Altered Mucosal-Associated Invariant T Cells Phenotype in Children with Newly Diagnosed Type 1 Diabetes but not in Autoantibody-Positive At-Risk Children

Introduction: Mucosal-associated invariant T (MAIT) cells are unconventional T cells, enriched in the gut. They express an invariant T-cell receptor and recognize riboflavin metabolites from bacteria presented by MHC-Ib-related protein 1 (MR1) molecules. Alterations in gut microbiota have been reported in patients with type 1 diabetes (T1D), even before the onset of the disease. These changes can potentially alter the frequency or phenotype of circulating MAIT cells. Methods: We characterized peripheral blood MAIT cells in a cohort of 51 children with newly diagnosed T1D, 27 at-risk children positive for multiple autoantibodies (AAb+) and 113 age-matched healthy children. Using multi-colour flow cytometry, we analysed the frequency, surface phenotype and cytokine production of MAIT cells. In addition, we characterized the frequency and surface phenotype of blood MAIT cells in 26 patients with long-standing T1D and 25 age-matched healthy controls. Results: No significant differences in MAIT cell frequency were observed between the study groups. Further phenotyping revealed that the expression of CD8, CD27, CCR5 and β7 integrin on MAIT cells was lower in children with newly diagnosed T1D compared to AAb+ and healthy children. The frequency of MAIT cells producing IFN-γ was also lower in children with newly diagnosed T1D, but the frequencies of IL-17A- and IL-4-secreting MAIT cells were similar in the study groups. Finally, the capacity of MAIT cells to be activated in vitro by E.coli bacteria through MR1 was comparable between the study groups. However, none of these changes was observed in adult patients with long-standing T1D. In contrast, a decreased frequency of MAIT cells and increased CD25 expression was observed in adult T1D patients with a short duration after diagnosis. Conclusion: There are subtle changes in the circulating MAIT compartment in patients with T1D at the onset of the disease as well as after clinical diagnosis, but not in AAb+ at-risk subjects including progression to clinical disease. Consequently, the alterations in blood MAIT cells are likely associated with the clinical manifestation of the disease rather than being features of earlier T1D autoimmunity

Mucosal-associated invariant T cell alterations during the development of human type 1 diabetes

Aims/hypothesis Mucosal-associated invariant T (MAIT) cells are innate-like T cells that recognise derivatives of bacterial riboflavin metabolites presented by MHC-Ib-related protein 1 (MR1) molecules and are important effector cells for mucosal immunity. Their development can be influenced by the intestinal microbiome. Since the development of type 1 diabetes has been associated with changes in the gut microbiome, this can be hypothesised to lead to alterations in circulating MAIT cells. Accordingly, peripheral blood MAIT cell alterations have been reported previously in patients with type 1 diabetes. However, a comprehensive analysis of the frequency and phenotype of circulating MAIT cells at different stages of type 1 diabetes progression is currently lacking. Methods We analysed the frequency, phenotype and functionality of peripheral blood MAIT cells, as well as gamma delta T cells, invariant natural killer T (iNKT) cells and natural killer (NK) cells with flow cytometry in a cross-sectional paediatric cohort (aged 2-15) consisting of 51 children with newly diagnosed type 1 diabetes, 27 autoantibody-positive (AAb(+)) at-risk children, and 113 healthy control children of similar age and HLA class II background. The frequency of MAIT cells was also assessed in a separate cross-sectional adult cohort (aged 19-39) of 33 adults with established type 1 diabetes and 37 healthy individuals of similar age. Results Children with newly diagnosed type 1 diabetes displayed a proportional increase of CD8(-)CD27(-)MAIT cells compared with healthy control children (median 4.6% vs 3.1% of MAIT cells, respectively, p = 0.004), which was associated with reduced expression of C-C chemokine receptor (CCR)5 (median 90.0% vs 94.3% of MAIT cells, p = 0.02) and beta 7 integrin (median 73.5% vs 81.7% of MAIT cells, p = 0.004), as well as decreased production of IFN-gamma (median 57.1% vs 69.3% of MAIT cells, p = 0.04) by the MAIT cells. The frequency of MAIT cells was also decreased in AAb(+)children who later progressed to type 1 diabetes compared with healthy control children (median 0.44% vs 0.96% of CD3(+)T cells, p = 0.04), as well as in adult patients with a short duration of type 1 diabetes (less than 6 years after diagnosis) compared with control individuals (median 0.87% vs 2.19% of CD3(+)T cells, p = 0.007). No alterations in gamma delta T cell, iNKT cell or NK cell frequencies were observed in children with type 1 diabetes or in AAb(+) children, with the exception of an increased frequency of IL-17A(+)gamma delta T cells in children with newly diagnosed diabetes compared with healthy control children (median 1.58% vs 1.09% of gamma delta T cells, p = 0.002). Conclusions/interpretation Changes in the frequency and phenotype of circulating MAIT cells were detectable before, at the onset and after diagnosis of type 1 diabetes in cross-sectional cohorts. Our results suggest a possible temporal association between peripheral blood MAIT cell alterations and the clinical onset of type 1 diabetes.Peer reviewe

Mucosal-associated invariant T cell alterations during the development of human type 1 diabetes

