International audienceThis study investigates the microplastic contamination of both urban compartments (wastewater and total atmospheric fallout) and surface water in a continental environment (Greater Paris, France). These first investigations on urban environment confirm the presence of microplastics in sewage, freshwater and total atmospheric fallout and provide knowledge on the type and size distribution of microplastics in the [100 µm-5 000 µm] range. For the first time, the presence of microplastics, mostly fibers, is highlighted in total atmospheric fallout (29-280 particles/m2/day). High levels of fibers were found in wastewater (260-320 x103 particles/m3). In treated effluent, the contamination significantly decreases to 14-50 x103 particles/m3. In River Seine, two sampling devices are used to collect both large and small microplastic particles: i) a plankton net (80 µm mesh) and ii) a manta trawl (330 µm mesh). Sampling with the plankton net showed a predominance of fibers with concentrations ranging from 3 to 108 particles/m3. A greater diversity of both microplastic shapes and types was encountered during manta trawl sampling but at much lower concentrations (0.28-0.47 particles/m3). This combined approach could be relevant and implemented in future studies to provide an accurate overview of microplastic distribution in freshwater

Melatonin receptors are seven transmembrane-spanning proteins belonging to the GPCR superfamily. In mammals, two melatonin receptor subtypes exist -MT 1 and MT 2 -encoded by the MTNR1A and MTNR1B genes respectively. The current review provides an update on melatonin receptors by the corresponding subcommittee of the International Union of Basic and Clinical Pharmacology. We will highlight recent developments of melatonin receptor ligands, including radioligands, and give an update on the latest phenotyping results of melatonin receptor knockout mice. The current status and perspectives of the structure of melatonin receptor will be summarized. The physiological importance of melatonin receptor dimers and biologically important and type 2 diabetes-associated genetic variants of melatonin receptors will be discussed. The role of melatonin receptors in physiology and disease will be further exemplified by their functions in the immune system and the CNS. Finally, antioxidant and free radical scavenger properties of melatonin and its relation to melatonin receptors will be critically addressed.

Genetic studies have shown that mutations of complement inhibitors such as membrane cofactor protein, Factors H, I, or B and C3 predispose patients to atypical hemolytic uremic syndrome (aHUS). Factor I is a circulating serine protease that inhibits complement by degrading C3b and up to now only a few mutations in the CFI gene have been characterized. In a large cohort of 202 patients with aHUS, we identified 23 patients carrying exonic mutations in CFI. Their overall clinical outcome was unfavorable, as half died or developed end-stage renal disease after their first syndrome episode. Eight patients with CFI mutations carried at least one additional known genetic risk factor for aHUS, such as a mutation in MCP, CFH, C3 or CFB; a compound heterozygous second mutation in CFI; or mutations in both the MCP and CFH genes. Five patients exhibited homozygous deletion of the Factor H-related protein 1 (CFHR-1) gene. Ten patients with aHUS had one mutation in their CFI gene (Factor I-aHUS), resulting in a quantitative or functional Factor I deficiency. Patients with a complete deletion of the CFHR-1 gene had a significantly higher risk of a bad prognosis compared with those with one Factor I mutation as their unique vulnerability feature. Our results emphasize the necessity of genetic screening for all susceptibility factors in patients with aHUS.

No abstract

Since the discovery in 1995 of α-galactosylceramide 1 (α-GalCer), also known as KRN7000,1 hundreds of compounds have been synthesized in order to activate invariant natural killer T (iNKT) cells. Such keen interest for this lymphocyte cell type is due to its ability to produce different cytokines that bias the immune response toward a Th1 or Th2 profile. Thus, an understanding of the immune polarization mechanism via iNKT activation may pave the way toward new therapeutics in various domains including cancer and infectious and autoimmune diseases. In this review, we propose an up-to-date analysis of iNKT activators associated with a structure-activity relationship (SAR) study aimed at complementing available reviews by highlighting molecular bases for a selective immune response.

