Strong polarization toward Th1 immune response in ANCA-associated glomerulonephritis

Old known and possible new biomarkers of ANCA-associated vasculitis

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) comprises a group of multisystem disorders involving severe, systemic, small-vessel vasculitis with short- and long term serious and life-threating complications. Despite the simplification of treatment, fundamental aspects concerning assessment of its efficacy and its adaptation to encountered complications or to the relapsing/remitting/subclinical disease course remain still unknown. The pathogenesis of AAV is complex and unique, and despite the progress achieved in the last years, much has not to be learnt. Foremost, there is still no accurate marker enabling us to monitoring disease and guide therapy. Therefore, the disease management relays often on clinical judgment and follows a" trial and error approach". In the recent years, an increasing number of new molecules s have been explored and used for this purpose including genomics, B- and T-cell subpopulations, complement system factors, cytokines, metabolomics, biospectroscopy and components of our microbiome. The aim of this review is to discuss both the role of known historical and clinically established biomarkers of AAV, as well as to highlight potential new ones, which could be used for timely diagnosis and monitoring of this devastating disease, with the goal to improve the effectiveness and ameliorate the complications of its demanding therapy.

Antineutrophil cytoplasmic antibody positivity and clinical implications in COVID-19

Aim: To investigate clinical implications of antineutrophil cytoplasmic antibody (ANCA) positivity detected in COVID-19 patients during follow up. Materials and methods: A retrospective survey in a hospital database was carried out to detect COVID-19 patients in which ANCAs had been tested. Clinical, laboratory and imaging data were collected from this hospital database and compared between ANCA-negative and -positive patients. Results: ANCAs were tested in 87 COVID-19 patients. Eight had positivity in at least one ANCA test. COVID-19 symptoms on admission and rate of pulmonary involvement were similar. Acute phase reactant levels were higher in ANCA-positive patients. Rate of mortality was higher in the ANCA-positive group without statistical significance. Conclusion: ANCA positivity detected during COVID-19 in patients without a prior diagnosis of any rheumatic condition may be related with worse outcomes.

Immunopathogenesis of ANCA-Associated Vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is an autoimmune disorder which affects small- and, to a lesser degree, medium-sized vessels. ANCA-associated vasculitis encompasses three disease phenotypes: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). This classification is largely based on clinical presentations and has several limitations. Recent research provided evidence that genetic background, risk of relapse, prognosis, and co-morbidities are more closely related to the ANCA serotype, proteinase 3 (PR3)-ANCA and myeloperoxidase (MPO)-ANCA, compared to the disease phenotypes GPA or MPA. This finding has been extended to the investigation of biomarkers predicting disease activity, which again more closely relate to the ANCA serotype. Discoveries related to the immunopathogenesis translated into clinical practice as targeted therapies are on the rise. This review will summarize the current understanding of the immunopathogenesis of ANCA-associated vasculitis and the interplay between ANCA serotype and proposed disease biomarkers and illustrate how the extending knowledge of the immunopathogenesis will likely translate into development of a personalized medicine approach in the management of ANCA-associated vasculitis.

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.

Chemokine receptor co-expression reveals aberrantly distributed TH effector memory cells in GPA patients

Background

Persistent expansion of circulating CD4⁺ effector memory T cells (T_EM) in patients with granulomatosis with polyangiitis (GPA) suggests their fundamental role in disease pathogenesis. Recent studies have shown that distinct functional CD4⁺ T_EM cell subsets can be identified based on expression patterns of chemokine receptors. The current study aimed to determine different CD4⁺ T_EM cell subsets based on chemokine receptor expression in peripheral blood of GPA patients. Identification of particular circulating CD4⁺ T_EM cells subsets may reveal distinct contributions of specific CD4⁺ T_EM subsets to the disease pathogenesis in GPA.

Method

Peripheral blood of 63 GPA patients in remission and 42 age- and sex-matched healthy controls was stained immediately after blood withdrawal with fluorochrome-conjugated antibodies for cell surface markers (CD3, CD4, CD45RO) and chemokine receptors (CCR4, CCR6, CCR7, CRTh2, CXCR3) followed by flow cytometry analysis. CD4⁺ T_EM memory cells (CD3⁺CD4⁺CD45RO⁺CCR7^-) were gated, and the expression patterns of chemokine receptors CXCR3⁺CCR4^-CCR6^-CRTh2^-, CXCR3^-CCR4⁺CCR6^-CRTh2⁺, CXCR3^-CCR4⁺CCR6⁺CRTh2^-, and CXCR3⁺CCR4^-CCR6⁺CRTh2^- were used to distinguish T_EM1, T_EM2, T_EM17, and T_EM17.1 cells, respectively.

