IL-1 and T Helper Immune Responses

TH17 cells are increased in the peripheral blood of patients with SAPHO syndrome

To assess whether the immune derangement previously observed in SAPHO syndrome could be linked to variations in blood TH1, TH2 or TH17 lymphocytes frequency. Seven SAPHO patients with a protracted course of the disease were studied ex-vivo for intracellular cytokines production by means of flow-cytometry and compared with matched groups of Psoriatic Arthritis patients and healthy controls. The Kruskal-Wallis test on the median of the three categories showed that there is a significant association between the TH17 levels and the category (p value = 0.02474). The mean and variance for the proportion of IL-17 producing CD4+ cells were compared between groups showing significant differences between SAPHO versus PsA subgroup (p = 0.05) and SAPHO versus healthy controls (p = 0.008). Interestingly, activation of TH17 axis, but not of TH1 and TH2, has been found, and can be observed both in patients with different activity of the disease or treated with different drugs. The TH17 increase in peripheral blood of our SAPHO subjects resembles the one recently found in patients with different AIDs. Novel therapeutic options in these patients may therefore include IL-17 blockade.

The role of the inflammasome in cardiovascular diseases

Inflammasome is a very important signaling platform sensing a variety of triggers of the innate immune system. Inflammasome promotes the production of important pro-inflammatory cytokines such as IL-1β and IL-18. Tight control of inflammasome activity is, therefore, essential and occurs at multiple levels. The activation of inflammasome pathways is linked to the pathogenesis of various prevalent disorders including cardiovascular disease such as atherosclerosis, ischemic injury, cardiomyopathy, and Kawasaki disease. The study of the inflammasome in the cardiovascular system has led to the identification of important triggers and endogenous modulators, and to the exploration of new treatment strategies based on the inhibition of inflammasome activation or its end products, i.e., IL-1β and IL-18. In summary, the discovery of the inflammasome has greatly advanced our understanding of how the innate immune system interferes with cardiovascular disease development and progression, and targeting inflammasome provides new avenues for the treatment and management of cardiovascular diseases.

The interleukin-1 family: back to the future

Interleukin-1 (IL-1) is a central mediator of innate immunity and inflammation. The IL-1 family includes seven ligands with agonist activity (IL-1α and IL-1β, IL-18, IL-33, IL-36α, IL-36β, IL-36γ), three receptor antagonists (IL-1Ra, IL-36Ra, IL-38), and an anti-inflammatory cytokine (IL-37). Members of the IL-1 Receptor (IL-1R) family include six receptor chains forming four signaling receptor complexes, two decoy receptors (IL-1R2, IL-18BP), and two negative regulators (TIR8 or SIGIRR, IL-1RAcPb). A tight regulation via receptor antagonists, decoy receptors, and signaling inhibitors ensures a balance between amplification of innate immunity and uncontrolled inflammation. All cells of the innate immune system express and/or are affected by IL-1 family members. Moreover, IL-1 family members play a key role in the differentiation and function of polarized innate and adaptive lymphoid cells. Here we will review the key properties of IL-1 family members, with emphasis on pathways of negative regulation and orchestration of innate and adaptive immunity.