frequency of CD4+CXCR5+ T cells and decreased the frequency of CD27+IgG+B cells. CD4+CXCR5+ T cells activated CD27+IgG+ B cells via the secretion of IL-21.     

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.     

Bacterial CpG induces hyper-IgM production in CD27(+) memory B cells in primary biliary cirrhosis

BACKGROUND AND AIMS: Sera from patients with primary biliary cirrhosis (PBC) are characterized by the presence of antimitochondrial antibodies and elevated levels of immunoglobulin (Ig) M. We hypothesized that the increase in serum IgM is the result of chronic B-cell activation induced via the Toll-like receptor (TLR) signaling pathway. METHODS: We analyzed peripheral blood mononuclear cells (PBMCs) from patients with PBC and controls following incubation with CpG, a natural ligand for TLR9, and determined the basal and stimulated levels of intracellular IgM, the density of TLR9, and the contribution of specific B-cell subpopulations. RESULTS: Our data demonstrate uniquely that in vitro incubation of PBMCs from PBC with CpG-B, but not CpG-A, led to a markedly high frequency of intracellular IgM-positive B cells, associated with high levels of synthesized IgM and identified to be a function of CD27(+) memory B cells. This memory B-cell subset also expressed higher densities of TLR9 as compared with naive B cells. These results were not due to increased proliferation, as defined by 5-carboxyfluoresein diacetate succinimidyl ester labeling, or an increase in the life span of B cells, as defined by Bcl-2 expression. CONCLUSIONS: These findings for the first time identify a major role for innate immune mechanisms in the induction and persistence of abnormal humoral immune responses in PBC.     

Recognition of Schistosoma mansoni Cathepsins B and L by human IgG1 and IgG4 antibodies

Human schistosome infections are chronic in nature and elevated IgG4 levels are associated with length of exposure. To examine how structure, localization and dynamics of exposure of a protein to the immune system can affect antibody isotype expression, specific antibody levels against two Schistosoma mansoni recombinant cathepsin molecules were determined in S. mansoni -infected individuals. Cathepsin B (rCatB, secreted in the gut) and cathepsin L (rCatL, localized in the reproductive structures) were used to determine IgG1 reactivity, as a measure of the stimulation of the immune response, and the switch to IgG4 as an indicator of the dynamics and rate of presentation to the immune system. Sera from three groups of S. mansoni -infected patients were used: individuals with life-long exposure in an endemic area in Burundi, a group from a recent endemic focus in Senegal, and of acutely infected European travellers. We report for the first time the ability of rCatL to trigger an immune response and show distinct antibody isotype reactivity between rCatB versus rCatL. Patients harbouring long-term chronic infections had elevated levels of IgG4 to both antigen, whereas individuals infected for less than four years had high IgG4 to rCatB but not to rCatL. Acutely infected travellers developed IgG1 to rCatB only. Our results demonstrate that an immune response is mounted more rapidly against a cathepsin molecule secreted in the gut of the worm than against an internally localized cathepsin.     

CD19+CD24hiCD27+调节性B细胞在人布鲁菌病中的变化和作用

目的 检测布鲁菌病(布病)急性期和慢性期患者治疗前后外周血CD19⁺CD24^hiCD27⁺调节性B细胞(regulatory B cells,Bregs)和血清细胞因子IL-10和IFN-γ水平。分析布病患者不同病程中Bregs和细胞因子变化特点,评估机体免疫反应状态。方法 选取2021年6月—2022年7月在新疆医科大学第八附属医院诊治的急、慢性期布病患者各20例,在治疗前后分别抽取血标本,并设立健康对照组(20例),入组后抽取血标本。应用流式细胞术检测各组Bregs水平,ELISA法检测外周血IL-10和IFN-γ水平,对各组检测结果进行统计学分析。结果 与健康对照组相比,急、慢性期2组患者治疗前Bregs水平均明显升高;治疗后水平均下降,但慢性期组仍高于健康对照组和急性期组,差异均有统计学意义(P均<0.05)。与健康对照组相比,治疗前急、慢性期组IL-10均明显升高,治疗后2组水平均下降,但仍高于健康对照组,且差异均具有统计学意义(P均<0.05)。与对照组相比,治疗前,急、慢性期组血清IFN-γ水平...     