Results

The percentage of CD4⁺ T_EM cells was significantly increased in GPA patients in remission compared to HCs. Chemokine receptor co-expression analysis within the CD4⁺ T_EM cell population demonstrated a significant increase in the proportion of T_EM17 cells with a concomitant significant decrease in the T_EM1 cells in GPA patients compared to HC. The percentage of T_EM17 cells correlated negatively with T_EM1 cells in GPA patients. Moreover, the circulating proportion of T_EM17 cells showed a positive correlation with the number of organs involved and an association with the tendency to relapse in GPA patients. Interestingly, the aberrant distribution of T_EM1 and T_EM17 cells is modulated in CMV- seropositive GPA patients.

Conclusions

Our data demonstrates the identification of different CD4⁺ T_EM cell subsets in peripheral blood of GPA patients based on chemokine receptor co-expression analysis. The aberrant balance between T_EM1 and T_EM17 cells in remission GPA patients, showed to be associated with disease pathogenesis in relation to organ involvement, and tendency to relapse.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1343-8) contains supplementary material, which is available to authorized users.

Isolation of vascular smooth muscle antigen-reactive CD4(+)αβTh1 clones that induce pulmonary vasculitis in MRL/Mp-Fas(+/+) mice

Here, we established CD4(+)αβTh1 clones specific for rat vascular smooth muscle antigen (VSMAg) that induced vasculitis lesions in the lungs of MRL/Mp-Fas(+/+) mice following adoptive transfer. Six different T cell clones, MV1b1 (Vβ1), MV1b4 (Vβ4), MV1b8.3 (Vβ8.3), MV1b61 (Vβ6), MV1b62 (Vβ6), and MV1b63 (Vβ6), were isolated from the MV1 T cell line from the regional lymph nodes of immunized MRL/Mp-Fas(+/+) mice; the three (Vβ6) clones had unique CDR3 amino acid sequences. Following stimulation with VSMAg-pulsed antigen presenting cells, MV1b61 and MV1b62 failed to secrete interferon-γ and tumor necrosis factor-α, although the other four clones secreted high levels of both cytokines. In adoptive transfer experiments, MV1b61 and MV1b62 did not induce organ involvement including pulmonary vasculitis. In contrast, MV1b1, MV1b4, MV1b8.3, and MV1b63 induced perivascular mononuclear cell infiltration in pulmonary small arteries. These clones may provide useful tools for investigating the underlying mechanisms of vasculitis syndromes and for developing therapeutic strategies.

Membranoproliferative glomerulonephritis with predominant IgG2 and IgG3 deposition in a patient with IgG4-related disease

Background

IgG4-related disease is a novel disease entity characterized by elevated serum IgG4 and tissue infiltration by IgG4-positive plasma cells. Typical renal pathology is tubulointerstitial nephritis with storiform fibrosis, although the co-existence of various glomerular lesions has been described. Here, we present the first report of a case of IgG4-related kidney disease and membranoproliferative glomerulonephritis showing the discrepancy in IgG subclasses between the kidney interstitium and glomeruli.

Case presentation

A 70-year-old Japanese woman was diagnosed with membranoproliferative glomerulonephritis and focal tubulointerstitial nephritis with IgG4-positive plasma cells. Immunofluorescence studies revealed predominant deposition of IgG3 and IgG2, but not IgG4 in the glomeruli. We administered oral prednisolone at 30 mg/day, and the abnormalities in urine and blood tests gradually resolved.

Conclusion

In this case, different patterns of IgG subclasses detected in the glomeruli and interstitial plasma cells suggest overlapping immunologic abnormalities. The favorable clinical course in our patient suggests that steroid therapy is promising in cases of IgG4-related kidney disease accompanied by glomerulonephritis.

Systemic lupus erythematosus associated with ANCA-associated vasculitis: an overlapping syndrome?

