Probiotics Interactions and the Modulation of Major Signalling Pathways in Host Model Organism Caenorhabditis elegans

Abstract

Microorganisms live in the human digestive system and the gut microbiome constitutes part of our prime determining component for healthy aging and wellness. Gut microbiota has broad influences on its host, beginning from the digestion of food and nutrients absorption to protective roles against invading pathogens and host immune system regulation. Dysbiosis of the gut microbial composition has been linked to numerous diseases and there is a need to have a better grasp on what makes a 'good' gut microbiome. Caenorhabditis elegans (C. elegans) model organism is considered as a well-suited in-vivo model system and, is at the frontline of probiotic research because of its well-defined characteristics and prolific nature. Most importantly, C. elegans feeds on bacteria, which speeds up manipulations and investigations in probiotics research tremendously. With its unique salient features of short lifespan, and ease of propagation, different unknown probiotics biological roles can be measured at an organism level with precision in the form of worm's stress responses, survivability, and lifespan. In this review, new insights on the different mechanisms underlying the establishment of probiotics regulations of conserved signalling pathways such as p38 MAPK/SKN-1, DAF-2/DAF-16, and JNK-1/DAF-16 is highlighted based on information obtained from C. elegans studies. Along with the current state of knowledge and the uniqueness of C. elegans as a model organism, explorations of its future contribution and scope in synthetic biology and probiotics engineering strains are also addressed. This is expected to strengthen our understanding of probiotics roles and to facilitate novel discovery and applications, for specific therapeutics against age-related disorders and various pathophysiological conditions.

Keywords: Aging; Caenorhabditis elegans; Lactobacilli; Probiotics; Signalling.

Fig. 1

An adult C. elegans hermaphrodite with its key anatomical features

Fig. 2

Overview of C. elegans as a model organism with simplified representation of approaches employing in probiotics research

Fig. 3

Schematic representation of the most common signalling pathways influenced by probiotic strains employed in C. elegans studies. Abbreviations used: (1) IIS (insulin/insulin-like growth factor-1) pathway: DAF-2: dauer formation 2, PDK-1: phosphoinositide-dependent kinase 1, AKT-1: serine/threonine protein kinase DAF-16: dauer formation 16. (2) AMPK: 5′ AMP-activated protein kinase) pathway. (3) β-catenin pathway: BAR-1: β-catenin/armadillo Related-1; DBL-1: DPP/BMP-Like-1. (4) JNK pathway: JKK-1: c-Jun N-terminal kinase kinase; JNK-1: c-Jun N-terminal kinase. (5) p38 MAPK pathway: MAPK: mitogen-activated protein kinase; NSY-1: neuronal symmetry-1; PMK-1: p38 mitogen-activated protein kinase-1; RACK-1: receptor activated protein C kinase; SEK-1: SAPK/ERK kinase-1; SMA: small; TIR-1: toll interleukin-1 receptor-1.5. (6) Germline signalling: MIR1: microRNA1; KIR: Krev interaction trapped/cerebral cavernous malformation 1