Serum MFAP4, a novel potential biomarker for liver cirrhosis screening, correlates with transient elastography in NAFLD patients.

Background and Aim: Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in different countries. Liver fibrosis is considered as the most appropriate predictor of NAFLD-associated outcome. Microfibrillar-associated protein 4 (MFAP4) is a glycoprotein located in the extracellular matrix. Circulatory MFAP4 has been suggested as a noninvasive biomarker for the assessment of hepatitis C virus and alcoholic liver disease associated liver fibrosis. In this study, we aimed to investigate the association between serum MFAP4 and liver fibrosis severity in NAFLD patients. Methods: A case-control study was conducted in which NAFLD patients (n = 25) and healthy participants (n = 12) were recruited. Liver fibrosis/cirrhosis was assessed by transient elastography (TE) and biochemical parameters were collected. Serum MFAP4 was measured by sandwich ELISA based on two monoclonal anti-MFAP4 antibodies and calibrated with a standard of recombinant MFAP4. Results: Serum MFAP4 levels increased with fibrosis severity and were highly upregulated in patients with cirrhosis (F4 fibrosis stage). In addition, serum MFAP4 levels positively correlated with TE measurement and showed significant association with the severely advanced fibrotic stage in NAFLD patients, in multiple linear regression analysis following adjustment for age, gender, and body mass index. Conclusion: This study suggests the use of MFAP4 as a potential diagnostic noninvasive biomarker for cirrhosis screening in NAFLD patients.

Microfibrillar-associated protein 4 in health and disease.

Microfibrillar-associated protein 4 (MFAP4) is an extracellular matrix protein belonging to the fibrinogen-related domain family. It has been localized to elastic fiber-rich regions in several tissues including the arteries, lungs, heart and skin. MFAP4 binds collagen, fibrillins and tropoelastin and contributes to the process of microfibrillar assembly and maturation of elastic fibers. MFAP4 can also bind RGD-dependent integrins, predominantly αVß3 and αVß5 through its N-terminal RGD sequence, modulating cellular behavior. Circulating MFAP4 was suggested as a robust biomarker for hepatitis C virus- and alcoholic liver disease-related liver fibrosis, cardiovascular disorders and chronic obstructive pulmonary disease. In mice, MFAP4 seems to have a widely redundant role under homeostatic conditions, as global MFAP4 deficiency results in a mild pulmonary phenotype, causing emphysema-like airspace enlargement that progresses with age. However, emerging in vivo and in vitro data suggest that MFAP4 is actively involved in the pathogenesis of remodeling-associated diseases, including fibrosis, cardiovascular disorders, aging, asthma and cancer through activation of integrin-mediated signaling as well as by modulating TGF-ß pathway, thus supporting maladaptive matrix remodeling. This review summarizes the current knowledge about MFAP4 structure and localization, its mechanisms of action in disease-induced tissue remodeling as well as its potential role as a clinical biomarker.

rs6837671A>G in FAM13A Is a Trans-Ethnic Genetic Variant Interacting with Vitamin D Levels to Affect Chronic Obstructive Pulmonary Disease.

(1) Background and objectives: Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality throughout the world. In addition to genetics, increasing evidence suggests that Vitamin D (VitD) might be involved in different pathogenic mechanisms in COPD. Furthermore, the prevalence of VitD insufficiency is exceptionally high in COPD patients and increases with the severity. Based on the above, we first tested the relation between the top 10 single nucleotide polymorphisms from genome-wide association studies and the risk of COPD. Then, we investigated whether VitD levels might also have a role in COPD. A meta-analysis followed, combining our participants with previously published European and non-European populations (15,716 cases and 48,107 controls). (2) Methods: 631 Lebanese participants were recruited, of which ~28% were affected with COPD. Demographic and clinical data were collected, and DNA was genotyped using Kompetitive allele-specific PCR (KASPTM). Adjusted multiple logistic regression models were used. Bonferroni corrections were also applied. The statistical power was also assessed. (3) Results: Both rs6837671A>G in FAM13A and VitD levels were significantly associated with increased risk of COPD (OR = 1.75, p = 0.01, and OR = 3.10, p < 0.001 respectively). An interaction between rs6837671A>G in FAM13A and VitD levels, which increased COPD risk, was found (OR = 3.35 and p < 0.001). The meta-analysis showed that rs6837671G increases COPD risk in populations from different origins; Europeans, Asians, and now in Middle-Eastern. (4) Conclusions: Our results suggest that rs6837671A>G in FAM13A is a trans-ethnic genetic variant that interact with VitD to affect COPD.

Surfactant protein-D, a potential mediator of inflammation in axial spondyloarthritis.