Systemic lupus erythematosus (SLE) and small-sized vessel vasculitis are usually two distinguishable autoimmune diseases. However, a vasculitis may be found in the course SLE but rarely corresponds to an ANCA-associated vasculitis (AAV). We report four cases of de novo SLE associated with AAV, our aim being to discuss the clinical significance of this association. We included four patients fulfilling the criteria for both SLE and AAV and followed in two different university hospitals between 1996 and 2009. In light of a 20-year literature review (25 described clinical cases), we discussed the etiopathogeny of such an association. All patients presented a severe renal involvement (creatininemia ranging from 120 to 370 μmol/l) and thrombopenia (ranging from 45,000 to 137,000 platelets/mm(3)). The other main clinical symptoms were arthritis (n = 3), serositis (n = 2) and intra-alveolar hemorrhage (n = 2). An inflammatory syndrome was noticed at diagnosis in all cases. ANCAs were MPO-ANCAs in all cases. Two out of these four patients were also diagnosed with antiphospholipid syndrome. The frequency of this association seems not fortuitous. Although the etiopathogenic mechanisms of such an association remain to be more precisely described, several clinical, histological and immunological features support the hypothesis of the existence of a SLE-AAV overlapping syndrome. Moreover, clinicians must be aware of such an overlapping syndrome, notably because its initial presentation can be very severe.

Intracellular cytokine production in ANCA-associated vasculitis: low levels of interleukin-10 in remission are associated with a higher relapse rate in the long-term follow-up

BACKGROUND AND AIMS

Dysregulation of cell-mediated immune response likely plays a role in the pathogenesis of anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV), but it has not yet been fully established. The aim of this study was to assess the intracellular cytokine production in patients with AAV at different stages of the disease, in particular, in relation to the long-term prognosis.

METHODS

We included 69 patients with AAV and 24 healthy controls. Using flow cytometry, the following intracellular cytokines (IC) were measured in all patients: interferon-gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), interleukin-2 and interleukin-4 in CD3+T cells and interleukin-10 (IL-10) and interleukin 12 (IL-12) in monocytes. Patients were then prospectively followed for a median of 43 months and cytokine production was related to the long-term prognosis.

RESULTS

When compared to healthy controls, increased IL-12 production was observed in AAV patients, both active (p<0.01) and in remission (p<0.05). In remission, increased IFN-gamma production was also found (p<0.01). IL-10 production was higher in active patients than in patients in remission (p<0.05) but did not differ from controls. Patients in remission who developed a relapse during follow-up had significantly lower IL-10 production than those without relapse (p<0.01). Results of this prospective study of IC production in AAV confirm findings of previous studies measuring circulating cytokine levels.

CONCLUSIONS

Activation of the immune system in AAV patients is noticeable even in remission. Patients with AAV display increased IL-12 production, which seems to be counterbalanced by IL-10. Low IL-10 levels in remission are associated with a higher relapse rate in the long-term follow-up.

Wegener's granulomatosis: a model of auto-antibodies in mucosal autoimmunity

Wegener's granulomatosis (WG) is an autoimmune condition marked by vasculitis of small and medium sized vessels particularly affecting the upper respiratory tract and kidneys. There is a strong mucosal component similar to other autoimmune conditions such as systemic lupus erythematosus and Behçet's disease. While the pathogenesis of WG is not completely known, auto-antibodies such as IgG ANCAs have been implicated in endovascular damage and modulation of neutrophil/monocyte responses by Fc receptor (FcR) signaling. Due to the substantial mucosal involvement in WG (oral, nasal, and upper respiratory tract involvement), it is probable that IgA antibodies (perhaps IgA ANCAs) play a role in disease. Given discrepancies in associating ANCA levels with disease activity, future work should determine if IgA ANCAs are present in WG patients and examine the biology underlying the ANCAs' signaling partners--the FcRs.

A new clinicopathological entity of IgG4-related inflammatory abdominal aortic aneurysm

OBJECTIVE

Recently, the relationship between immunoglobulin (Ig)G4 and idiopathic sclerosing lesions has attracted much attention. IgG4-related disease was first described with regard to the pancreas (autoimmune pancreatitis), and has been expanded to various organ systems. We previously reported that inflammatory abdominal aortic aneurysm (IAAA) could be one of the manifestations of IgG4-related disease. In this study, we tried to elucidate the clinical characteristics of IgG4-related IAAA.

METHODS

This study consisted of 23 cases of IAAA and 40 cases of atherosclerotic abdominal aortic aneurysm (AAA). Clinical presentation, laboratory findings, and pathological features were examined. Aneurysms of 13 cases histologically corresponded to IgG4-related IAAA.

