Maintaining bile acid homeostasis is essential for metabolic health. Bile acid homeostasis encompasses a complex interplay between biosynthesis, conjugation, secretion, and reabsorption. Beyond their vital role in digestion and absorption of lipid-soluble nutrients, bile acids are pivotal in systemic metabolic regulation. Recent studies have linked bile acid dysregulation to the pathogenesis of metabolic diseases, including obesity, type 2 diabetes mellitus (T2DM), and metabolic dysfunction-associated steatotic liver disease (MASLD). Bile acids are essential signaling molecules that regulate many critical biological processes, including lipid metabolism, energy expenditure, insulin sensitivity, and glucose metabolism. Disruption in bile acid homeostasis contributes to metabolic disease via altered bile acid feedback mechanisms, hormonal dysregulation, interactions with the gut microbiota, and changes in the expression and function of bile acid transporters and receptors. This review summarized the essential molecular pathways and regulatory mechanisms through which bile acid dysregulation contributes to the pathogenesis and progression of obesity, T2DM, and MASLD. We aim to underscore the significance of bile acids as potential diagnostic markers and therapeutic agents in the context of metabolic diseases, providing insights into their application in translational medicine.

Influenza A viruses (IAV) carrying reporter genes provide a powerful tool to study viral infection and pathogenesis in vivo, however, incorporating a non-essential gene into the IAV genome often results in virus attenuation and genetic instability. Very few studies have systematically compared different reporter IAVs, and most optimization attempts seem to lack authentic directions. In this study, we evaluated the ratio of genome copies to the number of infectious unit of two reporter IAVs, PR8-NS1-Gluc and PR8-PB2-Gluc. As a result, PR8-NS1-Gluc and PR8-PB2-Gluc produced 41.4 and 3.8 genomes containing noninfectious particles respectively for every such particle produced by parental PR8 virus. RdRp assay demonstrated that modification of segment NS by inserting reporter genes can interfere with the replication competitive property of the corresponding vRNAs, and the balance of the 8 segments of the reporter IAVs were drastically impaired in infected cells. As a consequence, large amounts of NS-null noninfectious particles were produced during the PR8-NS1-Gluc packaging. In summary, we unravel a mechanism underlying attenuation of reporter IAVs, which suggests a new approach to restore infectivity and virulence by introducing extra mutations compensating for the impaired replication property of corresponding segments.

Influenza A virus infections cause significant morbidity and mortality, and novel antivirals are urgently needed. Influenza RNA-dependent RNA polymerase (RdRp) activity has been acknowledged as a promising target for novel antivirals. In this study, a phenotypic versus target-based screening strategy was established to identify the influenza A virus inhibitors targeting the virus RNA transcription/replication steps by sequentially using an RdRp-targeted screen and a replication-competent reporter virus-based approach using the same compounds. To demonstrate the utility of this approach, a pilot screen of a library of 891 compounds derived from natural products was carried out. Quality control analysis indicates that the primary screen was robust for identification of influenza A virus inhibitors targeting RdRp activity. Finally, two hit candidates were identified, and one was validated as a putative RdRp inhibitor. This strategy can greatly reduce the number of false positives and improve the accuracy and efficacy of primary screening, thereby providing a powerful tool for antiviral discovery.

Reporter influenza A viruses (IAVs) carrying fluorescent or luminescent genes provide a powerful tool for both basic and translational research. Most reporter IAVs are based on the backbone of either subtype H1N1 viruses, A/Puerto Rico/8/1934 (PR8) or A/WSN/1933, but no reporter subtype H3N2 virus is currently available to our knowledge. Since the IAV subtype H3N2 co-circulates with H1N1 among humans causing annual epidemics, a reporter influenza A subtype H3N2 virus would be highly valuable. In this study, the segments of A/Wyoming/3/03 (NY, H3N2) virus encoding hemagglutinin and neuraminidase, respectively, were reassorted with the six internal genes of PR8 where the NS gene was fused with a Gaussia luciferase (Gluc) gene. Using reverse genetics, NY-r19-Gluc, a replication competent reassortant influenza A subtype H3N2 virus expressing reporter Gluc was successfully generated. This reporter virus is stable during replication in Madin-Darby canine kidney (MDCK) cells, and preliminary studies demonstrated it as a useful tool to evaluate antivirals. In addition, NY-r19-Gluc virus will be a powerful tool in other studies including the application of diagnostic and therapeutic antibodies as well as the evaluation of novel vaccines.

Traditional Chinese medicines (TCMs) have proven to possess advantages in counteracting virus infections according to clinical practices. It’s therefore of great value to discover novel antivirals from TCMs. In this paper, One hundred medicinal plants which have been included in TCM prescriptions for antiviral treatment were selected and prefractionated into 5 fractions each by sequentially using cyclohexane, dichloromethane, ethyl acetate, n‐butanol, and water. 500 TCM‐simplified extracts were then subjected to a phenotypic screening using a recombinant IAV expressing Gaussia luciferase. Ten TCM fractions were identified to possess antiviral activities against influenza virus. The IC50’s of the hit fractions range from 1.08 to 6.45 μg/mL, while the SIs, from 7.52 to 98.40. Furthermore, all the ten hit fractions inhibited the propagation of progeny influenza virus significantly at 20 μg/mL. The hit TCM fractions deserve further isolation for responsible constituents leading towards anti‐influenza drugs. Moreover, a library consisting of 500 simplified TCM extracts was established, facilitating antiviral screening in quick response to emerging and re‐emerging viruses such as Ebola virus and current SARS‐CoV‐2 pandemic.