Distinct responses of interleukin-6 and other laboratory parameters to treatment in a patient with Wegener's granulomatosis

The association of serum interleukin-6 levels with clinical outcomes in antineutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

To investigate serum IL-6 (sIL-6) levels during active disease, complete remission (CR), and relapse in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), and to explore the association of changes in sIL-6 with clinical outcomes.

METHODS

sIL-6 levels were measured at baseline and longitudinally over 18 months, in 78 patients with AAV enrolled in a randomized controlled trial comparing treatment with either rituximab (RTX) or cyclophosphamide (CYC)/azathioprine (AZA). Outcome variables included baseline clinical features, ANCA specificity, disease activity (active disease versus CR), time to relapse events, B cell repopulation, and ANCA titer increases.

RESULTS

At baseline, sIL6 levels were detectable in 81% of patients; 73% (n = 57) of subjects were proteinase 3 (PR3)-ANCA positive, sIL-6 levels were higher in subjects with PR3-ANCAs and positively correlated with their levels (r_s = 0.36,p < 0.01), but not with levels of myeloperoxidase (MPO)-ANCA (r_s = -0.17,p = 0.47). Higher baseline sIL-6 levels were associated with PR3-ANCA positivity, fever, pulmonary nodules/cavities, conductive deafness, and absence of urinary red blood cell casts (p < 0.05). Baseline sIL6 levels did not predict CR at month 6 (p = 0.71), and the median sIL-6 level declined from baseline with induction therapy, regardless of CR achievement. An increase in sIL-6 during CR was a predictor for subsequent severe relapse in RTX-treated patients (hazard ratio (HR):7.24,p = 0.01), but not in CYC/AZA-treated patients (HR:0.62,p = 0.50). In contrast, a sIL-6 increase did not predict B cell repopulation or ANCA titer increase in either treatment arm (p > 0.05).

CONCLUSION

At baseline, sIL-6 concentrations correlate with PR3-ANCA titers and are associated with specific clinical manifestations of AAV. Baseline sIL6 concentrations do not predict CR at 6 months, but the increase in sIL-6 concentrations during CR is associated with subsequent severe relapse among RTX-treated patients. Further investigation into the mechanistic role of IL6 in AAV might lead to identifying this pathway as a potential therapeutic target in this disease.

Interleukin-6 in ANCA-associated vasculitis: Rationale for successful treatment with tocilizumab

OBJECTIVE

Microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) are systemic, necrotizing, small-vessel vasculitis associated with circulating anti-neutrophil cytoplasmic autoantibodies (ANCA), and thus called ANCA-associated vasculitides (AAV). The aim of the present study is to evaluate a potential role of interleukin (IL)-6 and its pathway in the pathogenesis of AAV and to review previous evidence of IL-6 in MPA and GPA.

METHODS

Blood and histological samples from 10 untreated myeloperoxidase (MPO)-ANCA/proteinase 3 (PR3)-ANCA-positive patients with active AAV were studied. Serum levels of cytokines/chemokines were evaluated by means of a Bio-Plex Multiple Cytokine Assay. IL-6 production at sites of active vasculitis was assessed by means of both immunohistochemistry and in situ hybridization techniques. We also treated a patient with MPA who was resistant or allergic to conventional treatments with a 12-month course of the IL-6 inhibitor tocilizumab and followed him up for 24 additional months. We also reviewed all the published cases in the English literature of histologically confirmed MPA or GPA, in which elevated IL-6 serum levels or intralesional IL-6 expression were reported.

RESULTS

IL-6 serum levels were significantly increased in patients with AAV as compared to controls (median = 51.96pg/mL; range: 34.11-84.30; versus 0.68pg/mL; range: 0.01-1.81; P < 0.005). Also, IL-6 was expressed and produced at sites of active vasculitis. Treatment with tocilizumab was able to induce a complete and sustained disease remission in a patient with severe multisystemic MPA, as well as normalization of circulating levels of IL-6-associated pro-inflammatory cytokines and chemokines. Previous evidence of IL-6 pathway activation in AAV is scarce. Increased serum levels of IL-6 were reported in seven clinical studies for a total of approximately 120 patients, mainly affected by GPA.

CONCLUSION

The finding of an activated IL-6 pathway in patients with AAV, together with the observed effects of tocilizumab monotherapy, provides evidence for a possible central role of IL-6 in the pathogenesis of AAV and suggests its targeting as a potential treatment.

Wegener's granulomatosis followed by development of sarcoidosis

Although both Wegener's granulomatosis and sarcoidosis are considered granulomatous disorders, their clinical courses differ markedly, and typically patients with these two diseases are readily distinguishable. We report an unusual case in which the patient presented with a systemic vasculitis consistent with Wegener's granulomatosis that remitted with therapy and then, months later, developed sarcoidosis. This is the first case report of the sequential development of the two diseases. We review the relationship of vasculitis to sarcoidosis and speculate on the etiopathogenesis that might link the two.

Interleukin-6 activity in dogs with juvenile polyarteritis syndrome: effect of corticosteroids

Juvenile polyarteritis syndrome (JPS) is an idiopathic febrile disease in dogs. Elevated serum levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) have been reported in human patients with vasculitis. We investigated whether these cytokines are also elevated in serum of dogs with JPS using sensitive bioassays. Increased levels of IL-6 activity were detected in the serum of 12 acutely ill dogs, whereas the IL-6 activity decreased to low or undetectable levels during convalescence. Treatment of 5 acute JPS dogs with prednisone resulted in a rapid clinical improvement accompanied by a decrease of IL-6 activity. Withdrawal of prednisone treatment caused reappearance of clinical symptoms and high serum IL-6 activity within a few days. TNF activity could not be detected in the samples of normal dogs, convalescent JPS, or acute JPS dogs. These studies support a role for IL-6 in the pathogenesis of JPS.