Cardiac Abnormalities in Relation to the Disease Activity Index Among Systemic Lupus Erythematosus Patients in a Tertiary Hospital: A Cross-Sectional Study

BACKGROUND

 Systemic lupus erythematosus (SLE) is a multisystem autoimmune connective tissue disorder involving multiple organs and systems. Cardiovascular involvement in SLE patients is a major cause of morbidity and mortality. Although subclinical cardiac abnormalities exist among SLE patients, they are rarely screened for. Echocardiography has been demonstrated to be a useful tool for the early diagnosis of cardiac abnormalities in SLE patients, many of which are clinically silent. Early recognition of cardiovascular abnormalities is vital for the prompt initiation of the appropriate management. This study aims to determine the prevalence of various structural and functional cardiac abnormalities among SLE patients and to determine its association with the modified SLE Disease Activity Index 2000 (modified SLEDAI-2K).

METHODS

 The study was a cross-sectional study of SLE patients at the Korle-Bu Teaching Hospital (KBTH), Accra, Ghana, from June to December 2021. The setting was the rheumatology outpatient clinic of the KBTH and included adult men and women, 18 years and above, diagnosed with SLE with no known cardiac abnormalities. The baseline demographic and clinical characteristics of the participants were determined. A detailed transthoracic echocardiogram was performed for all patients. The frequency of common cardiac pathologies was determined and compared between those with a high modified SLEDAI-2K and those with a low modified SLEDAI-2K.

RESULTS

 Ninety-nine SLE patients participated in the study with a mean age of 35.12 years. Females formed the majority (90.9%) of the participants. The mean age at diagnosis of SLE was 28.7 years and the mean disease duration was 4.6 years. All of the participants were on at least two disease-modifying medications. The mean modified SLEDAI-2K score was 9.1. Thirty-five percent (35%) of the patients had mild to moderately active disease and 39% had severely active disease. Sixty-six (66%) out of the severely active disease group had abnormal echocardiographic findings, while 28% of those with mild to moderate disease had abnormal echocardiographic findings. Echocardiographic abnormalities were found in 56 patients (47%), out of which 8.7% had valvular involvement, 15.7% had diastolic dysfunction, 5.2% had left ventricular hypertrophy (LVH), and 0.9% had left ventricular systolic dysfunction (LVSD). About 12% of the participants had pulmonary hypertension and 1% had pericardial involvement. The odds of echocardiographic abnormalities were 13.7 times higher in SLE patients with high disease activity compared to those with low disease activity (odds ratio (OR) = 13.714, 95% confidence interval (CI) = 3.804-49.442, p < 0.001). There was no significant association between cardiac abnormalities and SLE duration. No significant correlation between cardiac abnormalities and modified SLEDAI-2K score was found.  Conclusion: Cardiac abnormalities, especially left ventricular diastolic dysfunction (LVDD), valvular involvement, and pulmonary hypertension, are common in SLE patients. For SLE patients, especially those with active diseases, echocardiographic assessment should be considered in the management of SLE patients to enable early detection of cardiac abnormalities, early treatment, and thus a decrease in morbidity and mortality associated with cardiovascular involvement in SLE patients.

B cell abnormalities and autoantibody production in patients with partial RAG deficiency

Mutations in the recombination activating gene 1 (RAG1) and RAG2 in humans are associated with a broad spectrum of clinical phenotypes, from severe combined immunodeficiency to immune dysregulation. Partial (hypomorphic) RAG deficiency (pRD) in particular, frequently leads to hyperinflammation and autoimmunity, with several underlying intrinsic and extrinsic mechanisms causing a break in tolerance centrally and peripherally during T and B cell development. However, the relative contributions of these processes to immune dysregulation remain unclear. In this review, we specifically focus on the recently described tolerance break and B cell abnormalities, as well as consequent molecular and cellular mechanisms of autoantibody production in patients with pRD.

