Citrullinated and MMP-degraded vimentin is associated with chronic pulmonary diseases and genetic variants in PADI3/PADI4 and CFH in postmenopausal women

Citrullinated vimentin has been linked to several chronic and autoimmune diseases, but how citrullinated vimentin is associated with disease prevalence and genetic variants in a clinical setting remains unknown. The aim of this study was to obtain a better understanding of the genetic variants and pathologies associated with citrullinated and MMP-degraded vimentin. Patient Registry data, serum samples and genotypes were collected for a total of 4369 Danish post-menopausal women enrolled in the Prospective Epidemiologic and Risk Factor study (PERF). Circulating citrullinated and MMP-degraded vimentin (VICM) was measured. Genome-wide association studies (GWAS) and phenome wide association studies (PheWAS) with levels of VICM were performed. High levels of VICM were significantly associated with the prevalence of chronic pulmonary diseases and death from respiratory and cardiovascular diseases (CVD). GWAS identified 33 single nucleotide polymorphisms (SNPs) with a significant association with VICM. These variants were in the peptidylarginine deiminase 3/4 (PADI3/PADI4) and Complement Factor H (CFH)/KCNT2 gene loci on chromosome 1. Serum levels of VICM, a marker of citrullinated and MMP-degraded vimentin, were associated with chronic pulmonary diseases and genetic variance in PADI3/PADI4 and CFH/ KCNT2. This points to the potential for VICM to be used as an activity marker of both citrullination and inflammation, identifying responders to targeted treatment and patients likely to experience disease progression.

A prospective pilot study of a gluten-free diet for primary sclerosing cholangitis and associated colitis

BACKGROUND

Primary sclerosing cholangitis (PSC) is a progressive bile duct disease associated with inflammatory bowel disease (PSC-IBD).

AIM

To investigate whether patients with PSC-IBD benefit from a gluten-free and amylase trypsin inhibitor (ATI)-free diet (GFD).

METHODS

We performed a prospective clinical pilot study administering an eight-week GFD. The primary outcomes were colonic inflammation assessed by proctosigmoidoscopy, and liver stiffness (surrogate for fibrosis, inflammation and cholestasis) measured by transient elastography before and after GFD. Amongst the secondary (exploratory) outcomes were colonic mucosal and serum cytokine/chemokine changes, the intestinal microbiome and transcriptome dynamics, and shifts in serum markers of hepatic fibrogenesis.

RESULTS

Fifteen patients with PSC-IBD completed the study. The study did not meet its primary outcome: the endoscopic score and liver stiffness remained unchanged. However, the expression of pro-inflammatory mucosal cytokines and chemokines such as IL6, IL8, CCL2, and TNFα was significantly down-regulated. Two critical markers of liver fibrosis and matrix remodelling, thrombospondin-2 and -4, decreased significantly. The microbiota composition changed slightly, including a decrease in the pathogen Romboutsia ilealis. The intestinal transcriptome indicated a gut barrier improvement. Pruritus, fatigue, overall well-being, faecal calprotectin levels, and serum alkaline phosphatase did not change significantly.

CONCLUSIONS

This study did not demonstrate a clinical improvement with short-term GFD in patients with PSC-IBD. However, a gluten/ATI-free diet may improve biomarkers of intestinal inflammation and barrier function in these patients with associated changes in the enteric microbiota. Further investigation of the therapeutic potential of the GFD in PSC-IBD is warranted.

Enhanced liver fibrosis test for the non-invasive diagnosis of fibrosis in patients with NAFLD: A systematic review and meta-analysis

BACKGROUND & AIMS

The enhanced liver fibrosis (ELF) test has been proposed for the non-invasive assessment of advanced fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). We performed a systematic review to estimate the accuracy of this test against biopsy.

METHODS

In this systematic review, we searched MEDLINE, Embase, Web of Science and the Cochrane Library for studies that included patients with NAFLD and that used both liver biopsy (as the reference standard) and the ELF test. Two authors independently screened the references, extracted the data and assessed the quality of included studies. Due to the variation in reported thresholds, we used a multiple thresholds random effects model for meta-analysis (diagmeta R-package).

RESULTS

The meta-analysis of 11 studies reporting advanced fibrosis and 5 studies reporting significant fibrosis showed that the ELF test had a sensitivity of >0.90 for excluding fibrosis at a threshold of 7.7. However, as a diagnostic test at high thresholds, the test only achieved specificity and positive predictive value >0.80 in very high prevalence settings (>50%). To achieve a specificity of 0.90 for advanced and significant fibrosis, thresholds of 10.18 (sensitivity: 0.57) and 9.86 (sensitivity: 0.55) were required, respectively.

