Synovial Regulatory T Cells Occupy a Discrete TCR Niche in Human Arthritis and Require Local Signals To Stabilize FOXP3 Protein Expression

Although there is great interest in harnessing the immunosuppressive potential of FOXP3+ regulatory T cells (Tregs) for treating autoimmunity, a sizeable knowledge gap exists regarding Treg fate in human disease. In juvenile idiopathic arthritis (JIA) patients, we have previously reported that atypical CD25+FOXP32 Treg-like cells uniquely populate the inflamed site. Intrigu-ingly, their proportions relative to CD25+FOXP3+ Tregs associate with arthritis course, suggesting a role in disease. The ontogeny of these FOXP32 Treg-like cells is, however, unknown. In this study, we interrogated clonal relationships between CD4+ T cell subsets in JIA, using high-throughput TCR repertoire analysis. We reveal that FOXP3+ Tregs possess highly exclusive TCRb usage from conventional T cells, in blood, and also at the inflamed site, where they are clonally expanded. Intriguingly, the repertoires of FOXP3+ Tregs in synovial fluid are highly overlapping with CD25+FOXP32 Treg-like cells, indicating fluctuations in FOXP3 expression in the inflamed joint. Furthermore, cultured synovial Tregs rapidly downregulated FOXP3 protein (but not mRNA), and this process was prevented by addition of synovial fluid from JIA patients, through an IL-6–independent mechanism. Our findings suggest that most Tregs arise from a separate lineage from conventional T cells, and that this repertoire divergence is largely maintained under chronic inflammatory conditions. We propose that subsequent Treg expansions at the inflamed site creates an environment that leads to competition for limited resources within the synovium, resulting in the destabilization of FOXP3 expression in some Tregs. The Journal of Immunology, 2015, 195: 5616–5624.

Myxosporean hyperparasites of gill monogeneans are basal to the Multivalvulida

Background: Myxosporeans are known from aquatic annelids but parasitism of platyhelminths by myxosporeans has not been widely reported. Hyperparasitism of gill monogeneans by Myxidium giardi has been reported from the European eel and Myxidium-like hyperparasites have also been observed during studies of gill monogeneans from Malaysia and Japan. The present study aimed to collect new hyperparasite material from Malaysia for morphological and molecular descriptions. In addition, PCR screening of host fish was undertaken to determine whether they are also hosts for the myxosporean. Results: Heavy myxosporean infections were observed in monogeneans from two out of 14 fish and were detected from a further five fish using specific PCRs and pooled monogenean DNA. Positive DNA isolates were sequenced and were from a single species of myxosporean. Myxospore morphology was consistent with Myxidium with histozoic development in the parenchymal tissues of the monogenean. Simultaneous infections in the fish could not be confirmed microscopically; however, identical myxosporean DNA could be amplified from kidney, spleen and intestinal tract tissues using the specific PCR. Small subunit (SSU) rDNA for the myxosporean was amplified and was found to be most similar (92%) to that of another hyperparasitic myxosporean from a gill monogenean from Japan and to numerous multivalvulidan myxosporeans from the genus Kudoa (89-91%). Phylogenetic analyses placed the hyperparasite sequence basally to clades containing Kudoa, Unicapsula and Sphaerospora. Conclusions: The myxosporean infecting the gill monogenean, Diplectanocotyla gracilis, from the Indo-Pacific tarpon, Megalops cyprinoides, is described as a new species, Myxidium incomptavermi, based on a histozoic development in the monogenean host and its phylogenetic placement. We have demonstrated for the first time that a myxosporean hyperparasite of gill monogeneans is detectable in the fish host. However, myxospores could not be isolated from the fish and confirmation was by PCR alone. The relationship between the myxosporean infection in gill monogeneans and the presence of parasitic DNA in fish is not yet fully understood. Nonetheless, myxospores with a Myxidium-like morphology, two of which we have shown to be phylogenetically related, have now been reported to develop in three different gill monogeneans, indicating that myxosporeans are true parasites of monogeneans

