Looking into the IL-1 of the storm: are inflammasomes the link between immunothrombosis and hyperinflammation in cytokine storm syndromes?

Inflammasomes and the interleukin (IL)-1 family of cytokines are key mediators of both inflammation and immunothrombosis. Inflammasomes are responsible for the release of the pro-inflammatory cytokines IL-1β and IL-18, as well as releasing tissue factor (TF), a pivotal initiator of the extrinsic coagulation cascade. Uncontrolled production of inflammatory cytokines results in what is known as a "cytokine storm" leading to hyperinflammatory disease. Cytokine storms can complicate a variety of diseases and results in hypercytokinemia, coagulopathies, tissue damage, multiorgan failure, and death. Patients presenting with cytokine storm syndromes have a high mortality rate, driven in part by disseminated intravascular coagulation (DIC). While our knowledge on the factors propagating cytokine storms is increasing, how cytokine storm influences DIC remains unknown, and therefore treatments for diseases, where these aspects are a key feature are limited, with most targeting specific cytokines. Currently, no therapies target the immunothrombosis aspect of hyperinflammatory syndromes. Here we discuss how targeting the inflammasome and pyroptosis may be a novel therapeutic strategy for the treatment of hyperinflammation and its associated pathologies.

Induction of the Histamine-Forming Enzyme Histidine Decarboxylase in Skeletal Muscles by Prolonged Muscular Work: Histological Demonstration and Mediation by Cytokines

Recent studies suggest that histamine-a regulator of the microcirculation-may play important roles in exercise. We have shown that the histamine-forming enzyme histidine decarboxylase (HDC) is induced in skeletal muscles by prolonged muscular work (PMW). However, histological analysis of such HDC induction is lacking due to appropriate anti-HDC antibodies being unavailable. We also showed that the inflammatory cytokines interleukin (IL)-1 and tumor necrosis factor (TNF)-α can induce HDC, and that PMW increases both IL-1α and IL-1β in skeletal muscles. Here, we examined the effects (a) of PMW on the histological evidence of HDC induction and (b) of IL-1β and TNF-α on HDC activity in skeletal muscles. By immunostaining using a recently introduced commercial polyclonal anti-HDC antibody, we found that cells in the endomysium and around blood vessels, and also some muscle fibers themselves, became HDC-positive after PMW. After PMW, TNF-α, but not IL-1α or IL-1β, was detected in the blood serum. The minimum intravenous dose of IL-1β that would induce HDC activity was about 1/10 that of TNF-α, while in combination they synergistically augmented HDC activity. These results suggest that PMW induces HDC in skeletal muscles, including cells in the endomysium and around blood vessels, and also some muscle fibers themselves, and that IL-1β and TNF-α may cooperatively mediate this induction.

Response to Interleukin-1 Inhibitors in 140 Italian Patients with Adult-Onset Still's Disease: A Multicentre Retrospective Observational Study

Background: Interleukin (IL)-1 plays a crucial role in the pathogenesis of Adult onset Still's disease (AOSD). Objectives: To evaluate the efficacy and safety of anakinra (ANA) and canakinumab (CAN) in a large group of AOSD patients. Methods: Data on clinical, serological features, and concomitant treatments were retrospectively collected at baseline and after 3, 6, and 12 months from AOSD patients (Yamaguchi criteria) referred by 18 Italian centers. Pouchot's score was used to evaluate disease severity. Results: One hundred forty patients were treated with ANA; 4 were subsequently switched to CAN after ANA failure. The systemic pattern of AOSD was identified in 104 (74.2%) of the ANA-treated and in 3 (75%) of the CAN-treated groups; the chronic-articular type of AOSD was identified in 48 (25.8%) of the ANA-treated and in 1 (25%) of the CAN-treated groups. Methotrexate (MTX) was the most frequent disease modifying anti-rheumatic drug (DMARD) used before beginning ANA or CAN [91/140 (75.8%), 2/4 (50%), respectively]. As a second-line biologic DMARD therapy in 29/140 (20.7%) of the patients, ANA was found effective in improving all clinical and serological manifestations (p < 0.0001), and Pouchot's score was found to be significantly reduced at all time points (p < 0.0001). No differences in treatment response were identified in the ANA-group when the patients were stratified according to age, sex, disease pattern or mono/combination therapy profile. ANA primary and secondary inefficacy at the 12-month time point was 15/140 (10.7%) and 11/140 (7.8%), respectively. Adverse events (AEs) [mainly represented by in situ (28/47, 59.5%) or diffuse (12/47, 25.5%) skin reactions and infections (7/47, 14.8%)] were the main causes for discontinuation. Pouchot's score and clinical and serological features were significantly ameliorated at all time points (p < 0.0001) in the CAN-group, and no AEs were registered during CAN therapy. Treatment was suspended for loss of efficacy only in one case (1/4, 25%). Conclusion: This is the largest retrospective observational study evaluating the efficacy and safety of IL-1 inhibitors in AOSD patients. A good response was noted at 3 months after therapy onset in both the ANA- and CAN-groups. Skin reaction may nevertheless represent a non-negligible AE during ANA treatment.

A Snapshot on the On-Label and Off-Label Use of the Interleukin-1 Inhibitors in Italy among Rheumatologists and Pediatric Rheumatologists: A Nationwide Multi-Center Retrospective Observational Study

Background: Interleukin (IL)-1 inhibitors have been suggested as possible therapeutic options in a large number of old and new clinical entities characterized by an IL-1 driven pathogenesis.

Objectives: To perform a nationwide snapshot of the on-label and off-label use of anakinra (ANA) and canakinumab (CAN) for different conditions both in children and adults.

Methods: We retrospectively collected demographic, clinical, and therapeutic data from both adult and pediatric patients treated with IL-1 inhibitors from January 2008 to July 2016.

Results: Five hundred and twenty-six treatment courses given to 475 patients (195 males, 280 females; 111 children and 364 adults) were evaluated. ANA was administered in 421 (80.04%) courses, CAN in 105 (19.96%). Sixty-two (32.1%) patients had been treated with both agents. IL-1 inhibitors were employed in 38 different indications (37 with ANA, 16 with CAN). Off-label use was more frequent for ANA than CAN (p < 0.0001). ANA was employed as first-line biologic approach in 323 (76.7%) cases, while CAN in 37 cases (35.2%). IL-1 inhibitors were associated with corticosteroids in 285 (54.18%) courses and disease modifying anti-rheumatic drugs (DMARDs) in 156 (29.65%). ANA dosage ranged from 30 to 200 mg/day (or 1.0–2.0 mg/kg/day) among adults and 2–4 mg/kg/day among children; regarding CAN, the most frequently used posologies were 150mg every 8 weeks, 150mg every 4 weeks and 150mg every 6 weeks. The frequency of failure was higher among patients treated with ANA at a dosage of 100 mg/day than those treated with 2 mg/kg/day (p = 0.03). Seventy-six patients (14.4%) reported an adverse event (AE) and 10 (1.9%) a severe AE. AEs occurred more frequently after the age of 65 compared to both children and patients aged between 16 and 65 (p = 0.003 and p = 0.03, respectively).

Conclusions: IL-1 inhibitors are mostly used off-label, especially ANA, during adulthood. The high frequency of good clinical responses suggests that IL-1 inhibitors are used with awareness of pathogenetic mechanisms; adult healthcare physicians generally employ standard dosages, while pediatricians are more prone in using a weight-based posology. Dose adjustments and switching between different agents showed to be effective treatment strategies. Our data confirm the good safety profile of IL-1 inhibitors.