CXCR4: from B-cell development to B cell-mediated diseases

Chemokine receptors are members of the G protein-coupled receptor superfamily. The C-X-C chemokine receptor type 4 (CXCR4), one of the most studied chemokine receptors, is widely expressed in hematopoietic and immune cell populations. It is involved in leukocyte trafficking in lymphoid organs and inflammatory sites through its interaction with its natural ligand CXCL12. CXCR4 assumes a pivotal role in B-cell development, ranging from early progenitors to the differentiation of antibody-secreting cells. This review emphasizes the significance of CXCR4 across the various stages of B-cell development, including central tolerance, and delves into the association between CXCR4 and B cell-mediated disorders, from immunodeficiencies such as WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome to autoimmune diseases such as systemic lupus erythematosus. The potential of CXCR4 as a therapeutic target is discussed, especially through the identification of novel molecules capable of modulating specific pockets of the CXCR4 molecule. These insights provide a basis for innovative therapeutic approaches in the field.

Sarcoidosis-Related Uveitis: A Review

Sarcoidosis is an inflammatory disease that involves the eyes in 10-55% of cases, sometimes without systemic involvement. All eye structures can be affected, but uveitis is the most common ocular manifestation and causes vision loss. The typical ophthalmological appearance of these uveitis is granulomatous (in cases with anterior involvement), which are usually bilateral and with synechiae. Posterior involvement includes vitritis, vasculitis and choroidal lesions. Tuberculosis is a classic differential diagnosis to be wary of, especially in people who have spent time in endemic areas. The diagnosis is based on histology with the presence of non-caseating epithelioid granulomas. However, due to the technical difficulty and yield of biopsies, the diagnosis of ocular sarcoidosis is often based on clinico-radiological features. The international criteria for the diagnosis of ocular sarcoidosis have recently been revised. Corticosteroids remain the first-line treatment for sarcoidosis, but up to 30% of patients require high doses, justifying the use of corticosteroid-sparing treatments. In these cases, immunosuppressive treatments such as methotrexate may be introduced. More recent biotherapies such as anti-TNF are also very effective (as they are in other non-infectious uveitis etiologies).

[Sarcoid uveitis: Ophthalmologist's and internist's viewpoints]

Sarcoidosis is one of the leading causes of inflammatory eye disease. All ocular structures can be affected, but uveitis is the main manifestation responsible for vision loss in ocular sarcoidosis. Typical sarcoid anterior uveitis presents with mutton-fat keratic precipitates, iris nodules, and posterior synechiae. Posterior involvement includes vitritis, vasculitis, and choroidal lesions. Cystoid macular edema is the most important and sight-threatening consequence of sarcoid uveitis. Patients with clinically isolated uveitis at diagnosis rarely develop other organ involvement. Even though, ocular sarcoidosis can have a severe impact on visual prognosis, early diagnosis and a wider range of available therapies (including intravitreal implants) have lessened the functional impact of the disease, particularly in the last decade. Corticosteroids are the cornerstone of treatment for sarcoidosis, but up to 30% of patients achieve remission with requiring high-dose systemic steroids. In these cases, the use of steroid-sparing immunosuppressive therapy (such as methotrexate) is unavoidable. Among these immunosuppressive treatments, anti TNF-α drugs have been a revolution in the management of non-infectious uveitis.

The course of non-infectious uveitis in pregnancy: a retrospective study of 79 pregnancies

PURPOSE

The study aims to describe the course and management of non-infectious uveitis during pregnancy and postpartum period in European populations.

METHODS

A retrospective observational study in two tertiary centers in France was performed. Pregnant patients during the follow-up of a non-infectious uveitis as well as those with new-onset uveitis were included. The medical records were analyzed with a systematic collection of the characteristics of the uveitis, the treatment and evolution of the uveitis, and the course of the pregnancy including obstetric complications.

