The human body gets its balance and homeostasis from the harbored useful microorganisms. Indeed, the human fetus experiences the first microbial exposure within his/her mother’s body. During the post-partum period, an infant gets formed to be inhabited by different types of useful microorganisms, e.g., archaea, bacteria, fungi, and viruses, collectively known as the microbiota. In particular, the evolution of the gut microbiota throughout life appears to play a pivotal role in both health and disease. On the one hand, metabolic regulation, homeostasis, and a strong immune system depend on gut microbiota balance or eubiosis. On the other hand, gut microbiota dysregulation or dysbiosis is observed in many diseases like diabetes, cancers, autoimmune diseases, inflammatory bowel disorders, atherosclerotic cardiovascular diseases, kidney diseases, neurological disorders, e.g., Alzheimer’s and Parkinson’s diseases, mental health disorders, etc. Interestingly, environmental factors and genetics are involved. Therefore, the interconnection between host-microbiota-environments is a fascinating and emerging area of research to understand health and disease. 
As aforementioned, the appearance of dysbiosis or eubiosis directly affects the human body’s status. This research topic aims to involve all the cases associated with gut microbiome composition, environmental factors (such as diet and nutrients), genetics and the related consequences whether positive or negative in both men and women. Hence, a wide range of items are regarded in the present Research Topic.  
?	Eubiosis: Health and homeostasis condition
 	Archaea
 	Bacteria 
 	Fungi 
 	Viruses
 	Predisposing factors (maternal microbiome, delivery condition, biomass index (BMI), diet, nutrition etc.)
 	Immune system maturity
 	Neonates
 	Infants
 	Children
 	Young adults
 	Adults
 	Genetics
 	Epigenetics
 	Females and Males
?	Gut microbiome and Metabolic regulation
 	Nutrients metabolisms
 	Risk and environmental factors
 	Sex-related factors
 	Genetics
 	Epigenetics
 	Diseases
?	Dysbiosis: Diseases and negative consequences
 	Atherosclerotic cardiovascular diseases
 	Autoimmune diseases
 	Bowel disorders
 	Cancers
 	Diabetes
 	Kidney diseases
 	Mental health disorders e.g., stress, psychotic disorders and diseases
 	Neurological disorders e.g., Alzheimer’s and Parkinson’s diseases
 	Obesity
 	Sex-related factors
 	Neonates
 	Infants
 	Children
 	Young adults
 	Adults
 	Genetics
 	Epigenetics
?	Gut microbiome and Immune network interactions
 	Innate immune cells
 	Cytokines, chemokines, Interleukins and the related signaling pathways
 	Receptors including Pattern Recognition Receptors (PRRs) e.g., Toll-like receptors (TLRs) and signaling pathways
 	Adaptive immune cells including B- and T cells
 	Non-immune cells
The human body gets its balance and homeostasis from the harbored useful microorganisms. Indeed, the human fetus experiences the first microbial exposure within his/her mother’s body. During the post-partum period, an infant gets formed to be inhabited by different types of useful microorganisms, e.g., archaea, bacteria, fungi, and viruses, collectively known as the microbiota. In particular, the evolution of the gut microbiota throughout life appears to play a pivotal role in both health and disease. On the one hand, metabolic regulation, homeostasis, and a strong immune system depend on gut microbiota balance or eubiosis. On the other hand, gut microbiota dysregulation or dysbiosis is observed in many diseases like diabetes, cancers, autoimmune diseases, inflammatory bowel disorders, atherosclerotic cardiovascular diseases, kidney diseases, neurological disorders, e.g., Alzheimer’s and Parkinson’s diseases, mental health disorders, etc. Interestingly, environmental factors and genetics are involved. Therefore, the interconnection between host-microbiota-environments is a fascinating and emerging area of research to understand health and disease. 
As aforementioned, the appearance of dysbiosis or eubiosis directly affects the human body’s status. This research topic aims to involve all the cases associated with gut microbiome composition, environmental factors (such as diet and nutrients), genetics and the related consequences whether positive or negative in both men and women. Hence, a wide range of items are regarded in the present Research Topic.  
?	Eubiosis: Health and homeostasis condition
 	Archaea
 	Bacteria 
 	Fungi 
 	Viruses
 	Predisposing factors (maternal microbiome, delivery condition, biomass index (BMI), diet, nutrition etc.)
 	Immune system maturity
 	Neonates
 	Infants
 	Children
 	Young adults
 	Adults
 	Genetics
 	Epigenetics
 	Females and Males
?	Gut microbiome and Metabolic regulation
 	Nutrients metabolisms
 	Risk and environmental factors
 	Sex-related factors
 	Genetics
 	Epigenetics
 	Diseases
?	Dysbiosis: Diseases and negative consequences
 	Atherosclerotic cardiovascular diseases
 	Autoimmune diseases
 	Bowel disorders
 	Cancers
 	Diabetes
 	Kidney diseases
 	Mental health disorders e.g., stress, psychotic disorders and diseases
 	Neurological disorders e.g., Alzheimer’s and Parkinson’s diseases
 	Obesity
 	Sex-related factors
 	Neonates
 	Infants
 	Children
 	Young adults
 	Adults
 	Genetics
 	Epigenetics
?	Gut microbiome and Immune network interactions
 	Innate immune cells
 	Cytokines, chemokines, Interleukins and the related signaling pathways
 	Receptors including Pattern Recognition Receptors (PRRs) e.g., Toll-like receptors (TLRs) and signaling pathways
 	Adaptive immune cells including B- and T cells
 	Non-immune cells