RESULTS

Those cases accounted for 5% of all surgical AAAs, and 57% of IAAAs. Compared to non-IgG4-related IAAA, IgG4-related cases were characterized by less frequent association with abdominal or back pain. Serum IgG4 concentrations were significantly elevated in IgG4-related cases. Interestingly, patients with IgG4-related IAAA frequently showed an allergic constitution, such as drug allergy, autoimmune diseases, high serum IgE concentrations, and a high titer of antinuclear antibody. Pathologically, IgG4-related cases were characterized by more significant thickening of the adventitia and more numerous IgG4-positive plasma cell infiltrations. Three non-IgG4-related cases showed aneurysmal rupture at the time of first presentation, whereas no IgG4-related cases showed rupture.

CONCLUSION

Recognizing a new disease entity of IgG4-related IAAA seems important because this was clinically and pathologically different from conventional aAAA and non-IgG4-related IAAA.

Osteopontin as an injury marker expressing in epithelial hyperplasia lesions helpful in prognosis of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is characterized by typical sclerosis but also shows other non-sclerotic lesions that provide prognostic informations. The glomerular epithelial hyperplasia lesion (EPHL) that develops earlier than the sclerotic lesions is a key determinant of progression of FSGS. However, the relationship among EPHL, glomeular sclerosis, and macrophage infiltration in FSGS is unclear, and the EPHL-associated markers helpful for prognosis of FSGS have still not been completely identified. Here, we performed clinicopathologic, immunochemical, and molecular analyses to examine whether osteopontin (OPN), a macrophage chemokine, is an injury marker of EPHLs correlating with glomerular sclerosis and macrophage mobilization. First, the FSGS model was induced in Balb/c mice by a single injection of adriamycin, and consecutive sclerosis changes were evaluated. In parallel, we used reverse transcription-polymerase chain reaction and Western blot analyses to determine levels of OPN in isolated glomeruli and urine, respectively. Immunohistochemistry was applied to assess the OPN expression in EPHLs and macrophage infiltration around the glomeruli. Our results showed that, within glomeruli, OPN expressed restrictedly within EPHL; the OPN mRNA and protein of glomeruli increased on day 11, correlating well with the early EPHL, and following sclerosis and macrophage infiltration. In addition, immunohistochemistry (IHC) staining of OPN greatly highlighted early glomerular EPHLs, helping microscopic identification of EPHLs. We propose that the OPN expression in EPHLs could contribute to the progression of FSGS by recruiting macrophage toward the compromised glomeruli. Detection of OPN in glomeruli and urine could be helpful in prognosis of FSGS.

Glomerulonephritis, Th1 and Th2: what's new?

Glomerulonephritis (GN), the major worldwide cause of chronic renal disease and renal failure, shows a wide spectrum of histological patterns, severity of injury and clinical outcomes that may be related to the nature of the nephritogenic immune response. In the majority of cases, there is evidence of a central role for cognate immunity in the initiation of human GN and contributions of both humoral and cellular effector mechanisms have been demonstrated in both humans and in animal models. T helper cell subsets are known to activate different immune effector mechanisms which influence disease outcomes in infectious and autoimmune diseases and evidence is now accumulating that Th1 and Th2 subsets direct diverging effector pathways that lead to different patterns and severity of glomerular injury in GN. Th1-predominant responses appear to be associated strongly with proliferative and crescentic forms of GN that result in severe renal injury, while Th2 responses are associated with membranous patterns of injury. The challenge remains to understand fully the relevance of T helper cell subset responses to the spectrum of human GN and to apply this new knowledge to the development of more potent and selective therapeutic strategies.

Off balance: T-cells in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides

There is substantial evidence that T-cells are off balance in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides. Genetic risk factors may influence shaping of the TCR repertoire and regulatory control of T-cells in predisposed individuals. T-cells are found in inflammatory lesions. Vigorous Th1-type responses are seen in Wegener's granulomatosis and microscopic angiitis, whereas a Th2-type response predominates in Churg-Strauss syndrome. Oligoclonality and shortened telomers indicate antigen-driven clonal expansion and replicative senescence of T-cells in ANCA-associated vasculitides. Potent CD28(-) Th1-type cells displaying an effector-memory/late differentiated, senescent phenotype are expanded in peripheral blood and are found in granulomatous lesions in Wegener's granulomatosis. Differences in proliferative peripheral blood T-cell responses to the autoantigens proteinase 3 (PR3)- and myeloperoxidase (MPO) have not consistently been detected between patients with ANCA-associated vasculitides and healthy controls in vitro. To recognize an autoantigen, break tolerance, and maintain autoimmune disease T- and B-cells require particular triggers and lymphoid structures. There is preliminary evidence of lymphoid-like structures and possible maturation of autoreactive PR3-ANCA-specific B-cells in granulomatous lesions in Wegener's granulomatosis. Alteration of the T-cell response and anomalous autoantigen-presentation in lymphoid-structures could facilitate development of autoimmune disease in ANCA-associated vasculitides.

