Microbiome Shift, Diversity, and Overabundance of Opportunistic Pathogens in Bovine Digital Dermatitis Revealed by 16S rRNA Amplicon Sequencing

The impact of gut microbial dysbiosis on the atrophy of the hippocampus and abnormal metabolism of N-acetyl aspartate in type 2 diabetic rats

Rationale and objectives

This study aimed to investigate the effect of intestinal dysbiosis on the hippocampal volume using proton magnetic resonance spectroscopy (1H-MRS) in a type 2 diabetes mellitus (T2DM) rat model.

Materials and methods

We established a T2DM animal model with high-fat diet and streptozotocin (HFD/STZ) administration to Sprague-Dawley rats. Short-term ceftriaxone sodium administration was used to establish a T2DM intestinal dysbiosis (T2DM-ID) model. After establishing the model, fecal microbiota were detected using 16S rRNA sequencing. The models were then subjected to magnetic resonance imaging (MRI). Associations between MRI findings and fecal microbiota were evaluated.

Results

Magnetic resonance imaging (MRI) showed that the bilateral hippocampal voxel value and N-acetylaspartate (NAA) level were lower in the experimental group than in the normal control (NC) group (p < 0.05) and that NAA/creatine in the left hippocampus was lower in the T2DM-ID group than in the NC group (p < 0.05). α and β diversities differed significantly among the three groups (p < 0.05). In the T2DM and T2DM-ID groups, the abundance of bacteria in the phylum Proteobacteria increased significantly, whereas that of bacteria in the phylum Firmicutes decreased. The relative abundance of Actinobacteria was significantly increased in the T2DM-ID group. The Chao1 index (r = 0.33, p < 0.05) and relative abundance of Firmicutes (r = 0.48, p < 0.05) were positively correlated with the left hippocampal voxel, while the relative abundance of Proteobacteria was negatively correlated with the left hippocampal voxel (r = -0.44, p < 0.05). NAA levels, bilateral hippocampal voxels, and the relative abundance of Lactobacillus, Clostridia_UCG_014, and other genera were correlated positively (r = 0.34-0.70, p < 0.05). NAA levels and the relative abundances of Blautia and Enterococcus were correlated negatively (r = -0.32-0.44, p < 0.05).

Conclusion

The T2DM-ID rat model showed hippocampal volume atrophy and decreased levels of neuronal markers (such as NAA). The abnormal content of specific gut microorganisms may be a key biomarker of T2DM-associated brain damage.

Fecal and vaginal microbiota of vaccinated and non-vaccinated pregnant elk challenged with Brucella abortus

Introduction

Brucella abortus is the causative agent of brucellosis in cattle and in humans, resulting in economic losses in the agricultural sector and representing a major threat to public health. Elk populations in the American Northwest are reservoirs for this bacterium and transmit the agent to domestic cattle herds. One potential strategy to mitigate the transmission of brucellosis by elk is vaccination of elk populations against B. abortus; however, elk appear to be immunologically distinct from cattle in their responses to current vaccination strategies. The differences in host response to B. abortus between cattle and elk could be attributed to differences between the cattle and elk innate and adaptive immune responses. Because species-specific interactions between the host microbiome and the immune system are also known to affect immunity, we sought to investigate interactions between the elk microbiome and B. abortus infection and vaccination.

Methods

We analyzed the fecal and vaginal microbial communities of B. abortus-vaccinated and unvaccinated elk which were challenged with B. abortus during the periparturient period.

Results

We observed that the elk fecal and vaginal microbiota are similar to those of other ruminants, and these microbial communities were affected both by time of sampling and by vaccination status. Notably, we observed that taxa representing ruminant reproductive tract pathogens tended to increase in abundance in the elk vaginal microbiome following parturition. Furthermore, many of these taxa differed significantly in abundance depending on vaccination status, indicating that vaccination against B. abortus affects the elk vaginal microbiota with potential implications for animal reproductive health.

Discussion

This study is the first to analyze the vaginal microbiota of any species of the genus Cervus and is also the first to assess the effects of B. abortus vaccination and challenge on the vaginal microbiome.

