Bifidobacterium in anticancer immunochemotherapy: friend or foe?

Abstract

The gut microbiome has received a crescendo of attention in recent years due to myriad influences on human pathophysiology, including cancer. Anticancer therapy research is constantly looking for new hints to improve response to therapy while reducing the risk of relapse. In this scenario, Bifidobacterium, which inhabits the gut microbial ecosystem (especially that of children) and is considered a health-associated microbe, has emerged as a key target to assist anticancer treatments for a better prognosis. However, some researchers have recently hypothesized an unfavorable role of Bifidobacterium spp. in anticancer immunochemotherapy, leading to some confusion in the field. This narrative review summarizes the current knowledge on the role of Bifidobacterium spp. in relation to anticancer treatments, discussing the pros and cons of its presence in the gut microbiome of cancer patients. The current intervention strategies based on the administration of probiotic strains of Bifidobacterium are then discussed. Finally, the need to conduct further studies, especially functional ones, is underlined to provide robust experimental evidence, especially on the underlying molecular mechanisms, and thus resolve the controversies on this microbe for the long-term success of immunochemotherapy.

Keywords: Bifidobacterium; anti-inflammatory; cancer; immunochemotherapy; lactate; pro-inflammatory; response to therapy.

Figure 1

Bifidobacterium and its controversial role in the response to anticancer immunochemotherapy. Bifidobacterium spp. have been associated with response to immunochemotherapy through stimulation and activation of effector T lymphocytes and dendritic cells. On the other hand, Bifidobacterium spp. have been associated with induction of Treg cells, stimulation of anti-inflammatory cytokines, and general immunosuppressive effects (also mediated by short-chain fatty acids – SCFAs). Furthermore, the ability of Bifidobacterium to produce lactate suggests a hypothetical link with the “Warburg effect”, known to promote tumor growth, thus potentially liming the effect of immunochemotherapy. The figure was partly generated using Servier Medical Art, provided by Servier, licensed under a Creative Commons Attribution 3.0 unported license and images from Flaticon resources.