Natural killer cells promote the differentiation of follicular helper T cells instead of inducing apoptosis in myasthenia gravis

NK Cells in the Lymph Nodes and Their Role in Anti-Tumour Immunity

The lymph nodes are vital to enable adaptive immune responses to infection. Natural killer (NK) cells are cytotoxic lymphocytes that directly kill cancer cells and modulate the activation of other immune cells during anti-tumour immune response. NK cells in the lymph nodes are involved in the regulation of T-cell and B-cell populations and the clearance of viral infections. In solid tumours, lymph nodes are a frequent site of metastasis and immune cell priming, whilst in haematological malignancies, tumour cells can proliferate in the lymph nodes. Thus, lymph nodes are an important site in anti-tumour immunity and therapy resistance. It is therefore crucial to identify strategies to increase recruitment and overcome suppression of NK cells in the lymph node microenvironment to improve tumour clearance. In this review, we summarise the literature interrogating NK cell phenotype and function in the lymph nodes in the context of infection and cancer and evaluate both current and potential strategies to mobilise and activate NK cells within the lymph nodes of cancer patients.

Therapeutic potential of natural killer cells in neuroimmunological diseases

Natural killer (NK) cells, a major component of the innate immune system, have prominent immunoregulatory, antitumor proliferation, and antiviral activities. NK cells act as a double-edged sword with therapeutic potential in neurological autoimmunity. Emerging evidence has identified NK cells are involved in the development and progression of neuroimmunological diseases such as multiple sclerosis, neuromyelitis optica spectrum disorders, autoimmune encephalitis, Guillain-Barré Syndrome, chronic inflammatory demyelinating polyneuropathy, myasthenia gravis, and idiopathic inflammatory myopathy. However, the regulatory mechanisms and functional roles of NK cells are highly variable in different clinical states of neuroimmunological diseases and need to be further determined. In this review, we summarize the evidence for the heterogenic involvement of NK cells in the above conditions. Further, we describe cutting-edge NK-cell-based immunotherapy for neuroimmunological diseases in preclinical and clinical development and highlight challenges that must be overcome to fully realize the therapeutic potential of NK cells.

The investigation of killer-cell immunoglobulin-like receptors (KIRs) and their HLA ligands in Iranian patients with myasthenia gravis

BACKGROUND

Myasthenia gravis (MG) is a disabling disease with the underlying pathophysiology of auto-antibodies attacking the postsynaptic acetylcholine receptors of neuromuscular junctions causing muscle weakness. Natural killer (NK) cells are innate immune cells that play an important regulative role in immune responses. The human killer-cell immunoglobulin-like receptors (KIRs) family is one of the receptors on NK cells that can either activate or inhibit NK cells. This study aimed to assess the possible role of KIR and their human leukocyte antigen (HLA) ligand genes susceptibility to MG in Iranian patients.

METHOD

One hundred and sixty-three patients with MG diagnosis based on the presence of clinical symptoms and laboratory tests and 400 healthy volunteers were studied. We used the polymerase chain reaction (PCR) technique for genotyping 15 KIRs and 5 HLA genes.

RESULTS

The results demonstrated that there was no significant difference in the frequency of KIR genes and inhibitory KIR genotypes between controls and patients. In MG patients, HLA-C1Asn80 was significantly less frequent than in matched controls. The frequency of HLA genotype number 7 was significantly lower in MG cases, compared to the controls. Analysis of activating KIR genotypes showed that genotype number 10 was significantly less frequent in MG cases than in matched controls.

CONCLUSION

Our results suggest that the presence HLA-C1Asn80 might play a protective role against the pathogenesis of MG. The significantly decreased prevalence of one activating KIR genotype and one of the HLA genotypes in MG cases suggest that these genotypes can reduce the risk of MG development. To specifically reveal the impact of KIR and HLA in MG, more studies are required.

Altered serum levels of cytokines in patients with myasthenia gravis

Background

Myasthenia gravis (MG) is an autoimmune disease characterized by generalized skeletal muscle contraction weakness due to autoantibodies targeting neural-muscular junctions. Here, we investigated the relationship between key cytokines and MG type, disease course, antibodies, and comorbidities.

Method

Cytokine levels in serum samples collected from MG (n = 45) and healthy control (HC, n = 38) patients from January 2020 to June 2022 were quantified via flow cytometry.

Results

Levels of IL-6 were higher in the MG group versus healthy individuals (p = 0.026) and in patients with generalized versus ocular MG (p = 0.019). IL-6 levels were positively correlated with QMG score. In patients with MG with both AChR and Titin antibodies, serum levels of sFas and granulysin were higher than in those with AChR alone (p = 0.036, and p = 0.028, respectively). LOMG had a reduction in serum levels of IL-2 compared to EOMG (p = 0.036). LOMG patients with diabetes had lower serum levels of IL-2, IL-4, and IFN-γ (p = 0.044, p = 0.038, and p = 0.047, respectively) versus those without diabetes. sFas in the MG with Abnormal thymus were reduced compared to those in MG with Normal thymus (p = 0.008).