Brief Report: Innate lymphoid cells and T-cells contribute to the IL-17A signature detected in the synovial fluid of patients with Juvenile Idiopathic Arthritis

OBJECTIVE: Evidence suggests that aberrant function of innate lymphoid cells (ILC), whose functional and transcriptional profile overlap with T helper (Th) cell subsets, contribute to immune-mediated pathologies. To date, analysis of Juvenile Idiopathic Arthritis (JIA) immune-pathology has concentrated on the contribution of CD4+ T-cells; we have previously identified an expansion of Th17 cells within the synovial fluid (SF) of JIA patients. Here, we extend this analysis to investigate a role for ILC and other IL-17 producing T-cell subsets. METHODS: ILC and CD3+ T-cell subsets were defined in peripheral blood mononuclear cells (PBMC) (healthy adult, healthy child and JIA patients) and JIA SF mononuclear cells (SFMC) using flow cytometry. Defined subsets in SFMC were correlated with clinical measures including physician's visual analogue scale (VAS), active joint count and erythrocyte sedimentation rate (ESR). Transcription factor and cytokine profiles of sorted ILC were assessed by qPCR. RESULTS: Group 1 ILC (ILC1), NKp44-group 3 ILC (NCR-ILC3) and NKp44+group 3 ILC (NCR+ILC3) were enriched in the JIA-SFMC compared to PBMC, which corresponded with an increase in transcripts for TBX21, IFNG and IL17A. Of the ILC subsets, NCR-ILC3 frequency in JIA-SFMC displayed the strongest positive association with clinical measures which was mirrored by an expansion in IL-17A+CD4+, IL-17A+CD8+ and IL-17A+γδ T-cells. CONCLUSION: We demonstrate that the strength of the IL-17A signature in JIA-SFMC is determined by multiple lymphoid cell-types, including NCR-ILC3, IL-17A+CD4+, IL-17A+CD8+ and IL-17A+γδ T-cells. These observations may have important implications for the development of stratified therapeutics. This article is protected by copyright. All rights reserved

Bone marrow dosimetry in peptide receptor radionuclide therapy with [177Lu-DOTA0,Tyr3]octreotate

Adequate dosimetry is mandatory for effective and safe peptide receptor radionuclide therapy (PRRT). Besides the kidneys, the bone marrow is a potentially dose-limiting organ. The radiation dose to the bone marrow is usually calculated according to the MIRD scheme, where the accumulated activity in the bone marrow is calculated from the accumulated radioactivity of the radiopharmaceutical in the blood. This may underestimate the absorbed dose since stem cells express somatostatin receptors. We verified the blood-based method by comparing the activity in the blood with the radioactivity in bone marrow aspirates. Also, we evaluated the absorbed cross-dose from the source organs (liver, spleen, kidneys and blood), tumours and the so-called "remainder of the body" to the bone marrow

Expression of FcRL4 defines a pro-inflammatory, RANKL-producing B cell subset in rheumatoid arthritis

OBJECTIVES: The success of B cell targeting therapies has highlighted the importance of B cells in rheumatoid arthritis pathogenesis. We have previously shown that B cells in the RA synovium are capable of producing pro-inflammatory and bone-destructive cytokines including RANKL. Here we sought to characterise the nature and functional relevance of the RANKL-producing B cell subset in the RA synovium. METHODS: Synovial fluid and peripheral blood B cells from patients with RA were analysed by flow cytometry for markers of B cell differentiation and activation and for chemokine receptors. FcRL4(+) and FcRL4(−) B cells sorted from synovial fluid were analysed for cytokine expression using Taqman low-density arrays. Synovial tissue biopsies obtained from patients with RA were analysed by immunofluorescence for CD20, RANKL and FcRL4. FCRL4 mRNA expression was determined in synovial tissue of RA patients and non-inflammatory control subjects by real-time PCR. RESULTS: RANKL-producing B cells in RA synovial tissue and fluid were identified as belonging to a distinct subset of B cells defined by expression of the transmembrane protein FcRL4. FcRL4+ B cells express a distinct combination of cytokines and surface proteins indicating a function distinct from that of FcRL4− B cells. Notably, FcRL4+ B cells expressed high levels of TNF-α and RANKL mRNA. CONCLUSIONS: We have identified a novel pro-inflammatory B cell population in the RA synovium which is defined by expression of FcRL4 and responsible for RANKL production. This B cell population expresses high levels of CD20, and its removal by rituximab may contribute to the anti-inflammatory effect of this drug