Aims/hypothesis Mucosal-associated invariant T (MAIT) cells are innate-like T cells that recognise derivatives of bacterial riboflavin metabolites presented by MHC-Ib-related protein 1 (MR1) molecules and are important effector cells for mucosal immunity. Their development can be influenced by the intestinal microbiome. Since the development of type 1 diabetes has been associated with changes in the gut microbiome, this can be hypothesised to lead to alterations in circulating MAIT cells. Accordingly, peripheral blood MAIT cell alterations have been reported previously in patients with type 1 diabetes. However, a comprehensive analysis of the frequency and phenotype of circulating MAIT cells at different stages of type 1 diabetes progression is currently lacking.Methods We analysed the frequency, phenotype and functionality of peripheral blood MAIT cells, as well as gamma delta T cells, invariant natural killer T (iNKT) cells and natural killer (NK) cells with flow cytometry in a cross-sectional paediatric cohort (aged 2-15) consisting of 51 children with newly diagnosed type 1 diabetes, 27 autoantibody-positive (AAb(+)) at-risk children, and 113 healthy control children of similar age and HLA class II background. The frequency of MAIT cells was also assessed in a separate cross-sectional adult cohort (aged 19-39) of 33 adults with established type 1 diabetes and 37 healthy individuals of similar age.Results Children with newly diagnosed type 1 diabetes displayed a proportional increase of CD8(-)CD27(-)MAIT cells compared with healthy control children (median 4.6% vs 3.1% of MAIT cells, respectively, p = 0.004), which was associated with reduced expression of C-C chemokine receptor (CCR)5 (median 90.0% vs 94.3% of MAIT cells, p = 0.02) and beta 7 integrin (median 73.5% vs 81.7% of MAIT cells, p = 0.004), as well as decreased production of IFN-gamma (median 57.1% vs 69.3% of MAIT cells, p = 0.04) by the MAIT cells. The frequency of MAIT cells was also decreased in AAb(+)children who later progressed to type 1 diabetes compared with healthy control children (median 0.44% vs 0.96% of CD3(+)T cells, p = 0.04), as well as in adult patients with a short duration of type 1 diabetes (less than 6 years after diagnosis) compared with control individuals (median 0.87% vs 2.19% of CD3(+)T cells, p = 0.007). No alterations in gamma delta T cell, iNKT cell or NK cell frequencies were observed in children with type 1 diabetes or in AAb(+) children, with the exception of an increased frequency of IL-17A(+)gamma delta T cells in children with newly diagnosed diabetes compared with healthy control children (median 1.58% vs 1.09% of gamma delta T cells, p = 0.002).Conclusions/interpretation Changes in the frequency and phenotype of circulating MAIT cells were detectable before, at the onset and after diagnosis of type 1 diabetes in cross-sectional cohorts. Our results suggest a possible temporal association between peripheral blood MAIT cell alterations and the clinical onset of type 1 diabetes

The first report of Gyrodactylus salaris Malmberg, 1957 (Platyhelminthes, Monogenea) on Italian cultured stocks of rainbow trout (Oncorhynchus mykiss Walbaum)

The monogenean Gyrodactylus salons Malmberg, 1957 is considered one of the most important parasites of wild salmonids in the European Community due to the heavy ecological and economical damage it has inflicted on Atlantic salmon (Salmo salar) part populations. Rainbow trout (Oncorhynchus mykiss) is susceptible to G. salaris and can act as a suitable carrier host and, consequently, its trade in EU territory is restricted in relation to the status of "recognized free" zones. Despite the economic importance of rainbow trout farming in Italy, information on the Italian gyrodactylid fauna is lacking and prior to this salons had not been officially reported. During a routine health examination of study farmed rainbow trout stock throughout Central and Northern Italy in 2004-2005, five fish farms were found to be infected with G. salons alongside three other gyrodactylids Morphological and molecular characterisation confirmed the presence of G. salons, Gyrodactylus teuchis Lautraite, Blanc, Thiery, Daniel et Vigneulle, 1999 and Gyrodactylus derjavinoides Malmberg, Collins, Cunningham et Jalah, 2007, while Gyrodactylus truttae Glaser, 1974 was identified by morphological analysis only. The findings from this study extend the distribution of G. salons within Europe and highlight the importance of the rainbow trout trade in its dissemination

The potential utility of the leopard pleco (Glyptoperichthys gibbiceps) as a biological control of the ciliate protozoan Ichthyophthirius multifiliis

BACKGROUND: Infections of the ciliate protozoan Ichthyophthirius multifiliis Fouquet, 1876, can cause heavy mortalities in freshwater aquaculture systems. Following the ban of malachite green on fish for human consumption, currently available chemical therapies are only partially efficacious even when repeatedly applied. There is, therefore, an urgent necessity to identify more efficient and environmentally friendly control strategies. In the present study, the use of a substrate algae feeder leopard pleco, Glyptoperichthys gibbiceps, as a biological agent to control I. multifiliis infections on blue tilapia, Oreochromis aureus, reared in a warm-water, experimental tank-based system is explored. RESULTS: The free-swimming protomont stage of I. multifiliis demonstrated selective settlement behaviour towards biofilm-covered substrates. Following a controlled exposure, the number of I. multifiliis trophonts establishing on naive blue tilapia, O. aureus, was 4.9 ± 0.4 when reared with G. gibbiceps, significantly lower than when reared in isolation (13.3 ± 0.9; ANOVA, P less than 0.001). CONCLUSION: This study demonstrates for the first time the potential of G. gibbiceps as a biological control to reduce I. multifiliis on commercially valuable fish stocks in warm-water systems. This likely originated from the grazing activity of G. gibbiceps on the biofilm layer upon which the multiplicative stage of I. multifiliis was shown preferentially to settle. Therapeutic strategies against pathogenic protozoan species like I. multifiliis could greatly benefit from incorporating, where appropriate, a biological control targeting the external multiplicative life stages of the parasite, potentially reducing the current dependence on chemical interventions