Inflammatory Markers are Quickly Improved by Tocilizumab in Early Polymyalgia Rheumatica and Might Predict Early Response to Interleukin-6 Blockade.

INTRODUCTION: It is unclear whether polymyalgia rheumatica (PMR) should be considered an inflammatory disease or an autoimmune disease. METHODS: Eighteen untreated early PMR patients and 18 sex- and age-matched healthy controls (HCs) were included. PMR patients received tocilizumab from week 0 to week 12 and glucocorticoids from week 12 to week 24. Leukocytes, neutrophils, platelets, hemoglobin, γ-globulins, IgG, IgA, and IgM were compared between the PMR patients and HCs and before and after tocilizumab treatment in the PMR group. RESULTS: The mean age was 68 ± 7 and 66 ± 11 years, and the mean serum C-reactive protein level was 82 ± 16 and 5 ± 2 mg/l for PMR patients and HCs, respectively. At inclusion, leukocytes (p < 0.0001), neutrophils (p < 0.0001), and platelets (p < 0.0001) were increased and hemoglobin (p < 0.0001) decreased in the PMR group compared to the HC group. After tocilizumab therapy, leukocytes, neutrophils, and platelets decreased, and hemoglobin increased. At inclusion, all four parameters were significantly associated with the serum IL-6 level, though it was not associated after tocilizumab therapy. Levels of γ-globulin were increased in the PMR patients compared to HCs (p = 0.0087), and PMR patients with γ-globulins levels over 11 g/l at inclusion responded more quickly to tocilizumab therapy. Autoantibody profiles did not differ between the PMR patients and HCs. CONCLUSIONS: This study suggests that PMR is more an inflammatory disease than an autoimmune disease. Tocilizumab improves all markers of inflammation. Patients with elevated γ-globulins respond more quickly to tocilizumab.

Could Lymphocyte Profiling be Useful to Diagnose Systemic Autoimmune Diseases?

Considering the implications of B, T, and natural killer (NK) cells in the pathophysiology of systemic autoimmune diseases, the assessment of their distribution in the blood could be helpful for physicians in the complex process of determining a precise diagnosis. In primary Sjögren's syndrome, transitional and active naive B cells are increased and memory B cells are decreased compared to healthy controls and other systemic diseases. However, their utility to improve the accuracy of classification criteria has not been proven. In early untreated rheumatoid arthritis, proportions of regulatory T cells are constantly reduced, but other patterns are difficult to determine given the heterogeneity of published studies. In systemic lupus erythematosus, the lack of studies using large cohorts of patients and the diversity of the possible pathological mechanisms involved are also important impediments. Nevertheless, transitional B cell and plasma cell proportions are increased in most of the studies, the CD4/CD8 ratio is decreased, and the number of NK cells is reduced. Despite the low number of studies, anomalies of lymphocyte subset distribution was also described in ANCA-associated vasculitis, systemic scleroderma, and myositis. For now, flow cytometric analysis of lymphocyte subsets has focused mainly on specific subpopulations and is more useful for basic and translational research than for diagnostics in clinical practice. However, new modern methods such as mass cytometry and bioinformatics analyses may offer the possibility to simultaneously account for the relative proportions of multiple lymphocyte subsets and define a global profile in homogeneous groups of patients. The years to come will certainly incorporate such global lymphocyte profiling in reclassification of systemic autoimmune diseases.