A Chitinase from Aeromonas veronii CD3 with the Potential to Control Myxozoan Disease

Background: The class Myxosporea encompasses about 2,400 species, most of which are parasites of fish and cause serious damage in aquaculture. Due to the concerns about food safety issues and limited knowledge of Myxozoa life cycle and fish immune system, no chemicals, antibiotics or immune modulators are available to control myxozoa infection. Therefore, little can be done once Myxozoa establishment has occurred. Methodology/Principal Findings: In this paper we isolated Aeromonas veronii CD3 with significant myxospore shell valvedegrading ability from pond sediment. A 3,057-bp full-length chitinase gene was consequently cloned, and the corresponding mature, recombinant chitinase (ChiCD3) produced by Escherichia coli had substantial chitinase activity. The deduced sequence of ChiCD3 contained one catalytic domain, two chitin-binding domains, and one putative signal peptide. ChiCD3 had an optimal activity at 50uC and pH 6.0, and retained more than 50 % of its optimal activity under warm water aquaculture conditions (,30uC and pH,7.0). After incubation with ChiCD3, 38.064.8 % of the myxospores had damaged shell valves, whereas myxospores incubated with commercially available chitinases remained intact. Conclusion/Significance: This study reveals a new strategy to control myxozoan disease. ChiCD3 that has capacity to damage the shell valve of myxospores can be supplemented into fish feed and used to control Myxozoa-induced disease

Acute maternal infection and risk of pre-eclampsia: a population-based case-control study.

BACKGROUND: Infection in pregnancy may be involved in the aetiology of pre-eclampsia. However, a clear association between acute maternal infection and pre-eclampsia has not been established. We assessed whether acute urinary tract infection, respiratory tract infection, and antibiotic drug prescriptions in pregnancy (a likely proxy for maternal infection) are associated with an increased risk of pre-eclampsia. METHODS AND FINDINGS: We used a matched nested case-control design and data from the UK General Practice Research Database to examine the association between maternal infection and pre-eclampsia. Primiparous women aged at least 13 years and registered with a participating practice between January 1987 and October 2007 were eligible for inclusion. We selected all cases of pre-eclampsia and a random sample of primiparous women without pre-eclampsia (controls). Cases (n=1533) were individually matched with up to ten controls (n=14236) on practice and year of delivery. We calculated odds ratios and 95% confidence intervals for pre-eclampsia comparing women exposed and unexposed to infection using multivariable conditional logistic regression. After adjusting for maternal age, pre-gestational hypertension, diabetes, renal disease and multifetal gestation, the odds of pre-eclampsia were increased in women prescribed antibiotic drugs (adjusted odds ratio 1.28;1.14-1.44) and in women with urinary tract infection (adjusted odds ratio 1.22;1.03-1.45). We found no association with maternal respiratory tract infection (adjusted odds ratio 0.91;0.72-1.16). Further adjustment for maternal smoking and pre-pregnancy body mass index made no difference to our findings. CONCLUSIONS: Women who acquire a urinary infection during pregnancy, but not those who have a respiratory infection, are at an increased risk of pre-eclampsia. Maternal antibiotic prescriptions are also associated with an increased risk. Further research is required to elucidate the underlying mechanism of this association and to determine whether, among women who acquire infections in pregnancy, prompt treatment or prophylaxis against infection might reduce the risk of pre-eclampsia