Uterine microbial ecology and disease in cattle: A review

Due to the critical contribution of the uterine-associated microbiota in reproductive health, physiology, and performance, culture-independent methods have been increasingly employed to unravel key aspects of microbial ecology in the uterus of cattle. Nowadays, we know that bacterial diversity is crucial to maintain uterine health, however, there is still no consensus on the exact composition of a healthy uterine microbiota (or eubiosis). Generally, loss of bacterial diversity (or dysbiosis) contributes to the development of uterine infections, associated with increased relative abundances of Bacteroides, Fusobacterium, Trueperella, and Porphyromonas. Uterine infections are highly prevalent and gravely influence the profitability of cattle operations, animal welfare, and public health. Thus, understanding the dynamics of uterine microbial ecology is essential to develop effective strategies focused on preventing and mitigating the adverse effects of uterine dysbiosis as well as assisting in the process of restoring the core, healthy uterine microbiota. The aim of this review is to summarize research conducted in the microbial ecology of bovine uteri. We discuss the origin of the uterine microflora of healthy cows and the factors influencing its composition. In addition, we review the biology of specific pathogens that are known to increase in abundance during the occurrence of uterine disease. Lastly, we provide an overview of the bacterial biofilm in the bovine endometrium, and we briefly summarize the rationale for the use of probiotics to prevent uterine disease in cattle.

The bovine foot skin microbiota is associated with host genotype and the development of infectious digital dermatitis lesions

BACKGROUND

Bovine Digital Dermatitis (BDD) is a prevalent infectious disease, causing painful foot skin lesions and lameness in cattle. We describe herein the bovine foot skin microbiota and its associations with BDD using 16S rRNA gene amplicon and shotgun metagenomic sequencing on samples from 259 dairy cows from three UK dairy farms.

RESULTS

We show evidence of dysbiosis, and differences in taxonomy and functional profiles in the bovine foot skin microbiome of clinically healthy animals that subsequently develop BDD lesions, compared to those that do not. Our results suggest that taxonomical and functional differences together with alterations in ecological interactions between bacteria in the normal foot skin microbiome may predispose an animal to develop BDD lesions. Using genome-wide association and regional heritability mapping approaches, we provide first evidence for interactions between host genotype and certain members of the foot skin microbiota. We show the existence of significant genetic variation in the relative abundance of Treponema spp. and Peptoclostridium spp. and identify regions in the bovine genome that explain a significant proportion of this variation.

CONCLUSIONS

Collectively this work shows early changes in taxonomic and functional profiles of the bovine foot-skin microbiota in clinically healthy animals which are associated with subsequent development of BDD and could be relevant to prevention of disease. The description of host genetic control of members of the foot skin microbiota, combined with the association of the latter with BDD development offer new insights into a complex relationship that can be exploited in selective breeding programmes. Video Abstract.

Continuous activation of the IL-17F driven inflammatory pathway in acute and chronic digital dermatitis lesions in dairy cattle

Objectives of the present study were to get a deeper insight into the course of the inflammatory pathways of digital dermatitis lesions in dairy cattle by investigating the gene expression patterns throughout the different clinical stages (M0 to M4.1) of the disease. Normal skin samples (M0) were used as a reference for comparing the gene expression levels in the other M-stages through RNA Seq-technology. Principal component analysis revealed a distinct gene expression pattern associated with digital dermatitis lesions in comparison to healthy skin with a further clustering of the acute M1, M2 and M4.1 stages versus the chronic M3 and M4 stages. The majority of the up-and downregulated genes in the acute and chronic stages can be placed into a common 'core' set of genes involved in inflammation, such as A2ML1, PI3, CCL11 and elafin-like protein, whereas the most downregulated genes included keratins and anti-inflammatory molecules such as SCGB1D and MGC151921. Pathway analysis indicated the activation of the pro-inflammatory IL-17 signaling pathway in all the M stages through the upregulation of IL-17F. These results indicate that digital dermatitis is associated with an excessive inflammatory immune response concomitant with a disrupted skin barrier and impaired wound repair mechanism. Importantly, despite their macroscopically healed appearance, a significant inflammatory response (Padj < 0.05) was still measurable in the M3 and M4 lesions, potentially explaining the frequent re-activation of such lesions.