Biology subjects

Romeo, S.

Publications and source records attributed to Romeo, S..

4 recordsLinked to original sources

bioRxiv2024

A post-mitotic in vitro murine as a model of muscle damage and repair

Sarcopenia is a degenerative condition characterized by the atrophy and functional decline of myofibers, resulting in disability. While the clinical risk factors are known, there is no validated in vitro model to understand the molecular mechanisms and identify therapeutics. To tackle this challenge, we generated an in vitro post-mitotic muscular system by differentiating mouse myoblast cells, namely C2C12. After 12 days of differentiation, cells were expressing physiological markers of myotubes and became self-contracting. Importantly, transcriptomic analyses demonstrated high similarity (r=0.70) when compared to primary human myotubes (HSkMC) providing evidence of resemblance to human cells. Next, we starved and incubated cells with dexamethasone and observed myotube shrinkage, oxidative stress, modification of anabolic, inflammatory, and catabolic markers recapitulating sarcopenia. Conversely, cell refeeding resulted in a recovery in the model with nutrient deprivation but not when incubated also with dexamethasone. In conclusion, we present a model of sarcopenia due to nutrient deprivation and corticosteroids. This model may allow more efficient and effective future research to identify therapeutics against sarcopenia in humans.

cell biology↗

bioRxiv2021

Disease-specific eQTL screening reveals an anti-fibrotic effect of AGXT2 in nonalcoholic fatty liver disease

Background & AimsNonalcoholic fatty liver disease (NAFLD) poses an impending clinical burden. Genome-wide association studies have revealed a limited contribution of genomic variants to the disease, requiring alternative but robust approaches to identify disease-associated variants and genes. We carried out a disease-specific expression quantitative trait loci (eQTL) screen to identify novel genetic factors that specifically act on NAFLD progression on the basis of genotype. MethodsWe recruited 125 Korean biopsy-proven NAFLD patients and healthy individuals and performed eQTL analyses using 21,272 transcripts and 3,234,941 genotyped and imputed SNPs. We then selected eQTLs that were detected only in the NAFLD group, but not in the control group (i.e., NAFLD-eQTLs). An additional cohort of 162 Korean NAFLD individuals was used for replication. The function of the selected eQTL toward NAFLD development was validated using HepG2, primary hepatocytes and NAFLD mouse models. ResultsThe NAFLD-specific eQTL screening yielded 242 loci. Among them, AGXT2, encoding alanine-glyoxylate aminotransferase 2, displayed decreased expression in NAFLD patients homozygous for the non-reference allele of rs2291702, compared to no-NAFLD subjects with the same genotype (P = 4.79 x 10-6). This change was replicated in an additional 162 individuals, yielding a combined P-value of 8.05 x 10-8 from a total of 245 NAFLD patients and 48 controls. Knockdown of AGXT2 induced palmitate-overloaded hepatocyte death by increasing ER stress, and exacerbated NAFLD diet-induced liver fibrosis in mice. However, overexpression of AGXT2 reversely attenuated liver fibrosis and steatosis as well. ConclusionsWe implicate a new molecular role of AGXT2 in NAFLD. Our overall approach will serve as an efficient tool for uncovering novel genetic factors that contribute to liver steatosis and fibrosis in patients with NAFLD. Lay summaryElucidating causal genes for NAFLD has been challenging due to limited tissue availability and the polygenic nature of the disease. Using liver and blood samples from 125 biopsy-proven NAFLD and no-NAFLD Korean individuals and an additional 162 individuals for replication, we devised a new analytic method to identify causal genes. Among the candidates, we found that AGXT2-rs2291702 protects against liver fibrosis in a genotype-dependent manner with the potential for therapeutic interventions. Our approach enables the discovery of NAFLD causal genes that act on the basis of genotype.

genetics↗

bioRxiv2020

Macrophage Scavenger Receptor 1 mediates lipid-induced inflammation in non-alcoholic fatty liver disease

Obesity-associated inflammation is a key player in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the exact mechanisms remain incompletely understood. Here we demonstrate that macrophage scavenger receptor 1 (MSR1, CD204) expression is associated with the occurrence of hepatic lipid-laden foamy macrophages and correlates with the degree of steatosis and steatohepatitis in a cohort of 170 NAFLD patients. Mice lacking Msr1 are protected against high fat-cholesterol diet (HFD)-induced metabolic disorder, showing fewer hepatic lipid-laden foamy macrophages, less hepatic inflammation, improved dyslipidemia and glucose tolerance, while showing a change in hepatic lipid metabolism. We show that MSR1 induces a pro-inflammatory response via the JNK signaling pathway upon triggering by saturated fatty acids. In vitro blockade of the receptor prevented the accumulation of lipids in primary macrophages which inhibited the switch towards a pro-inflammatory phenotype and the release of cytokines such as TNFa. Targeting MSR1 using monoclonal antibody therapy in an obesity-associated NAFLD mouse model and ex vivo human liver slices resulted in the prevention of foamy macrophage formation and liver inflammation. Moreover, we identified that rs41505344, a polymorphism in the upstream transcriptional region of MSR1, was associated with altered serum triglycerides and aspartate transaminase levels in a cohort of over 400,000 patients. Taken together, our data suggest a critical role for MSR1 in lipid homeostasis and a potential therapeutic target for the treatment of NAFLD. One Sentence SummaryThe immunometabolic role of MSR1 in human NAFLD.

immunology↗

bioRxiv2020

Effects of C-peptide replacement therapy on bone microarchitecture parameters in streptozotocin-diabetic rats.

Pathological pathways involved in the development of diabetic complications are still unclear. Several studies suggested a pathogenic role of C-peptide deficiency in vascular and neuropathic complications. However, to date, the role of C-peptide on diabetes-related bone loss has not been investigated. The objective of this study was to test the effects of a 6-week regimen of rat C-peptide infusion on bone by combining micro-CT imaging with histological testing. Twenty-three, four-month-old male Wistar rats were randomly divided into three groups: Normal control group; Sham diabetic control group; Diabetic plus C-peptide group. Diabetes was induced by injection of streptozotocin. Rat C-peptide was delivered via subcutaneously osmopumps. We assessed several trabecular microarchitectural parameters and cellular and matrix proteins in bone tissue sections. At the end of the study, both the normal control and diabetic plus C-peptide groups had a higher tibia weight than the diabetic control group (p = 0.05 and p = 0.02, respectively). C-peptide levels significantly and positively correlated with the trabecular thickness (r= 0.45, p=0.08) and negatively with structure model index (r= -0.40, p=0.09). Furthermore, it positively correlated with one of the histological assessments (i.e. PLIN1 score; p=0.02). Micro-CT evaluation showed significant inter-group differences in trabecular thickness (p=0.02), trabecular space (p = 0.05) and cross-sectional thickness (p=0.05). Diabetic plus C-peptide group showed a higher trabecular thickness (p<0.001), cross-sectional thickness (p=0.03) and a lower trabecular space (p=0.05) than the normal control group. Both the normal control and diabetic plus C-peptide groups had more Runx-2 and PLIN1 positive cells in comparison to the diabetic control group (p = 0.045 and p = 0.034). For the first time we demonstrated that the diabetic rats receiving rat C-peptide had higher quality of trabecular bone, than diabetic rats not receiving it. C-peptide could have a role in the prevention of diabetes-related bone loss.

systems biology↗