The role of CD19+CD24highCD38high and CD19+CD24highCD27+ regulatory B cells in patients with type 1 autoimmune pancreatitis

BackgroundPatients with type 1 autoimmune pancreatitis (AIP) have several immunologic and histologic abnormalities. It is known that depletion of B cells by rituximab is effective for treatment of IgG4-related disease (IgG4-RD) such as type 1 AIP, suggesting that B cells may be a key player in IgG4-RD. However, the role of regulatory B cells (Bregs) in type 1 AIP is unclear, and the objective of this paper is to clarify the role of Bregs in the pathophysiology of type 1 AIP by analyzing circulating Bregs.MethodWe recruited 21 patients with type 1 AIP as determined by the International Consensus Diagnostic Criteria for AIP (ICDC). No patients received corticosteroid treatments. For comparison, we recruited 14 patients with chronic pancreatitis (CP), 20 patients with pancreatic cancer, and 25 healthy subjects as controls. We analyzed Bregs as CD19⁺CD24^highCD38^high and CD19⁺CD24^highCD27⁺ from peripheral blood by flow cytometry.ResultsIn peripheral blood, CD19⁺CD24^highCD38^high Bregs were significantly increased in type 1 AIP patients compared with CP, pancreatic cancer, and healthy controls. Although not significant different, CD19⁺CD24^highCD27⁺ Bregs of type 1 AIP were decreased compared to those of other groups. IL-10⁺ B cells were not significantly different from type 1 AIP patients and healthy controls. In untreated type 1 AIP patients, the number of CD19⁺CD24^highCD38^high Bregs and IgG4 were not correlated.ConclusionsOur data suggested that CD19⁺CD24^highCD38^high Bregs seemed to increase reactively to suppress the disease activity, and are consistent with the hypothesis that CD19⁺CD24^highCD27⁺ Bregs might be involved in the development of type 1 AIP, although it still remains unclear whether the decrease of CD19⁺CD24^highCD27⁺ cells is cause or effect of AIP.     

TSLP production by epithelial cells exposed to immunodeficiency virus triggers DC-mediated mucosal infection of CD4+ T cells

Mucosal dendritic cells have been implicated in the capture, storage, and transmission of HIV to CD4⁺ T cells as well as in the promotion of HIV replication in activated CD4⁺ T cells during the cognate T-cell and DC interaction. We report that HIV induces human genital mucosal epithelial cells to produce thymic stromal lymphopoietin (TSLP) via activation of the NFκB signaling pathway. The TSLP secreted by HIV exposed epithelial cells activated DC, which promoted proliferation and HIV-1 replication of co-cultured autologous CD4⁺ T cells. In rhesus macaques, we observed dramatic increases in TSLP expression concurrent with an increase in viral replication in the vaginal tissues within the first 2 weeks after vaginal SIV exposure. These data suggest that HIV-mediated TSLP production by mucosal epithelial cells is a critical trigger for DC-mediated amplification of HIV-infection in activated CD4⁺ T cells. The cross talk between mucosal epithelial cells and DC, mediated by HIV-induced TSLP, may be an important mechanism for the high rate of HIV infection in women through the vaginal mucosa.     

Human leucocyte antigen‐B27 subtypes in Korean patients with ankylosing spondylitis: higher B*2705 in the patient group

Aim: To investigate the distribution of human leucocyte antigen (HLA) class I antigens and B27 subtypings in a group of B27(+) ankylosing spondylitis (AS) patients and a group of B27(+) control individuals, and to compare differences in their clinical features using subtyping. Methods: At otal of 143 B27(+) AS samples and 32 B27(+) control samples were collected consecutively from two rheumatology centres in South Korea. All patients were diagnosed according to the modified New York criteria for AS. Medical records of the patients were retrospectively reviewed for demographic information, Bath disease activity index (BASDAI) scores, laboratory parameters at diagnosis and extra‐articular manifestations. Polymerase chain reaction‐sequence‐specific primer typing for the B27 subtypes was performed using the Dynal HLA‐B27 high resolution kit. Results: Whereas subtypes in Korean AS patients include B*2704 (n = 11, 7.7%) B*2705 (n = 130, 90.9%), and B*2710 (n = 2, 1.4%), those of the control groups include B*2704 (n = 11, 34.4%), B*2705 (n = 19, 59.4%), B*2710 (n = 1, 3.1%), and B*2715 (n = 1, 3.1%). The proportion of B*2705 subtypes were significantly higher in the AS group than the control group (P < 0.01). There were no differences in clinical features (peripheral arthritis, uveitis, BASDAI scores) or laboratory parameters between the two groups. Conclusion: In Korean AS patients, not in the control group, the HLA‐B*2705 subtype was higher than other subtypes, in contrast to AS patients from Japan and China. B27 subtypes in AS patients were not associated with clinical features or laboratory parameters.     