Treatment of refractory Wegener's granulomatosis with antithymocyte globulin (ATG): an open study in 15 patients

BACKGROUND

A subset of patients with Wegener's granulomatosis does not respond sufficiently to cyclophosphamide and glucocorticosteroids or suffers of intolerable side effects. Anecdotal data suggest that antithymocyte globulin (ATG) may be a treatment option for these patients. We now describe 15 patients treated with ATG for refractory Wegener's granulomatosis.

METHODS

Fifteen patients with histologically proven active refractory Wegener's granulomatosis (seven unresponsive to cyclophosphamide, eight intolerant) were treated with ATG by a protocol (SOLUTION protocol) designed by the European Vasculitis Study (EUVAS) Group.

RESULTS

Before ATG administration, patients had received a mean of 5.2 (range 2 to 7) different therapeutic approaches including glucocorticosteroids and cyclophosphamide in all and experimental therapies in six, without control of disease activity [2.8 (range 1 to 7) relapses during a disease duration of 63.2 (range 18 to 180) months]. Thirteen of 15 patients showed a favorable response to ATG with partial (N= 9) or complete (N= 4) remission. During a follow-up of 21.8 (range 6 to 68) months, seven patients relapsed after a mean of 8.4 (range 2 to 24) months (five minor and two major relapses). Six patients are free of relapse for 22.3 (range 7 to 64) months. Two patients died, 1 and 3 days following the first dose of ATG, due to pulmonary hemorrhage and infection (one each). Although further immunosuppressive treatment was required in all surviving patients, a less intensive regimen could be applied in 12. Beside fever and chills associated with the first gift of ATG, ATG was well tolerated, with infections being observed in five cases and serum sickness in two.

CONCLUSION

Anti-T-cell-directed treatment with ATG may be a therapeutic option for severe refractory Wegener's granulomatosis if simultaneous infections and fluid overload have been ruled out. In patients with alveolar hemorrhage, ATG should only be used under special caution.

Up-regulated interleukin-4 production by peripheral T-helper cells in idiopathic membranous nephropathy

BACKGROUND

Helper T (Th) cells are classified into Th1 and Th2 subsets based on cytokine production and the Th1/Th2 paradigm explains differences in inflammatory effector pathways in various human diseases. Membranous nephropathy (MN) is an immune complex disease associated with Th2 nephritogenic immune response. However, overproduction of interleukin (IL)-4, a principal Th2 cytokine, has not been demonstrated. We investigated Th1/Th2 cytokine production by peripheral Th cells and its association with the degree of proteinuria in MN.

METHODS

We analysed production of Th1/Th2 cytokines, interferon (IFN)-gamma and IL-4 by peripheral Th cells, using an intracellular cytokine detection method with flow cytometry in patients with MN (n = 24). The data were compared with data from healthy subjects (n = 51), subjects with minimal change nephrotic syndrome (MCNS; n = 13) and subjects with focal segmental glomerulosclerosis (FSGS; n = 12). We compared the percentages of IFN-gamma+ and IL-4+ Th cells and the peripheral Th1/Th2 ratio (IFN-gamma/IL-4 ratio) among the four groups. We also examined the association of IFN-gamma and IL-4 production with clinical parameters of MN.

RESULTS

The mean percentage of IL-4+ cells in MN (3.9+/-1.2%) was significantly higher than in the control (2.4+/-1.0%), MCNS (2.3+/-1.4%) and FSGS (2.3+/-1.2%) groups (P<0.001, respectively). The Th1/Th2 ratio was significantly lower in MN (5.3+/-2.0) than in the control (8.2+/-4.2, P<0.05), MCNS (10.0+/-5.3, P<0.01) and FSGS (10.2+/-5.3, P<0.01) groups. Moreover, the percentage of IL-4+ cells correlated significantly with the amount of proteinuria in MN (r = 0.57, P<0.01).

CONCLUSIONS

IL-4 production by peripheral Th cells is up-regulated in patients with MN and correlated with the severity of proteinuria. Intracellular cytokine analysis could be a useful index in idiopathic MN.