Can Calprotectin Show Subclinical Inflammation in Familial Mediterranean Fever Patients?

Exploring S100A8/A9, neopterin, and MMP3 in familial Mediterranean fever

Familial Mediterranean fever (FMF) is characterized by inflammatory attacks due to overactivation of pyrin inflammasome. This study aimed to investigate the reliability of S100A8/A9, neopterin, and matrix metalloproteinase 3 (MMP3) at monitoring subclinical inflammation and disease activity, and at differentiating FMF attacks from appendicitis, the most common misdiagnosis among FMF patients. Blood samples (n = 75), comprising from FMF patients during an attack (n = 20), the same FMF patients during the attack-free period (n = 14), patients with appendicitis (n = 24), and healthy volunteers (n = 17) were obtained. Duplicate determinations of S100A8/A9, neopterin, and MMP-3 levels were conducted using the enzyme-linked immunosorbent assay (ELISA). FMF patients with and without attack and patients with appendicitis had significantly elevated S100A8/A9 levels compared to healthy volunteers (P-values: < 0.001, 0.036, 0.002, respectively). Patients with appendicitis and FMF patients with and without attack had significantly increased serum neopterin levels compared to healthy volunteers (P-value: < 0.001). MMP3 levels were significantly higher among patients with appendicitis and FMF patients during attack compared to healthy controls (P-values: < 0.001, 0.001). Serum levels of S100A8/A9, neopterin, and MMP3 were increased significantly during attacks compared to attack-free periods among FMF patients (P-values: 0.03, 0.047, 0.007). S100A8/A9 emerges as a valuable marker for monitoring disease activity. Neopterin and S100A8/A9 might help physicians to monitor subclinical inflammation during the attack-free periods of FMF patients. MMP3 might aid in diagnosing FMF attacks when distinguishing between attack and attack-free periods is challenging.

Role of serum calprotectin in identifying familial Mediterranean fever attacks

BACKGROUND/AIM

The aim of the study was to evaluate serum calprotectin (CLP) levels in familial Mediterranean fever (FMF) patients and to investigate the utility of CLP in distinguishing patients with attack from patients without attack.

MATERIAL AND METHOD

FMF patients, rheumatoid arthritis (RA) patients, and healthy controls were included. Serum calprotectin levels were quantified utilizing the enzyme-linked immunosorbent assay (ELISA) method. Receiver operating characteristic (ROC) curve analysis was used to identify the cut-off value of serum CLP level to differentiate FMF patients with attack from those without. Logistic regression analysis was performed to identify predictors.

RESULTS

Significant differences were observed among the three groups concerning white blood cell (WBC), neutrophil, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum CLP levels (p = 0.003, p = 0.004, p < 0.001, p < 0.001, and p = 0.002, respectively). Higher ESR, CRP, and serum CLP levels were observed in FMF patients with attacks than those without (all, p < 0.001). Serum CLP was significantly higher in RA patients than in FMF patients in remission (p < 0.001). ROC analysis identified a threshold CLP concentration in FMF with an attack to be 47.1 pg/mL (83.3% sensitivity, 60.6% specificity, AUC = 0.74, 95% CI = 0.63-0.85, p < 0.001). In univariate logistic regression analysis, CLP (β = 1.045, 95% CI = 1.017-1.073, p = 0.001) was predictive of FMF patients experiencing an attack.

CONCLUSION

Serum CLP proves to be as productive as ESR in illustrating inflammation and demonstrating the existence of attacks in FMF patients.

The diagnostic value of serum hepcidin in acute appendicitis

BACKGROUND

Acute appendicitis (AA) is the primary cause of acute abdomen in patients presenting to the emergency department with abdominal pain. Limited studies have explored the relationship between serum hepcidin levels and AA. This study aimed to measure serum hepcidin levels in patients undergoing surgery with a preliminary diagnosis of AA and to assess whether these levels can serve as a biochemical marker for diagnosing AA.

METHODS

This study included patients aged 18 or older who presented to the emergency department between April 2018 and May 2019 and underwent surgery with a diagnosis of AA. The cohort comprised 94 patients with surgical pathology results compatible with AA (Group A), 16 patients with results not compatible with AA (Group B), and 42 healthy controls. Serum hepcidin levels were measured from venous blood samples.

