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Having previously shown that soluble E-cadherin (sE-cad) is found in sera of Q fever patients and that infection of BeWo cells by C. burnetii leads to modulation of the E-cad/β-cat pathway, our purpose was to identify which sheddase(s) might catalyze the cleavage of E-cad. Here, we searched for a direct mechanism of cleavage initiated by the bacterium itself, assuming the possible synthesis of a sheddase encoded in the genome of C. burnetii or an indirect mechanism based on the activation of a human sheddase. Using a straightforward bioinformatics approach to scan the complete genomes of four laboratory strains of C. burnetii, we demonstrate that C. burnetii encodes a 451 amino acid sheddase (CbHtrA) belonging to the HtrA family that is differently expressed according to the bacterial virulence. An artificial CbHtrA gene (CoxbHtrA) was expressed, and the CoxbHtrA recombinant protein was found to have sheddase activity. We also found evidence that the C. burnetii infection triggers an over-induction of the human HuHtrA gene expression. Finally, we demonstrate that cleavage of E-cad by CoxbHtrA on macrophages-THP-1 cells leads to an M2 polarization of the target cells and the induction of their secretion of IL-10, which “disarms” the target cells and improves C. burnetii replication. Taken together, these results demonstrate that the genome of C. burnetii encodes a functional HtrA sheddase and establishes a link between the HtrA sheddase-induced cleavage of E-cad, the M2 polarization of the target cells and their secretion of IL-10, and the intracellular replication of C. burnetii.

Objectives Define the cutoff thresholds of the Kappa (K) and Lambda (L) free light chains (FLC) indices for the detection of intrathecal immunoglobulin synthesis (IIS) using the new K and L FLC ELISA from SEBIA. The reference technique, which is not readily standardized between laboratories, is based on the demonstration of oligoclonal banding (OCB) in cerebrospinal fluid (CSF) which is absent in serum. For the past 6 years, we have also routinely calculated the K FLC index using The Binding Site (TBS) reagents on an Optilite instrument, an approach increasingly used as an alternative and/or a complement to electrophoretic analysis. Methods We analyzed 391 serum/CSF pairs divided into three groups. The first group were cases without OCB and with normal albumin CSF/serum ratio (n=174). The second group were cases with specific OCB (n=73). The last group included patients with increased albumin CSF/sera ratio without OCB (n=142). Results Analysis of the first group determined that the cutoffs for detection of IIS are respectively 2.55 and 1.02 for the K FLC and L FLC indices. Of the 73 cases with IIS, only 2 had a K FLC index below this threshold (sensitivity of 97.26%), while 16 out of 73 cases (78.08%) and 13 out of 72 cases (81.94%) had an IgG and L FLC index below the cutoffs, respectively. Additionally, we illustrate equivalent performances for prediction of the presence of OCB between SEBIA and TBS methods. Conclusions Sebia K FLC and L FLC assays are adequate alternative methods for the diagnosis of IIS.

Enterococcus mundtii ( E. mundtii ), a commensal intestinal bacterium, was demonstrated to inhibit the growth of some Mycobacterium tuberculosis ( M. tuberculosis ) complex (MTC) species that cause tuberculosis in humans and mammals. To further expand this preliminary observation, we cross-investigated five E. mundtii strains and seven MTC strains representative of four MTC species using a standardized quantitative agar well diffusion assay. All five E. mundtii strains, calibrated at 3.10 9 colony forming units/mL, inhibited the growth of all M. tuberculosis strains with various susceptibility profiles, but no inhibition was observed with lower inoculums. Further, 9 Enterococcus species freeze-dried cell-free culture supernatants (CFCS) including Enterococcus avium, Enterococcus devriesei , Enterococcus durans , Enterococcus dispar , Enterococcus hirae , Enterococcus casseliflavus , Enterococcus faecalis , Enterococcus faecium , and E. mundtii, inhibited the growth of M. tuberculosis , Mycobacterium africanum ( M. africanum ), Mycobacterium bovis ( M. bovis ) and Mycobacterium canettii ( M. canettii ), the most susceptible MTC species (inhibition diameter 25 ±1 mm), proportionally to CFCS protein concentrations. Data reported here indicated that the Enterococcus secretome inhibits growth of main MTC species of medical interest, which broadens previously reported data. In the gut, the Enterococcus secretome may modulate the expression of tuberculosis, exhibiting an anti-tuberculosis effect, with some protective roles in human and animal health.

