Uncovering a neurological protein signature for severe COVID-19.

"to address these questions we used high throughput olink proteomics analysis of plasma samples from patients with severe complications versus mild symptoms and control subjects and assessed changes in neurological protein profiles and pathways associated with severe covid-19 2 2 1 we used two cohorts for this study; one cohort of covid-19 patients and one cohort of healthy subjects( ) ( table 1 supplementary data 1).; protein expression values were calculated as log2(npx) and olink data that did not pass quality control were excluded from the analyses ( supplementary data 2 ) 2 3 using single molecule array (simoa) technology (quanterix) we measured four neurology biomarkers in human plasma samples from mild and severe cases of covid-19 as well as healthy controls.; the cohort was recruited at hmc hospital in doha qatar and included 49 subjects with severe and 50 subjects with mild disease; and 40 healthy control subjects ( table 1 supplementary data 1).; for a comprehensive molecular view we carried out the analysis after combining the data from the two olink panels in a single dataset (supplementary data 3).; the number of differentially expressed proteins (deps) is summarized in fig 1 b and supplementary data 4 .; we found that 13 pathways associated with nervous system functions were significantly enriched in patients with severe disease as compared to healthy subjects (neurotrophin signaling pathway regulation of synapse assembly nervous system development neuron projection axon guidance receptor activity semaphorin receptor complex and axon guidance) ( fig 2 a-d supplementary data 5).; overall severe vs mild cases showed 2 downregulated pathways and 3 upregulated pathways with 2 non-overlapping pathways with severe vs controls (pns development pathway and semaphoring receptor activity) (sup fig 2 a-d supplementary data 6 ).; such enrichment with neurological pathways was absent in mild vs controls (sup fig 2 e supplementary data 7) suggesting that mild and control groups might be devoid of neurological complications.; next we ran ipa pathway analysis for severe cases versus controls and we found 7 neurological pathways significantly affected in severe covid-19 patients such as axonal guidance signaling synaptogenesis signaling semaphorin neuronal repulsive signaling neuroprotective role of thop1 in alzheimer's disease gdnf family ligand receptor interaction neuroinflammation signaling and ephrin a signaling (sup fig 3 supplementary data 8 ) 3 4 to predict the risk of neurological complications of severe covid-19 we set out to create a blood-based neurological protein signature.; a network of 155 proteins was identified and divided into 4 modules ( fig 3 a supplementary data 9).; fig 4 3 5 next we validated the 34-neurological protein signature using the massachusetts general hospital (mgh cohort) olink dataset( ) ( supplementary data 10 ).; we considered cases under acuities (death at 28 days and intubated ventilated supplemented oxygen n = 71) as severe covid-19 cases and cases under acuities (hospitalized with supplemented o 2 and hospitalized without supplemented o 2 n = 68) as mild covid-19 cases (supplementary data 11).; out of the 34 proteins we found that 21 proteins were significantly upregulated and 1 protein was significantly downregulated in mgh severe covid-19 patients compared to the mild cases ( fig 4 b and c supplementary data 12 ).; interestingly all the 22 mgh cohort proteins positively correlated with qatar cohort severe covid-19 protein signature profile with 21 upregulated proteins and 1 downregulated protein ( fig 4 d supplementary data 13).; interestingly comparison of protein expression in patients with severe covid-19 and symptomatic non covid-19 related respiratory infections confirmed 21 out of the 22 severity-associated proteins to be significantly altered in patients with severe covid-19 disease only (sup fig 5 supplementary data 14 ).; more interestingly using rna data from whole blood of covid-19 patients critical in icu with ards( ) ( fig 5 b) or peripheral blood mononuclear cells of severe covid-19 patients( ) (sup fig 6a-b) we detected most of the overlapping genes correlated positively to the neurological protein signature while fewer genes had negative correlations (supplementary data 15).; we found 15 brain and nervous system disorders positively correlated with the covid-19 protein signature such as nerve injury parkinson's disease alzheimer's disease schizophrenia and amyotrophic lateral sclerosis (16 9 6 6 and 3 studies respectively) and 3 neurological diseases negatively correlated with the proteins signature such as meningitis and epilepsy ( table 2 supplementary data 16 ).; in addition using the bsce pharmaco atlas we analyzed protein signature- drug correlations in independent studies and identified 42 and 58 drugs respectively to be positively and negatively correlated with the 34-protein signature (supplementary data 17) 4 there is an increasing interest in understanding the mechanisms underlying the neurological complications seen in some covid-19 patients as well as revealing new health issues arising from covid-19 neurological complications.; as highlighted by tnfrsf12a alike severe covid-19 signature 12 out of 16 biosets had upregulated tnfrsf12a expression (sup fig 8 supplementary data 16 )( ; ; ; ).; we next looked at parkinson's disease curated studies we found five out of six were snp/gwas: 2 studies had upregulated correlation of cd38 while scarb2 correlated in 1 study tnfrsf12a and layn were concordantly upregulated in severe covid-19 protein signature and rna expression from parkinson's disease ips derived neurons bioset (sup fig 9 supplementary data 16 )( ; ; ; ).; in superior frontal gyrus post central gyrus and prefrontal cortex of brain post-mortem alzheimer's disease patients plxnb1 was upregulated while adam22 and adam 23 were downregulated similar to severe covid-19 protein signature (sup fig 10 supplementary data 16 )( ; ; ; ; ).; further relevance was evident for ggt5 cd300lf and msr1 being upregulated in severe covid-19 and in human als spinal cord rna expression as well as in a fus1 overexpression mouse als model (sup fig 11 and 12 supplementary data 16 )( ; ; ).; draxin was upregulated in severe covid-19 protein signature as well as in schizophrenia-derived ipsc patients and schizophrenia associated snp study (sup fig 13 supplementary data 16 )( ; ).; furthermore gfra3 had an inverse relationship of downregulated protein and upregulated rna (sup fig 14 supplementary data 17)."

"Declaration of Competing Interest None."

"Funding Research conducted on Qatar cohort was funded by the Infectious Disease Interdisciplinary Research Program (QB-10-ID-IDRP) at QBRI and a grant fund from 10.13039/100007833Hamad Medical Corporation (fund number MRC-05-003)."