Complex regulation of alarmins S100A8/A9 and secretion via gasdermin D pores exacerbates autoinflammation in familial Mediterranean fever.

BACKGROUND: Familial Mediterranean fever (FMF), caused by mutations in the pyrin-encoding MEFV gene, is characterized by uncontrolled caspase-1 activation and IL-1ß secretion. A similar mechanism drives inflammation in cryopyrin-associated periodic fever syndrome (CAPS) caused by mutations in NLRP3. CAPS and FMF, however, result in largely different clinical manifestations, pointing to additional, autoinflammatory pathways involved in FMF. Another hallmark of FMF is extraordinarily high expression of S100A8 and S100A9. These alarmins are ligands of Toll-like receptor 4 and amplifiers of inflammation. However, the relevance of this inflammatory pathway for the pathogenesis of FMF is unknown. OBJECTIVE: This study investigated whether mutations in pyrin result in specific secretion of S100A8/A9 alarmins through gasdermin D pores' amplifying FMF pathology. METHODS: S100A8/A9 levels in FMF patients were quantified by enzyme-linked immunosorbent assay. In vitro models with knockout cell lines and specific protein inhibitors were used to unravel the S100A8/A9 secretion mechanism. The impact of S100A8/A9 to the pathophysiology of FMF was analyzed with FMF (MEFVV726A/V726A) and S100A9-/- mouse models. Pyrin-S100A8/A9 interaction was investigated by coimmunoprecipitation, immunofluorescence, and enzyme-linked immunosorbent assay studies. RESULTS: The S100A8/A9 complexes directly interacted with pyrin. Knocking out pyrin, caspase-1, or gasdermin D inhibited the secretion of these S100 alarmins. Inflammatory S100A8/A9 dimers were inactivated by tetramer formation. Blocking this inactivation by targeted S100A9 deletion in a murine FMF model demonstrated the relevance of this novel autoinflammatory pathway in FMF. CONCLUSION: This is the first proof that members of the S100 alarmin family are released in a pyrin/caspase-1/gasdermin D-dependent pathway and directly drive autoinflammation in vivo.

Increased levels of S100A8/A9, IL-1ß and IL-18 as a novel biomarker for recurrent tonsillitis.

BACKGROUND: Acute tonsillitis represents one of the most frequent reasons patients seek primary medical care and otorhinolaryngology consultation. Therefore, recurrent episodes of acute tonsillitis (RAT), also called chronic tonsillitis, exhaust a substantial amount of medical and financial resources. Diagnosis of tonsillitis depends on a physical examination, which therefore does not allow for a reliable differentiation between viral and bacterial infection. However, the frequency of bacterial infections during the previous three years is currently being used as the major deciding factor in patient selection for tonsillectomy. The aim of the present study was to determine an objective biomarker to help in the identification of patients suffering from recurrent tonsillitis. RESULTS: By analyzing a panel of cytokines and chemokines in serum and saliva of patients with RAT compared to healthy controls, increased levels of IL-1ß (153.7 ± 48.5 pg/ml vs 23.3 ± 6.6 pg/ml, p = 0.021), IL-18 (120.2 ± 16.5 vs 50.6 ± 9.3 pg/ml, p = 0.007) and/or S100A8/A9 (996 ± 102 ng/ml vs 546 ± 86 ng/ml, p = 0.042) could be observed in patients suffering from RAT. Cut-off values of these parameters were determined and combined to a new RAT-score allowing for reliable identification of patients suffering from recurrent tonsillitis with a sensitivity of 95% and a specificity of 88%. CONCLUSION: The RAT-score represents the first objective criterion as a tool for the diagnosis of recurrent tonsillitis and it also improves patient selection for tonsillectomy.

Evaluation of the QUANTUM BLUE sCAL rapid test as a point of care tool to identify patients with peritonsillar abscess.

S100A8/A9 (Calprotectin) serves as a biomarker for various inflammatory diseases, such as for peritonsillar abscess (PTA). Recently, the PTA score was developed for reliable PTA identification. It uses a combination of characteristic clinical symptoms and elevated calprotectin levels in serum and saliva to determine this score. Although well-established point-of-care tests (POCT) to determine serum or faecal calprotectin levels exist, a reliable and rapid tool to analyse salivary calprotectin has not yet been described. In this study, we analysed the potential of the QUANTUM BLUE sCAL Test (QBT, BÜHLMANN Laboratories AG, Switzerland) to determine S100A8/A9 levels during outpatient management. These QBT measurements are combined with other clinical factors to determine the PTA score. Significantly higher calprotectin levels were determined by QBT in patients with PTA compared to healthy controls. The receiver operating characteristic (ROC) curves for the QBT revealed cut-off values of 2940 ng/ml (sensitivity = 0.88, specificity = 0.78) in serum and 5310 ng/ml (sensitivity = 0.80, specificity = 0.50) in saliva. By adding the QBT results to determine PTA values, a ROC analysis provided a statistical cut-off score of 2.5 points to identify the existence of a PTA with a sensitivity of 100% and a specificity of 89.3%. The QUANTUM BLUE sCAL Test (QBT) is an appropriate POCT to determine serum and salivary calprotectin levels. Thus, PTA scores can be determined within a short time frame by applying the QBT during outpatient management.

IL-8 and IFN-γ as Preoperative Predictors of the Outcome of Tonsillectomy.

OBJECTIVES: Tonsillectomy (TE) and tonsillotomy (TO) due to recurrent episodes of acute tonsillitis (RAT) belong to the most frequent surgical procedures. However, an adequate objective marker predicting the outcome of TE/TO preoperatively is missing. METHODS: Patients with RAT who underwent TE/TO (n = 31) were included in this pilot study. A panel of cytokines and chemokines in serum and saliva were determined preoperatively. Health-related quality of life was assessed pre- and postoperatively by the Tonsillectomy Outcome Inventory-14. RESULTS: Health-related quality of life improved significantly after surgery. Increased serum levels of interleukin-8 (IL-8) and interferon gamma (IFN-γ) are associated with a less successful outcome. No correlation between the number of acute tonsillitis episodes and the health-related quality of life after TE or TO could be observed. CONCLUSIONS: Tonsillectomy and TO improve health-related quality of life independently from the number of past acute tonsillitis episodes. Interleukin-8 and IFN-γ in serum may serve as promising markers, predicting the benefit of TE or TO for patients preoperatively.