Natural Th17 cells are critically regulated by functional medullary thymic microenvironments

AbstractThe thymic medulla is critical for the enforcement of central tolerance. In addition to deletion of auto-reactive T-cells, the thymic medulla supports the maturation of heterogeneous natural αβT-cells linked to tolerance mechanisms. Natural IL-17-secreting CD4+αβT-cells (nTh17) represent recently described natural αβT-cells that mature and undergo functional priming intrathymically. Despite a proposed potential to impact upon either protective or pathological inflammatory responses, the intrathymic mechanisms regulating the balance of nTh17 development are unclear. Here we compare the development of distinct natural αβT-cells in the thymus. We reveal that thymic stromal MHC class II expression and RelB-dependent medullary thymic epithelial cells (mTEC), including Aire+ mTEC, are an essential requirement for nTh17 development. nTh17 demonstrate a partial, non-redundant requirement for both ICOS-ligand and CD80/86 costimulation, with a dispensable role for CD80/86 expression by thymic epithelial cells. Although mTEC constitutively expressed inducible nitric oxide synthase (iNOS), a critical negative regulator of conventional Th17 differentiation, iNOS was not essential to constrain thymic nTh17. These findings highlight the critical role of the thymic medulla in the differential regulation of novel natural αβT-cell subsets, and reveal additional layers of thymic medullary regulation of T-cell driven autoimmunity and inflammation

Fibroblastic reticular cells provide a supportive niche for lymph node–resident macrophages

The lymph node (LN) is home to resident macrophage populations that are essential for immune function and homeostasis, but key factors controlling this niche are undefined. Here, we show that fibroblastic reticular cells (FRCs) are an essential component of the LN macrophage niche. Genetic ablation of FRCs caused rapid loss of macrophages and monocytes from LNs across two in vivo models. Macrophages co‐localized with FRCs in human LNs, and murine single‐cell RNA‐sequencing revealed that FRC subsets broadly expressed master macrophage regulator CSF1. Functional assays containing purified FRCs and monocytes showed that CSF1R signaling was sufficient to support macrophage development. These effects were conserved between mouse and human systems. These data indicate an important role for FRCs in maintaining the LN parenchymal macrophage niche

Peripheral lymph nodes contain migratory and resident innate lymphoid cell populations

Tissue residency is considered a defining feature of the innate lymphoid cell (ILC) populations located within mucosal and adipose tissues. ILCs are also present within all lymphoid tissues, but whether ILCs migrate between lymphoid and nonlymphoid sites and in what context is poorly understood. To determine whether migratory ILCs exist within peripheral lymph nodes (LNs), we labeled all cells within the brachial LN (bLN) of transgenic mice expressing a photoconvertible fluorescent protein by direct exposure to light. Tracking of cellular changes in the labeled LN revealed the gradual migration of new ILCs into the tissue, balanced by egress of ILCs dependent on sphingosine-1-phosphate receptors. Most of the migratory ILCs were ILC1s, entering LNs directly from the circulation in a CD62L- and CCR7-dependent manner and thus behaving like conventional natural killer (cNK) cells. Upon egress, both ILC1s and cNK cells were found to recirculate through peripheral LNs. A distinct population of migratory ILC2s were detected in the LN, but most of the ILC3s were tissue resident. Functionally, both migratory and resident ILC1s within LNs were able to rapidly produce IFN-γ to support the generation of robust TH1 T cell responses after immunization. Thus, migratory and resident ILC populations exist within peripheral LNs, with ILC1s, akin to cNK cells, able to traffic into these tissues where they can contribute to the initiation of adaptive immunity

Biliary epithelium and liver B cells exposed to bacteria activate intrahepatic MAIT cells through MR1

Background & AimsMucosal-Associated Invariant T (MAIT) cells are innate-like T cells characterised by the invariant TCR-chain, Vα7.2-Jα33, and are restricted by MR1, which presents bacterial vitamin B metabolites. They are important for antibacterial immunity at mucosal sites; however, detailed characteristics of liver-infiltrating MAIT (LI-MAIT) and their role in biliary immune surveillance remain unexplored.MethodsThe phenotype and intrahepatic localisation of human LI-MAIT cells was examined in diseased and normal livers. MAIT cell activation in response to E. coli-exposed macrophages, biliary epithelial cells (BEC) and liver B cells was assessed with/without anti-MR1.ResultsIntrahepatic MAIT cells predominantly localised to bile ducts in the portal tracts. Consistent with this distribution, they expressed biliary tropic chemokine receptors CCR6, CXCR6, and integrin αEβ7. LI-MAIT cells were also present in the hepatic sinusoids and possessed tissue-homing chemokine receptor CXCR3 and integrins LFA-1 and VLA-4, suggesting their recruitment via hepatic sinusoids. LI-MAIT cells were enriched in the parenchyma of acute liver failure livers compared to chronic diseased livers. LI-MAIT cells had an activated, effector memory phenotype, expressed α4β7 and receptors for IL-12, IL-18, and IL-23. Importantly, in response to E. coli-exposed macrophages, liver B cells and BEC, MAIT cells upregulated IFN-γ and CD40 Ligand and degranulated in an MR1-dependent, cytokine-independent manner. In addition, diseased liver MAIT cells expressed T-bet and RORγt and the cytokines IFN-γ, TNF-α, and IL-17.ConclusionsOur findings provide the first evidence of an immune surveillance effector response for MAIT cells towards BEC in human liver; thus they could be manipulated for treatment of biliary disease in the future

