Description of a Murine Model of Pneumocystis Pneumonia.

Pneumocystis pneumonia is a serious lung infection caused by an original ubiquitous fungus with opportunistic behavior, referred to as Pneumocystis jirovecii. P. jirovecii is the second most common fungal agent among invasive fungal infections after Candida spp. Unfortunately, there is still an inability to culture P. jirovecii in vitro, and so a great impairment to improve knowledge on the pathogenesis of Pneumocystis pneumonia. In this context, animal models have a high value to address complex interplay between Pneumocystis and the components of the host immune system. Here, we propose a protocol for a murine model of Pneumocystis pneumonia. Animals become susceptible to Pneumocystis by acquiring an immunocompromised status induced by iterative administration of steroids within drinking water. Thereafter, the experimental infection is completed by an intranasal challenge with homogenates of mouse lungs containing Pneumocystis murina. The onset of clinical signs occurs within 5 weeks following the infectious challenge and immunosuppression can then be withdrawn. At termination, lungs and bronchoalveolar lavage (BAL) fluids from infected mice are analyzed for fungal load (qPCR) and immune response (flow cytometry and biochemical assays). The model is a useful tool in studies focusing on immune responses initiated after the establishment of Pneumocystis pneumonia.

No evidence for systemic low-grade inflammation in adult patients with early-treated phenylketonuria: The INGRAPH study.

The question of an increased cardiovascular risk has been recently raised in adults with phenylketonuria (PKU). As low-grade systemic inflammation increases cardiovascular risk, the INGRAPH study aimed to evaluate low-grade inflammation in adult PKU patients compared to healthy controls and to determine the potential influence of Phe-controlled diet on inflammation. Twenty early-treated adult PKU patients, including a subgroup of 15 classical PKU patients, and 20 healthy volunteers were included. PKU patients and healthy subjects were matched on age, sex and body mass index class. Plasma concentrations of CRP, IFNg, IL1a, IL1b, IL2, IL6, IL10, and TNFα were measured in PKU patients and compared to controls. Plasma CRP was not different in the PKU group as compared to controls. No significant differences were observed between the two groups concerning plasma cytokines concentrations. Plasma CRP and cytokine profile were not different between "on diet" and "off diet" PKU patients. All these results were similar considering only the classical PKU subgroup. No differences were shown in plasma CRP and pro-inflammatory cytokines between adult PKU patients and healthy controls. Further studies are needed, including more patients and extensive characterization of systemic low-grade inflammation, as cardiovascular risk appears to be a new concern in adult PKU population.

Inflammatory mediators, lipoproteins and apolipoproteins in early diagnosis of amyotrophic lateral sclerosis.

There is currently no diagnostic or prognostic biomarker available in clinical practice for Amyotrophic Lateral Sclerosis (ALS). The objective of this study was to monitor a combination of various inflammatory markers, lipids, and apolipoproteins alterations in ALS patients at the time of diagnosis, to assess their role as early diagnostic or prognostic biomarker candidates. C-reactive protein, orosomucoid, prealbumin, calprotectin, lipids and apoliproteins were determined in the blood of all subjects (25 ALS patients, 23 controls) as routinely performed in our laboratory. Inflammatory mediators were evaluated by a bead-based multiplex assay. A two-step approach was used for each analytical strategy: univariate analysis followed by multivariate analysis. Eight features were significantly different between ALS patients and controls, sometimes with important fold changes. The supervised Partial least Squares Discriminant Analysis separated ALS and controls with great accuracy (94 %) and the permutation test was significant (p < 0.01), ensuring the robustness of the model. The prediction model leads to a mean sensitivity and specificity of 90 (+/- 10) and 78 (+/- 10) %, respectively, with a mean predictive positive value and negative predictive value of 80 (+/- 8.9) and 89 (+/- 11.8) %, respectively. However, the models did not discriminate subgroups of ALS patients based on ALS characteristics. This study highlights the usefulness of evaluating a combination of multiple pathways rather than focusing on a single target. These promising results suggest the need for the longitudinal monitoring of these candidates to determine their role in disease evolution.

Regulation and Functions of Protumoral Unconventional T Cells in Solid Tumors.

