Human inborn errors of immunity mediated by the cytokines interleukin (IL)-17A/F underlie mucocutaneous candidiasis, whereas inborn errors of interferon (IFN)-γ immunity underlie mycobacterial disease. We report the discovery of bi-allelic RORC loss-of-function mutations in seven individuals from three kindreds of different ethnic origins with both candidiasis and mycobacteriosis. The lack of functional RORγ and RORγT isoforms resulted in the absence of IL-17A/F-producing T cells in these individuals, probably accounting for their chronic candidiasis. Unexpectedly, leukocytes from RORγ- and RORγT-deficient individuals also displayed an impaired IFN-γ response to Mycobacterium. This principally reflected profoundly defective IFN-γ production by circulating γδ T cells and CD4+CCR6+ CXCR3+ αβ T cells. In humans, both mucocutaneous immunity to Candida and systemic immunity to Mycobacterium require RORγ, or RORγT, or both.

Background T follicular helper (Tfh) cells underpin T-cell dependent humoral immunity and the success of most vaccines. Tfh cells also contribute to human immune disorders such as autoimmunity, immunodeficiency and malignancy. Understanding the molecular requirements for the generation and function of Tfh cells will provide strategies for targeting these cells to modulate their behavior in the setting of these immunological abnormalities. Objective To determine the signaling pathways and cellular interactions required for the development and function of Tfh cells in humans. Methods Human primary immunodeficiencies (PIDs) resulting from monogenic mutations provide a unique opportunity to assess the requirement for particular molecules in regulating human lymphocyte function. Circulating Tfh (cTfh) cell subsets, memory B cells and serum Ig levels were quantified and functionally assessed in healthy controls as well as patients with PIDs resulting from mutations in STAT3, STAT1, TYK2, IL21, IL21R, IL10R, IFNGR1/2, IL12RB1, CD40LG, NEMO, ICOS or BTK. Results Loss-of function (LOF) mutations in STAT3, IL10R, CD40LG, NEMO, ICOS or BTK reduced cTfh frequencies. STAT3, IL21/R LOF and STAT1 gain-of function mutations skewed cTfh differentiation towards a phenotype characterized by over-expression of IFNγ and programmed death -1 (PD-1). IFNγ inhibited cTfh function in vitro and in vivo, corroborated by hypergammaglobulinemia in patients with IFNGR1/2, STAT1 and IL12RB1 LOF mutations. Conclusion Specific mutations impact the quantity and quality of cTfh cells, highlighting the need to assess Tfh cells in patients by multiple criteria, including phenotype and function. Furthermore, IFNγ functions in vivo to restrain Tfh-induced B cell differentiation. These findings shed new light on Tfh biology and the integrated signaling pathways required for their generation, maintenance and effector function, and explain compromised humoral immunity in some PIDs.

Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia, especially in southern China. One of the most striking features of this disease is its close relationship with Epstein-Barr Virus (EBV). However, to date there is no direct study on the mechanisms involved in the role of EBV in the tumorigenesis of NPC, largely due to lack of an experimental model. Available hypotheses on the association between EBV and NPC are generated from non-nasopharyngeal epithelial cell systems such as human keratinocytes or mouse epithelial cells, which may not truly represent the biological properties of nasopharyngeal epithelial (NP) cells. In this study, we report the establishment of two immortalized NP cell lines, NP69SV40T and NP39E6/E7, using SV40T and HPV16E6/E7 oncogenes. We found that NP60SV40T and NP39E6/E7 cell lines not only maintained many characteristics of normal NP cells (i.e. keratin profile and responsive to TGFbeta inhibition) but also highly responsive to one of the EBV encoded genes, LMP1. Comparative genome hybridization (CGH) analysis showed that these two cell lines contained multiple genetic alterations, some of which have been described in NPC. The immortalized NP cell lines are non-tumorigenic and exhibit anchorage-dependent growth. These cell lines may provide a possible cell model system for studying the mechanisms involved in the tumorigenesis of NPC.