Itch regulation of innate and adaptive immune responses in mice and humans

The E3 ubiquitin ligase Itch has long been appreciated to be a critical suppressor of inflammation, first identified as a regulator of Th2 differentiation and lung inflammation. Recent studies have revealed novel roles for this protein in mouse and human disease, and it is now clear that Itch also limits the function of other lymphocytes, innate immune cells, and nonhematopoietic cells to regulate immunity. In addition to Th2 cells, Itch also regulates Th17 and regulatory T cells. Itch regulates humoral immunity through direct roles in T follicular helper cells and T follicular regulatory cells, and B cells. Furthermore, Itch limits innate immune responses, such as macrophage cytokine production. Through these cell-intrinsic functions, Itch regulates the interplay between innate and adaptive immune cells, resulting in profound autoinflammation in Itch-deficient mice. Whereas Itch deficiency was previously thought to be an extremely rare occurrence humans, whole exome sequencing of patients with unexplained autoimmune disease has revealed at least two additional cases of Itch deficiency in the last year alone, each caused by distinct mutations within the Itch gene. The recent identification of these patients suggests that Itch mutations may be more common than previously thought, and demonstrates the need to understand how this protein regulates inflammation and autoimmune disease.

TLR7/TLR9- and B Cell Receptor-Signaling Crosstalk: Promotion of Potentially Dangerous B Cells

B cells are capable of receptor-mediated responses to foreign antigens. Recognition of microbial-derived nucleic acid (NA) by toll-like receptors (TLRs) 7 and 9 in B cells has been substantiated. Endogenous NA released from damaged or dying cells can also be immunogenic in certain contexts and can incite aberrant activation of B cells. When TLR-driven B cell receptor (BCR)-activated B cells are not properly constrained, pathologic autoantibodies are produced. It is also clear that endosomal TLR7/TLR9 can operate in conjunction with BCR. In addition to BCR signaling, a balance between TLR7 and TLR9 is pivotal in the development of B cell autoreactivity. While TLR9 is important in normal memory B cell responses through BCR, TLR9 activation has been implicated in autoantibody production. Paradoxically, TLR9 also plays known protective roles against autoimmunity by directly and indirectly inhibiting TLR7-mediated autoantibody production. Herein, we summarize literature supporting mechanisms underpinning the promotion of pathological BCR-activated B cells by TLR7 and TLR9. We focus on the literature regarding known points of TLR7/TLR9 and BCR crosstalk. Data also suggest that the degree of TLR responsiveness relies on alterations of certain intrinsic B-cell signaling molecules and is also context specific. Because allogeneic hematopoietic stem cell transplantation is a high NA and B cell-activating factor environment, we conclude that B cell studies of synergistic TLR-BCR signaling in human diseases like chronic graft-versus-host disease are warranted. Further understanding of the distinct molecular pathways mediating TLR-BCR synergy will lead to the development of therapeutic strategies in autoimmune disease states.

Preventive Effect of Lactobacillus helveticus SBT2171 on Collagen-Induced Arthritis in Mice

We recently reported that the intraperitoneal inoculation of Lactobacillus helveticus SBT2171 inhibited the development of collagen-induced arthritis (CIA), a murine model of rheumatoid arthritis (RA). In the present study, we evaluated the effect of the oral administration of L. helveticus SBT2171 on CIA development and on the regulation of antigen-specific antibody production and inflammatory immune cells, which have been implicated in the development of RA. Both oral administration and intraperitoneal inoculation of L. helveticus SBT2171 reduced joint swelling, body weight loss, and the serum level of bovine type II collagen (CII)-specific antibodies in the CIA mouse model. The intraperitoneal inoculation also decreased the arthritis incidence, joint damage, and serum level of interleukin (IL)-6. In addition, the numbers of total immune cells, total B cells, germinal center B cells, and CD4⁺ T cells in the draining lymph nodes were decreased following intraperitoneal inoculation of L. helveticus SBT2171. These findings demonstrate the ability of L. helveticus SBT2171 to downregulate the abundance of immune cells and the subsequent production of CII-specific antibodies and IL-6, thereby suppressing the CIA symptoms, indicating its potential for use in the prevention of RA.

