Chemokine/Cytokine Levels Correlate with Organ Involvement in PR3-ANCA-Associated Vasculitis

Chemokine expression in sera of patients with microscopic polyangiitis and granulomatosis with polyangiitis

We evaluated chemokine expression and its correlation with disease activity in patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) (MPA/GPA). Serum CCL2, CCL4, CCL19, CXCL1, CXCL2, and CX3CL1 level in 80 patients were analysed using multiple enzyme-linked immunosorbent assays. Correlations between variables were investigated using Pearson's correlation analysis, and receiver operator curve analysis was performed to identify optimal CX3CL1 values in determining active disease. Multivariate logistic regression analysis was done to evaluate predictors of active disease. CCL4 (r = 0.251, p = 0.025), CXCL1 (r = 0.270, p = 0.015), and CX3CL1 (r = 0.295, p = 0.008) significantly correlated with BVAS, while CX3CL1 was associated with five-factor score (r =  - 0.290, p = 0.009). Correlations were revealed between CCL2 and CCL4 (r = 0.267, p = 0.017), CCL4 and CXCL1 (r = 0.368, p < 0.001), CCL4 and CXCL2 (r = 0.436, p < 0.001), and CXCL1 and CXCL2 (r = 0.518, p < 0.001). Multivariate analysis revealed serum CX3CL1 levels > 2408.92 pg/mL could predict active disease (odds ratio, 27.401, p < 0.001). Serum chemokine levels of CCL4, CXCL1, and CX3CL1 showed association with disease activity and especially, CX3CL1 > 2408.92 pg/mL showed potential in predicting active MPA/GPA.

Thrombopoietin-Dependent Myelo-Megakaryopoiesis Fuels Thromboinflammation and Worsens Antibody-Mediated Chronic Renal Microvascular Injury

SIGNIFICANCE STATEMENT

Kidney-derived thrombopoietin (TPO) increases myeloid cell and platelet production during antibody-mediated chronic kidney disease (AMCKD) in a mouse model, exacerbating chronic thromobinflammation in microvessels. The effect is mirrored in patients with extracapillary glomerulonephritis associated with thromboinflammation, TGF β -dependent glomerulosclerosis, and increased bioavailability of TPO. Neutralization of TPO in mice normalized hematopoiesis, reduced chronic thromboinflammation, and ameliorated renal disease. The findings suggest that TPO is a relevant biomarker and a promising therapeutic target for patients with CKD and other chronic thromboinflammatory diseases.Neutralization of TPO in mice normalized hematopoiesis, reduced chronic thromboinflammation, and ameliorated renal disease. The findings suggest that TPO is a relevant biomarker and a promising therapeutic target for patients with CKD and other chronic thromboinflammatory diseases.

BACKGROUND

Chronic thromboinflammation provokes microvascular alterations and rarefaction, promoting organ dysfunction in individuals with various life-threatening diseases. Hematopoietic growth factors (HGFs) released by the affected organ may sustain emergency hematopoiesis and fuel the thromboinflammatory process.

METHODS

Using a murine model of antibody-mediated chronic kidney disease (AMCKD) and pharmacological interventions, we comprehensively monitored the response to injury in the circulating blood, urine, bone marrow, and kidney.

RESULTS

Experimental AMCKD was associated with chronic thromboinflammation and the production of HGFs, especially thrombopoietin (TPO), by the injured kidney, which stimulated and skewed hematopoiesis toward myelo-megakaryopoiesis. AMCKD was characterized by vascular and kidney dysfunction, TGF β -dependent glomerulosclerosis, and microvascular rarefaction. In humans, extracapillary glomerulonephritis is associated with thromboinflammation, TGF β -dependent glomerulosclerosis, and increased bioavailability of TPO. Analysis of albumin, HGF, and inflammatory cytokine levels in sera from patients with extracapillary glomerulonephritis allowed us to identify treatment responders. Strikingly, TPO neutralization in the experimental AMCKD model normalized hematopoiesis, reduced chronic thromboinflammation, and ameliorated renal disease.

CONCLUSION

TPO-skewed hematopoiesis exacerbates chronic thromboinflammation in microvessels and worsens AMCKD. TPO is both a relevant biomarker and a promising therapeutic target in humans with CKD and other chronic thromboinflammatory diseases.

Translational implications of humoral and cellular immune dysfunction in granulomatosis with polyangiitis

Granulomatosis with polyangiitis (GPA) is a rare systemic ANCA (Anti-neutrophil cytoplasmic antibodies) associated vasculitis (AAV). In the last couple of decades, GPA has emerged as a disease of concern due to rapid increase in the prevalence and incidence especially in developing countries. Unknown aetiology and rapid progression have made GPA a critical disease. Thus, establishing specific tools to facilitate early and faster disease diagnosis and efficient disease management has immense importance. GPA may develop in genetically predisposed individuals on receiving the external stimulus (i.e. microbial pathogen, pollutant etc.) that triggers the immune response. B-cell activating factor (BAFF) produced by the neutrophils, promotes the B-cell maturation and survival which leads to increased ANCA production. Abnormal B-cell and T-cell proliferation and their cytokine response plays a major role in disease pathogenesis and granuloma formation. ANCA interacts with neutrophils and induces the neutrophil extracellular traps (NETs) formation and reactive oxygen species (ROS) production which leads to the endothelial cell injury. This review article summarizes the critical pathological events and how cytokines and immune cells shape the GPA pathogenesis. Decoding this complex network would facilitate in developing tools for diagnosis, prognosis and disease management. Recently developed specific monoclonal antibodies (MAbs) targeting cytokines and immune cells are being used for safer treatment and achieving longer remission.

Alarmins in autoimmune diseases

Alarmins are endogenous, constitutively expressed, chemotacting and immune activating proteins or peptides released because of non-programmed cell death (i.e. infections, trauma, etc). They are considered endogenous damage-associated molecular patterns (DAMPs), able to induce a sterile inflammation. In the last years, several studies highlighted a possible role of different alarmins in the pathogenesis of various autoimmune and immune-mediated diseases. We reviewed the relevant literature about this topic, for about 160 articles. Particularly, we focused on systemic autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, idiopathic inflammatory myopathies, ANCA-associated vasculitides, Behçet's disease) and cutaneous organ-specific autoimmune diseases (vitiligo, psoriasis, alopecia, pemphigo). Finally, we discussed about future perspectives and potential therapeutic implications of alarmins in autoimmune diseases. In fact, identification of receptors and downstream signal transducers of alarmins may lead to the identification of antagonistic inhibitors and agonists, with the capacity to modulate alarmins-related pathways and potential therapeutic applicability.