Conditional ablation of NKp46+ cells using a novel Ncr1greenCre mouse strain: NK cells are essential for protection against pulmonary B16 metastases

To study gene functions specifically in NKp46⁺ cells we developed novel Cre mice allowing for conditional gene targeting in cells expressing Ncr1 (encoding NKp46). We generated transgenic Ncr1^greenCre mice carrying an EGFPcre fusion under the control of a proximal Ncr1 promoter that faithfully directed EGFPcre expression to NKp46⁺ cells from lymphoid and nonlymphoid tissues. This approach allowed for direct detection of Cre‐expressing NKp46⁺ cells via their GFP signature by flow cytometry and histology. Cre was functional as evidenced by the NKp46⁺ cell‐specific expression of RFP in Ncr1^greenCreRosa‐dtRFP reporter mice. We generated Ncr1^greenCreIl2rg^fl/fl mice that lack NKp46⁺ cells in an otherwise intact hematopoietic environment. Il2rg encodes the common gamma chain (γ_c), which is an essential receptor subunit for cytokines (IL‐2, ‐4, ‐7, ‐9, ‐15, and ‐21) that stimulate lymphocyte development and function. In Ncr1^greenCreIl2rg^fl/fl mice, NK cells are severely reduced and the few remaining NKp46⁺ cells escaping γc deletion failed to express GFP. Using this new NK‐cell‐deficient model, we demonstrate that the homeostasis of NKp46⁺ cells from all tissues (including the recently described intraepithelial ILC1 subset) requires Il2rg. Finally, Ncr1^greenCreIl2rg^fl/fl mice are unable to reject B16 lung metastases demonstrating the essential role of NKp46⁺ cells in antimelanoma immune responses.     

IL-36R ligands are potent regulators of dendritic and T cells

IL-36α (IL-1F6), IL-36β (IL-1F8), and IL-36γ (IL-1F9) are members of the IL-1 family of cytokines. These cytokines bind to IL-36R (IL-1Rrp2) and IL-1RAcP, activating similar intracellular signals as IL-1, whereas IL-36Ra (IL-1F5) acts as an IL-36R antagonist (IL-36Ra). In this study, we show that both murine bone marrow-derived dendritic cells (BMDCs) and CD4(+) T lymphocytes constitutively express IL-36R and respond to IL-36α, IL-36β, and IL-36γ. IL-36 induced the production of proinflammatory cytokines, including IL-12, IL-1β, IL-6, TNF-α, and IL-23 by BMDCs with a more potent stimulatory effect than that of other IL-1 cytokines. In addition, IL-36β enhanced the expression of CD80, CD86, and MHC class II by BMDCs. IL-36 also induced the production of IFN-γ, IL-4, and IL-17 by CD4(+) T cells and cultured splenocytes. These stimulatory effects were antagonized by IL-36Ra when used in 100- to 1000-fold molar excess. The immunization of mice with IL-36β significantly and specifically promoted Th1 responses. Our data thus indicate a critical role of IL-36R ligands in the interface between innate and adaptive immunity, leading to the stimulation of T helper responses.     

Bone microarchitecture is more severely affected in patients on hemodialysis than in those receiving peritoneal dialysis

We used high-resolution quantitative computed tomography to study the microarchitecture of bone in patients with chronic kidney disease on dialysis. We compared bone characteristics in 56 maintenance hemodialysis (21 women, 14 post-menopausal) and 23 peritoneal dialysis patients (9 women, 6 post-menopausal) to 79 healthy men and women from two cohorts matched for age, body mass index, gender, and menopausal status. All underwent dual-energy X-ray absorptiometry of the spine and hip to measure areal bone mineral density, and high-resolution peripheral quantitative computed tomography of the radius and tibia to measure volumetric bone mineral density and microarchitecture. When compared to their matched healthy controls, patients receiving hemodialysis and peritoneal dialysis had a significantly lower areal bone mineral density in the hip. Hemodialysis patients had significantly lower total, cortical, and trabecular volumetric bone mineral density at both sites. Hemodialysis patients had significantly lower trabecular volumetric bone mineral density and microarchitecture at the tibia than the peritoneal dialysis patients. Overall, peritoneal dialysis patients were less affected, their cortical thickness at the distal tibia being the only significant difference versus controls. Thus, we found more severe trabecular damage at the weight-bearing tibia in hemodialysis compared to peritoneal dialysis patients, but this latter finding needs confirmation in larger cohorts.     

