Background & Aims
Reactivity to various factors is a vitally important mechanism warranting survival for an organism. One of the components of reactivity and resistance is the intestinal biobarrier including gut microbiome (GM). Direct/feedback relationships between GM and brain functions are emerging and at the same time neuronal control of intestinal function contributes to the individual reactivity of an organism and the maintenance of tissue homeostasis [1-3]. Inflammation causes complex changes in enteric neurons, visceromotor sympathetic neurons in the prevertebral ganglia, gut epithelia and microbiota, even after resolution of inflammation. The identification of sex-specific molecular and functional differences, a better understanding remain an unmet medical need. Based on the sexually dimorphic response to short-chain fatty acids of Nav1.8-positive sensory neurons in male and femal mice [2], we aimed to explore how Nav1.8 expressing neurons innervating the gut relate to the composition of GM.
Methods
Feces adult female and male mice with a conditional depletion of the IL-6 signal transducer gp130 in Nav1.8 expressing neurons (SNS-gp130?/?) as well as control mice (gp130fl/fl) were obtained and subjected to 16S RNA sequencing (RNASeq) and bioinformatic analyses of diversity and differentially expressed microbiota. For bacterial cultures, we performed serial dilutions of each sample in PBS for the Schädler media (1:1,000; 1:10,000). 100 µL of a serial dilution were inoculated in aerobic conditions on Müller-Hinton agar, McConkey agar, and Columbia agar plates for 48 h at 37°C. For anaerobic conditions, fecal solutions were inoculated on Schaedler agar plates and incubated for 72 h at 37°C in an anaerobic environment. For analysis, bacterial colonies were distinguished by morphology, and species were identified by Matrix Assisted Laser Desorption/Ionisation Time of Flight (MALDI-TOF) mass spectrometry. Three colonies with different morphologies were isolated for identification (CFU).
Results
Whereas no differences in overall diversity were detectable in 16S RNAseq, sex-dependent differences in individual strains were retrieved as indicated by 16S RNAseq as well as cultures between SNS-gp130?/? and control mice. The number of bacterial species, specifically of opportunistic species, e.g. Staphylococcus sciuri – gram-positive opportunistic coccus, was higher in males of both genotypes. SNS-gp130?/? male mice showed higher numbers of two strains of Lactobacillus spp. with probiotic properties (Lactobacillus johnsonii and reuteri) compared to control flox mice. In addition, we discovered sex/genotype-related correlations in Lactobacillus johnsonii (R=0.620, ?=0.004) and Lactobacillus reuteri (R=0.509, ?=0.022). In control female mice commensal bacteria (Lactobacillus spp., Enterococcus faecalis) were more abundant than in male mice. Furthermore, male control mice showed higher amounts of Staphylococcus sciuri and Escherichia coli compared to female control mice.
Conclusions
Conclusion. The significant differences revealed by two independent methods showing higher intestinal colonisation resistance in SNS-gp130?/? male mice due to a higher content of probiotic Lactobacilli (reuteri and jonsonii) support the concept that male individuals are more resistant to inflammatory processes. The peculiarities of the intestinal microflora in SNS-gp130?/? mice suggest that primary sensory afferent neurons can regulate mouse microbiome gut composition, and this may be a protective link in the pathogenesis of neuropathic pain and inflammation.
References
1.Bayrer, J. R., Castro, J., Venkataraman, A., Touhara, K. K., Rossen, N. D., Morrie, R. D., Maddern, J., Hendry, A., Braverman, K. N., Garcia-Caraballo, S., Schober, G., Brizuela, M., Castro Navarro, F. M., Bueno-Silva, C., Ingraham, H. A., Brierley, S. M., & Julius, D. (2023). Gut enterochromaffin cells drive visceral pain and anxiety. Nature, 616(7955), 137–142. https://doi.org/10.1038/s41586-023-05829-8
2.Brierley, S., Linden, D. Neuroplasticity and dysfunction after gastrointestinal inflammation. Nat Rev Gastroenterol Hepatol 11, 611–627 (2014). https://doi.org/10.1038/nrgastro.2014.103
3.Yang, D., Almanzar, N., & Chiu, I. M. (2023). The role of cellular and molecular neuroimmune crosstalk in gut immunity. Cellular & molecular immunology, 20(11), 1259–1269. https://doi.org/10.1038/s41423-023-01054-5
Presenting Author
Nadiia Rykalo
Poster Authors
Nadiia Rykalo
Dr.med.
Medical University of Innsbruck, Austria
Lead Author
Lydia Riehl
Medical University Innsbruck, Institute of Physiology
Lead Author
Stephan Steixner
Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
Lead Author
Cornelia Lass-Flörl
Univ. Proff.
Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
Lead Author
Maximilian Zeidler
PhD
Institute of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck,
Lead Author
Theodora Kalpachidou
Medical University of Innsbruck
Lead Author
Michaela Kress
Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria
Lead Author
Topics
- Models: Chronic Pain - Neuropathic