Background and purpose: For many years, it was suspected that sheep expressed only one melatonin receptor (closely resembling MT1 from other mammal species). Here we report the cloning of another melatonin receptor, MT2, from sheep. Experimental approach: Using a thermo-resistant reverse transcriptase and polymerase chain reaction primer set homologous to the bovine MT2 mRNA sequence, we have cloned and characterized MT2 receptors from sheep retina. Key results: The ovine MT2 receptor presents 96%, 72% and 67% identity with cattle, human and rat respectively. This MT2 receptor stably expressed in CHO-K1 cells showed high-affinity 2[ 125 I]-iodomelatonin binding (KD = 0.04 nM). The rank order of inhibition of 2[ 125 I]-iodomelatonin binding by melatonin, 4-phenyl-2-propionamidotetralin and luzindole was similar to that exhibited by MT2 receptors of other species (melatonin > 4-phenyl-2-propionamidotetralin > luzindole). However, its pharmacological profile was closer to that of rat, rather than human MT2 receptors. Functionally, the ovine MT2 receptors were coupled to Gi proteins leading to inhibition of adenylyl cyclase, as the other melatonin receptors. In sheep brain, MT2 mRNA was expressed in pars tuberalis, choroid plexus and retina, and moderately in mammillary bodies. Real-time polymerase chain reaction showed that in sheep pars tuberalis, premammillary hypothalamus and mammillary bodies, the temporal pattern of expression of MT1 and MT2 mRNA was not parallel in the three tissues. Conclusion and implications: Co-expression of MT1 and MT2 receptors in all analysed sheep brain tissues suggests that MT2 receptors may participate in melatonin regulation of seasonal anovulatory activity in ewes by modulating MT1 receptor action.

Complete deficiency of complement inhibitor factor I (FI) results in secondary complement deficiency due to uncontrolled spontaneous alternative pathway activation leading to susceptibility to infections. Current genetic examination of two patients with near complete FI deficiency and three patients with no detectable serum FI and also close family members revealed homozygous or compound heterozygous mutations in several domains of FI. These mutations were introduced into recombinant FI and the resulting proteins were purified for functional studies, while transient transfection was used to analyze expression and secretion. The G170V mutation resulted in a protein that was not expressed, whereas the mutations Q232K, C237Y, S250L, I339M and H400L affected secretion. Furthermore, the C237Y and the S250L mutants did not degrade C4b and C3b as efficiently as the WT. The truncated Q336x mutant could be expressed, in vitro, but was not functional because it lacks the serine protease domain. Furthermore, this truncated FI was not detected in serum of the patient. Structural investigations using molecular modeling were performed to predict the potential impact the mutations have on FI structure. This is the first study that investigates, at the functional level, the consequences of molecular defects identified in patients with full FI deficiency.Key words: Complement . Factor I . Human . Immunodeficiency disease IntroductionThe complement system is a very powerful enzymatic cascade, which is beneficial when activated in response to foreign pathogens, but can be destructive when self-tissues give rise to activation. Therefore, the body is equipped with membrane-bound and soluble complement inhibitors, many of which inhibit complement by acting as cofactors for the serine proteinase factor I (FI). In the presence of cofactors, FI inhibits all pathways of complement by degrading the a 0 -chain of the activated complement components C4b and C3b.Several cases of near complete FI deficiencies have been reported and were found to lead to systemic consumption of C3, 310factor H (FH) and factor B (FB) due to uninhibited activation of the alternative pathway. Because of this consumption, opsonization with C3b cannot occur and patients are much more susceptible to recurrent pyogenic infections, such as otitis media, pneumonia and meningitis [1][2][3][4]. There have also been reports of FI-deficient patients who suffer from glomerulonephritis [5] or systemic lupus erythematosus (SLE) [6]. To date, only three studies have identified a molecular defect in FI at the DNA level in patients with a full FI deficiency [7][8][9]. The remainder of the literature comprises reports of clinical presentation [1-6, 10, 11]. The mutant FI proteins in question have not yet been expressed in a recombinant form and therefore there is no information available concerning the effects of these mutations on FI secretion and function. Mutations in FI have also been identified in atypical hemolytic uremic syndrome (aHUS) patients, where they always occur i...

Only a subpopulation of non-small cell lung cancer (NSCLC) patients responds to immunotherapies, highlighting the urgent need to develop therapeutic strategies to improve patient outcome. We develop a chemical positive modulator (HEI3090) of the purinergic P2RX7 receptor that potentiates αPD-1 treatment to effectively control the growth of lung tumors in transplantable and oncogene-induced mouse models and triggers long lasting antitumor immune responses. Mechanistically, the molecule stimulates dendritic P2RX7-expressing cells to generate IL-18 which leads to the production of IFN-γ by Natural Killer and CD4+ T cells within tumors. Combined with immune checkpoint inhibitor, the molecule induces a complete tumor regression in 80% of LLC tumor-bearing mice. Cured mice are also protected against tumor re-challenge due to a CD8-dependent protective response. Hence, combination treatment of small-molecule P2RX7 activator followed by immune checkpoint inhibitor represents a strategy that may be active against NSCLC.