RESULTS

Seventy-nine pregnancies in 59 women were included: 48 patients (68 pregnancies) were followed for uveitis and 11 had a new-onset uveitis diagnosis. Most patients had idiopathic uveitis (32.2%) or sarcoid uveitis (27.1%). Among the patients followed for uveitis at the time of conception, there were 18 relapses (26.5%) requiring treatment escalation. Relapses occurred mainly in the two first trimester (n = 12) or during the postpartum period (n = 5) and were significantly associated with an active uveitis at the time of conception (OR = 9.2, 95% CI [1.57-48.4], p = 0.01). The characteristics of the new-onset uveitis were similar to those already existing before pregnancy. Obstetric complications occurred in 25 pregnancies (31.6%), mainly gestational hypertension and gestational diabetes.

CONCLUSION

The frequency of non-infectious uveitis relapses decreases as pregnancy progresses, in agreement with data from other non-European studies. However, multidisciplinary monitoring should be advised, especially to uncontrolled patients at the time of conception.

CD4 T cell-intrinsic STING signaling controls the differentiation and effector functions of TH1 and TH9 cells

Background

While stimulator of interferon genes (STING) activation in innate immune cells of the tumor microenvironment can result in CD8 T cell-dependent antitumor immunity, whether STING signaling affects CD4 T-cell responses remains elusive.

Methods

Here, we tested whether STING activation modulated the effector functions of CD4 T cells in vivo by analyzing tumor-infiltrating CD4 T cells and evaluating the contribution of the CD4 T cell-derived cytokines in the antitumor activity of the STING ligand 2′3′-cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) in two mouse tumor models. We performed ex vivo experiments to assess the impact of STING activation on CD4 T-cell differentiation and investigate the underlying molecular mechanisms. Finally, we tested whether STING activation enhances T_H9 cell antitumor activity against mouse melanoma upon adoptive transfer.

Results

We found that activation of STING signaling cell-intrinsically enhances the differentiation and antitumor functions of T_H1 and T_H9 cells by increasing their respective production of interferon gamma (IFN-γ) and interleukin-9. IRF3 and type I interferon receptors (IFNARs) are required for the STING-driven enhancement of T_H1 cell differentiation. However, STING activation favors T_H9 cell differentiation independently of the IFNARs/IRF3 pathway but through mammalian target of rapamycin (mTOR) signaling, underscoring that STING activation differentially affects the fate of distinct CD4 T-cell subsets. The therapeutic effect of STING activation relies on T_H1 and T_H9-derived cytokines, and STING activation enhances the antitumor activity of T_H9 cells upon adoptive transfer.

Conclusion

Our results reveal the STING signaling pathway as a therapeutic target to boost CD4 T-cell effector functions and antitumor immunity.

Prevalence of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis and spatial association with quarries in a French Northeast region

OBJECTIVE

Silica is one of the strongest environmental substances linked with autoimmunity. The aim of this study was to assess the prevalence of granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and renal limited vasculitis (RLV) in a French northeast region, and their geospatial association with quarries.

METHODS

Potential ANCA-Associated Vasculitis (AAV) cases were identified using three sources: hospital records, immunology laboratories and the National Health Insurance System. Patients who resided in Alsace on January 1, 2016 and fulfilled ACR AAV criteria or Chapel Hill Consensus Conference 2012 definition were included. Incomplete case ascertainment was corrected using capture-recapture analysis. The spatial association between the number of cases and quarries in each administrative entity was assessed using geographical weighted regression (GWR).

RESULTS

From 910 potential AAV cases, we identified 185 patients meeting inclusion criteria: 120 GPA, 35 MPA, 30 RLV. The number of cases missed by any source was 6.4 (95%CI 3.6-11.5). Accordingly, the 2016 estimated prevalence in Alsace was 65.5 cases per million inhabitants (95%CI 47.3-93.0) for GPA, 19.1 (95%CI 11.3-34.3) for MPA, and 16.8 (95%CI 8.7-35.2) for RLV. The risk of AAV was significantly increased in communes with quarries (OR: 2.51 [95%CI: 1.66-3.80]) and GWR revealed a significant spatial association between quarries and GPA cases (p = 0.039), and, regarding ANCA serotype, between quarries and both PR3-AAV (p = 0.04) and MPO-AAV (p = 0.03)."

CONCLUSION

In a region with a high density of quarries, the spatial association of AAV with quarries supports the role of silica as a specific environmental factor.