Immune checkpoints and the multiple faces of B cells in systemic lupus erythematosus

Efgartigimod as a novel FcRn inhibitor for autoimmune disease

Immunoglobulin G (IgG) autoantibodies can lead to the formation of autoimmune diseases through Fab and/or Fc-mediated interactions with host molecules as well as activated T cells. The neonatal Fc receptor (FcRn) binds at acidic pH IgG and albumin, and the mechanism for prolonging serum IgG half-life is making IgG re-entry into circulation by prompting it not to be degraded by lysosomes and back to the cell surface. Given the FcRn receptor's essential role in IgG homeostasis, one of the strategies to promote the quick degradation of endogenous IgG is to suppress the function of FcRn, which is beneficial to the treatment of IgG-driven autoimmune disorders like myasthenia gravis (MG), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), stiff person syndrome, and immune thrombocytopenia (ITP). We elaborately read the literature about efgartigimod and systematically reviewed the research progress and clinical application of this novel FcRn inhibitor in autoimmune diseases. Efgartigimod is the firstly FcRn antagonist developed and was approved on 17 December 2021 by the United States for the therapy of acetylcholine receptor-positive MG. In January 2022, efgartigimod received its second regulatory approval in Japan. In addition, the market authorization application in Europe was submitted and validated in August 2021. China's National Medical Products Administration officially accepted the marketing application of efgartigimod on July 13, 2022. To suppress the function of FcRn, which is beneficial to the treatment of IgG-driven autoimmune disorders like MG, CIDP, ITP, and stiff person syndrome. We review the rationale, clinical evidence, and future perspectives of efgartigimod for the treatment of autoimmune disease.

PD-1/PD-L1 governed cross-talk of exhausted CD8+ T and memory B cells in systemic lupus erythematosus

BACKGROUND

Indeterminate readout of the quantitative interferon-γ release test (QFT) for Mycobacterium tuberculosis screening is a specific laboratory finding for systemic lupus erythematosus (SLE), which may be due to T-cell exhaustion and abnormal programmed death receptor 1 (PD-1)/programmed death-ligand 1 (PD-L1) signalling.

METHODS

We enrolled 104 patients with SLE and 225 with other rheumatic musculoskeletal diseases (RMDs) who presented to the outpatient clinic between 2020 and 2023. Twenty healthy donors served as the controls. The QFT was performed in all participants, and those with indeterminate results were compared among the groups. Immunophenotyping and functional assays were performed using blood mononuclear cells. Interferon (IFN)-γ was detected in vitro and ex vivo in patients with SLE with indeterminate or negative QFT results, before or after rituximab therapy.

RESULTS

104 patients with SLE had a significantly higher rate of indeterminate QFT results was significantly higher (17.31%) than that of 225 patients with RMD (3.56%). Patients with SLE with indeterminate QFT had more active disease (SLEDAI-2K, mean 10.94 vs 4.02, p<0.0001), including a higher incidence of active nephritis (55.56% vs 29.07%). Indeterminate QFT in SLE is mainly caused by an insufficient IFN-γ response in CD8+T cells with exhausted immunophenotypes. The abnormal interaction between exhausted PD-1 high CD8+ T cells and activated PD-L1 low memory B cells in SLE can be reversed with a PD-1 agonist or increased PD-L1 expression. Rituximab treatment indirectly reversed this IFN-γ response.

CONCLUSION

The PD-1/PD-L1 signalling pathway, which governs the crosstalk between exhausted CD8+ T cells and activated memory B cells, is a mechanistic explanation for insufficient interferon-γ response in patients with SLE.

Translational implications of newly characterized pathogenic pathways in systemic lupus erythematosus

Improved characterization of relevant pathogenic pathways in systemic lupus erythematosus (SLE) has been further delineated over the last decades. This led to the development of targeted treatments including belimumab and anifrolumab, which recently became available in clinics. Therapeutic targets in SLE encompass interferon (IFN) signaling, B-T costimulation including immune checkpoints, and increasing modalities of B lineage targeting, such as chimeric antigen receptor (CAR) T cells directed against CD19 or sequential anti-B cell targeting. Patient profiling based on characterization of underlying molecular abnormalities, often performed through comprehensive omics analyses, has recently been shown to better predict patients' treatment responses and also holds promise to unravel key molecular mechanisms driving SLE. SLE carries two key signatures, namely the IFN and B lineage/plasma cell signatures. Recent advances in SLE treatments clearly indicate that targeting innate and adaptive immunity is successful in such a complex autoimmune disease. Although those signatures may interact at the molecular level and provide the basis for the first selective treatments in SLE, it remains to be clarified whether these distinct treatments show different treatment responses among certain patient subsets. In fact, notwithstanding the remarkable amount of novel clues for innovative SLE treatment, harmonization of big data within tailored treatment strategies will be instrumental to better understand and treat this challenging autoimmune disorder. This review will provide an overview of recent improvements in SLE pathogenesis, related insights by analyses of big data and machine learning as well as technical improvements in conducting clinical trials with the ultimate goal that translational research results in improved patient outcomes.

