Loss of Sour Taste Is the Striking Feature among Four Basic Taste Qualities in Tunisian COVID-19 Patients.

BACKGROUND: Taste disorders (TDs) have been reported to be very common in patients suffering from coronavirus disease 2019 (COVID-19), which is caused by the SARS-CoV-2 virus. In most of the hitherto conducted studies, a gustatory assessment was performed on the basis of surveys or self-reports by patients. The aim of our study was to undertake an objective assessment of four basic taste qualities by conducting tasting sessions that allowed detection thresholds in COVID-19 Tunisian patients and to study their associations with inflammation. METHODS: This analytical cross-sectional study was conducted on 89 patients aged between 21 to 70 years who had been diagnosed with COVID-19. We used Burghart taste strips to assess taste perception of the four taste qualities, i.e., sour, bitter, sweet, and salty. Serum levels of interleukin-1ß (IL-1ß), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and C-reactive protein (CRP) were measured. RESULTS: Taste disorders were reported by 40.4% of the patients, while objective assessments revealed that 63.8% of participants were suffering from hypogeusia and/or ageusia. Sour taste was the most altered (70.8%) gustatory quality. Patients with severe COVID-19 had significantly lower sour and bitter taste scores when compared to patients with minor/moderate forms. There was no significant association between serum inflammatory markers and taste disorders. However, the relationship between bitter and sweet taste qualities and IL-1ß levels was significant (p = 0.018 and p = 0.041). CONCLUSIONS: Our results demonstrate the interest in the objective assessment of taste dysfunctions in COVID-19 patients.

A place for neutrophils in the beneficial pathogen-agnostic effects of the BCG vaccine.

The BCG vaccine has long been recognized for reducing the risk to suffer from infectious diseases unrelated to its target disease, tuberculosis. Evidence from human trials demonstrate substantial reductions in all-cause mortality, especially in the first week of life. Observational studies have identified an association between BCG vaccination and reduced risk of respiratory infectious disease and clinical malaria later in childhood. The mechanistic basis for these pathogen-agnostic benefits, also known as beneficial non-specific effects (NSE) of BCG have been attributed to trained immunity, or epigenetic reprogramming of hematopoietic cells that give rise to innate immune cells responding more efficiently to a broad range of pathogens. Furthermore, within trained immunity, the focus so far has been on enhanced monocyte function. However, polymorphonuclear cells, namely neutrophils, are not only major constituents of the hematopoietic compartment but functionally as well as numerically represent a prominent component of the immune system. The beneficial NSEs of the BCG vaccine on newborn sepsis was recently demonstrated to be driven by a BCG-mediated numeric increase of neutrophils (emergency granulopoiesis (EG)). And experimental evidence in animal models suggest that BCG can modulate neutrophil function as well. Together, these findings suggest that neutrophils are crucial to at least the immediate beneficial NSE of the BCG vaccine. Efforts to uncover the full gamut of mechanisms underpinning the broad beneficial effects of BCG should therefore include neutrophils at the forefront.

Clinical Protocol for a Longitudinal Cohort Study Employing Systems Biology to Identify Markers of Vaccine Immunogenicity in Newborn Infants in The Gambia and Papua New Guinea.

Background: Infection contributes to significant morbidity and mortality particularly in the very young and in low- and middle-income countries. While vaccines are a highly cost-effective tool against infectious disease little is known regarding the cellular and molecular pathways by which vaccines induce protection at an early age. Immunity is distinct in early life and greater precision is required in our understanding of mechanisms of early life protection to inform development of new pediatric vaccines. Methods and Analysis: We will apply transcriptomic, proteomic, metabolomic, multiplex cytokine/chemokine, adenosine deaminase, and flow cytometry immune cell phenotyping to delineate early cellular and molecular signatures that correspond to vaccine immunogenicity. This approach will be applied to a neonatal cohort in The Gambia (N ~ 720) receiving at birth: (1) Hepatitis B (HepB) vaccine alone, (2) Bacille Calmette Guerin (BCG) vaccine alone, or (3) HepB and BCG vaccines, (4) HepB and BCG vaccines delayed till day 10 at the latest. Each study participant will have a baseline peripheral blood sample drawn at DOL0 and a second blood sample at DOL1,-3, or-7 as well as late timepoints to assess HepB vaccine immunogenicity. Blood will be fractionated via a "small sample big data" standard operating procedure that enables multiple downstream systems biology assays. We will apply both univariate and multivariate frameworks and multi-OMIC data integration to identify features associated with anti-Hepatitis B (anti-HB) titer, an established correlate of protection. Cord blood sample collection from a subset of participants will enable human in vitro modeling to test mechanistic hypotheses identified in silico regarding vaccine action. Maternal anti-HB titer and the infant microbiome will also be correlated with our findings which will be validated in a smaller cohort in Papua New Guinea (N ~ 80). Ethics and Dissemination: The study has been approved by The Gambia Government/MRCG Joint Ethics Committee and The Boston Children's Hospital Institutional Review Board. Ethics review is ongoing with the Papua New Guinea Medical Research Advisory Committee. All de-identified data will be uploaded to public repositories following submission of study output for publication. Feedback meetings will be organized to disseminate output to the study communities. Clinical Trial Registration: Clinicaltrials.gov Registration Number: NCT03246230.

