LC-MS/MS Analysis Offers Insights into Intestinal Microbiota and Metabolites in Camels

A joint study between the Gansu Agricultural University (Gansu, China) and the School of Animal and Veterinary Sciences at the University of Adelaide (Roseworthy, SA, Australia) analyzed the microbial and metabolic characteristics in various segments of the Bactrian camel's small intestine to further elucidate how the immune system varies across different regions. In this study, the microbiota and metabolite of 36 intestinal mucosal samples, including duodenal (D-PPs), jejunal (J-PPs), and ileal PPs (I-PPs), were profiled for six Bactrian camels using 16S rRNA gene sequencing and liquid chromatography with tandem mass spectrometry (LC-MS/MS). A paper based on their findings was published in Frontiers in Immunology (1).

Bactrian camels (Camelus bactrianus) are large even-toed ungulates primarily found in China and other Central Asian regions. There are two distinct subspecies of this camel—the domestic Bactrian camel (Camelus bactrianus) and the wild Bactrian camel (Camelus ferus). Each can easily adapt to the extreme living conditions of deserts and cold locations. Due to their distinctive immune traits, camels exhibit greater resilience to specific viral illnesses and environmental stresses compared to other species inhabiting the same geographical area (7). Camels possess a unique area of lymph aggregation in the abomasum, which is potentially associated with its distinct immunological attributes. While this area has similar protein expression profile with ileal PPs (8), there are variations within the microbial communities (8,9). Intestinal location affects the expression pattern of PPs genes, with significantly lower expression in the duodenum compared to the jejunum and ileum (10).

Housing a diverse array of immune cells with unique properties, the gastrointestinal system (or gut) is the largest immunological organ in both humans and animalsand relies on several immune compartments to effectively respond to the numerous antigens and stimuli it encounters (2). The mesenteric lymph nodes and gut-associated lymphoid tissue, as induction sites, play a crucial role in initiating immune responses by capturing, processing, and presenting antigens, with PPs serving as a prime example of this function. Intestinal lamina propria and epithelial cells serve as effector sites, and different types of immune cells are responsible for clearing antigens to maintain the integrity of the barrier. Trillions of bacteria residing in the gut are necessary for the enhancement of nutrient absorption as well as for energy metabolism (3,4), the maintenance of a healthy immune system (5), and the treatment or prevention of intestinal diseases (6).

Metabolic profiles of PPs in the duodenum, jejunum, and ileum of Bactrian camels were compared using a non-targeted LC-MS/MS approach to analyze metabolite alterations. Eighteen samples and six quality control (QC) samples were tested in positive and negative modes using LC-MS/MS (1).

The authors report that their findings indicate that the microbiota and metabolites of D-PPs exhibited unique characteristics compared to those of J-PPs and I-PPs with the J-PPs and I-PPs displaying similarities in intestinal environment. Similar conclusions were drawn for immunoglobulin expression. The authors believe that these results provide important insights into the regionalization of intestinal immunity in unique animalsand offers a new perspective for disease prevention and breed management of Bactrian camels, as well as enhances our understanding of the immune and digestive characteristics of their intestinal mucosa (1).

Bactrian camel in the steppes of Mongolia. © Hunta- stock.adobe.com

References

1. Cheng, Y.; Ren, Y.; Zhang, W.; Lu, J.; Xie, F.; Fang, Y. D.; Fan, X.; He, W.; Wang, W. Regionalization of Intestinal Microbiota and Metabolites in the Small Intestine of the Bactrian Camel. Front Immunol. 2024,15,1464664. DOI: 10.3389/fimmu.2024.1464664

2. Mörbe, U. M.; Jørgensen, P. B.; Fenton, T. M.; von Burg, N.; Riis, L. B.; Spencer, J.; Agace, W. W. Human Gut-Associated Lymphoid Tissues (GALT); Diversity, Structure, and Function. Mucosal. Immunol.2021,14(4), P793–802. DOI: 10.1038/s41385-021-00389-4

3. Bäckhed, F.; Ley, R. E.; Sonnenburg, J. L.; Peterson, D. A.; Gordon, J. I. Host-Bacterial Mutualism in the Human Intestine. Science 2005,307(5717), 1915–1920. DOI: 10.1126/science.1104816

4. White, B. A.; Lamed, R.; Bayer, E. A.; Flint, H. J. Biomass Utilization by Gut Microbiomes. Annu. Rev Microbiol. 2014, 68, 279–296. DOI: 10.1146/annurev-micro-092412-155618

5. Hooper, L. V.; Littman, D. R.; Macpherson, A. J. Interactions Between the Microbiota and the Immune System. Science 2012,336(6086), 1268–1273. DOI: 10.1126/science.1223490

6. Buffie, C. G.; Pamer E. G. Microbiota-Mediated Colonization Resistance Against Intestinal Pathogens. Nat. Rev. Immunol.2013, 13(11), 790–801. DOI: 10.1038/nri3535

7. Hussen, J.; Schuberth, H. J. Recent Advances in Camel Immunology. Front Immunol. 2021, 11, 614150. DOI: 10.3389/fimmu.2020.614150

8. Cheng, Y.; Ren, Y.; Wang, W.; Zhang, W. Similar Proteome Expression Profiles of the Aggregated Lymphoid Nodules Area and Peyer's Patches in Bactrian Camel. BMC Genomics 2023, 24 (1), 608. DOI: 10.1186/s12864-023-09715-5

9. Zhang, W. D.; Yao, W. L.; He, W. H.; Li, J. F.; Wu, X. P.; Chen, Z. H.; Liu, L.; Wang, W. H. Bacterial Community Analysis on the Different Mucosal Immune Inductive Sites of Gastrointestinal Tract in Bactrian Camels. PLoS One 2020, 15 (10), e0239987. DOI: 10.1371/journal.pone.0239987

10. Phillips, C. L.; Welch, B. A.; Garrett, M. R.; Grayson, B. E. Regional Heterogeneity in Rat Peyer's Patches Through Whole Transcriptome Analysis. Exp. Biol. Med. (Maywood) 2021, 246 (5), 513–522. DOI: 10.1177/1535370220973014