A Framework to Overcome Challenges in the Management of Infections in Patients with Systemic Lupus Erythematosus

Infections remain one of the leading causes of death in systemic lupus erythematosus (SLE), despite awareness of factors contributing to increased susceptibility to infectious diseases in SLE. Clinicians report challenges and barriers when encountering infection in SLE as certain infections may mimic a lupus flare. There are no evidence-based practice guidelines in the management of fever in SLE, with suboptimal implementations of evidence-based benefits related to infectious disease control and/or prevention strategies in SLE. Vigilance in identifying an opportunistic infection must be stressed when confronted by a diagnostic challenge during a presentation with a febrile illness in SLE. A balanced approach must focus on management of infections in SLE, and reduction in the glucocorticoids dose, given the need to control lupus disease activity to avoid lupus related organ damage and mortality. Clinical judgement and application of biomarkers of lupus flares could reduce false positives and overdiagnosis and improve differentiation of infections from lupus flares. Further precision-based risk and screening measures must identify individuals who would benefit most from low dose immunosuppressive therapy, targeted immune therapy, and vaccination programs.

High serum immunoglobulin D levels in systemic lupus erythematosus: more to be found?

INTRODUCTION

Many studies have shown that serum immunoglobulin D (IgD) is usually increased in autoimmune diseases. The potential role of IgD in systemic lupus erythematosus (SLE) is still unclear. Our study aimed to compare the serum IgD levels of SLE with different population and to evaluate the relationship between serum IgD and SLE.

METHODS

Fifty SLE patients, 40 non-SLE chronic kidney disease (CKD) patients, and 50 healthy volunteers were enrolled in this study. Serum IgD levels were analyzed by ELISA assay and compared between groups. The correlation of serum IgD and SLE disease were evaluated. The ability of serum IgD to predict SLE was analyzed by graphing receiver operating characteristic curves.

RESULTS

Serum IgD levels were significantly higher in SLE patients compared to non-SLE CKD and healthy controls (7436.1 ± 5862.1 vs. 4517.8 ± 5255.2 vs. 4180.4 ± 4881 ng/mL, p = 0.01, p = 0.002, respectively), and in patients with high SLE Disease Activity Index (SLEDAI) scores compared with those with low scores (8572.9 ± 5968.7 vs. 5020.4 ± 4972.5 ng/mL, p = 0.044). High level of inflammatory cytokines and decreased circulating basophil counts were found in SLE patients (p < 0.05). No correlations was identified between serum IgD levels and SLEDAI scores (p > 0.05). Serum IgD was noninferior to IgG or IgE in discriminating SLE with an area under the curve of 0.672 (95% CI, 0.59-0.75).

CONCLUSIONS

Serum IgD levels are significantly elevated in SLE patients with high SLEDAI scores. Simultaneous occurrence of increased inflammatory cytokines and decreased basophil counts highlights the potential role of IgD-targets interaction in SLE pathogenesis. Key points • Total serum IgD levels were elevated in SLE patients. • High IgD levels were significantly higher in SLE patients with high SLEDAI scores. • The ability of serum IgD was equivalent to IgG or IgE in discriminating SLE from CKD and healthy adult.

Inducible costimulator ligand (ICOSL) on CD19+ B cells is involved in immunopathological damage of rheumatoid arthritis (RA)

Inducible costimulator (ICOS) and its ligand (ICOSL) are critical to regulate the immune response in autoimmune diseases. The participation of B lymphocytes exhibits pathogenic potential in the disease process of rheumatoid arthritis (RA). However, the precise role of ICOSL in RA remains unclear. In this study, we aimed to explore the regulatory effects of CD19+ICOSL+ B cells in the pathogenesis of RA. We demonstrated the increased expression of ICOS and ICOSL in patients with RA and collagen-induced arthritis (CIA) mice. The population of CD19+ICOSL+ B-cell subset was significantly correlated with clinicopathological characteristics of RA patients and CIA mice. Adoptive transfer of CD19+ICOSL+ B cells aggravated arthritic progression in CIA mice. Moreover, microarray analysis revealed that CD19+ICOSL+ cells could exert pivotal effect in pathological process of RA. Further blocking of ICOSL significantly inhibited proinflammatory responses and ameliorated arthritic progression. Therefore, CD19+ICOSL+ B-cell subset could be defined as a specific pathogenic cell subpopulation involved in immunopathological damage of RA. Blockade of ICOSL is promising to be a potential new approach for RA therapy.