Conclusions

This study revealed a positive correlation between IL-6 level and MG status. Serum cytokine levels of the AChR + Titin MG group differed from those of the AChR group. LOMG had a lower IL-2 level. Comorbidities affect some cytokines in peripheral blood in MG serum.

Interleukin-21 promotes Type-1 activation and cytotoxicity of CD56dimCD16bright natural killer cells during kidney allograft antibody-mediated rejection showing a new link between adaptive and innate humoral allo-immunity

The role of Natural killer (NK) cells during kidney allograft antibody-mediated rejection (ABMR) is increasingly recognized, but an in-depth characterization of mechanisms that contribute to such immune response is still under investigation. Here, we characterized phenotypic, functional, and transcriptomic profiles of peripheral blood circulating and allograft infiltrating CD56dimCD16bright NK cells during anti-HLA donor-specific antibody (DSA)+ ABMR. Cross-sectional analyses performed in 71 kidney transplant recipients identified a unique phenotypic circulating CD56dimCD16bright NK cell cluster expanded in DSA+ ABMR. This cluster co-expressed high levels of the interleukin-21 Receptor (IL-21R); Type-1 transcription factors T-bet and EOMES, CD160 and natural killer group 2D cytotoxic and activating co-stimulatory receptors. CD160+ IL-21R+ NK cells correlated with elevated plasma IL-21, Ki-67+ ICOS+ (CD278) IL-21-producing circulating T follicular helper cells, enhanced Type-1 pro-inflammatory cytokines, NK cell cytotoxicity, worse microvascular inflammation and graft loss. Single-cell transcriptomic analysis of circulating NK cells delineated an expanded cluster in DSA+ ABMR characterized by elevated pro-inflammatory/cytotoxic pathways, IL-21/STAT3 signaling, and leukocyte trans-endothelial migration pathways. Infiltration of CD160+ IL-21R+ NK cells with similar transcriptomic profile was detected in DSA+ ABMR allograft biopsies, potentially contributing to allograft injury. Thus, the IL-21/IL-21R axis, linking adaptive and innate humoral allo-immunity, or NK cells may represent appealing immunotherapy targets in DSA+ ABMR.

Plasma C18:0-ceramide is a novel potential biomarker for disease severity in myasthenia gravis

Myasthenia gravis (MG) is an antibody-mediated autoimmune disorder characterized by fluctuation of fatigue and weakness of muscle. Due to the heterogeneity of the course of MG, available biomarkers for prognostic prediction are urgently needed. Ceramide (Cer) was reported to participate in immune regulation and many autoimmune diseases, but its effects on MG remain undefined. This study aimed to investigate the ceramides expression levels in MG patients and their potential as novel biomarkers of disease severity. Levels of plasma ceramides were determined by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Severity of disease was assessed by quantitative MG scores (QMGs), MG-specific activities of daily living scale (MG-ADLs) and 15-item MG quality of Life (MG-QOL15). The concentrations of serum interleukin-1β (IL-1β), IL-6, IL-17A, and IL-21 were determined by enzyme-linked immunosorbent assay (ELISA), and the proportions of circulating memory B cells and plasmablasts were detected by flow-cytometry assay. Four plasma ceramides levels we studied were detected higher in MG patients. And three of them (C16:0-Cer, C18:0-Cer, and C24:0-Cer) were positively associated with QMGs. In addition, receiver operating characteristic (ROC) analysis suggested that plasma ceramides have a good ability of differentiating MG from HCs. Importantly, only C18:0-Cer was shown to be positively associated with the concentration of serum IL and circulating memory B cells, and the decrease in plasma C18:0-Cer paralleled the clinical improvement of patients with MG. All together, our data suggest that ceramides may play an important role in the immunopathological mechanism of MG, and C18:0-Cer has the potential to be a novel biomarker for disease severity in MG.

Circulating CXCR5+ natural killer cells are expanded in patients with myasthenia gravis

Objectives

Myasthenia gravis (MG) is a classic autoantibody-mediated disease in which pathogenic antibodies target postsynaptic membrane components, causing fluctuating skeletal muscle weakness and fatigue. Natural killer (NK) cells are heterogeneous lymphocytes that have gained increasing attention owing to their potential roles in autoimmune disorders. This study will investigate the relationship between the distinct NK cell subsets and MG pathogenesis.

Methods

A total of 33 MG patients and 19 healthy controls were enrolled in the present study. Circulating NK cells, their subtypes and follicular helper T cells were analysed by flow cytometry. Serum acetylcholine receptor (AChR) antibody levels were determined by ELISA. The role of NK cells in the regulation of B cells was verified using a co-culture assay.

