Автоімунні захворювання щитоподібної залози та основні маркери їх патогенезу і діагностики

Огляд присвячено оцінці основних гуморальних факторів у патогенезі автоімунних захворювань щитоподібної залози (АЗЩЗ) та можливості їх використання при діагностиці та складанні прогнозу. Показано, що клінічно різні тиреоїдит Хашимото (ТХ), хвороба Грейвса (ХГ) та офтальмопатія Грейвса (ОГ) тісно пов’язані патофізіологічно і мають подібні імуноопосередковані механізми — продукцію автоантитіл до тиреоїдних антигенів і лімфоїдну інфільтрацію тиреоїдної паренхіми. Втрата імунної толерантності до автоантигенів тиреоїдної пероксидази (thyroid peroxidase, TPO), тиреоглобуліну (thyroglobulin, Tg) та рецептору тиреотропного гормону (thyroid-stimulating hormone receptor, TSHR) є основою розвитку АЗЩЗ. Наголошується на ролі прозапальних та протизапальних цитокінів, які продукуються клітинами імунної системи та тиреоцитами. Цитокіни беруть участь в індукторній та ефекторній фазі імунної відповіді та запалення, відіграючи ключову роль у патогенезі АЗЩЗ. Значний вплив на розвиток і прогресування АЗЩЗ має дисбаланс між Th17- лімфоцитами, які підтримують автоімунну відповідь, та регуляторними Т-клітинами (regulatory T cells, Treg), які пригнічують автоімунний процес. Недостатність регуляторних В-клітин (regulatory B cells, Breg) та Тreg, які виробляють протизапальні цитокіни, порушує імунологічну толерантність і викликає аномальну продукцію прозапальних цитокінів, відіграє певну роль у патогенезі АЗЩЗ. Виявлення імунних клітин та антитиреоїдних антитіл у тканині щитоподібної залози (ЩЗ) та визначення рівнів прозапальних та протизапальних цитокінів у сироватці крові можуть дати інформацію про їх участь у патогенезі АЗЩЗ та можуть служити маркерами активності захворювання. Розглянуто діагностичне значення рівня цитокінів, тиреоїдних автоантитіл при ТХ, ХГ і ОГ та їх здатність відображати наявність та активність захворювання.

Continued dysregulation of the B cell lineage promotes multiple sclerosis activity despite disease modifying therapies

A clear understanding of the origin and role of the different subtypes of the B cell lineage involved in the activity or remission of multiple sclerosis (MS) is important for the treatment and follow-up of patients living with this disease. B cells, however, are dynamic and can play an anti-inflammatory or pro-inflammatory role, depending on their milieu. Depletion of B cells has been effective in controlling the progression of MS, but it can have adverse side effects. A better understanding of the role of the B cell subtypes, through the use of surface biomarkers of cellular activity with special attention to the function of memory and regulatory B cells (Bregs), will be necessary in order to offer specific treatments without inducing undesirable effects.

Interleukin-35 Prevents Development of Autoimmune Diabetes Possibly by Maintaining the Phenotype of Regulatory B Cells

The anti-inflammatory role of regulatory B cells (Breg cells) has been associated with IL-35 based on studies of experimental autoimmune uveitis and encephalitis. The role of Breg cells and IL-35+ Breg cells for type 1 diabetes (T1D) remains to be investigated. We studied PBMCs from T1D subjects and healthy controls (HC) and found lowered proportions of Breg cells and IL-35+ Breg cells in T1D. To elucidate the role of Breg cells, the lymphoid organs of two mouse models of T1D were examined. Lower proportions of Breg cells and IL-35+ Breg cells were found in the animal models of T1D compared with control mice. In addition, the systemic administration of recombinant mouse IL-35 prevented hyperglycemia after multiple low dose streptozotocin (MLDSTZ) injections and increased the proportions of Breg cells and IL-35+ Breg cells. A higher proportion of IFN-γ+ cells among Breg cells were found in the PBMCs of the T1D subjects. In the MLDSTZ mice, IL-35 administration decreased the proportions of IFN-γ+ cells among the Breg cells. Our data illustrate that Breg cells may play an important role in the development of T1D and that IL-35 treatment prevents the development of hyperglycemia by maintaining the phenotype of the Breg cells under an experimental T1D condition.