FcRn Antagonism Leads to a Decrease of Desmoglein-Specific B Cells: Secondary Analysis of a Phase 2 Study of Efgartigimod in Pemphigus Vulgaris and Pemphigus Foliaceus

Background

Immunoglobulin G (IgG) levels are maintained by the IgG-recycling neonatal Fc-receptor (FcRn). Pemphigus vulgaris and pemphigus foliaceus are debilitating autoimmune disorders triggered by IgG autoantibodies against mucosal and epidermal desmogleins. Recently, a phase 2 clinical trial (NCT03334058; https://clinicaltrials.gov/NCT03334058) was completed in participants with pemphigus using efgartigimod, an FcRn inhibitor, in combination with prednisone. Efgartigimod demonstrated an early effect on diease activity and was well tolerated. In addition to the safety and efficacy assessment, clinical trials present an opportunity to gain more insights into the mechanism of disease, the mode of action of treatment, and potential for corticosteroid-sparing activity.

Objective

The aim of our study was to assess the impact of FcRn antagonism by efgartigimod on immunological parameters known to be directly involved in pemphigus pathology, such as cellular and serological responses.

Methods

We investigated total and antigen-specific IgG subclass level kinetics during and after treatment, assessed antigen-specific B-cell responses, followed T- and B-cell immunophenotypes, and analyzed how different immunophenotypes link to clinical response.

Results

Treatment resulted in reduction of total IgG as well as autoreactive IgG antibody levels. Surprisingly, unlike total IgG and vaccine- or natural-infection-elicited IgG, which returned to baseline levels after stopping efgartigimod treatment, autoreactive antibody levels remained low in several study participants. Efgartigimod showed no effect on total leukocytes, neutrophils, monocytes, or lymphocytes in patients treated with extended efgartigimod therapy. Intriguingly, antigen-specific analyses revealed a loss of desmoglein-specific B cells in several participants responding to efgartigimod, in line with prolonged reduction of pathogenic IgG levels.

Conclusions

Efgartigimod treatment of participants with pemphigus improved their conditions and exerted an immunomodulatory effect beyond the blockade of IgG recycling. Further studies in larger populations with an appropriate placebo control are needed to confirm these potentially important observations to establish long-term clinical responses in autoimmune diseases.

Survival Prognosis, Tumor Immune Landscape, and Immune Responses of ADAMTS14 in Clear Cell Renal Cell Carcinoma and Its Potential Mechanisms

Background

ADAMTS14 played a crucial role in the formation and development of various cancers. Currently, no associations had been revealed between ADAMTS14 and clear cell renal cell carcinoma (ccRCC). Hence, this study was designed to assess the prognostic values and immunological roles of ADAMTS14 in ccRCC and to reveal its potential mechanisms.

Methods

ADAMTS14-related expression profiles and related clinical data were downloaded from The Cancer Genome Atlas (TCGA) dataset, validated by the ICGC dataset, qRT-PCR, and immunohistochemistry. We utilized gene set enrichment analysis (GSEA) to find potentially ADAMTS14-related pathways and applied univariate/multivariate Cox regression analyses to identify independent factors significantly related to overall survival (OS) for ccRCC. A nomogram consisted of independent prognostic factors was also conducted. We further explored the associations between ADAMTS14 with immunity and revealed its potential mechanisms.

Results

ADAMTS14 displayed a higher expression in ccRCC tumor than in adjacent normal tissues, and further validated results of the ICGC dataset; qRT-PCR and immunohistochemistry remained consistent (all p < 0.05). Moreover, elevated ADAMTS14 expression was significantly associated with poor OS (p < 0.001). Through univariate/multivariate Cox regression analyses, ADAMTS14 was found to be an independent prognostic factor for ccRCC (both p < 0.05) and GSEA identified several signaling pathways including INSULIN, MTOR, and PPAR pathways. The nomogram based on independent prognostic factors was successfully established and well evaluated. Moreover, the expression of ADAMTS14 was remarkably associated with immune checkpoint molecules, tumor mutational burden (TMB), immune cells, and tumor immune microenvironment (all p < 0.05). Results from TIDE and TCIA showed that highly expressed ADAMTS14 could predict worse efficacy of immunotherapy (all p < 0.05). As for its potential mechanisms, we also revealed several LncRNA/RNA binding protein (RBP)/ADAMTS14 mRNA networks.