Results

Myasthenia gravis patients with acute exacerbations had a reduced number of total NK cells, CD56^dim NK cells and IFN-γ-secreting NK cells in the peripheral blood, while CXCR5⁺ NK cells were significantly elevated. CXCR5⁺ NK cells expressed a higher level of ICOS and PD-1 and a lower level of IFN-γ than those in CXCR5^- NK cells and were positively correlated with Tfh cell and AChR antibody levels. In vitro experiments demonstrated that NK cells suppressed plasmablast differentiation while promoting CD80 and PD-L1 expression on B cells in an IFN-γ-dependent manner. Furthermore, CXCR5^- NK cells inhibited plasmablast differentiation, while CXCR5⁺ NK cells could more efficiently promote B cell proliferation.

Conclusion

These results reveal that CXCR5⁺ NK cells exhibit distinct phenotypes and functions compared with CXCR5^- NK cells and might participate in the pathogenesis of MG.

Landscape analysis of m6A modification regulators related biological functions and immune characteristics in myasthenia gravis

BACKGROUND

N6-methyladenosine (m6A) modification has been recognized to play fundamental roles in the development of autoimmune diseases. However, the implication of m6A modification in myasthenia gravis (MG) remains largely unknown. Thus, we aimed to systematically explore the potential functions and related immune characteristics of m6A regulators in MG.

METHODS

The GSE85452 dataset with MG and healthy samples was downloaded from Gene Expression Omnibus (GEO) database. m6A modification regulators were manually curated. The targets of m6A regulators were obtained from m6A2Target database. The differential expressed m6A regulators in GSE85452 dataset were identified by "limma" package and were validated by RT-PCR. Function enrichment analysis of dysregulated m6A regulators was performed using "clusterProfiler" package. Correlation analysis was applied for analyzing the relationships between m6A regulators and immune characteristics. Unsupervised clustering analysis was used to identify distinct m6A modification subtypes. The differences between subtypes were analyzed, including the expression level of all genes and the enrichment degree of immune characteristics. Weighted gene co-expression network analysis (WGCNA) was conducted to obtain modules associated with m6A modification subtypes.

RESULTS

We found that CBLL1, RBM15 and YTHDF1 were upregulated in MG samples of GSE85452 dataset, and the results were verified by RT-PCR in blood samples from19 MG patients and 19 controls. The targeted genes common modified by CBLL1, RBM15, and YTHDF1 were mainly enriched in histone modification and Wnt signaling pathway. Correlation analysis showed that three dysregulated m6A regulators were closely associated with immune characteristics. Among them, RBM15 possessed the strongest correlation with immune characteristics, including CD56dim natural killer cell (r = 0.77, P = 0.0023), T follicular helper cell (r = - 0.86, P = 0.0002), Interferon Receptor (r = 0.78, P = 0.0017), and HLA-DOA (r = 0.64, P = 0.0200). Further two distinct m6A modification patterns mediated by three dysregulated m6A regulators was identified. Bioinformatics analysis found that there were 3029 differentially expressed genes and different immune characteristics between two m6A modification patterns. Finally, WGCNA analysis obtained a total of 12 modules and yellow module was the most positively correlated to subtype-2.

CONCLUSION

Our findings suggested that m6A RNA modification had an important effect on immunity molecular mechanism of MG and provided a new perspective into understanding the pathogenesis of MG.

T follicular helper cells in autoimmune diseases

T follicular helper (Tfh) cells with the phenotype of mainly expressing surface molecules C-X-C motif chemokine receptor type 5 (CXCR5), inducible co-stimulator (ICOS), secreting cytokine interleukin-21 (IL-21) and requiring the transcription factor B cell lymphoma 6 (BCL-6) have been recently defined as a new subset of CD4⁺ T cells. They exist in germinal centers (GCs) of lymphoid organs and in peripheral blood. With the ability to promote B cell development, GC formation and antibody production, Tfh cells play critical roles in the pathogenesis of many autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), primary Sjögren's syndrome (pSS), etc. The aberrant proliferation and function of Tfh cells will cause the pathological process like autoantibody production and tissue injury. In this paper, we review the recent advances in Tfh cell biology and their roles in autoimmune diseases, with a mention of their use as therapeutic targets, which will shed more light on the pathogenesis and treatment of certain autoimmune diseases.

DCAF12 and HSPA1A May Serve as Potential Diagnostic Biomarkers for Myasthenia Gravis

Background

Myasthenia gravis (MG) is an autoimmune disease that severely affects the life quality of patients. This study explores the differences in immune cell types between MG and healthy control and the role of immune-related genes in the diagnosis of MG.