Persistent polyclonal B-cell lymphocytosis is an expansion of functional IgD(+)CD27(+) memory B cells

Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare disorder of unknown aetiology affecting predominantly young to middle-aged women. It is characterized by a polyclonal expansion of B cells, including typical binucleated lymphocytes, and is associated with the presence of the translocation t(14;18), involving the bcl-2 oncogene. The stage of differentiation of the B cells expanded in PPBL is not known. We analysed the immunophenotype of the expanded B-cell subset in five new patients with PPBL and found a large uniform expansion of a recently defined human memory B-cell population, IgD(+)CD27(+) memory B cells. After in vitro stimulation with interleukin 2 (IL-2) and Staphylococcus aureus Cowan strain I, B cells from PPBL patients produced high levels of IgM immunoglobulins, which is a characteristic feature of IgD(+)CD27(+) memory B cells. Using a quantitative real-time polymerase chain reaction method, we found a high frequency of the translocation t(14;18) in the range of 1000-3000 per 106 B cells in PPBL patients. In contrast, a much smaller number of cells with a t(14;18) was found in B cells from healthy individuals. Our finding that PPBL is an accumulation of memory B cells further suggests that chronic antigeneic stimulation plays an important part in the pathogenesis of this disorder. This IgD(+)CD27(+) memory B-cell population might harbour a certain number of 'physiological' t(14;18) translocations that increases as this population expands in PPBL patients and constitutes the majority of peripheral blood lymphocytes.     

B cell activation through CD40 and IL4R ligation modulates the response of chronic lymphocytic leukaemia cells to BAFF and APRIL

The two tumour necrosis factor family proteins BAFF (TNFSF13B) and APRIL (TNFSF13) and their receptors [BAFF‐R (TNFRSF13C), TACI (TNFRSF13B), BCMA (TNFRSF17)] play a critical role in the survival of normal B cells. The sensitivity of normal B cells to BAFF and APRIL can be modulated by signals regulated by their receptors. This modulation, however, has not been extensively investigated in chronic lymphocytic leukaemia (CLL) cells. We evaluated the expression, regulation and signalling of BAFF and APRIL receptors in normal and in CLL cells upon stimulation through CD40+IL4R and BCR. We further analysed the prognostic value of BAFF and APRIL receptors expression in patients with CLL. BCMA expression was significantly higher on CLL cells than on normal B cells. BCR and CD40+IL4R stimulation promoted an increase in TACI and BCMA expression, cell viability and activation in normal B cells. A similar effect was observed in CLL cells after CD40+IL4R but not BCR stimulation. BCMA expression correlated with unmutated IGHV genes, poor‐risk cytogenetics, and short progression‐free survival. These findings further characterize the link between CD40+IL4R regulatory signals, BAFF, APRIL and their receptors and the survival of leukaemic cells and clinical features of CLL.     

Role of CYP27B1+2838 promoter polymorphism in the treatment of chronic hepatitis B HBeAg negative with PEG‐interferon

In HBV‐infected patients, the vitamin D deficiency has been related to chronic liver diseases, progression of hepatic fibrosis and poor response to the treatment. The CYP27B1 gene, which encodes the 1‐α‐hidroxylase and involved in the 1,25‐dihydroxyvitamin D synthesis, was recently associated to type‐1 diabetes, autoimmune disorders and treatment response in HCV. Then, we aimed to investigate the role of CYP27B1 polymorphisms in HBV treatment with PEG‐IFN. We retrospectively enrolled 190 patients with chronic hepatitis B HBeAg negative treated for 48 weeks with PEG‐IFN α‐2a. We examined the role of rs4646536 CYP27B1 SNP (CYP27B1+2838) according to virological and serological response. Our results showed that the TT genotype of CYP27B1+2838 was significantly prevalent in patients with end‐of‐therapy virological response (37.6%) vs CT/CC (9.4%) (P < 0.001). Virological relapse was prevalent in patients with CT/CC genotype (12.6%) vs TT genotype (2.1%) (P < 0.001). TT genotype was also related to HBsAg loss (P = 0.004) and anti‐HBs appearance (P = 0.002). In the multivariate analysis, the TT genotype resulted to be a good positive predictor of sustained virological response (OR = 5.632, IC = 1.938–16.368, P = 0.001) and serological response (OR = 6.161, IC = 1.856–20.457, P = 0.003). The CYP27B1+2838 polymorphism may be useful as pretreatment factor to selection of patients with higher probability of response to therapy.     

In vitro stimulation of naive mouse lymphocytes by Heligmosomoides polygyrus adult worm antigens induces the production of IgG1

The production of high levels of IgG1, by mice chronically infected with the parasitic nematode Heligmosomoides polygyrus , has been documented for a number of years. In order to investigate this phenomenon, naive lymphocytes from B10.D2 mice were incubated in vitro with H. polygyrus adult worm homogenate (AWH) and the culture supernatants examined for immunoglobulin production. Stimulation of pooled naive splenocytes by AWH was found to produce IgG1, but not IgM, in an antigen dose dependent manner. Identical stimulation of splenocytes of individual inbred mice, indicated that this effect was reproducible but with considerable variation between mice. When the IgG1 produced was tested for specificity, it was found that there was little evidence that the immunoglobulin produced was able to bind to the inducing parasite antigens. Analysis of purified T cells reconstituted with splenocytes, demonstrated that T cells were the target lymphocytes of the stimulating molecule, contained within AWH. These results show that H. polygyrus AWH can induce the production of non-parasite specific IgG1 from naive splenocytes and that this production is crucially dependent upon the cell content of the in vitro culture. Furthermore, the production of IgG1 is not proportional to the degree of lymphocyte proliferation. It is suggested that at least part of the hypergammaglobulinaemia produced during a primary H. polygyrus infection, is due to this non-specific stimulation of mouse lymphocytes by the parasite.     

