Antineutrophil cytoplasmic antibody associated vasculitides with renal involvement: Open challenges in the remission induction therapy

Irisin in atherosclerosis

Irisin, a novel exercise-induced myokine, has been shown to play important roles in increasing white adipose tissue browning, regulating energy metabolism and improving insulin resistance. Growing evidence suggests a direct role for irisin in preventing atherosclerosis (AS) by inhibiting oxidative stress, improving dyslipidemia, facilitating anti-inflammation, reducing cellular damage and recovering endothelial function. In addition, some studies have noted that serum irisin levels play an essential role in cardiovascular diseases (CVDs) risk prediction, highlighting that irisin has the potential to be a useful predictive marker and therapeutic target of AS, especially in monitoring therapeutic efficacy. This review summarizes the understanding of irisin-mediated regulation in essential biological pathways and functions in atherosclerosis and prompts further exploitation of the biological properties of irisin in the pathogenesis of atherosclerosis.

Narrative Review of Hypercoagulability in Small-Vessel Vasculitis

Pauci-immune necrotizing and crescentic glomerulonephritis (GN) is the most common etiology of rapidly progressive GN. Clinical presentation in those afflicted is usually related to rapid loss of kidney function. We report the case of a 70-year-old woman who came to medical attention for signs and symptoms related to lower-extremity deep vein thrombosis (DVT). At presentation, the patient had biochemical abnormalities consistent with active GN, which quickly progressed to rapid loss in kidney function requiring renal replacement therapy. Kidney biopsy revealed small-vessel vasculitis with glomerular crescents. Serologic studies were negative for antineutrophil cytoplasmic antibody antibodies and other causes of acute GN. Plasmapheresis, immunosuppressive, and anticoagulant therapies were prescribed. Absence of other apparent end-organ involvement with vasculitis pointed toward renal-limited small-vessel vasculitis, yet presence of unprovoked DVT argues for systemic vascular inflammation. This case illustrates that venous thrombosis can be the presenting manifestation in patients with vasculitis and silent, severe end-organ involvement. The epidemiology and pathophysiology of venous thromboembolism in small-vessel vasculitis are discussed in this report.

Exploring Frequencies of Circulating Specific Th17 Cells against Myeloperoxidase and Proteinase 3 in ANCA Associated Vasculitis

Background: The role of the T helper 17 (Th17) cell subset in anti-neutrophil cytoplasm antibodies (ANCA) associated vasculitis (AAV) is controversial. We hypothesized that a specific Th17 response to myeloperoxidase (MPO) or proteinase 3 (PR3) is detectable in AAV patients and is different among the disease phases. Methods: We analyzed 43 AAV patients with renal involvement (21 acute and 22 remission patients), and 12 healthy controls. Peripheral blood mononuclear cells (PBMCs) were cultured with PR3/MPO over 48 h. Thereafter, frequencies of MPO/PR3-specific Th17 cells were assessed using an enzyme-linked immunosorbent spot (ELISpot) assay. Supernatant IL-17 concentration was quantified using ELISA. Finally, specific Th17 response after depletion of T regulatory lymphocytes (T-regs) in some remission patients was compared to the non T-reg-depleted response. Results: Specific Th17 cell number was higher in acute patients compared to remission (p = 0.004). Specific Th17 cell number performed well in the disease activity detection (ROC curve area under the curve (AUC) = 0.87; p = 0.0001) with an optimal cut-off of 6 spots/million. Patients above this cut-off showed higher serum creatinine (p = 0.004), C-reactive protein (CRP) (p = 0.001) and ANCA titer (p = 0.032). Supernatant IL-17 concentration was higher in acute patients compared to remission (p = 0.035) and did not normalize to healthy control levels (p = 0.01). Conclusions: A specific Th17 cell response is present in AAV patients. This response is more pronounced in the acute phase, but persists in remission.

T-lymphocyte in ANCA-associated vasculitis: what do we know? A pathophysiological and therapeutic approach

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is an autoimmune condition that commonly causes kidney impairment and can be fatal. The key participation of B-lymphocytes as ANCA producers and neutrophils as target of these antibodies is widely described as the mechanism of endothelial damage in this disease. There has been a rising interest in the role of T-lymphocytes in AAV in recent years. Evidence is strong from animal models, and T-lymphocytes can be found infiltrating kidney tissue and other tissue sites in AAV patients. Furthermore, the different subsets of T-lymphocytes are also key players in the aberrant immune response observed in AAV. Polarization towards a predominant Th1 and Th17 response in the acute phase of the disease has been described, along with a decline in the number of T-regulatory lymphocytes, which, in turn, show functional impairment. Interactions between different T-cell subsets, and between T-cells and neutrophils and B-cells, also enhance the inflammatory response, constituting a complex network. Novel therapies targeting T-cell immunity are emerging in this scenario and may constitute an interesting alternative to conventional therapy in selected patients. This review aims to summarize the available evidence regarding T-cell imbalances and functional impairment, especially focusing on renal involvement of AAV.