Objectives: Surfactant protein-D (SP-D), an innate immune defence molecule of the collectin family, is expressed in lungs and additional extrapulmonary epithelia. SP-D has immune modulatory and anti-microbial effects depending on its oligomerization. The ratio of high molecular weight (HMW): low molecular weight (LMW) SP-D in serum is mainly determined by the Met11Thr polymorphism (SNP rs721917). We aimed to study the SP-D serum level and the molecular size distribution in patients with untreated axial spondyloarthritis (axSpA) as compared with control subjects. Methods: Thirty-four patients with disease modifier untreated axSpA according to the ASAS criteria, age 19-63 years, disease duration 3.9 (2.2-5.6) years were included. Demographics, smoking habits, HLA-B27 status, ASDAS, BASDAI, BASFI, BASMI and visual analogue scale scores were recorded. SP-D in serum was measured by ELISA. DNA was isolated from whole blood and single nucleotide polymorphism rs721917 was genotyped. SP-D molecular size distribution was determined using gel filtration chromatography. Results: SP-D in serum did not differ between patients with axSpA and healthy controls, 1177 (869, 1536) vs 910 (494, 1682) (P = 0.35) and SP-D did not correlate with disease activity. However, the HMW/LMW ratio of SP-D in serum was significantly lower in axSpA, 0.38 (0.18, 0.53) compared with controls 1.49 (0.37, 3.24) when adjusting for the Met11Thr polymorphism, gender, age, BMI and smoking (P = 0.0004). There was no correlation between HMW/LMW ratio and CRP or composite diseases outcome measures. Conclusion: We suggest that predominance of LMW oligomeric variants of SP-D may enhance local or systemic inflammatory responses in axSpA.

Surfactant protein D multimerization and gene polymorphism in COPD and asthma.

BACKGROUND AND OBJECTIVE: A structural single nucleotide polymorphism rs721917 in the surfactant protein D (SP-D) gene, known as Met11Thr, was reported to influence the circulating levels and degree of multimerization of SP-D and was associated with both COPD and atopy in asthma. Moreover, disease-related processes are known to degrade multimerized SP-D, however, the degree of the protein degradation in these diseases is not clarified. We aimed to determine the distribution of multimerized (high molecular weight (HMW)) and non-multimerized (low molecular weight (LMW)) species of serum SP-D and their correlation with genetic polymorphisms and presence of disease in Lebanese COPD and asthmatic patients. METHODS: Serum SP-D levels were measured by ELISA in 88 COPD, 121 asthmatic patients and 223 controls. Randomly selected subjects were chosen for genotyping of rs721917 and multimerization studies. HMW and LMW SP-D were separated by gel permeation chromatography. RESULTS: Serum SP-D levels were significantly increased in patients with COPD, but not in asthmatic patients, when compared to controls. Met11Thr variation strongly affected serum SP-D levels and the degree of multimerization, but was not associated with COPD and asthma in the study. Remarkably, HMW/LMW serum SP-D ratio was significantly lower in Met11/Met11 COPD and asthmatic patients compared to controls. CONCLUSION: Collectively, non-multimerized species of serum SP-D were dominant in COPD and asthmatic patients suggesting that degradation of SP-D takes place to a significant degree in pulmonary disease. Assays that can separate SP-D proteolytic breakdown products or modified forms from naturally occurring SP-D trimers may result in optimal disease markers for pulmonary inflammatory diseases.

RAC1 expression and role in IL-1ß production and oxidative stress generation in familial Mediterranean fever (FMF) patients.

Familial Mediterranean fever (FMF) is a recessively inherited autoinflammatory disorder. The caspase-1-dependent cytokine, IL-1ß, plays an important role in FMF pathogenesis, and RAC1 protein has been recently involved in IL-1ß secretion. This study aims to investigate RAC1 expression and role in IL-1ß and caspase-1 production and oxidative stress generation in FMF. The study included 25 FMF patients (nine during attack and remission, and 16 during remission only), and 25 controls. RAC1 expression levels were analyzed by real-time PCR. Ex vivo production of caspase-1, IL-1ß, IL-6 and markers of oxidative stress (malondialdehyde, catalase, and glutathione system) were evaluated respectively in supernatants of patients' and controls' PBMC and PMN cultures, in the presence and absence of RAC1 inhibitor. RAC1 gene expression and IL-1ß levels were increased in patients in crises compared to those in remission or controls. RAC1 expression levels were correlated with MEFV genotypes, patients carrying the M694V/M694V genotype having a two-fold increase in the expression levels compared to those carrying other genotypes. Caspase-1 levels were higher in LPS-induced PBMC of patients in remission than controls. Spontaneous and LPS-induced IL-1ß production were comparable in patients in remission and controls, whereas LPS-induced IL-6 production was enhanced in patients, compared to controls. RAC1 inhibition resulted in a decrease in caspase-1 and IL-1ß, but not IL-6, levels. Malondialdehyde levels produced by LPS-stimulated PMNs were increased in patients in remission compared to those in controls, but decreased following RAC1 inhibition. Catalase and GSH activities were reduced in unstimulated PMN culture supernatants of patients in remission compared to controls and were increased in the presence of RAC1 inhibitor. These results show the involvement of RAC1 in the inflammatory process of FMF by enhancing IL-1ß production, through caspase-1 activation, and generating oxidative stress, even during asymptomatic periods.

