IL-6 contributes to an immune tolerance checkpoint in post germinal center B cells

Diversity and Epitope Spreading of Anti-RNA Polymerase III Antibodies in Systemic Sclerosis: A Potential Biomarker for Skin and Lung Involvement

OBJECTIVE

Epitope spreading (ES), involving autoantibodies, plays a crucial role in the development and persistence of autoimmune reactions in various autoimmune diseases. This study aimed to investigate the relationship between ES of anti-RNA polymerase III (RNAP III) antibodies (ARAs) and the clinical manifestations of systemic sclerosis (SSc).

METHODS

We investigated whether intermolecular ES occurs in the subunits of the RNAP III complex and whether intramolecular ES targets the major antigen, RNA polymerase III subunit A (RPC1), in patients with SSc. To achieve this, we synthesized 17 full-length subunit proteins of the RNAP III complex and 5 truncated forms of RPC1 in vitro using a wheat germ cell-free translation system. Subsequently, we prepared antigen-binding plates and measured autoantibodies in the serum of patients with SSc.

RESULTS

Autoantibodies against different RNAP III complex subunits were found in patients who were ARA-positive with SSc. The intermolecular ES indicators significantly correlated with the modified Rodnan skin thickness score (mRSS) and surfactant protein-D, a biomarker of interstitial lung disease. However, the extent of disease on high-resolution computed tomography or pulmonary function tests did not show any significant correlation. Intramolecular ES indicator against RPC1 were significantly correlated with mRSS and renal crisis. Furthermore, longitudinal assessment of ES in RNAP III complex subunits correlated with mRSS and exhibited potential as a disease activity biomarker.

CONCLUSION

Our findings indicate a correlation between ES levels and the severity of skin sclerosis or the risk of other complications in SSc. This study suggests that measuring ES in SSc serves as a novel biomarker for disease activity.

Differential gene expression of cytokines, receptors, and miRNAs in individuals living with HIV-1 and vaccinated against yellow fever

Between 2016 and 2018, Brazil faced a yellow fever (YF) outbreak, which led to an expansion of vaccination coverage. The coexistence of the YF outbreak and the HIV-1 epidemic in Brazil raised concerns regarding the immune response and vaccine effectiveness in individuals living with HIV (PLWH). The aim of this study was to investigate the immune response to YF vaccination in PLWH and HIV-uninfected individuals as controls. Transcript levels of immunomodulatory molecules, including IL-6, IL-10, IL-21, TGF-β, CD19, CD163, miR-21, miR-146, and miR-155, were measured using RTqPCR. TCD4+ cells were evaluated by cytometry, and neutralizing antibody (Nab) titers were detected by a micro plaque-reduction neutralization test. The findings of our study revealed several noteworthy observations. First, there was a notable reduction in the circulation of TCD4+ cells postvaccination. Among people living with HIV (PLWH), we observed an increase in the expression of IL-10 following vaccination, while IL-6 expression was diminished in PLWH with lower TCD4+ counts. Furthermore, we identified the downregulation of CD19 and TGF-β, along with the upregulation of IL-21 and CD163. Notably, we observed positive correlations between the levels of IL-10/IL-21, IL-10/CD163, and IL-6/CD19. Additionally, there was a positive correlation between miRNAs 146 and 155. It is important to emphasize that all participants exhibited robust neutralizing antibody responses after receiving 17DD YF vaccination. In this context, the gene expression data presented can be useful for biomarker studies of protective antibodies induced by YF vaccination. This study sheds light on immune mechanisms in individuals living with HIV and YF vaccination.

Interleukin-6: designing specific therapeutics for a complex cytokine

Interleukin-6 (IL-6) is a pivotal cytokine with a diverse repertoire of physiological functions that include regulation of immune cell proliferation and differentiation. Dysregulation of IL-6 signalling is associated with inflammatory and lymphoproliferative disorders such as rheumatoid arthritis and Castleman disease, and several classes of therapeutics have been developed that target components of the IL-6 signalling pathway. So far, monoclonal antibodies against IL-6 or IL-6 receptor (IL-6R) and Janus kinases (JAK) inhibitors have been successfully developed for the treatment of autoimmune diseases such as rheumatoid arthritis. However, clinical trials of agents targeting IL-6 signalling have also raised questions about the diseases and patient populations for which such agents have an appropriate benefit-risk profile. Knowledge from clinical trials and advances in our understanding of the complexities of IL-6 signalling, including the potential to target an IL-6 trans-signalling pathway, are now indicating novel opportunities for therapeutic intervention. In this Review, we overview the roles of IL-6 in health and disease and analyse progress with several approaches of inhibiting IL-6-signalling, with the aim of illuminating when and how to apply IL-6 blockade.

