The human gastrointestinal tract is inhabited by the largest microbial community within the human body consisting of trillions of microbes called gut microbiota. The normal flora is the site of many physiological functions such as enhancing the host immunity, participating in the nutrient absorption and protecting the body against pathogenic microorganisms. Numerous investigations showed a bidirectional interplay between gut microbiota and many organs within the human body such as the intestines, the lungs, the brain, and the skin. Large body of evidence demonstrated, more than a decade ago, that the gut microbial alteration is a key factor in the pathogenesis of many local and systemic disorders. In this regard, a deep understanding of the mechanisms involved in the gut microbial symbiosis/dysbiosis is crucial for the clinical and health field. We review the most recent studies on the involvement of gut microbiota in the pathogenesis of many diseases. We also elaborate the different strategies used to manipulate the gut microbiota in the prevention and treatment of disorders. The future of medicine is strongly related to the quality of our microbiota. Targeting microbiota dysbiosis will be a huge challenge.

The coronavirus 2 (SARS-CoV-2) pandemic is viciously spreading through the continents with rapidly increasing mortality rates. Current management of COVID-19 is based on that respiratory failure is the leading cause of mortality. However, mounting evidence link accelerated pathogenesis in gravely ill COVID-19 patients to a hyper-inflammatory state involving a cytokine storm. Several components of the heightened inflammatory state were addressed as therapeutic targets. Another key component of the heightened inflammatory state is hyper-ferritinemia which reportedly identifies patients with increased mortality risk. In spite of its strong association with mortality, it is not yet clear if hyper-ferritinemia in COVID-19 patients is merely a systemic marker of disease progression, or a key modulator in disease pathogenesis. Here we address implications of a possible role for hyper-ferritinemia, and altered iron homeostasis in COVID-19 pathogenesis, and potential therapeutic targets in this regard.

New discoveries in metagenomics and clinical research have highlighted the importance of the gut microbiota for human health through the regulation of the host immune response and energetic metabolism. The microbiota interacts with host cells in particular by intermingling with the mitochondrial activities. This mitochondria–microbiota cross-talk is intriguing because mitochondria share many common structural and functional features with the prokaryotic world. Several studies reported a correlation between microbiota quality and diversity and mitochondrial function. The mitochondrial production of reactive oxygen species (ROS) plays an important role during the innate immune response and inflammation, and is often targeted by pathogenic bacteria. Data suggest that excessive mitochondrial ROS production may affect ROS signaling induced by the microbiota to regulate the gut epithelial barrier. Finally, the microbiota releases metabolites that can directly interfere with the mitochondrial respiratory chain and ATP production. Short chain fatty acids have beneficial effects on mitochondrial activity. All these data suggest that the microbiota targets mitochondria to regulate its interaction with the host. Imbalance of this targeting may result in a pathogenic state as observed in numerous studies. The challenge to find new treatments will be to find strategies to modulate the quality and diversity of the microbiota rather than acting on microbiota metabolites and microbiota-related factors.