Biology subjects

Kouvela, A.

Publications and source records attributed to Kouvela, A..

3 recordsLinked to original sources

bioRxiv2026

Monocyte microRNA signatures in late-onset neonatal sepsis

Abstract Purpose: Neonatal late-onset sepsis (LOS) remains a major cause of neonatal morbidity and its non-specific presentation challenges early diagnosis. MicroRNAs (miRNAs) are promising biomarkers, but unbiased next-generation sequencing (NGS) of monocyte-specific miRNA has not been applied to neonatal LOS. We aimed to identify the monocyte-specific miRNA expression profile in neonatal LOS and its associations with the neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII). Methods: In a prospective study at the University General Hospital of Patras, 30 samples from 15 neonates with LOS and 8 healthy controls were analyzed. Monocyte miRNA expression was characterized by NGS pre and post antimicrobial therapy in cases and controls. Predicted target genes of the major candidate miRNAs were evaluated by RT-qPCR in an independent cohort. Clinical severity was assessed using NLR and SII. Results: Hsa-miR-6743-3p was significantly upregulated on day 0 and returned to control levels by day 2. Four additional miRNAs (hsa-miR-7108-5p, hsa-miR-3940-5p, hsa-miR-6851-3p and hsa-miR-1909-3p) exhibited a consistent trend toward upregulation in acute LOS. NLR, but not SII, was significantly elevated at diagnosis and showed excellent diagnostic performance (AUC 0.958), normalizing by day 2. Hsa-miR-7108-5p correlated positively with NLR on day 0. In the RT-qPCR cohort, its predicted target DRAM2, was reduced on day 0 and partially recovered by day 2. Conclusion: Monocyte miRNA profiling identified transient alterations in neonatal LOS that parallel clinical severity, while NLR showed high discriminatory performance. These exploratory findings warrant validation in larger cohorts to verify monocyte miRNAs as potential biomarkers of neonatal LOS.

biochemistry↗

bioRxiv2022

Integrated signaling and transcriptome analysis reveals Src-family kinase individualities and novel pathways controlled by their constitutive activity

The Src family kinases (SFKs) Lck and Lyn are crucial for lymphocyte development and function. Albeit tissue-restricted expression patterns, the two kinases share common functions, the most pronounced one, being the phosphorylation of ITAM motifs in the cytoplasmic tails of antigenic receptors. Lck is predominantly expressed in T-lymphocytes; however, it can be ectopically found in B-1 cell subsets and numerous pathologies including acute and chronic B-cell leukemias. The exact impact of Lck on the B-cell signaling apparatus remains enigmatic and is followed by the long-lasting open question of mechanisms granting selectivity amongst SFK members. In this work we sought to investigate the mechanistic basis of ectopic Lck function in B-cells and compare it to events elicited by the predominant B-cell SFK, Lyn. Our results reveal substrate promiscuity displayed by the two SFKs, which however, is buffered by their differential susceptibility towards regulatory mechanisms, revealing a so far unappreciated aspect of SFK member-specific fine-tuning. Furthermore, we show that Lck- and Lyn-generated signals suffice to induce transcriptome alterations, reminiscent of B-cell activation, in the absence of receptor/co-receptor engagement. Finally, our analyses revealed a yet unrecognized role of SFKs in tipping the balance of cellular stress responses, by promoting the onset of ER-phagy, an as yet completely uncharacterized process in B-lymphocytes. SignificanceThe Src-family-kinases Lck and Lyn are mandatory for lymphocyte function. However, several aspects of their regulation and critical pathways they control remain elusive. Using signaling and transcriptome analysis we show that the two kinases share substrate preferences; yet they display differential susceptibility towards regulatory mechanisms, revealing a so far unappreciated aspect of SFK member-specific fine-tuning. Furthermore, overexpression of both kinases suffices to induce receptor-ligation independent signaling responses. Finally, our analyses reveal a novel role of SFKs in tipping the balance of cellular stress responses, by promoting ER-phagy, in the expense of proteasomal degradation and the Unfolded Protein Response. These data advance our understanding of molecular individualities amongst SFK members, and identifies novel networks significant for lymphocyte activation and effector function.

immunology↗

bioRxiv2020

From qualitative to quantitative insect metabarcoding: an in tandem multilocus mosquito identification methodology

In the era of emergence and re-emergence of vector-borne diseases, a high throughput trap-based insect monitoring is essential for the identification of invasive species, study of mosquito populations and risk assessment of disease outbreaks. Insect DNA metabarcoding technology has emerged as a highly promising methodology for unbiased and large-scale surveillance. Despite significant attempts to introduce DNA metabarcoding in mosquito or other insect surveillance qualitative and quantitative metabarcoding remains a challenge. In the present study, we have developed a methodology of in-tandem identification and quantification using cytochrome oxidase subunit I (COI) combined with a secondary multilocus identification and quantification involving three loci of 28S ribosomal DNA. The presented methodology was able to identify individual species in pools of mosquitoes with 95.94% accuracy and resolve with high accuracy (p = 1,{chi} 2 = 2.55) mosquito population composition providing a technology capable of revolutionizing mosquito surveillance through metabarcoding. The methodology, given the respective dataset, has the potential to be applied to various small animal populations.

genomics↗