Methods

The GSE85452 dataset was downloaded from the Gene Expression Omnibus (GEO) database and analyzed using the limma package to determine differentially expressed genes (DEGs) between patients with MG and the control group. Differentially expressed immune cells were analyzed using single-sample gene set enrichment analysis (GSEA), while immune cell-associated modules were identified by weighted gene coexpression network analysis (WGCNA). Then, the expression of the identified hub genes was confirmed by RT-PCR in peripheral blood mononuclear cells (PBMCs) of MG patients. The R package pROC was used to plot the receiver operating characteristics (ROC) curves.

Results

The modules related to CD56bright natural killer cells were identified by GSEA and WGCNA. The proportion of CD56bright natural killer cells in the peripheral blood of MG patients is low. The results of RT-PCR showed that the levels of DDB1- and CUL4-associated factor 12 (DCAF12) and heat shock protein family A member 1A (HSPA1A) were significantly decreased in peripheral blood mononuclear cells of MG patients compared with healthy controls. The ROC curve results of DCAF12 and HSPA1A mRNA in MG diagnosis were 0.780 and 0.830, respectively.

Conclusions

CD56bright NK cell is lower in MG patients and may affect MG occurrence. DCAF12 and HSPA1A are lowly expressed in PBMCs of MG patients and may serve as the diagnostic biomarkers of MG.

Transcriptomic profiling of pemphigus lesion infiltrating mononuclear cells reveals a distinct local immune microenvironment and novel lncRNA regulators

Pemphigus is an autoimmune skin disease. Ectopic lymphoid-like structures (ELSs) were found to be commonly present in the pemphigus lesions, presumably supporting in situ desmoglein (Dsg)-specific antibody production. Yet functional phenotypes and the regulators of Lymphoid aggregates in pemphigus lesions remain largely unknown. Herein, we used microarray technology to profile the gene expression in skin lesion infiltrating mononuclear cells (SIMC) from pemphigus patients. On top of that, we compared SIMC dataset to peripheral blood mononuclear cells (PBMC) dataset to characterize the unique role of SIMC. Functional enrichment results showed that mononuclear cells in skin lesions and peripheral blood both had over-represented IL-17 signaling pathways while neither was characterized by an activation of type I Interferon signaling pathways. Cell-type identification with relative subsets of known RNA transcripts (CIBERSORT) results showed that naïve natural killer cells (NK cells) were significantly more abundant in pemphigus lesions, and their relative abundance positively correlated with B cells abundance. Meanwhile, plasma cells population highly correlated with type 1 macrophages (M1) abundance. In addition, we also identified a lncRNA LINC01588 which might epigenetically regulate T helper 17 cells (Th17)/regulatory T cells (Treg) balance via the peroxisome proliferator-activated receptor (PPAR) signaling pathway. Here, we provide the first transcriptomic characterization of lesion infiltrating immune cells which illustrates a distinct interplay network between adaptive and innate immune cells. It helps discover new regulators of local immune response, which potentially will provide a novel path forward to further uncover pemphigus pathological mechanisms and develop targeted therapy.

T follicular helper cells improve the response of patients with chronic hepatitis B to interferon by promoting HBsAb production

BACKGROUND AND AIMS

Hepatitis B surface antigen (HBsAg) seroconversion is considered the optimal outcome of the treatment of chronic hepatitis B virus (HBV) infection. In this study, we aimed to determine the cellular and molecular mechanisms by which pegylated interferon alpha (PEG-IFN-α) improves the seroconversion rate in patients with chronic hepatitis B (CHB).

METHODS

Flow cytometry was performed using circulating T follicular helper (TFH) cells from 15 healthy individuals and 45 patients with CHB presenting different treatment responses [complete response group (CRG), incomplete response group (ICRG), and nonresponse group (NRG)] to the standard 48-week regimen of PEG-IFN-α monotherapy to examine the significance of circulating TFH cells in the therapeutic response of patients with CHB to PEG-IFN-α. In addition, the capacities of different TFH subsets to activate B cells and stimulate IgG production were assessed by performing coculture experiments.

RESULTS

Longitudinal analysis revealed specific and significant increases in the numbers of CD40L⁺CD4⁺CXCR5⁺ TFH cells in the CRG compared with the NRG and ICRG. According to the results of in vitro coculture experiments, blocking CD40-CD40L signaling, but not ICOS-ICOSL signaling, specifically inhibits B-cell activation and IgG production. HBV may impair TFH cell function by enhancing inhibitory regulatory T-cell activity. Transcriptome analysis further revealed the upregulation of CD40L, but not of ICOS, in TFH cells isolated from the CRG.

CONCLUSIONS

TFH cells, particularly those with CD40L expression, stimulate B-cell differentiation and improve the HBsAg seroconversion rate in patients with CHB treated with PEG-IFN-α monotherapy.