Colonic Insult Impairs Lymph Flow, Increases Cellular Content of the Lymph, Alters Local Lymphatic Microenvironment, and Leads to Sustained Inflammation in the Rat Ileum

BACKGROUND

Lymphatic dysfunction has been linked to inflammation since the 1930s. Lymphatic function in the gut and mesentery is grossly underexplored in models of inflammatory bowel disease despite the use of lymphatic occlusion in early models of inflammatory bowel disease. Activation of the innate and adaptive immune system is a hallmark of TNBS-induced inflammation and is linked to disruption of the intrinsic lymph pump. Recent identification of crosstalk between lymphatic vessel resident immune cells and regulation of lymphatic vessel contractility underscore the importance of the timing of lymphatic dysfunction during tissue inflammation in response to TNBS.

METHODS

To evaluate lymphatic function in TNBS induced inflammation, lymph was collected and flow measured from mesenteric lymphatics. Cellularity and cytokine profile of the lymph was also measured. Histopathology was performed to determine severity of injury and immunofluorescent staining of the mesentery was done to evaluate changes in the population of immune cells that reside near and on gastro-intestinal collecting lymphatics.

RESULTS

Lymph transport fell 24 hours after TNBS administration and began recovering at 72 hours. Significant reduction of lymph flow preceded significant increase in histopathological score and occurred simultaneously with increased myeloperoxidase activity. These changes were preceded by increased MHCII cells surrounding mesenteric lymphatics leading to an altered lymphatic environment that would favor dysfunction.

CONCLUSIONS

Alterations in environmental factors that effect lymphatic function occur before the development of gross GI inflammation. Reduced lymphatic function in TNBS-mediated inflammation is likely an early factor in the development of injury and that recovery of function is associated with resolution of inflammation.

From defining antigens to new therapies in multiple sclerosis: honoring the contributions of Ruth Arnon and Michael Sela

Ruth Arnon and Michael Sela profoundly influenced the development of a model system to test new therapies in multiple sclerosis (MS). Their application of the animal model, known as experimental autoimmune encephalomyelitis (EAE), for the discovery of Copaxone, opened a new path for testing of drug candidates in MS. By measuring clinical, pathologic, and immunologic outcomes, the biological implications of new drugs could be elucidated. Using EAE they established the efficacy of Copaxone as a therapy for preventing and reducing paralysis and inflammation in the central nervous system without massive immune suppression. This had a huge impact on the field of drug discovery for MS. Much like the use of parabiosis to discover soluble factors associated with obesity, or the replica plating system to probe antibiotic resistance in bacteria, the pioneering research on Copaxone using the EAE model, paved the way for the discovery of other therapeutics in MS, including Natalizumab and Fingolimod. Future applications of this approach may well elucidate novel therapies for the neurodegenerative phase of multiple sclerosis associated with disease progression.

Regulation of B lymphocytes and plasma cells by innate immune mechanisms and stromal cells in rheumatoid arthritis

B cells mediate multiple functions that influence immune and inflammatory responses in rheumatoid arthritis. Production of a diverse array of autoantibodies can happen at different stages of the disease, and are important markers of disease outcome. In turn, the magnitude and quality of acquired humoral immune responses is strongly dependent on signals delivered by innate immune cells. Additionally, the milieu of cells and chemokines that constitute a niche for plasma cells rely strongly on signals provided by stromal cells at different anatomical locations and times. The chronic inflammatory state therefore importantly impacts the developing humoral immune response and its intensity and specificity. We focus this review on B cell biology and the role of the innate immune system in the development of autoimmunity in patients with rheumatoid arthritis.