Surfactant protein D, a clinical biomarker for chronic obstructive pulmonary disease with excellent discriminant values.

Biological markers can help to better identify a disease or refine its diagnosis. In the present study, the association between surfactant protein D (SP-D) and chronic obstructive pulmonary disease (COPD) was studied among subjects consulting for respiratory diseases or symptoms and was compared with C-reactive protein (CRP) and fibrinogen. A further aim of this study was to identify the optimal cut-off point of SP-D able to discriminate COPD patients. A case-control study including 90 COPD patients, 124 asthma patients and 180 controls was conducted. Standardized questionnaires were administered and lung function tests were performed. Biological markers were measured in blood samples according to standardized procedures. The association between SP-D and COPD was investigated using logistic regression models. Receiver-operating characteristic curves were used for threshold identification. SP-D levels above the median value were positively associated with COPD [adjusted odds ratio (OR)=3.86, 95% confidence interval (CI): 1.51-9.85, P=0.005). No associations with COPD or asthma were found for CRP or fibrinogen levels. Scores for COPD diagnosis in all COPD patients or ever-smoker COPD patients were identified (sensitivity, 76.4 and 77.8%; specificity, 89.3 and 88.5%, respectively). The results indicate that SP-D can differentiate COPD from other respiratory symptoms or diseases. Used with socio-demographic characteristics and respiratory symptoms, SP-D is able to discriminate COPD patients from controls, particularly among smokers.

Protective effects of surfactant protein D treatment in 1,3-ß-glucan-modulated allergic inflammation.

Surfactant protein D (SP-D) is a pulmonary collectin important in lung immunity. SP-D-deficient mice (Sftpd(-/-)) are reported to be susceptible to ovalbumin (OVA)- and fungal allergen-induced pulmonary inflammation, while treatment with exogenous SP-D has therapeutic effects in such disease models. ß-Glucans are a diverse group of polysaccharides previously suggested to serve as fungal ligands for SP-D. We set out to investigate if SP-D could interact with 1,3-ß-glucan and attenuate allergic pulmonary inflammation in the presence of 1,3-ß-glucan. Allergic airway disease was induced in Sftpd(-/-) and Sftpd(+/+) mice by OVA sensitization and subsequent challenge with OVA, 1,3-ß-glucan, or OVA/1,3-ß-glucan together. Mice in the combined treatment group were further treated with a high dose of recombinant fragment of human SP-D (rfhSP-D). We demonstrated direct interaction between SP-D and 1,3-ß-glucan. OVA-induced mucous cell metaplasia was increased in Sftpd(-/-) mice, supporting previously reported protective effects of endogenous SP-D in allergy. OVA-induced parenchymal CCL11 levels and eosinophilic infiltration in bronchoalveolar lavage were unaffected by 1,3-ß-glucan, but were reversed with rfhSP-D treatment. 1,3-ß-Glucan treatment did, however, induce pulmonary neutrophilic infiltration and increased TNF-α levels in bronchoalveolar lavage, independently of OVA-induced allergy. This infiltration was also reversed by treatment with rfhSP-D. 1,3-ß-Glucan reduced OVA-induced mucous cell metaplasia, T helper 2 cytokines, and IFN-γ production. rfhSP-D treatment further reduced mucous metaplasia and T helper 2 cytokine secretion to background levels. In summary, rfhSP-D treatment resulted in attenuation of both allergic inflammation and 1,3-ß-glucan-mediated neutrophilic inflammation. Our data suggest that treatment with high-dose SP-D protects from mold-induced exacerbations of allergic asthma.

Hypovitaminosis D in a Young Lebanese Population: Effect of GC Gene Polymorphisms on Vitamin D and Vitamin D Binding Protein Levels.

Bioactive vitamin D is a steroid hormone transported in blood via the vitamin D binding protein (DBP). Our study aimed to investigate the vitamin D status in a young Lebanese population and study the association of hypovitaminosis with levels of DBP. Polymorphisms in the GC gene that encodes DBP were also screened. Blood samples were collected from 179 university students. Vitamin D status and DBP levels were assayed by enzyme-linked immunosorbent assay (ELISA). DNA was extracted from 128 participants, and genotyping of the two GC gene SNPs, rs7041, and rs4588, was carried out by restriction fragment length polymorphism. Forty-seven percent of participants had hypovitaminosis D (<20 ng/ml). A significant positive correlation was observed between vitamin D status and DBP. Genotyping data showed that participants carrying the rs7041 GG and rs4588 AA genotypes had higher concentrations of DBP than those carrying other genotypes. Four allelic versions of the GC gene were observed, one of which, GC*3, was encountered for the first time in this study, and was found to be associated with both normal vitamin D and high DBP levels. Modifying genes such as GC could therefore affect DBP levels, and contribute, along with environmental factors, to the hypovitaminosis D observed in sunny countries.