Longitudinal proteomic profiling of dialysis patients with COVID-19 reveals markers of severity and predictors of death

Funder: The Sidharth Burman endowmentEnd-stage kidney disease (ESKD) patients are at high risk of severe COVID-19. We measured 436 circulating proteins in serial blood samples from hospitalised and non-hospitalised ESKD patients with COVID-19 (n = 256 samples from 55 patients). Comparison to 51 non-infected patients revealed 221 differentially expressed proteins, with consistent results in a separate subcohort of 46 COVID-19 patients. Two hundred and three proteins were associated with clinical severity, including IL6, markers of monocyte recruitment (e.g. CCL2, CCL7), neutrophil activation (e.g. proteinase-3), and epithelial injury (e.g. KRT19). Machine-learning identified predictors of severity including IL18BP, CTSD, GDF15, and KRT19. Survival analysis with joint models revealed 69 predictors of death. Longitudinal modelling with linear mixed models uncovered 32 proteins displaying different temporal profiles in severe versus non-severe disease, including integrins and adhesion molecules. These data implicate epithelial damage, innate immune activation, and leucocyte–endothelial interactions in the pathology of severe COVID-19 and provide a resource for identifying drug targets

Ten-year mortality, disease progression, and treatment-related side effects in men with localised prostate cancer from the ProtecT randomised controlled trial according to treatment received

Background The ProtecT trial reported intention-to-treat analysis of men with localised prostate cancer randomly allocated to active monitoring (AM), radical prostatectomy, and external beam radiotherapy. Objective To report outcomes according to treatment received in men in randomised and treatment choice cohorts. Design, setting, and participants This study focuses on secondary care. Men with clinically localised prostate cancer at one of nine UK centres were invited to participate in the treatment trial comparing AM, radical prostatectomy, and radiotherapy. Intervention Two cohorts included 1643 men who agreed to be randomised and 997 who declined randomisation and chose treatment. Outcome measurements and statistical analysis Analysis was carried out to assess mortality, metastasis and progression and health-related quality of life impacts on urinary, bowel, and sexual function using patient-reported outcome measures. Analysis was based on comparisons between groups defined by treatment received for both randomised and treatment choice cohorts in turn, with pooled estimates of intervention effect obtained using meta-analysis. Differences were estimated with adjustment for known prognostic factors using propensity scores. Results and limitations According to treatment received, more men receiving AM died of PCa (AM 1.85%, surgery 0.67%, radiotherapy 0.73%), whilst this difference remained consistent with chance in the randomised cohort (p = 0.08); stronger evidence was found in the exploratory analyses (randomised plus choice cohort) when AM was compared with the combined radical treatment group (p = 0.003). There was also strong evidence that metastasis (AM 5.6%, surgery 2.4%, radiotherapy 2.7%) and disease progression (AM 20.35%, surgery 5.87%, radiotherapy 6.62%) were more common in the AM group. Compared with AM, there were higher risks of sexual dysfunction (95% at 6 mo) and urinary incontinence (55% at 6 mo) after surgery, and of sexual dysfunction (88% at 6 mo) and bowel dysfunction (5% at 6 mo) after radiotherapy. The key limitations are the potential for bias when comparing groups defined by treatment received and changes in the protocol for AM during the lengthy follow-up required in trials of screen-detected PCa. Conclusions Analyses according to treatment received showed increased rates of disease-related events and lower rates of patient-reported harms in men managed by AM compared with men managed by radical treatment, and stronger evidence of greater PCa mortality in the AM group. Patient summary More than 95 out of every 100 men with low or intermediate risk localised prostate cancer do not die of prostate cancer within 10 yr, irrespective of whether treatment is by means of monitoring, surgery, or radiotherapy. Side effects on sexual and bladder function are better after active monitoring, but the risks of spreading of prostate cancer are more common

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]