Less travelled roads in clinical immunology and allergy: drug reactions and the environmental influence

Allergy and clinical immunology are examples of areas of knowledge in which working hypotheses are dominant over mechanistic understanding. As such, sometimes scientific efforts follow major streams and overlook some epidemiologically prevalent conditions that thus become underestimated by the research community. For this reason, we welcome the present issue of Clinical Reviews in Allergy and Immunology that is dedicated to uncommon themes in clinical immunology and allergy. First, comprehensive discussions are provided for allergy phenomena of large potential impact in clinical practice such as reactions to cephalosporins or aspirin-induced asthma and in everyday life such as allergies to food additives or legumes. Further, the issue addresses other uncommon themes such as urticaria and angioedema, cercarial dermatitis, or late-onset inflammation to soft tissue fillers. Last, there will be discussion on transversal issues such as olfactory defects in autoimmunity, interleukin 1 beta pathway, and the search for new serological markers in chronic inflammation. As a result, we are convinced that this issue will be of help to clinicians involved in internal medicine as well as to allergists and clinical immunologists. More importantly, we are convinced that these discussions will be of interest also to basic scientists for the numerous translational implications.

BANK1 controls CpG-induced IL-6 secretion via a p38 and MNK1/2/eIF4E translation initiation pathway

BANK1, an adaptor protein expressed in B cells, plays a little understood role in B cell signaling. Because BANK1 contains an N-terminal putative Toll/IL-1R receptor domain, we used mouse Bank1(-/-) splenic B cells to test whether BANK1 affects signaling induced by the TLR9 agonist CpG. Following CpG stimulation, BANK1 deficiency reduced p38 phosphorylation without affecting that of ERK or JNK and reduced IL-6 secretion. Bank1(-/-) B cells showed reduced phosphorylation of MNK1/2 and eIF4E, suggesting an effect on translation initiation, whereas Bank1(-/-) had no effect on IL-6 mRNA stability, thus suggesting that BANK1 has no effect on MK2 signaling. IL-6 secretion observed when CpG stimulation was combined with anti-CD40 was reduced in the absence of BANK1. Whereas in the presence of anti-CD40 stimulation CpG induced a stronger phosphorylation of AKT, mTOR, and 4E-BP1, Bank1(-/-) had no effect on phosphorylation of mTOR and 4E-BP1, and a weak effect on AKT, implying that BANK1 does not affect the release of eIF4E by phospho-4E-BP1. Taken together, these data establish a previously unrecognized role for BANK1 in CpG-induced responses by splenic B cells on p38 signaling and control of translation initiation of IL-6 via MNK1/2 and eIF4E.

The autoimmune side of heart and lung diseases

The elevated cardiovascular morbidity in rheumatoid arthritis, systemic lupus erythematosus, and the antiphospholipid syndrome is well known, as well as the pulmonary involvement observed in these conditions and to a major extent in systemic sclerosis. These manifestations constitute a major challenge for clinicians involved in patient management. Moreover, several issues regarding the link between autoimmune rheumatic diseases and cardio pulmonary morbidity remain largely enigmatic. The mechanistic role of certain autoantibodies frequently observed in association with heart and lung diseases or the pathogenetic link between chronic inflammation and the pathways leading to atherosclerosis or pulmonary vascular changes are yet to be elucidated. As such, these questions as well as treatment strategies are of common interest to rheumatologists, immunologist, pulmonologists, and cardiologists and thus call for an interdisciplinary approach. This paradigm has been well established for rare conditions such as the Churg-Strauss syndrome. Nowadays, it seems that this approach should be expanded to encompass more common conditions such as coronary heart disease, pulmonary arterial hypertension or dilated cardiomyopathy. The present issue of Clinical Reviews in Allergy and Immunology addresses the new knowledge and concepts of autoimmune-related cardiopulmonary diseases. The issue derives from the 2010 International Autoimmunity Meeting held in Ljubljana, Slovenia and is thus timely and dedicated to the latest developments in this new multidisciplinary field.

Fate determination of mature autoreactive B cells

A large antibody repertoire is generated in developing B cells in the bone marrow. Before these B cells achieve immunocompetence, those expressing autospecificities must be purged. To that end, B cells within the bone marrow and just following egress from the bone marrow are subject to tolerance induction. Once B cells achieve immunocompetence, the antibody repertoire can be further diversified by somatic hypermutation of immunoglobulin genes in B cells that have been activated by antigen and cognate T cell help and have undergone a germinal center (GC) response. This process also leads to the generation of autoreactive B cells which must be again purged to protect the host. Thus, B cells within the GC and just following egress from the GC are also subject to tolerance induction. Available data suggest that B cell intrinsic processes triggered by signaling through the B cell receptor activate tolerance mechanisms at both time points. Recent data suggest that GC and post-GC B cells are also subject to B cell extrinsic tolerance mechanisms mediated through soluble and membrane-bound factors derived from various T cell subsets.