Indoleamine 2, 3-Dioxygenase Promotes Aryl Hydrocarbon Receptor-Dependent Differentiation Of Regulatory B Cells in Lung Cancer

Regulatory B cells (Breg) are IL-10 producing subsets of B cells that contribute to immunosuppression in the tumor microenvironment (TME). Breg are elevated in patients with lung cancer; however, the mechanisms underlying Breg development and their function in lung cancer have not been adequately elucidated. Herein, we report a novel role for Indoleamine 2, 3- dioxygenase (IDO), a metabolic enzyme that degrades tryptophan (Trp) and the Trp metabolite L-kynurenine (L-Kyn) in the regulation of Breg differentiation in the lung TME. Using a syngeneic mouse model of lung cancer, we report that Breg frequencies significantly increased during tumor progression in the lung TME and secondary lymphoid organs, while Breg were reduced in tumor-bearing IDO deficient mice (IDO-/-). Trp metabolite L-Kyn promoted Breg differentiation in-vitro in an aryl hydrocarbon receptor (AhR), toll-like receptor-4-myeloid differentiation primary response 88, (TLR4-MyD88) dependent manner. Importantly, using mouse models with conditional deletion of IDO in myeloid-lineage cells, we identified a significant role for immunosuppressive myeloid-derived suppressor cell (MDSC)-associated IDO in modulating in-vivo and ex-vivo differentiation of Breg. Our studies thus identify Trp metabolism as a therapeutic target to modulate regulatory B cell function during lung cancer progression.

Porphyromonas Gingivalis Lipopolysaccharide-induced B Cell Differentiation by Toll-like Receptors 2 and 4

Background: : Porphyromonasgingivalis (P. gingivalis) is a pathogenic bacterium widely present in subgingival plaques of patients with periodontitis. It induces periodontitis with bone loss as its main feature by changing the number and composition of symbiotic microorganisms, as well as inducing the natural immune response of the host. However, the mechanism of the latter remains unclear. Objective:: This study aims to investigate the effect of P. gingivalis lipopolysaccharide (LPS) on regulatory B cells (Breg) in the occurrence and development of periodontitis. Method:: We detected the mRNA levels of IL-10 in B cells under the stimulation of P. gingivalis LPS and/or E. coli LPS, distinguished IL-10-producing cells from different B cell subgroups using flow cytometry. Through toll-like receptor (TLR) knockout mice, the role of TLR2 and TLR4 in this process were also evaluated. Results : Results showed that P. gingivalis stimulated B cells to produce IL-10 via TLR2/4. CD5+B1 subset is the main source of IL-10+Breg cell. Under P. gingivalis LPS stimulation, CD5+IgM+CD93-IL-10+B cell subset increased significantly which was regulated through TLR2/4. Conclusion: The results of this study provides new insights into the immunopathogenic mechanism of P. gingivalis, preliminarily discussed the effect of P. gingivalis on the production of Breg, and present a theoretical foundation for subsequent investigations on the occurrence and development of periodontitis.