RESULTS

Mean hepcidin levels were 1750±285 pg/mL in Group A, 1349±381 pg/mL in Group B, and 1066±225 pg/mL in the control group. Statistically significant differences in serum hepcidin levels were observed between Group A and the control group (p<0.05).

CONCLUSION

Hepcidin levels were significantly higher in patients with AA compared to both the control group and patients with surgically confirmed non-AA pathology. Therefore, hepcidin may serve as a useful adjunct in diagnosing acute appendicitis.

Assessment of serum neopterin and calprotectin as biomarkers for subclinical inflammation in patients with familial Mediterranean fever

BACKGROUND

Familial Mediterranean fever (FMF) is the most common autoinflammatory disease characterized by short, repeated, and self-limiting attacks of fever and serositis. Subclinical inflammation can persist in the periods with no symptoms and result in amyloidosis even with colchicine treatment. Neopterin and calprotectin have been considered essential players in inflammation and immune response.

AIM

The study was aimed to measure serum levels of neopterin and calprotectin in patients with FMF in the attack-free period.

METHODS

A total of 160 participants were recruited from the rheumatology department in this single-center, case-control study. Individuals having the inclusion criteria were divided into healthy controls (n = 80) and FMF (n = 80). The laboratory data were acquired from the electronic registration database. Serum calprotectin and neopterin were measured with ELISA test kits. FMF patients and healthy controls' laboratory findings were compared.

RESULTS

FMF patients' serum red cell distribution width (RDW), calprotectin, and neopterin values were significantly higher compared to healthy controls. There were no statistically significant differences between calprotectin and neopterin regarding gender, family history, and colchicine response of the FMF patients.

CONCLUSIONS

Calprotectin, neopterin, and RDW can be valuable marker candidates to be used in the follow-up of subclinical inflammation in FMF patients.

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-1β 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.

Evaluation of serum CXC chemokine ligand 16 (CXCL16) as a novel inflammatory bio- marker or familial Mediterranean fever disease

Background/aim

Familial Mediterranean fever ( FMF) is a disease that is mainly diagnosed with clinical features. Several well-known inflammatory markers increase in FMF. However, there is still a need for diagnostic tests for specifying FMF and monitoring inflammatory activity. CXCL16 is a chemokine produced by inflammatory cells that demonstrate efficacy in the acute phase response. In this study, we aimed to investigate the relationship between CXCL16 levels and FMF disease and to evaluate CXCL16 levels as a novel biomarker for FMF.

Materials and methods

Fifty-three male patients diagnosed with FMF and sixty healthy individuals were included in this cross-sectional study. Blood samples were taken in the first 24 h of the attack periods. Serum soluble CXCL16 was evaluated by enzyme-linked immunosorbent assay (ELISA) method.

Results

CXCL16 (P < 0.001), erythrocyte sedimentation rate (P < 0.001), C-reactive protein (P < 0.001), and fibrinogen (P = 0.005) were significantly higher in FMF group than in control group. Receiver operating characteristic (ROC) curve analysis revealed a cut off value of CXCL16 as 2.68 ng/ml with 83% sensitivity and 68% specificity (P < 0.001). Logistic regression analysis indicated that high CXCL16 and erythrocyte sedimentation rate levels were predictive parameters for FMF disease (OR 8.31; 95% CI 2.59-26.62; p <0.001) (OR 1.27; 95% CI 1.12-1.44; P < 0.001). There was no correlation between CXCL16 levels and attack frequency and disease duration (P = 0.395, P = 0.956).

Conclusion

To the best of our knowledge, this is the first study evaluating serum soluble CXCL16 levels as a biomarker for FMF. CXCL16 levels were significantly higher and were predictive for monitoring inflammatory activity in patients with FMF. CXCL16 may be a promising biomarker for FMF diagnosis.

Familial Mediterranean Fever: Clinical State Of The Art

As the inflammation research improves year by year, so does our understanding of the autoinflammatory conditions. Over the past years, the number of monogenic autoinflammatory conditions snowballed thanks to our understanding of basic immunology and genetics. Familial Mediterranean Fever (FMF), being the entrance to this fascinating world, still has clinical relevance as it enables us to understand our approach to these patients, treatment modalities, and pathological mechanisms. This review can be used as a tool for clinicians already working with FMF patients to update themselves on recent scientific literature.