Performance of serum apolipoprotein-A1 as a sentinel of Covid-19

BackgroundSince 1920, a decrease in serum cholesterol has been identified as a marker of severe pneumonia. We have assessed the performance of serum apolipoprotein-A1, the main transporter of HDL-cholesterol, to identify the early spread of coronavirus disease 2019 (Covid-19) in the general population and its diagnostic performance for the Covid-19. MethodsWe compared the daily mean serum apolipoprotein-A1 during the first 30 weeks of 2020 in a population that is routinely followed for a risk of liver fibrosis risk in the USA (183,112 sera) and in France (18,316 sera) in relation to a local increase in confirmed cases, and in comparison to the same period in 2019 (respectively 234,881 and 26,056 sera). We prospectively assessed the sensitivity of this marker in an observational study of 136 consecutive hospitalized cases and retrospectively evaluated its specificity in 7,481 controls representing the general population. ResultsThe mean serum apolipoprotein-A1 levels in these populations began decreasing in January 2020, compared to the same 30 weeks in 2019. This decrease was highly correlated to and in parallel with the daily increase in confirmed Covid-19 cases in the following 30 weeks, in both France and USA, including the June and mid-July recovery periods in France. Apolipoprotein-A1 at the 1.25 g/L cutoff had a sensitivity of 90.6% (95%CI84.2-95.1) and a specificity of 96.1% (95.7-96.6%) for the diagnosis of Covid-19. The area under the characteristics curve was 0.978 (0.957-0.988), and outperformed haptoglobin and liver function tests. The adjusted risk ratio for survival without transfer to intensive care unit was 5.61 (95%CI 1.02-31.0;P=0.04). ConclusionApolipoprotein-A1 could be both a sentinel of the pandemic in existing routine surveillance of the general population with no new blood sample, as well as a candidate predictor of suspected Covid-19 in multivariate analysis in cases with a negative virological test. NCT01927133, CER-2020-14. Key Points QuestionDoes serum apolipoprotein-A1 decrease could be a very early biomarker of SARS-CoV-2 pandemic? FindingsDuring the 30 weeks of 2020 we observed in two large cohorts of patients at risk of liver fibrosis a highly significant decrease of serum apolipoprotein-A1, not observed in previous years. This decrease was highly correlated to and in parallel with the daily increase in confirmed Covid-19 cases, including the recovery period. MeaningApolipoprotein-A1 could be used as a sentinel of the pandemic in existing routine surveillance of the general population.

TRPV1 and TRPA1 in cutaneous neurogenic and chronic inflammation: pro-inflammatory response induced by their activation and their sensitization

Cutaneous neurogenic inflammation (CNI) is inflammation that is induced (or enhanced) in the skin by the release of neuropeptides from sensory nerve endings. Clinical manifestations are mainly sensory and vascular disorders such as pruritus and erythema. Transient receptor potential vanilloid 1 and ankyrin 1 (TRPV1 and TRPA1, respectively) are non-selective cation channels known to specifically participate in pain and CNI. Both TRPV1 and TRPA1 are co-expressed in a large subset of sensory nerves, where they integrate numerous noxious stimuli. It is now clear that the expression of both channels also extends far beyond the sensory nerves in the skin, occuring also in keratinocytes, mast cells, dendritic cells, and endothelial cells. In these non-neuronal cells, TRPV1 and TRPA1 also act as nociceptive sensors and potentiate the inflammatory process. This review discusses the role of TRPV1 and TRPA1 in the modulation of inflammatory genes that leads to or maintains CNI in sensory neurons and non-neuronal skin cells. In addition, this review provides a summary of current research on the intracellular sensitization pathways of both TRP channels by other endogenous inflammatory mediators that promote the self-maintenance of CNI.