International audience; Circadian rhythms have been described in numerous tissues of living organisms and are necessary for homeostasis. The understanding of their role in normal and pathological pregnancy is only just emerging. It has been established that clock genes are expressed in the placenta of animals and humans, but the rhythmicity of placenta immune cells is not known. Macrophages from healthy placenta of women at term were isolated and the expression of clock genes BMAL1, CLOCK, PER2, CRY2, and NR1D1 was assessed by qRT-PCR every 4 h over 24 h. Raw data were treated with cosinor analysis to evaluate the significance of the oscillations. Placental macrophages exhibited significant circadian expression of clock genes but one third of placental macrophages lost clock gene rhythmicity; the clock gene oscillations were restored by co-culture with trophoblasts. We wondered if melatonin, a key hormone regulating circadian rhythm, was involved in the oscillations of placental cells. We showed that macrophages and trophoblasts produced melatonin and expressed MT2 receptor. In women who developed preeclampsia during pregnancy, circadian oscillations of placental macrophages were lost and could not be rescued by coculture with trophoblasts from healthy women. Moreover, production and oscillations of melatonin were altered in preeclamptic macrophages. For the first time to our knowledge, this study shows circadian rhythms and melatonin production by placental macrophages. It also shows that preeclampsia is associated with a disruption of the circadian rhythm of placental cells. These results represent a new scientific breakthrough that may contribute to the prevention and treatment of obstetrical pathologies.

Having previously shown that soluble E-cadherin (sE-cad) is found in sera of Q fever patients, and that infection of BeWo cells byC. burnetiileads to modulation of the E-cad/β-cat pathway, our purpose was to identify which sheddase(s) might catalyze the cleavage of E-cad. Here, we searched for a direct mechanism of cleavage initiated by the bacterium itself, assuming the possible synthesis of a sheddase encoded in the genome ofC. burnetiior an indirect mechanism based on the activation of a human sheddase. Using a straightforward bioinformatics approach to scan the complete genomes of four laboratory strains ofC. burnetii, we demonstrate thatC. burnetiiencodes a 451 amino acid sheddase (CbHtrA) belonging to the HtrA family and differently expressed according to the bacterial virulence. An artificial CbHtrA gene (CoxbHtrA) was expressed and the CoxbHtrA recombinant protein was found to have sheddase activity. We also found evidence that theC. burnetiiinfection triggers an over-induction of the human HuHtrA gene expression. Finally, we demonstrate that cleavage of E-cad by CoxbHtrA on THP-1-cells leads to an M2 polarization of the target cells and the induction of their secretion of IL-10, which ‘disarms’ the target cells and improvesC. burnetiireplication. Taken together these results demonstrate that the genome ofC.burnetiiencodes a functional HtrA sheddase and establish a link between the HtrA sheddase-induced cleavage of E-cad, the M2 polarization of the target cells and their secretion of IL-10, and the intracellular replication ofC. burnetii.