CONCLUSION

The ELF test showed high sensitivity but limited specificity to exclude advanced and significant fibrosis at low cut-offs. The diagnostic performance of the test at higher thresholds was found to be more limited in low-prevalence settings. We conclude that clinicians should carefully consider the likely disease prevalence in their practice setting and adopt suitable test thresholds to achieve the desired performance.

LAY SUMMARY

The enhanced liver fibrosis test has been suggested as a non-invasive blood test to aid the diagnosis of severe liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). Our study results showed that the test has a high negative predictive value, especially in populations with low disease prevalence (likely encountered in primary care); so, it can exclude advanced fibrosis in patients with NAFLD. However, when prevalence is low, the positive predictive value of the enhanced liver fibrosis test is low, suggesting that additional strategies may be needed to make a positive diagnosis in such settings.

Role of plasminogen activator inhibitor-1 (PAI-1) levels in the diagnosis of BMT-associated hepatic veno-occlusive disease and monitoring of subsequent therapy with defibrotide (DF)

Hepatic veno-occlusive disease (VOD) is a common and potentially fatal complication of high dose chemotherapy with allogeneic/autologous stem cell transplant (SCT). The diagnosis and treatment of hepatic VOD is controversial. Clinical features are non-specific and may be mimicked by a number of other conditions causing hyperbilirubinaemia post-transplantation. Plasminogen activator inhibitor-1 (PAI-1) has been proposed as a specific marker of VOD [1]. Defibrotide (DF) is a polydeoxyribonucleotide, which has been found to have anti-thrombotic, anti-ischaemic and thrombolytic properties without causing significant anti-coagulation. Recent evidence [2,3] suggests that use of DF in patients with severe VOD results in a promising response rate without attributable significant toxicity. Between January 1998 and July 1999, PAI-1 levels were measured serially in 16 patients undergoing SCT who had subsequently developed hyperbilirubinaemia. Diagnosis of VOD was made by established clinical criteria [4,5]. At the time of diagnosis, PAI-1 levels (mean+/-SD) were significantly elevated in patients with VOD (90.7+/-47 ng/ml, n=7) when compared with patients with jaundice from other causes post transplantation (12.1+/-6.4 ng/ml, n=9). Five of the patients with VOD received treatment with DF. Four out of five patients showed an initial response to DF (significant fall in bilirubin and improvement in other signs/symptoms) with one of these patients having a complete response (bilirubin < 2.0 mg/dl and full resolution of signs/symptoms and end-organ toxicity). Following treatment with DF, a corresponding fall in PAI-1 levels was noted in those responding, with non-responders maintaining raised levels.

CONCLUSION

Raised PAI-1 levels post stem cell transplant are specific for VOD and a subsequent decrease in levels following treatment with DF may be associated with response to treatment.

The importance of locally derived reference ranges and standardized calculation of dilute Russell's viper venom time results in screening for lupus anticoagulant

Three commercial dilute Russell's viper venom time (DRVVT) kits were evaluated at four UK centres experienced at performing lupus anticoagulant (LA) tests. Each centre established a normal reference range for the DRVVT ratio calculated against local pooled normal plasma from 20 healthy normal subjects. Plasma from LA-positive patients and LA-negative thrombophilia patients was also tested. DRVVT ratios and the degree of correction were assessed in a variety of ways to reflect not only the UK national Guidelines, but also the manufacturers' recommendations. The reference range data showed a normal distribution in each case, but considerable variation in the mean and SD between the centres and reagents, with the mean +2SD value ranging from 1.06 to 1.19. The use of an arbitrary DRVVT ratio of < 1.1 as the cut-off value for normality, which is applied in many laboratories, is therefore inappropriate. Although no single kit had a clear overall advantage in terms of sensitivity and specificity, the way in which the screen and confirmation data were analysed had a major impact on the interpretation of the results. A data analysis method employing a mean plus two standard deviations (SDs) cut-off for normality, and judgement regarding confirmation of LA based on a percentage correction of DRVVT ratio, was the simplest and most consistent, with overall sensitivity and specificity values of 81% and 94%, respectively, for uncomplicated LA-positive and LA-negative thrombophilia samples. We conclude that the 1991 BSCH Guidelines are in need of revision, each laboratory should establish its own normal reference range for the DRVVT ratio and a common method should be used for calculating the degree of correction with confirmation reagents, so that LA results can be correctly interpreted between laboratories. Standardizing DRVVT interpretation in this way should improve the consistency of LA detection.