FELASA guidelines for the accreditation of health monitoring programs and testing laboratories involved in health monitoring

Targeting gut microbiota and barrier function with prebiotics to alleviate autoimmune manifestations in NOD mice

AIMS/HYPOTHESIS

Adopting a diet containing indigestible fibre compounds such as prebiotics to fuel advantageous bacteria has proven beneficial for alleviating inflammation. The effect of the microbial changes on autoimmunity, however, remains unknown. We studied the effects of prebiotic xylooligosaccharides (XOS) on pancreatic islet and salivary gland inflammation in NOD mice and tested whether these were mediated by the gut microbiota.

METHODS

Mother and offspring mice were fed an XOS-supplemented diet until diabetes onset or weaning and were compared with a control-fed group. Diabetes incidence was monitored, insulitis and sialadenitis were scored in histological sections from adult mice, and several metabolic and immune variables were analysed in mice before the development of diabetes. Gut barrier function was assessed using an in vivo FITC-dextran permeability test. The importance of XOS-mediated gut microbial changes were evaluated in antibiotic-treated mice fed either XOS or control diet or given a faecal microbiota transplant from test animals.

RESULTS

Diabetes onset was delayed in the XOS-fed mice, which also had fewer cellular infiltrations in their pancreatic islets and salivary glands. Interestingly, insulitis was most reduced in the XOS-fed groups when the mice were also treated with an antibiotic cocktail. There was no difference in sialadenitis between the dietary groups treated with antibiotics; the mice were protected by microbiota depletion regardless of diet. Faecal microbiota transplantation was not able to transfer protection. No major differences in glucose-insulin regulation, glucagon-like peptide-1, or short-chain fatty acid production were related to the XOS diet. The XOS diet did, however, reduce gut permeability markers in the small and large intestine. This was accompanied by a more anti-inflammatory environment locally and systemically, dominated by a shift from M1 to M2 macrophages, a higher abundance of activated regulatory T cells, and lower levels of induction of natural killer T cells and cytotoxic T cells.

CONCLUSIONS/INTERPRETATION

Prebiotic XOS have microbiota-dependent effects on salivary gland inflammation and microbiota-independent effects on pancreatic islet pathology that are accompanied by an improved gut barrier that seems able to heighten control of intestinal diabetogenic antigens that have the potential to penetrate the mucosa to activate autoreactive immune responses.

The first-line antiepileptic drug carbamazepine: Reaction with biologically relevant free radicals

Carbamazepine (CBZ) is one of the most widely used antiepileptic drugs by both adults and children. Despite its widespread use, CBZ is associated with central nervous system toxicity and severe hypersensitivity reactions, which raise concerns about its chronic use. While the precise mechanisms of CBZ-induced adverse events are still unclear, metabolic activation to the epoxide (CBZ-EP) has been thought to play a significant role. This work reports first-hand evidence that CBZ reacts readily with biologically relevant thiyl radicals with no need for bioactivation. Using liquid chromatography coupled with high resolution mass spectrometry, multiple products from direct reaction of CBZ with glutathione (GSH) and N-acetyl-L-cysteine (NAC) were unequivocally identified, including the same product obtained upon ring-opening of CBZ-EP. The product profile is complex and consistent with radical-mediated mechanisms. Importantly, side products and adducts compatible with this non-enzymatic pathway were identified in liver extracts from CBZ-treated Wistar rats. The reaction of CBZ with GSH and NAC is more extensive in the presence of oxygen. Taking into consideration that GSH conjugation is, in general, a detoxification pathway, these results suggest that under hyperoxia/oxidative stress conditions the bioavailability of the parent drug may be compromised. Additionally, this non-enzymatic process can be anticipated to play, at least in part, a role in the onset of CBZ-induced adverse reactions due to the concomitant generation of reactive oxygen species. Therefore, the search for causal relationships between the formation of non-enzymatically-driven CBZ products and the occurrence of CBZ-induced adverse events in human patients merits further research, aiming the translation of basic mechanistic findings into a clinical context that may ultimately lead to a safer CBZ prescription.

MHC class II alleles associated with Th1 rather than Th17 type immunity drive the onset of early arthritis in a rat model of rheumatoid arthritis

Polymorphisms in the MHC class II (MHCII) genes are strongly associated with rheumatoid arthritis, supporting the importance of autoreactive T helper (Th) cells for the development of this disease. Here, we used pristane-induced arthritis (PIA), induced by the non-antigenic hydrocarbon pristane, to study the impact of different MHCII alleles on T-cell activation and differentiation. In MHCII-congenic rats with disease-promoting MHCII alleles, pristane primarily induced activation of Th1 cells, whereas activated T cells were Th17 biased in rats with protective MHCII alleles. Neutralization of IFN-γ during T-cell activation abrogated the development of disease, suggesting that Th1 immunity is important for disease induction. Neutralization of IL-17, by contrast, suppressed arthritis only when performed in rats with established disease. Adoptive T-cell transfers showed that T cells acquired arthritogenic capacity earlier in strains with a prevailing Th1 response. Moreover, upon pristane injection, these strains exhibited more Ag-primed OX40+ and proliferating T cells of polyclonal origin. These data show that T cells are polarized upon the first encounter with peptide-MHCII complexes in an allele-dependent fashion. In PIA, the polyclonal expansion of autoreactive Th1 cells was necessary for the onset of arthritis, while IL-17 mediated immunity contributed to the progression to chronic disease.