The vast majority of studies on T cell biology in tumor immunity have focused on peptide-reactive conventional T cells that are restricted to polymorphic major histocompatibility complex molecules. However, emerging evidence indicated that unconventional T cells, including γδ T cells, natural killer T (NKT) cells and mucosal-associated invariant T (MAIT) cells are also involved in tumor immunity. Unconventional T cells span the innate-adaptive continuum and possess the unique ability to rapidly react to nonpeptide antigens via their conserved T cell receptors (TCRs) and/or to activating cytokines to orchestrate many aspects of the immune response. Since unconventional T cell lineages comprise discrete functional subsets, they can mediate both anti- and protumoral activities. Here, we review the current understanding of the functions and regulatory mechanisms of protumoral unconventional T cell subsets in the tumor environment. We also discuss the therapeutic potential of these deleterious subsets in solid cancers and why further feasibility studies are warranted.

Phenotypical and functional alteration of unconventional T cells in severe COVID-19 patients.

COVID-19 includes lung infection ranging from mild pneumonia to life-threatening acute respiratory distress syndrome (ARDS). Dysregulated host immune response in the lung is a key feature in ARDS pathophysiology. However, cellular actors involved in COVID-19-driven ARDS are poorly understood. Here, in blood and airways of severe COVID-19 patients, we serially analyzed unconventional T cells, a heterogeneous class of T lymphocytes (MAIT, γδT, and iNKT cells) with potent antimicrobial and regulatory functions. Circulating unconventional T cells of COVID-19 patients presented with a profound and persistent phenotypic alteration. In the airways, highly activated unconventional T cells were detected, suggesting a potential contribution in the regulation of local inflammation. Finally, expression of the CD69 activation marker on blood iNKT and MAIT cells of COVID-19 patients on admission was predictive of clinical course and disease severity. Thus, COVID-19 patients present with an altered unconventional T cell biology, and further investigations will be required to precisely assess their functions during SARS-CoV-2-driven ARDS.

High Dimensional Single-Cell Analysis Reveals iNKT Cell Developmental Trajectories and Effector Fate Decision.

CD1d-restricted invariant Natural Killer T (iNKT) cells represent a unique class of T lymphocytes endowed with potent regulatory and effector immune functions. Although these functions are acquired during thymic ontogeny, the sequence of events that gives rise to discrete effector subsets remains unclear. Using an unbiased single-cell transcriptomic analysis combined with functional assays, we reveal an unappreciated diversity among thymic iNKT cells, especially among iNKT1 cells. Mathematical modeling and biological methods unravel a developmental map whereby iNKT2 cells constitute a transient branching point toward the generation of iNKT1 and iNKT17 cells, which reconciles the two previously proposed models. In addition, we identify the transcription co-factor Four-and-a-half LIM domains protein 2 (FHL2) as a critical cell-intrinsic regulator of iNKT1 specification. Thus, these data illustrate the changing transcriptional network that guides iNKT cell effector fate.

Interleukin-7 protects against bacterial respiratory infection by promoting IL-17A-producing innate T-cell response.

Interleukin-7 (IL-7) is a critical cytokine in B- and T-lymphocyte development and maturation. Recent evidence suggests that IL-7 is a preferential homeostatic and survival factor for RORγt+ innate T cells such as natural killer T (NKT) cells, γδT cells, and mucosal-associated invariant T (MAIT) cells in the periphery. Given the important contribution of these populations in antibacterial immunity at barrier sites, we questioned whether IL-7 could be instrumental in boosting the local host immune response against respiratory bacterial infection. By using a cytokine-monoclonal antibody approach, we illustrated a role for topical IL-7 delivery in increasing the pool of RORγt+ IL-17A-producing innate T cells. Prophylactic IL-7 treatment prior to Streptococcus pneumoniae infection led to better bacterial containment, a process associated with increased neutrophilia and that depended on γδT cells and IL-17A. Last, combined delivery of IL-7 and α-galactosylceramide (α-GalCer), a potent agonist for invariant NKT (iNKT) cells, conferred an almost total protection in terms of survival, an effect associated with enhanced IL-17 production by innate T cells and neutrophilia. Collectively, we provide a proof of concept that IL-7 enables fine-tuning of innate T- cell functions. This might pave the way for considering IL-7 as an innovative biotherapeutic against bacterial infection.