The macrophage activation marker CD163 is associated with IL28B genotype and hepatic inflammation in chronic hepatitis C virus infected patients

Recent data highlighted the association of the macrophage activation marker CD163 with histological inflammation and fibrosis in chronic hepatitis C virus (HCV) infection. The aim of this study was to investigate the influence of successful antiviral treatment and IL28B genotypes on macrophage activation reflected by CD163 levels in HCV infected patients. In a retrospective cohort study, serum sCD163 levels were correlated with results of liver histopathology, IL28B genotyping and clinical parameters in 329 patients with HCV infection, 15 healthy controls and in 161 patients who achieved a sustained virologic response after antiviral treatment. sCD163 levels were significantly higher in patients with chronic HCV infection in comparison to healthy controls (5202 vs 896 ng/mL, P < 0.001). In the multivariate logistic regression analyses, sCD163 was independently associated with histologically determined inflammation (P = 0.043) but not with fibrosis (P = 0.091). sCD163 dropped significantly after successful antiviral treatment in comparison to baseline values (5202 vs 3093 ng/mL, P < 0.001). In the univariate analyses, sCD163 was significantly associated with IL28B genotype (C/C vs C/T+T/T) with higher values in the C/C group (6098 vs 4812 ng/mL, P = 0.003). In the multivariate logistic regression model, sCD163 levels were significantly associated with IL28B genotype (P = 0.003) and sustained virologic response (SVR) (P < 0.001). Our data support the association of activated liver macrophages with hepatic necroinflammation in chronic HCV infection as sCD163 levels drop rapidly after SVR. The irresponsiveness of IL28B minor genotypes to interferon might be related to a lower level of macrophage activation in these patients.     

Correlation of HLA B27 subtypes with clinical features of ankylosing spondylitis

Aim: The aim of the present study was to identify the B*27 subtypes associated with ankylosing spondylitis (AS) in our population and correlate them with clinical features of AS. Method: Whole blood samples were collected from 81 HLA‐B27 positive AS patients and 29 controls (asymptomatic healthy unrelated individuals) positive for HLA‐B27. Clinical details of the patients were recorded which included history of inflammatory back pain, sacroiliitis, spine involvement, enthesitis, peripheral arthritis and uveitis. HLA‐B27 subtypes were detected using commercially available techniques. Fisher’s exact test was used for statistical analysis. Results: The subtypes observed in AS patients were B*2705 (67.9%, 55/81), B*2704 (28.4%, 23/81), B*2707 (2/81) and B*2702 (1/81). Subtypes in the controls were B*2705 (62.07%, 18/29), B*2707 (27.59%, 8/29) and B*2704 (10.34%, 3/29). Uveitis was observed more in B*2704‐positive AS patients (34.78%, 8/23) compared to B*2705‐positive AS patients (16.36%, 9/55). However, the difference was not statistically significant (P = 0.130). No major differences were found between B*2705 and B*2704 for other clinical features. Conclusion: B*2705 was the main subtype observed in both patient and control groups. Frequency of B*2704 was more in AS patients compared to controls. Occurrence of AS‐associated uveitis was more often in B*2704‐positive AS patients compared to B*2705‐positive ones.     

Aberrant expression and reverse signalling of CD70 on malignant B cells

In normal lymphoid tissues the tumour necrosis factor-receptor family member CD27 and its ligand CD70 have a restricted expression pattern. Previously, we reported that expression of CD27 is deregulated in B-cell leukaemias and lymphomas. Here we show that, although infrequently expressed by normal human B cells in vivo, CD70 is found on 50% of B-CLLs, 33% of follicle centre lymphomas, 71% of large B-cell lymphomas, and 25% of mantle cell lymphomas. Interestingly, in the majority of leukaemias and lymphomas examined, CD70 was found to have a capped appearance, a feature that coincided with co-expression of CD27. Functional analysis showed that a subset of B-CLLs could proliferate vigorously in response to CD70 mAb but not to CD27 mAb. This response was synergistically enhanced by ligation of CD40 but inhibited by the presence of IL-4. Additional experiments indicated that the proliferative response was due to an agonistic signal delivered via CD70, rather than blocking of negative signalling by CD27. Thus, next to its role as ligand, in a subset of malignant B cells CD70 can operate as receptor and as such might contribute to progression of these B-cell malignancies.