Malt1 deficient mice develop osteoporosis independent of osteoclast-intrinsic effects of Malt1 deficiency.

This study tested the hypothesis that mucosa associated lymphoid tissue 1 (Malt1) deficiency causes osteoporosis in mice by increasing osteoclastogenesis and osteoclast activity. A patient with combined immunodeficiency (CID) caused by MALT1 deficiency had low bone mineral density resulting in multiple low impact fractures that was corrected by hematopoietic stem cell transplant (HSCT). We have reported that Malt1 deficient Mϕs, another myeloid cell type, are hyper-responsive to inflammatory stimuli. Our objectives were to determine whether Malt1 deficient mice develop an osteoporosis-like phenotype and whether it was caused by Malt1 deficiency in osteoclasts. We found that Malt1 deficient mice had low bone volume by 12 weeks of age, which was primarily associated with reduced trabecular bone. Malt1 protein is expressed and active in osteoclasts and is induced by receptor activator of NF-κB ligand (RANKL) in preosteoclasts. Malt1 deficiency did not impact osteoclast differentiation or activity in vitro. However, Malt1 deficient (Malt1-/- ) mice had more osteoclasts in vivo and had lower levels of serum osteoprotegerin (OPG), an endogenous inhibitor of osteoclastogenesis. Inhibition of Malt1 activity in Mϕs induced MCSF production, required for osteoclastogenesis, and decreased OPG production in response to inflammatory stimuli. In vitro, MCSF increased and OPG inhibited osteoclastogenesis, but effects were not enhanced in Malt1 deficient osteoclasts. These data support the hypothesis that Malt1 deficient mice develop an osteoporotic phenotype with increased osteoclastogenesis in vivo, but suggest that this is caused by inflammation rather than an effect of Malt1 deficiency in osteoclasts.

Leishmania-mediated inhibition of iron export promotes parasite replication in macrophages.

Leishmania parasites infect macrophages, cells that play an important role in organismal iron homeostasis. By expressing ferroportin, a membrane protein specialized in iron export, macrophages release iron stored intracellularly into the circulation. Iron is essential for the intracellular replication of Leishmania, but how the parasites compete with the iron export function of their host cell is unknown. Here, we show that infection with Leishmania amazonensis inhibits ferroportin expression in macrophages. In a TLR4-dependent manner, infected macrophages upregulated transcription of hepcidin, a peptide hormone that triggers ferroportin degradation. Parasite replication was inhibited in hepcidin-deficient macrophages and in wild type macrophages overexpressing mutant ferroportin that is resistant to hepcidin-induced degradation. Conversely, intracellular growth was enhanced by exogenously added hepcidin, or by expression of dominant-negative ferroportin. Importantly, dominant-negative ferroportin and macrophages from flatiron mice, a mouse model for human type IV hereditary hemochromatosis, restored the infectivity of mutant parasite strains defective in iron acquisition. Thus, inhibition of ferroportin expression is a specific strategy used by L. amazonensis to inhibit iron export and promote their own intracellular growth.

Comparative analysis of resistant and susceptible macrophage gene expression response to Leishmania major parasite.

BACKGROUND: Leishmania are obligated intracellular pathogens that replicate almost exclusively in macrophages. The outcome of infection depends largely on parasite pathogenicity and virulence but also on the activation status and genetic background of macrophages. Animal models are essential for a better understanding of pathogenesis of different microbes including Leishmania. RESULTS: Here we compared the transcriptional signatures of resistant (C57BL/6) and susceptible (BALB/c) mouse bone marrow-derived macrophages in response to Leishmania major (L. major) promastigotes infection.Microarray results were first analyzed for significant pathways using the Kyoto Encylopedia of Genes and Genomes (KEGG) database. The analysis revealed that a large set of the shared genes is involved in the immune response and that difference in the expression level of some chemokines and chemokine receptors could partially explain differences in resistance. We next focused on up-regulated genes unique to either BALB/c or C57BL/6 derived macrophages and identified, using KEGG database, signal transduction pathways among the most relevant pathways unique to both susceptible and resistant derived macrophages. Indeed, genes unique to C57BL/6 BMdMs were associated with target of rapamycin (mTOR) signaling pathway while a range of genes unique to BALB/c BMdMs, belong to p53 signaling pathway. We next investigated whether, in a given mice strain derived macrophages, the different up-regulated unique genes could be coordinately regulated. Using GeneMapp Cytoscape, we showed that the induced genes unique to BALB/c or C57BL/6 BMdMs are interconnected. Finally, we examined whether the induced pathways unique to BALB/c derived macrophages interfere with the ones unique to C57BL/6 derived macrophages. Protein-protein interaction analysis using String database highlights the existence of a cross-talk between p53 and mTOR signaling pathways respectively specific to susceptible and resistant BMdMs. CONCLUSIONS: Taken together our results suggest that strains specific pathogenesis may be due to a difference in the magnitude of the same pathways and/or to differentially expressed pathways in the two mouse strains derived macrophages. We identify signal transduction pathways among the most relevant pathways modulated by L. major infection, unique to BALB/c and C57BL/6 BMdM and postulate that the interplay between these potentially interconnected pathways could direct the macrophage response toward a given phenotype.

