Major approaches to bone regeneration process with gut microbiota, exosomes, and microRNAs: a systematic review

Introduction: The incidence and mortality of bone diseases are still steadily increasing, creating a significant financial burden for societies across the world. To prevent the occurrence of bone diseases, slow their progression, or reverse the injuries they cause, new alternatives or complementary treatments need to be developed. The gut microbiota plays a role in bone metabolism and the pathogenesis of osteoporosis. Objective: It was to analyze through a systematic review the main considerations and clinical findings of the bone formation process through the modulation of the gut microbiota, as well as the functions of microRNAs and exosomes. Methods: The systematic review rules (PRISMA) were followed. The search was carried out from August to September 2022 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases, using scientific articles from 2001 to 2022. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 126 articles were found. A total of 34 articles were fully evaluated and 26 were included in this systematic review. Most studies showed homogeneity in their results, with I2 =98.8%>50%. The symmetrical funnel plot does not suggest a risk of bias between small sample-size studies. The gut microbiota plays an important role in the modulation of bone healing and bone health through the traffic of inflammatory TNF+ T and Th17 cells to the bone marrow, influencing the inflammatory state of the patient, determining the “brain-gut-bone” axis. It has been shown that the diversity of the gut microbiota is decreased in patients with osteoporosis, leading to a state of dysbiosis. There is a relationship between the microbiome, osteoblasts, osteoclasts, and nuclear factor ligand receptor-kappa-B (RANKL) activator. Studies have proposed several mechanisms of gut microbiome interaction with osteoclastogenesis and bone health, including microRNA, insulin-like growth factor 1, and immune system mediation. Therefore, bone regeneration requires that the basic biological principles of osteogenesis, osteoinduction, osteoconduction, and biocompatibility are followed

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field