Hundreds of patients with autosomal recessive, complete IL-12p40 or IL-12Rβ1 deficiency have been diagnosed over the last 20 years. They typically suffer from invasive mycobacteriosis and, occasionally, from mucocutaneous candidiasis. Susceptibility to these infections is thought to be due to impairments of IL-12-dependent IFN-γ immunity, and IL-23-dependent IL-17A/IL-17F immunity, respectively. We report here patients with autosomal recessive, complete IL-12Rβ2 or IL-23R deficiency, lacking responses to IL-12 or IL-23 only, all of whom, surprisingly, display mycobacteriosis without candidiasis. We show that αβ T, γδ T, B, NK, ILC1, and ILC2 cells from healthy donors preferentially produce IFN-γ in response to IL-12, whereas NKT, MAIT, and ILC3 cells preferentially produce IFN-γ in response to IL-23. We also show that the development of IFN-γ- producing CD4+ T cells, including, in particular, mycobacterium-specific Th1* cells (CD45RA-CCR6+), is dependent on both IL-12 and IL-23. Finally, we show that IL12RB1, IL12RB2, and IL23R have similar frequencies of deleterious variants in the general population. The comparative rarity of symptomatic patients with IL-12Rβ2 or IL-23R deficiency, relative to IL-12Rβ1 deficiency, is, therefore, due to lower clinical penetrance. These experiments of Nature show that human IL-12 and IL-23 are both crucial for IFN-γ- dependent immunity to mycobacteria, both individually and much more so cooperatively.

Tangye and collaborators use a series of mutants to elucidate the pathways required to generate distinct subsets of human effector CD4+ T cells.

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Consensus was achieved to direct training curriculum, oversight, quality assurance and maintenance of competence for critical care ultrasound. In providing the first national guideline of its kind, these Canadian recommendations may also serve as a model of critical care ultrasound dissemination for other countries.

Background Microglia are active modulators of Alzheimer’s disease but their role in relation to amyloid plaques and synaptic changes due to rising amyloid beta is unclear. We add novel findings concerning these relationships and investigate which of our previously reported results from transgenic mice can be validated in knock-in mice, in which overexpression and other artefacts of transgenic technology are avoided. Methods AppNL-F and AppNL-G-F knock-in mice expressing humanised amyloid beta with mutations in App that cause familial Alzheimer’s disease were compared to wild type mice throughout life. In vitro approaches were used to understand microglial alterations at the genetic and protein levels and synaptic function and plasticity in CA1 hippocampal neurones, each in relationship to both age and stage of amyloid beta pathology. The contribution of microglia to neuronal function was further investigated by ablating microglia with CSF1R inhibitor PLX5622. Results Both App knock-in lines showed increased glutamate release probability prior to detection of plaques. Consistent with results in transgenic mice, this persisted throughout life in AppNL-F mice but was not evident in AppNL-G-F with sparse plaques. Unlike transgenic mice, loss of spontaneous excitatory activity only occurred at the latest stages, while no change could be detected in spontaneous inhibitory synaptic transmission or magnitude of long-term potentiation. Also, in contrast to transgenic mice, the microglial response in both App knock-in lines was delayed until a moderate plaque load developed. Surviving PLX5266-depleted microglia tended to be CD68-positive. Partial microglial ablation led to aged but not young wild type animals mimicking the increased glutamate release probability in App knock-ins and exacerbated the App knock-in phenotype. Complete ablation was less effective in altering synaptic function, while neither treatment altered plaque load. Conclusions Increased glutamate release probability is similar across knock-in and transgenic mouse models of Alzheimer’s disease, likely reflecting acute physiological effects of soluble amyloid beta. Microglia respond later to increased amyloid beta levels by proliferating and upregulating Cd68 and Trem2. Partial depletion of microglia suggests that, in wild type mice, alteration of surviving phagocytic microglia, rather than microglial loss, drives age-dependent effects on glutamate release that become exacerbated in Alzheimer’s disease.