Ex vivo PBMC cytokine profile in familial Mediterranean fever patients: Involvement of IL-1ß, IL-1α and Th17-associated cytokines and decrease of Th1 and Th2 cytokines.

In order to clarify the inflammatory mechanism underlying familial Mediterranean fever (FMF), we aimed to evaluate the ex vivo cytokine profile of FMF patients during acute attacks and attack-free periods, and compare it with that of healthy controls. The study included 34 FMF patients, of whom 9 were studied during attack and remission and 24 healthy controls. Cytokine levels were evaluated by Luminex technology in serum and supernatants of PBMC (Peripheral Blood Mononuclear Cells) cultures with and without 24h stimulation of monocytes by LPS and T lymphocytes by anti-CD3/CD28 beads. Levels of IL-6 and TNF-α were higher in unstimulated and LPS-stimulated PBMC supernatants of FMF patients in crises compared to controls. In response to LPS stimulation, higher levels of IL-1ß and IL-1α were found in PBMC supernatants of patients during crises compared to those in remission and to controls. IFN-γ and IL-4 levels were the lowest in unstimulated and anti-CD3/CD28 stimulated PBMCs supernatants of patients during crises compared to remission and controls. The Th17 cytokines IL-17 and IL-22 were respectively higher in anti-CD3/CD28 stimulated PBMC supernatants of FMF patients during and between crises compared to controls. Amongst cytokines tested in serum, only IL-6 and TNFα were enhanced in FMF patients. The ex vivo study represents an interesting approach to evaluate cytokines' involvement in FMF. Our results suggest an ongoing subclinical inflammation and define an elevated inflammatory cytokine signature, distinctly for M694V homozygous patients. The absence of spontaneous IL-1ß release by PBMCs reflects no constitutive activation of the inflammasome in FMF physiopathology.

Binding and agglutination of Streptococcus pneumoniae by human surfactant protein D (SP-D) vary between strains, but SP-D fails to enhance killing by neutrophils.

Recombinant human surfactant protein D (SP-D) expressed in Escherichia coli, consisting of the head and neck regions of the native molecule, bound to all strains of Streptococcus pneumoniae that were tested, but the extent of binding varied between strains of differing capsular serotypes. The recombinant protein expressed in the yeast Pichia pastoris did not bind. Full-length native SP-D aggregated pneumococci in a calcium-dependent manner that was inhibited by maltose acting as a competitive sugar. The ability of SP-D to modulate the uptake and killing of pneumococci by human neutrophils was also addressed. Neither recombinant truncated SP-D nor native full-length SP-D enhanced the killing of pneumococci by human neutrophils. Aggregation of pneumococci varied not only between strains of the same multilocus sequence type and different serotypes but also between strains of the same serotype. However, use of recombinant strains in which the serotype had been changed showed that the degree of aggregation was influenced by the capsular type. Indeed, a 19F serotype strain which was not aggregated by SP-D did exhibit aggregation when the original isogenic strain was capsule switched to capsular serotype 3. However, although our results show that SP-D is capable of aggregating most pneumococci, no correlation between the degree of aggregation and the capsule or multilocus sequence type of the pneumococcus was clearly apparent. Therefore, although the capsule serotype is not the only determinant of aggregation by SP-D, the data presented here indicate that it does have a role to play.

Pneumococcal behavior and host responses during bronchopneumonia are affected differently by the cytolytic and complement-activating activities of pneumolysin.

Pneumolysin, a multifunctional toxin produced by all clinical isolates of Streptococcus pneumoniae, is strongly implicated in the pathogenesis of pneumococcal bronchopneumonia and septicemia. Using isogenic mutant strains, we examined the effect of deletion of the cytotoxic activity or complement-activating activity of pneumolysin on bacterial growth in lungs and blood, histological changes in infected lung tissue, and the pattern of inflammatory cell recruitment. Both of the activities of pneumolysin contributed to the pathology in the lungs, as well as the timing of the onset of bacteremia. Histological changes in the lungs were delayed after infection with either mutant compared to the changes seen after infection with the wild-type pneumococcus. The complement-activating activity of pneumolysin affected the accumulation of T cells, whereas the toxin's cytolytic activity influenced neutrophil recruitment into lung tissue.