Animal Models of Rheumatoid Arthritis (I): Pristane-Induced Arthritis in the Rat

Background

To facilitate the development of therapies for rheumatoid arthritis (RA), the Innovative Medicines Initiative BTCure has combined the experience from several laboratories worldwide to establish a series of protocols for different animal models of arthritis that reflect the pathogenesis of RA. Here, we describe chronic pristane-induced arthritis (PIA) model in DA rats, and provide detailed instructions to set up and evaluate the model and for reporting data.

Methods

We optimized dose of pristane and immunization procedures and determined the effect of age, gender, and housing conditions. We further assessed cage-effects, reproducibility, and frequency of chronic arthritis, disease markers, and efficacy of standard and novel therapies.

Results

Out of 271 rats, 99.6% developed arthritis after pristane-administration. Mean values for day of onset, day of maximum arthritis severity and maximum clinical scores were 11.8±2.0 days, 20.3±5.1 days and 34.2±11 points on a 60-point scale, respectively. The mean frequency of chronic arthritis was 86% but approached 100% in long-term experiments over 110 days. Pristane was arthritogenic even at 5 microliters dose but needed to be administrated intradermally to induce robust disease with minimal variation. The development of arthritis was age-dependent but independent of gender and whether the rats were housed in conventional or barrier facilities. PIA correlated well with weight loss and acute phase reactants, and was ameliorated by etanercept, dexamethasone, cyclosporine A and fingolimod treatment.

Conclusions

PIA has high incidence and excellent reproducibility. The chronic relapsing-remitting disease and limited systemic manifestations make it more suitable than adjuvant arthritis for long-term studies of joint-inflammation and screening and validation of new therapeutics.

An Overview of Typical Infections of Research Mice: Health Monitoring and Prevention of Infection

There are many reasons to keep research mice healthy and free from infections. The two most important of these are to protect the health and welfare of research mice and to prevent infections from negatively impacting research. Just as the genetic integrity of a mouse strain will influence the reproducibility and validity of research data, so too will the microbiologic integrity of the animals. This has been repeatedly demonstrated in the literature of laboratory animal sciences wherein the direct impact of infections on physiologic parameters under study have been described. Therefore, it is of great importance that scientists pay close attention to the health status of their research animal colonies and maintain good communications with the animal facility personnel at their institution about mouse health issues. This overview provides information about animal health monitoring (HM) in research mouse colonies including commonly monitored agents, diagnostic methods, HM program, risk assessment, and animal facility biosecurity. Lastly, matters of communication with laboratory animal professionals at research institutions are also addressed. © 2015 by John Wiley & Sons, Inc.

Mode of delivery shapes gut colonization pattern and modulates regulatory immunity in mice

Delivery mode has been associated with long-term changes in gut microbiota composition and more recently also with changes in the immune system. This has further been suggested to link Cesarean section (C-section) with an increased risk for development of immune-mediated diseases such as type 1 diabetes. In this study, we demonstrate that both C-section and cross-fostering with a genetically distinct strain influence the gut microbiota composition and immune key markers in mice. Gut microbiota profiling by denaturing gradient gel electrophoresis and 454/FLX-based 16S rRNA gene amplicon sequencing revealed that mice born by C-section had a distinct bacterial profile at weaning characterized by higher abundance of Bacteroides and Lachnospiraceae, and less Rikenellaceae and Ruminococcus. No clustering according to delivery method as determined by principal component analysis of denaturing gradient gel electrophoresis profiles was evident in adult mice. However, the adult C-section-born mice had lower proportions of Foxp3(+) regulatory T cells, tolerogenic CD103(+) dendritic cells, and less Il10 gene expression in mesenteric lymph nodes and spleens. This demonstrates long-term systemic effect on the regulatory immune system that was also evident in NOD mice, a model of type 1 diabetes, born by C-section. However, no effect of delivery mode was seen on diabetes incidence or insulitis development. In conclusion, the first exposure to microorganisms seems to be crucial for the early life gut microbiota and priming of regulatory immune system in mice, and mode of delivery strongly influences this.