Immune Regulatory Cell Bias Following Alemtuzumab Treatment in Relapsing-Remitting Multiple Sclerosis

Alemtuzumab is a highly effective treatment for relapsing-remitting multiple sclerosis. It selectively targets the CD52 antigen to induce profound lymphocyte depletion, followed by recovery of T and B cells with regulatory phenotypes. We previously showed that regulatory T cell function is restored with cellular repletion, but little is known about the functional capacity of regulatory B-cells and peripheral blood monocytes during the repletion phase. In this study (ClinicalTrials.gov ID# NCT03647722) we simultaneously analyzed the change in composition and function of both regulatory lymphocyte populations and distinct monocyte subsets in cross-sectional cohorts of MS patients prior to or 6, 12, 18, 24 or 36 months after their first course of alemtuzumab treatment. We found that the absolute number and percentage of cells with a regulatory B cell phenotype were significantly higher after treatment and were positivity correlated with regulatory T cells. In addition, B cells from treated patients secreted higher levels of IL-10 and BDNF, and inhibited the proliferation of autologous CD4+CD25- T cell targets. Though there was little change in monocytes populations overall, following the second annual course of treatment, CD14+ monocytes had a significantly increased anti-inflammatory bias in cytokine secretion patterns. These results confirmed that the immune system in alemtuzumab-treated patients is altered in favor of a regulatory milieu that involves expansion and increased functionality of multiple regulatory populations including B cells, T cells and monocytes. Here, we showed for the first time that functionally competent regulatory B cells re-appear with similar kinetics to that of regulatory T-cells, whereas the change in anti-inflammatory bias of monocytes does not occur until after the second treatment course. These findings justify future studies of all regulatory cell types following alemtuzumab treatment to reveal further insights into mechanisms of drug action, and to identify key immunological predictors of durable clinical efficacy in alemtuzumab-treated patients.

Regulatory B Cells Involvement in Autoimmune Phenomena Occurring in Pediatric Graves’ Disease Patients

Graves’s disease is the most common type of autoimmune hyperthyroidism. Numerous studies indicate different factors contributing to the onset of the disease. Despite years of research, the exact pathomechanism of Graves’ disease still remains unresolved, especially in the context of immune response. B cells can play a dual role in autoimmune reactions, on the one hand, as a source of autoantibody mainly targeted in the thyroid hormone receptor (TSHR) and, on the other, by suppressing the activity of proinflammatory cells (as regulatory B cells). To date, data on the contribution of Bregs in Graves’ pathomechanism, especially in children, are scarce. Here, we investigated the frequencies of Bregs before and during a methimazole therapy approach. We reported higher Foxp3+ and IL-10+ Breg levels with CD38- phenotype and reduced numbers of CD38 + Foxp3 + IL-10+ in pediatric Graves’ patients. In addition, selected Breg subsets were found to correlate with TSH and TRAb levels significantly. Noteworthy, certain subpopulations of Bregs were demonstrated as prognostic factors for methimazole therapy outcome. Our data demonstrate the crucial role of Bregs and their potential use as a biomarker in Graves’ disease management.

Case Report: Sustained Remission Due to PD-1-Inhibition in a Metastatic Melanoma Patient With Depleted B Cells

IntroductionCheckpoint-Inhibition (CPI) with PD-1- and PD-L1-inhibitors is a well-established therapy for advanced stage melanoma patients. CPI mainly acts via T-lymphocytes. However, recent literature suggests also a role for B cells modulating its efficacy and tolerability of CPI.Case ReportWe report a 48-year-old female patient with metastatic melanoma affecting brain, lung, skin and lymph nodes. A preexisting granulomatosis with polyangiitis was treated with rituximab over five years prior to the diagnosis of melanoma, resulting in a complete depletion of B cells both in peripheral blood as well as the tumor tissue. In the absence of the mutation of the proto-oncogene b-raf, treatment with the PD-1 inhibitor nivolumab was initiated. This therapy was well tolerated and resulted in a deep partial response, which is ongoing for 14+ months. Flow cytometric analysis of peripheral blood mononuclear cells revealed 15% IL-10 producing and 14% CD24 and CD38 double positive regulatory B cells.ConclusionThe exceptional clinical response to nivolumab monotherapy in our patient with depleted B cells sheds a new light on the relevance of B cells in the modulation of immune responses to melanoma. Obviously, B cells were not required for the efficacy of CPI in our patient. Moreover, the depletion of regulatory B cells may have improved efficacy of CPI.