IAPP/amylin deposition, which is correlated with expressions of ASC and IL-1ß in ß-cells of Langerhans' islets, directly initiates NLRP3 inflammasome activation.

Recent findings revealed that type 2 diabetes mellitus (T2D) is a chronic inflammatory disease and an islet amyloid polypeptide (IAPP)/amylin, is deposited within pancreatic islets. IAPP/amylin has been reported to activate NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in infiltrated macrophages. NLRP3, an intracellular pattern recognition receptor, has been shown to recognize pathogens and/or metabolites and complexes with the adopter protein apoptosis-associated speck-like protein containing a caspase-recruitment domain ASC to form a huge complex, called an inflammasome, an interleukin (IL)-1ß-processing platform. Although reactive oxygen species (ROS) were reported to be involved in activation of NLRP3 inflammasome, we were hypothesized that IAPP could directly activate NLRP3 inflammasome, leading to islets ß-cell death. We analyzed expression of the inflammasome components ASC, NLRP3, caspase-1, IL-1ß, IAPP/amylin, and insulin immunohistochemically in Langerhans' islets of autopsy cases. The initial event of NLRP3 inflammasome activation was assessed using a cell-free system consisting of NLRP3 and ASC with the amplified luminescent proximity homogeneous assay. IAPP/amylin deposition in Langerhans' islets was detected and significantly correlated with expressions of IL-1ß and ASC. IAPP/amylin directly interacted with NLRP3 and initiated an interaction between NLRP3 and ASC in a cell-free system. The deposition of IAPP/amylin in ß-cells of Langerhans' islets may act together with the expression level of an inflammasome component, ASC, to regulate IL-1ß processing, and directly lead to the dysfunction of ß-cells. The interaction between IAPP/amylin and NLRP3 could be an attractive drug target to avoid both inflammation and ß-cell death for T2D therapy.

Defect of suppression of inflammasome-independent interleukin-8 secretion from SW982 synovial sarcoma cells by familial Mediterranean fever-derived pyrin mutations.

Familial Mediterranean fever (FMF) is a recessive inherited autoinflammatory syndrome. Patients with FMF have symptoms such as recurrent fever and abdominal pain, sometimes accompanied by arthralgia. Biopsy specimens have revealed substantial neutrophil infiltration into synovia. FMF patients have a mutation in the Mediterranean fever gene, encoding pyrin, which is known to regulate the inflammasome, a platform for processing interleukin (IL)-1ß. FMF patients heterozygous for E148Q mutation, heterozygous for M694I mutation, or combined heterozygous for E148Q and M694I mutations, which were found to be major mutations in an FMF study group in Japan, suffer from arthritis, the severity of which is likely to be lower than in FMF patients with M694V mutations. Expression plasmids of wild-type (WT) pyrin and mutated pyrin, such as E148Q, M694I, M694V, and E148Q+M694I, were constructed, and SW982 synovial sarcoma cells were transfected with these expression plasmids. IL-8 and IL-6 were spontaneously secreted from the culture supernatant of SW982 cells without any stimulation, whereas IL-1ß and TNF-α could not be detected even when stimulated with lipopolysaccharide. Notably, two inflammasome components, ASC and caspase-1, could not be detected in SW982 cells by Western blotting. IL-8 but not IL-6 secretion from SW982 cells was largely suppressed by WT pyrin, but less suppressed by mutated pyrin, which appeared to become weaker in the order of E148Q, M694I, E148Q+M694I, and M694V mutations. As for IL-8 and IL-6, similar results were obtained using stable THP-1 cells expressing the WT pyrin or mutated pyrins, such as M694V or E148Q, when stimulated by LPS. In addition, IL-8 secretion from mononuclear cells of FMF patients was significantly higher than that of healthy volunteers when incubated on a culture plate. Thus, our results suggest that IL-8 secretion from SW982 synovial sarcoma cells suppressed by pyrin independently of inflammasome is affected by pyrin mutations, which may reflect the activity in FMF arthritis.

Tocilizumab improved clinical symptoms of a patient with systemic tophaceous gout who had symmetric polyarthritis and fever: An alternative treatment by blockade of interleukin-6 signaling.

Chronic tophaceous gout is the end stage of gout. We employed a blockade of interleukin-6 signaling therapy by tocilizumab instead of anakinra, an interleukin-1 receptor antagonist, for a 61-year-old Japanese woman diagnosed with tophaceous gout. Laboratory data showed that serum interleukin-6 concentration was elevated. Serum interleukin-1ß concentration was under the detectable level, although serum uric acid was elevated due to renal dysfunction. The secretion patterns of interleukin-1ß, tumor-necrosis factor-α, interleukin-6, and interleukin-8 from peripheral mononuclear cells isolated from the patient exhibited no remarkable differences compared with those of healthy volunteers. After treatment with the interleukin-6 receptor antagonist tocilizumab, serum interleukin-6 concentration decreased followed by improved clinical symptoms, such as reduced size of the subcutaneous nodules, no fever, and no acute gouty attacks during the treatment. Our case suggests that tocilizumab markedly improves clinical and laboratory manifestations in tophaceous gout with arthritis and fever as well as interleukin-1 blockade therapy.

[The inflammasome].

Inflammation is a protective response intended to eliminate primary causes of tissue injury, leading to tissue repair and adaptation in a focal lesion. It is thought that various factors are involved in the histopathological responses to tissue injury. One of the inflammatory cytokines, interleukin(IL)-1beta, is thought to play an important role in inflammatory responses. The inflammasome is a multi-protein complex, required for IL-1beta processing and activation to induce inflammation. Over the past decade, evidence has accumulated that the inflammasome contributes significantly to the pathogenesis of various diseases. In this review, we discuss the function of inflammasome and inflammasome-related diseases, that are now expanding beyond inflammation.