Inflammatory Signature in Acute-on-Chronic Liver Failure Includes Increased Expression of Neutrophil Specific Genes ELANE, MPO and CD177 Running Title: Neutrophil Transcriptomics in ACLF

Background and Aims: Acute-on-Chronic Liver Failure (ACLF) is associated with innate immune dysfunction and high short-term mortality. Neutrophils have been identified to influence prognosis in ACLF. Neutrophil biology is under-evaluated in ACLF. Therefore, we investigated neutrophil-specific genes and their association with ACLF outcomes. Methods: : This is an observational study. Enriched polymorphonuclear cells, containing neutrophils, isolated from study participants in three groups- ACLF(n=10), chronic liver disease (CLD, n=5) and healthy controls (HC, n=4), were analysed by microarray. Differentially expressed genes were identified and validated by qRT-PCR in an independent cohort of ACLF, CLD and HC (n=30, 15 and 15 respectively). The association of confirmed overexpressed genes with ACLF 28-day non-survivors was investigated. The protein expression of selected neutrophil genes was confirmed using flow cytometry and IHC. Results: : Differential gene expression analysis showed 1140 downregulated and 928 upregulated genes for ACLF vs CLD and 2086 downregulated and 1091 upregulated genes for ACLF vs HC. Significant upregulation of neutrophilic inflammatory signatures were found in ACLF compared to CLD and HC. Neutrophil-specific genes ELANE, MPO and CD177 were highly upregulated in ACLF and their expression was higher in ACLF 28-day non-survivors. Elevated expression of CD177 protein on neutrophil surface in ACLF was confirmed by flow cytometry. IHC analysis in archival post mortem liver biopsies showed the presence of CD177 + neutrophils in the liver tissue of ACLF patients. Conclusions: : Neutrophil-specific genes ELANE, MPO and CD177 are highly overexpressed in ACLF neutrophils as compared to CLD or HC. Further, these genes are highly overexpressed in ACLF 28-day non-survivors.