Transcriptomic signature of Leishmania infected mice macrophages: a metabolic point of view.

We analyzed the transcriptional signatures of mouse bone marrow-derived macrophages at different times after infection with promastigotes of the protozoan parasite Leishmania major. Ingenuity Pathway Analysis revealed that the macrophage metabolic pathways including carbohydrate and lipid metabolisms were among the most altered pathways at later time points of infection. Indeed, L. major promastiogtes induced increased mRNA levels of the glucose transporter and almost all of the genes associated with glycolysis and lactate dehydrogenase, suggesting a shift to anaerobic glycolysis. On the other hand, L. major promastigotes enhanced the expression of scavenger receptors involved in the uptake of Low-Density Lipoprotein (LDL), inhibited the expression of genes coding for proteins regulating cholesterol efflux, and induced the synthesis of triacylglycerides. These data suggested that Leishmania infection disturbs cholesterol and triglycerides homeostasis and may lead to cholesterol accumulation and foam cell formation. Using Filipin and Bodipy staining, we showed cholesterol and triglycerides accumulation in infected macrophages. Moreover, Bodipy-positive lipid droplets accumulated in close proximity to parasitophorous vacuoles, suggesting that intracellular L. major may take advantage of these organelles as high-energy substrate sources. While the effect of infection on cholesterol accumulation and lipid droplet formation was independent on parasite development, our data indicate that anaerobic glycolysis is actively induced by L. major during the establishment of infection.

Leishmania major parasites induced macrophage tolerance: implication of MAPK and NF-kappaB pathways.

During infection pathogens elicit early inflammatory events and modulate mediators of the host inflammatory response. We show in the present study that the two stages of the Leishmania parasite differentially modulate the production of inflammatory cytokines with amastigotes inducing cytokine production but not promastigotes. However once they infect macrophages both stages were able to induce a state of tolerance characterized by the inhibition of TNFalpha production in response to a subsequent contact with the parasite. This effect was not due to the action of soluble deactivating cytokines released in the supernatant, but likely reflect direct cell-parasite interactions. Moreover, we show that parasite viability is required for macrophage tolerisation. Cross-stimulation experiments using two stimuli namely Leishmania and LPS, demonstrated a hierarchy of signalling with LPS mediating abrogation of Leishmania tolerance but not vice versa. Indeed, while LPS was able to overcome Leishmania induced tolerance LPS induced cell tolerance was refractory to subsequent Leishmania stimulation. This state of tolerance correlates with the hypo responsiveness of MAPK transduction pathways and defective activation of NF-kappaB transcription factor.

Leishmania initially activates but subsequently down-regulates intracellular mitogen-activated protein kinases and nuclear factor-kappaB signaling in macrophages.

The complex interactions between Leishmania and macrophages are central to the outcome of parasite infection. Disrupting signaling molecules to impair macrophage function, is a subversive strategy used by several pathogens. In the present study, we show that the initial contact of Leishmania with human naïves macrophages and murine Raw264.7 macrophage cell line induced a rapid and transient activation of extracellular-signal-regulated kinases 1 and 2 (ERK1/2) and p38MAPK. This activation is an actin-dependent mechanism that requires internalization of live parasites. Once stably infected, macrophages become unresponsive to subsequent parasite infection. Priming of cells with IFNgamma, prior to Leishmania infection, did not prevent the silencing of MAPKs pathways induced by Leishmania parasites. NF-kappaB transcriptional activity in response to Leishmania infection is also impaired in stably infected cells. This impairment was not due to MAPK deactivation as inhibition of ERK1/2 and p38MAPK, actually enhances the transcriptional activity of NF-kappaB in response to initial contact of Leishmania with the murine macrophagic cell line Raw264.7. Moreover, Leishmania parasites could not reverse the hyporesponsive state induced by LPS. These effects do not reflect a general down-regulation of macrophages signaling by parasites, as cells with established Leishmania infection display normal response to PMA. In addition we show that the mechanisms of Leishmania-induced hyporesponsive state is not due to the induction of a cellular tyrosine phosphatase activity as previously reported in LPS treated cells.