The Intestinal Microbiota May Be a Potential Theranostic Tool for Personalized Medicine

Abstract

The human intestine is colonized by a huge number of microorganisms from the moment of birth. This set of microorganisms found throughout the human body, is called the microbiota; the microbiome indicates the totality of genes that the microbiota can express, i.e., its genetic heritage. Thus, microbiota participates in and influences the proper functioning of the organism. The microbiota is unique for each person; it differs in the types of microorganisms it contains, the number of each microorganism, and the ratio between them, but mainly it changes over time and under the influence of many factors. Therefore, the correct functioning of the human body depends not only on the expression of its genes but also on the expression of the genes of the microorganisms it coexists with. This fact makes clear the enormous interest of community science in studying the relationship of the human microbiota with human health and the incidence of disease. The microbiota is like a unique personalized "mold" for each person; it differs quantitatively and qualitatively for the microorganisms it contains together with the relationship between them, and it changes over time and under the influence of many factors. We are attempting to modulate the microbial components in the human intestinal microbiota over time to provide positive feedback on the health of the host, from intestinal diseases to cancer. These interventions to modulate the intestinal microbiota as well as to identify the relative microbiome (genetic analysis) can range from dietary (with adjuvant prebiotics or probiotics) to fecal transplantation. This article researches the recent advances in these strategies by exploring their advantages and limitations. Furthermore, we aim to understand the relationship between intestinal dysbiosis and pathologies, through the research of resident microbiota, that would allow the personalization of the therapeutic antibiotic strategy.

Keywords: clinical biochemistry; clinical microbiology; immune system and dysbiosis; intestinal microbiota; laboratory medicine; microbiota; microbiota analysis; oral microbiota; probiotics; theranostic and translational research.

Figure 1

There are complex host–microbe interactions in the gut ranging from direct cell-to-cell to broader systemic communication, involving various organs including the central nervous system (CNS), e.g., diarrhea after broad-spectrum antibiotic treatment for C. difficile. Therefore, a cause that leads to an alteration of the qualitative and quantitative composition also leads to a continuous cycle of disharmony (among the local bacterial populations and mucosa), thus creating a state of inflammation in the intestinal mucosa that, if it persists, causes pathogenic bacteria to find room to proliferate and subsequently to move, so that we can define it as a local humoral immunity interactions cycle (LHII). This can lead to an immune upregulation with subsequent imbalance (extraintestinal dysbiosis) of all the microbiota’s axes interconnected with the intestinal microbiota in various organs and, if it persists, it creates a cross-talking gut axes alteration cycle (CGAAC), which leads to an increase in local and systemic dysfunction in the organism’s host over time, creating “reflex” diseases. Credits: Original figure by I.A. Charitos.