Hematopoiesis and the bacterial microbiome

Abstract

Recent studies have revealed that the intestinal bacterial microbiome plays an important role in the regulation of hematopoiesis. A correlation between adverse hematologic effects and imbalance of the intestinal microbiome, or dysbiosis, is evident in several human conditions, such as inflammatory bowel disease, obesity, and, critically, in the setting of antibiotic exposure. Here we review the effects of gut dysbiosis on the hematological compartment and our current understanding of the mechanisms through which changes in the bacterial microbiome affect hematopoiesis.

Environmental influences on clonal hematopoiesis

“…Obesity-induced changes in the microbiome have also been reported to alter the HSC niche and promote myelopoiesis [66,74]. Whether these changes in the microbiome are responsible for age-related changes in HSCs and their niche, leading to the emergence of CH, remains to be tested.…”

Fate of Hematopoiesis During Aging. What Do We Really Know, and What are its Implications?

“…GF mice demonstrated myelosuppression, smaller HSC, MPP, and common lymphoid progenitor (CLP) populations, and impaired neutrophils, monocytes, and T-cell functions. Recolonization of GF mice restored immune response to infection [ 96 , 228 , 231 ]. However, a closer evaluation of HSCs and HPCs in oral antibiotic-treated mice revealed normal HSC and HPC populations but reduced mature T cell, B cell, and granulocyte populations, suggesting impaired differentiation of mature immune cells in microbiota-depleted mice after oral antibiotics treatment and introduced some discrepancies between animal models used to study the microbiome [ 232 ].…”

Microbial sensing by haematopoietic stem and progenitor cells: Vigilance against infections and immune education of myeloid cells

“…In addition to the impacts of host-microbiota interactions on innate and adaptive immune function, recent studies have shown that microbiota can affect haematopoiesis. 70 Previous studies in humans showed that around 5%-15% of patients treated with beta-lactam antibiotics developed neutropenia, which returned to normal in most patients after treatment. 71 Depleting the microbiota with antibiotic treatment also SIOUD altered haematopoiesis in the steady-state.…”

“…72 Other signalling pathways, such as MyD88/TICAM1 and NOD1, were also involved. 70,75 Lee et al demonstrated that, under steadystate conditions, microbiota-derived compounds regulate the basal expansion of haematopoietic progenitors and their differentiation potential along the myeloid lineages indirectly via cytokines. 76 The authors showed that microbiotaderived PAMPs were transferred to the BM and sensed by the local immune cells to control haematopoiesis.…”