Conclusions

ADAMTS14 was found to play oncogenic roles in ccRCC and to be significantly associated with immunity. Several LncRNA/RBP/ADAMTS14 mRNA networks were also identified for its potential mechanisms.

Epigenetic Alterations in Immune Cells of Systemic Lupus Erythematosus and Therapeutic Implications

Systemic lupus erythematosus (SLE) is an autoimmune disorder that is characterized by autoantibody production and dysregulated immune cell activation. Although the exact etiology of SLE remains unknown, genetic, hormonal, and complex environmental factors are known to be critical for pathologic immune activation. In addition to the inherited genetic predisposition, epigenetic processes that do not change the genomic code, such as DNA methylation, histone modification, and noncoding RNAs are increasingly appreciated to play important roles in lupus pathogenesis. We herein focus on the up-to-date findings of lupus-associated epigenetic alterations and their pathophysiology in lupus development. We also summarize the therapeutic potential of the new findings. It is likely that advances in the epigenetic study will help to predict individual disease outcomes, promise diagnostic accuracy, and design new target-directed immunotherapies.

Circular RNAs in peripheral blood mononuclear cells from ankylosing spondylitis

BACKGROUND

Circular RNA (circRNA) is a type of closed circular noncoding RNA (ncRNA), mostly formed by back-splicing or alternative splicing of pre-messenger RNA (mRNA). The aim of this study was to explore the expression profile of circRNA in peripheral blood mononuclear cells (PBMCs) of patients with ankylosing spondylitis (AS) and discover potential molecular markers of AS.

METHODS

The circRNA microarray technology was used to detect the expression of circRNAs in the peripheral blood of 6 patients with AS and 6 healthy controls (HC). To screen the differentially expressed circRNAs by fold change (FC) and P value, these differentially expressed circRNAs were analyzed by bioinformatics. In 60 cases of AS and 30 cases of HC, 4 circRNAs were subjected to real-time fluorescence quantitative polymerase chain reaction (RT-qPCR), and their correlation with various clinical indicators was analyzed. Finally, the receiver operating characteristic (ROC) curve was used to analyze their potential as AS diagnostic markers.

RESULTS

The microarray results showed that there were 1369 significantly differently expressed (P < 0.05, FC > 1.5) circRNAs between the AS and HC groups (675 upregulated and 694 downregulated). The results of bioinformatics analysis suggested that they were mainly involved in "enzyme binding," "adenosine ribonucleotide binding," "MAPK signaling pathway", etc. The RT-qPCR results showed that the expressions of hsa_circRNA_001544 (U = 486.5, P < 0.05) and hsa_circRNA_102532 (U = 645, P < 0.05) were significantly different between the AS group and the HC group. The AS group was further divided into two subgroups: active AS (ASA) and stable AS (ASS). After analysis, it was found that compared with the HC group, hsa_circRNA_001544 was significantly increased in both ASA (U = 214, P < 0.05) and ASS groups (U = 273, P < 0.05), while hsa_circRNA_008961 (U = 250, P < 0.05) and hsa_circRNA_102532 (U = 295, P < 0.05) were only significantly increased in the ASA group. Furthermore, hsa_circRNA_012732 was significantly different between the ASA and ASS groups (U = 194, P < 0.05), and there was no statistical significance among the remaining groups. Correlation analysis results showed that hsa_circRNA_012732 was negatively correlated with Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), high-sensitivity C-reactive protein (hsCRP), and globulin (GLOB) and positively correlated with lymphocyte count (LY), mean corpusular volume, and albumin (ALB), and hsa_circRNA_008961 was negatively correlated with platelet (PLT) count. ROC curve analysis showed that hsa_circRNA_001544 (95% CI = 0.610-0.831, P < 0.05) and hsa_circRNA_102532 (95% CI = 0.521-0.762, P < 0.05) were statistically significant, and their area under curve (AUC) values were 0.720 and 0.642, respectively.

CONCLUSIONS

There are differentially expressed circRNAs in PBMCs of AS patients, and they may be involved in the occurrence and development of AS. Among these differentially expressed circRNAs, hsa_circRNA_012732 has the potential to become an indicator of disease activity, and hsa_circRNA_001544 has the potential to become a molecular marker for AS diagnosis.