Optimized purification strategies for the elimination of non-specific products in the isolation of GAD65-specific monoclonal autoantibodies

Autoantibodies against antigens expressed by insulin-producing β cells are circulating in both healthy individuals and patients at risk of developing Type 1 diabetes. Recent studies suggest that another set of antibodies (anti-idiotypic antibodies) exists in this antibody/antigen interacting network to regulate auto-reactive responses. Anti-idiotypic antibodies may block the antigen-binding site of autoantibodies or inhibit autoantibody expression and secretion. The equilibrium between autoantibodies and anti-idiotypic antibodies plays a critical role in mediating or preventing autoimmunity. In order to investigate the molecular mechanisms underlying such a network in autoimmunity and potentially develop neutralizing reagents to prevent or treat Type 1 diabetes, we need to produce autoantibodies and autoantigens with high quality and purity. Herein, using GAD65/anti-GAD65 autoantibodies as a model system, we aimed to establish reliable approaches for the preparation of highly pure autoantibodies suitable for downstream investigation.

Circulating CXCR5+CD4+helper T cells in systemic lupus erythematosus patients share phenotypic properties with germinal center follicular helper T cells and promote antibody production

OBJECTIVE

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies. Recently, a specific highly activated T helper cell subset, follicular helper T (Tfh) cell, has emerged as a key immunoregulator of germinal center (GC) formation and high-affinity antibody production. To identify the pathophysiological role of Tfh cells in SLE patients, we compared the phenotypic and functional properties of circulating Tfh-like cells in lupus patients to GC-Tfh cells, and correlated the percentage of Tfh-like cells with autoantibody production and SLE disease activity.

METHODS

Peripheral blood was collected from 29 lupus patients and 25 healthy controls. Tonsils were obtained surgically from non-SLE controls and used as a source of GC-Tfh cells. Tfh cells were defined by their signature surface markers (CXCR5, ICOS, CD57, PD-1 and BTLA) via flow cytometry. IL-21 expression levels from Tfh cells were measured by real-time PCR and intracellular staining. The function of Tfh cells was carried out by co-culture of Tfh cells and autologous B cells in vitro. IgG in the culture supernatant was detected by ELISA.

RESULTS

The frequency of circulating Tfh-like cells was significantly increased in SLE patients compared to healthy controls (p < 0.05). The Tfh-like cells not only display similar phenotypes and signature cytokines with GC-Tfh cells, but also are capable of driving B cells to differentiate into IgG-secreting plasma cells in vitro. In addition, the frequency of Tfh-like cells correlated positively with the percentage of circulating plasmablasts, levels of serum anti-dsDNA antibodies and ANA.

CONCLUSION

The accumulated circulating Tfh-like cells in lupus patients share phenotypic and functional properties with GC-Tfh cells. Tfh-like cells may serve as perpetuators in the pathogenesis of SLE by enhancing the self-reactive B cell clones to further differentiate into auto antibody-producing plasmablasts, and ultimately cause autoimmunity.

Simultaneous activation of natural killer T cells and autoantibody production in mice injected with denatured syngeneic liver tissue

Denatured syngeneic liver tissue prepared by mechanical procedures was intraperitoneally injected into adult C57BL/6 mice. In parallel with a decrease in the total number of lymphocytes in the liver, spleen, and thymus from days 1-7 after the injection, the proportion of the CD4+NK1.1+CD3(int) subset of these cells (i.e. natural killer T or NKT cells) increased in the liver. Even the absolute number of these NKT cells increased in the liver on days 14 and 21. In response to the injection of denatured liver tissue, tissue damage was induced in the liver, as shown by elevated levels of serum transaminases and hepatocyte degeneration observed by electron microscopy. Sera obtained on days 7 and 14 contained autoantibodies including anti-DNA antibodies. The proportion of CD1d(high)B cells in the liver was found to decrease on days 1-7. In other words, denatured liver tissue stimulated both NKT cells and certain B cells in the liver. These results suggest that liver lymphocytes might contain not only autoreactive T cells (e.g. CD3(int) or NKT cells) but also some B cells (e.g. B-1 cells) which produce autoantibodies and that the denatured tissue had the potential to stimulate these lymphocytes and to evoke an autoimmune-like state.