FELASA recommendations for the health monitoring of mouse, rat, hamster, guinea pig and rabbit colonies in breeding and experimental units

The microbiological quality of experimental animals can critically influence animal welfare and the validity and reproducibility of research data. It is therefore important for breeding and experimental facilities to establish a laboratory animal health monitoring (HM) programme as an integrated part of any quality assurance system. FELASA has published recommendations for the HM of rodent and rabbit colonies in breeding and experimental units (Nicklas et al. Laboratory Animals, 2002), with the intention of harmonizing HM programmes. As stated in the preamble, these recommendations need to be adapted periodically to meet current developments in laboratory animal medicine. Accordingly, previous recommendations have been revised and shall be replaced by the present recommendations. These recommendations are aimed at all breeders and users of laboratory mice, rats, Syrian hamsters, guinea pigs and rabbits as well as diagnostic laboratories. They describe essential aspects of HM, such as the choice of agents, selection of animals and tissues for testing, frequency of sampling, commonly used test methods, interpretation of results and HM reporting. Compared with previous recommendations, more emphasis is put on the role of a person with sufficient understanding of the principles of HM, opportunistic agents, the use of sentinel animals (particularly under conditions of cage-level containment) and the interpretation and reporting of HM results. Relevant agents, testing frequencies and literature references are updated. Supplementary information on specific agents and the number of animals to be monitored and an example of a HM programme description is provided in the appendices.

Customizing laboratory mice by modifying gut microbiota and host immunity in an early "window of opportunity"

We recently investigated how post-natal microbial gut colonization is important for the development of the immune system, especially in the systemic compartments. This addendum presents additional data which in accordance with our previous findings show that early life microbial colonization is critical for a fine-tuned immune homeostasis to develop also in the intestinal environment. A generalized reduction in the expression of immune signaling related genes in the small intestine may explain previously shown increased systemic adaptive immune reactivity, if the regulatory cross-talk between intra- and extra-intestinal immune cells is immature following a neonatal germ-free period. These findings are furthermore discussed in the context of recently published results on how lack of microbial exposure in the neonatal life modifies disease expression in rodents used as models mimicking human inflammatory diseases. In particular, with a focus on how these interesting findings could be used to optimize the use of rodent models.

The complement anaphylatoxin C3a receptor (C3aR) contributes to the inflammatory response in dextran sulfate sodium (DSS)-induced colitis in mice

Inflammatory bowel diseases are a critical public health issue, and as treatment options remain limited, there is a need to unravel the underlying pathomechanisms in order to identify new therapeutic targets. Complement activation was found in patients suffering from inflammatory bowel disease, and the complement anaphylatoxin C5a and its receptor C5aR have been implicated in disease pathogenesis in animal models of bowel inflammation. To further characterize complement-related pathomechanisms in inflammatory bowel disease, we have investigated the role of the anaphylatoxin C3a receptor in acute dextran sulfate sodium-induced colitis in mice. For this, colitis was induced in C3a receptor-deficient BALB/c and C57BL/6 mice, and disease severity was evaluated by clinical and histological examination, and by measuring the mRNA expression or protein levels of inflammatory mediators in the tissue. C3a receptor deficiency was partially protective in BALB/c mice, which had significantly reduced weight loss, clinical and histological scores, colon shortening, and CXCL-1/KC mRNA, myeloperoxidase and interleukin-6 tissue levels compared to the corresponding wild type mice. In C57BL/6 mice the differences between wild type and C3a receptor-deficient animals were much smaller and reached no significance. Our data demonstrate that the contribution of C3a receptor to disease pathogenesis and severity of dextran sulfate sodium-induced colitis in mice depends on the genetic background. Further studies will be required to clarify whether targeting of C3a receptor, possibly in combination with C5a receptor, might be considered as a therapeutic strategy for inflammatory bowel disease.

Gut microbiota regulates NKG2D ligand expression on intestinal epithelial cells

Intestinal epithelial cells (IECs) are one of a few cell types in the body with constitutive surface expression of natural killer group 2 member D (NKG2D) ligands, although the magnitude of ligand expression by IECs varies. Here, we investigated whether the gut microbiota regulates the NKG2D ligand expression on small IECs. Germ-free and ampicillin-treated mice were shown to have a significant increase in NKG2D ligand expression. Interestingly, vancomycin treatment, which propagated the bacterium Akkermansia muciniphila and reduced the level of IFN-γ and IL-15 in the intestine, decreased the NKG2D ligand expression on IECs. In addition, a similar increase in A. muciniphila and a decreased NKG2D ligand expression was seen after feeding with dietary xylooligosaccharides. A pronounced increase in NKG2D ligand expression was furthermore observed in IL-10-deficient mice. In summary, our results suggest that the constitutive levels of NKG2D ligand expression on IECs are regulated by microbial signaling in the gut and further disfavor the intuitive notion that IEC NKG2D ligand expression is caused by low-grade immune reaction against commensal bacteria. It is more likely that constitutively high IEC NKG2D ligand expression is kept in check by an intestinal regulatory immune milieu induced by members of the gut microbiota, for example A. muciniphila.