Performances,feasibility and acceptability of nasopharyngeal swab,saliva and oral-self sampling swab for the detection of severe acute respiratory syndrome coronavirus 2

European Journal of Clinical Microbiology & Infectious Diseases - Molecular diagnosis on nasopharyngeal swabs (NPS) is the current standard for COVID-19 diagnosis, but saliva may be an...     

Interaction of macrocyclic lactones with P-glycoprotein: structure-affinity relationship.

P-glycoprotein (P-gp) is involved in the ATP-dependant cellular efflux of a large number of drugs including ivermectin, a macrocyclic lactone (ML) endectocide, widely used in livestock and human antiparasitic therapy. The interactions of P-gp with ivermectin and other MLs were studied. In a first approach, the ability of ivermectin (IVM), eprinomectin (EPR), abamectin (ABA), doramectin (DOR), selamectin (SEL), or moxidectin (MOX) to inhibit the rhodamine123 efflux was measured in recombinant cells overexpressing P-gp. Then, the influence of these compounds on the P-gp ATPase activity was tested on membrane vesicles prepared from fibroblasts overexpressing P-gp. All the MLs tested increased the intracellular rhodamine123. However, the potency of MOX to inhibit P-gp function was 10 times lower than the other MLs. They all inhibited the basal and decreased the verapamil-stimulated P-gp ATPase activity. But SEL and MOX were less potent than the other MLs when competing with verapamil. According to the structural specificity of SEL and MOX, we conclude that the integrity of the sugar moiety is determinant to achieve the optimal interaction of macrocyclic lactones with P-gp. The structure-affinity relationship for interaction with P-gp is important information for improving ML bioavailability and reversal of multidrug resistance (MDR).     

Secular trends in nosocomial infections and mortality associated with noninvasive ventilation in patients with exacerbation of COPD and pulmonary edema

Context  Randomized controlled trials have shown that the use of noninvasive ventilation (NIV) reduces the need for endotracheal intubation and invasive mechanical ventilation and reduces complication rates and mortality in selected groups of patients. But whether these benefits translate to a clinical setting is unclear. Objective  To evaluate longitudinally the routine implementation of NIV and its effect on patients admitted to the intensive care unit (ICU) with acute exacerbation of chronic obstructive pulmonary disease (COPD) or severe cardiogenic pulmonary edema (CPE). Design  Retrospective, observational cohort study using prospectively collected data from January 1, 1994, through December 31, 2001. Setting  A 26-bed medical intensive care unit (ICU) of a French university referral hospital. Participants  A cohort of 479 consecutive patients ventilated for acute exacerbation of COPD or CPE. Main Outcome Measures  The ICU mortality and incidence rates of ICU-acquired infections. Results  A significant increase in NIV use and a concomitant decrease in mortality and ICU-acquired infection rates were observed over the study years. With adjustment for relevant covariates and propensity scores, NIV was identified as an independent factor linked with a reduced risk of death in the cohort (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.18-0.78), whereas a high severity score on admission (OR, 1.05; 95% CI, 1.01-1.10) and the occurrence of a nosocomial infection (OR, 3.08; 95% CI, 1.62-5.84) were independently associated with death. Rates of ICU-acquired pneumonia decreased from 20% in 1994 to 8% in 2001 (P = .04). Conclusion  Implementing routine use of NIV in critically ill patients with acute exacerbation of COPD or severe CPE was associated with improved survival and reduction of nosocomial infections.