Associations of serum monocyte-to-high-density lipoprotein cholesterol ratio with digital ulcers and skin fibrosis in patients with systemic sclerosis

Objective: To investigate the relationship between the monocyte-to-high-density lipoprotein cholesterol ratio (MHR) and clinical manifestations in patients with systemic sclerosis (SSc).Method: This was a cross-sectional analysis of a cohort study comprising 111 female SSc patients recruited from a tertiary care rheumatology centre. We also assessed 222 age-matched female healthy controls. Serum MHR was measured in all study participants. Digital ulcer (DU) was defined as an active or healed ulceration, and the magnitude of skin fibrosis was determined according to the modified Rodnan skin score (mRSS).Results: The mean age and median disease duration in patients with SSc were 56.3 years and 98 months, respectively. The MHR in SSc patients was significantly higher than that in controls. DU was found in 35 patients (31.5%) with SSc (active in 12 and healed in 23), and the median mRSS was 8. SSc patients with DU had a significantly higher median MHR than those without (11.43 vs 7.62, p < 0.001), and MHR significantly positively correlated with mRSS (ρ = 0.289, p = 0.002). Multivariable logistic regression revealed that an elevated MHR was independently associated with increased risk of DU (odds ratio = 1.21; 95% confidence interval = 1.07-1.35; p = 0.002). In the multivariable linear regression analysis, higher MHR showed a significant association with increased log-transformed mRSS (unstandardized β = 0.052, p = 0.003).Conclusion: Our findings suggest that the MHR could be serve as a potential biomarker of the risk of DU and advanced skin fibrosis in patients with SSc.

Cysteine biosynthesis pathway in the archaeon Methanosarcina barkeri encoded by acquired bacterial genes?

The pathway of cysteine biosynthesis in archaea is still unexplored. Complementation of a cysteine auxotrophic Escherichia coli strain NK3 led to the isolation of the Methanosarcina barkeri cysK gene [encoding O-acetylserine (thiol)-lyase-A], which displays great similarity to bacterial cysK genes. Adjacent to cysK is an open reading frame orthologous to bacterial cysE (serine transacetylase) genes. These two genes could account for cysteine biosynthesis in this archaeon. Analysis of recent genome data revealed the presence of bacteria-like cysM genes [encoding O-acetylserine (thiol)-lyase-B] in Pyrococcus spp., Sulfolobus solfataricus, and Thermoplasma acidophilum. However, no orthologs for these genes can be found in Methanococcus jannaschii, Methanobacterium thermoautotrophicum, and Archaeoglobus fulgidus, implying the existence of unrecognizable genes for the same function or a different cysteine biosynthesis pathway.