Infection by Coxiella burnetii, the etiological agent of Q fever, poses the risk of causing severe obstetrical complications in pregnant women. C. burnetii is known for its placental tropism based on animal models of infection. The Nine Mile strain has been mostly used to study C. burnetii pathogenicity but the contribution of human isolates to C. burnetii pathogenicity is poorly understood. In this study, we compared five C. burnetii isolates from human placentas with C. burnetii strains including Nine Mile (NM) as reference. Comparative genomic analysis revealed that the Cb122 isolate was distinct from other placental isolates and the C. burnetii NM strain with a set of unique genes involved in energy generation and a type 1 secretion system. The infection of Balb/C mice with the Cb122 isolate showed higher virulence than that of NM or other placental isolates. We evaluated the pathogenicity of the Cb122 isolate by in vitro and ex vivo experiments. As C. burnetii is known to infect and survive within macrophages, we isolated monocytes and placental macrophages from healthy donors and infected them with the Cb122 isolate and the reference strain. We showed that bacteria from the Cb122 isolate were less internalized by monocyte-derived macrophages (MDM) than NM bacteria but the reference strain and the Cb122 isolate were similarly internalized by placental macrophages. The Cb122 isolate and the reference strain survived similarly in the two macrophage types. While the Cb122 isolate and the NM strain stimulated a poorly inflammatory program in MDM, they elicited an inflammatory program in placenta macrophages. We also reported that the Cb122 isolate and NM strain were internalized by trophoblastic cell lines and primary trophoblasts without specific replicative profiles. Placental explants were then infected with the Cb122 isolate and the NM strain. The bacteria from the Cb122 isolate were enriched in the chorionic villous foetal side. It is likely that the Cb122 isolate exhibited increased virulence in the multicellular environment provided by explants. Taken together, these results showed that the placental isolate of C. burnetii exhibits a specific infectious profile but its pathogenic role is not as high as the host immune response in pregnant women.

International audience; Background Although the triple positivity of antiphospholipid antibodies (aPL) is important for classifying high-risk patients, interpretation of aPL positivity, namely the lupus anticoagulant (LA), anti-cardiolipin (aCL), and anti-beta2-glycoprotein I autoantibodies (aB2GPI) remains challenging for thrombotic risk stratification. Objective To compare biological and clinical data between triple aPL- and single aCL-positive patients. Methods Of the 6500 patients assayed for aPL in daily practice within 3 years, we retrospectively analyzed data from 161 patients that were either triple aPL-positive or single aCL-positive with 5 years' follow-up for 121 of them. Results Whatever triple or single aPL positivity, we found a high prevalence of "carrier" patients (43%), which led us to question the clinical relevance of the triple aPL positivity. This result also justified the need to identify high-risk profiles. In asymptomatic patients, high risk of thrombotic events is associated with (1) two positive tests for LA or a Rosner Index >27 combined with both aCL-IgG and aB2GPI-IgG positivity, (2) persistent single aCL positivity without an associated autoimmune disease. In symptomatic patients, we demonstrated differences in the phenotype of patients and their therapeutic anticoagulation according to the number of positive aPL but we did not find differences in the number of clinical events, recurrence, or relapse, even in the absence of treatment. Conclusion This study shows that the thrombotic risk does not necessarily increase with the number of positive tests and raises the question of the therapeutic management of single aCL-positive patients.

IntroductionThe emergence of several SARS-CoV-2 variants during the COVID pandemic has revealed the impact of variant diversity on viral infectivity and host immune responses. While antibodies and CD8 T cells are essential to clear viral infection, the protective role of innate immunity including macrophages has been recognized. The aims of our study were to compare the infectivity of different SARS-CoV-2 variants in monocyte-derived macrophages (MDM) and to assess their activation profiles and the role of ACE2 (Angiotensin-converting enzyme 2), the main SARS-CoV-2 receptor. We also studied the ability of macrophages infected to affect other immune cells such as γδ2 T cells, another partner of innate immune response to viral infections.ResultsWe showed that the SARS-CoV-2 variants α-B.1.1.7 (United Kingdom), β-B.1.351 (South Africa), γ-P.1 (Brazil), δ-B.1.617 (India) and B.1.1.529 (Omicron), infected MDM without replication, the γ-Brazil variant exhibiting increased infectivity for MDM. No clear polarization profile of SARS-CoV-2 variants-infected MDM was observed. The β-B.1.351 (South Africa) variant induced macrophage activation while B.1.1.529 (Omicron) was rather inhibitory. We observed that SARS-CoV-2 variants modulated ACE2 expression in MDM. In particular, the β-B.1.351 (South Africa) variant induced a higher expression of ACE2, related to MDM activation. Finally, all variants were able to activate γδ2 cells among which γ-P.1 (Brazil) and β-B.1.351 (South Africa) variants were the most efficient.ConclusionOur data show that SARS-CoV-2 variants can infect MDM and modulate their activation, which was correlated with the ACE2 expression. They also affect γδ2 T cell activation. The macrophage response to SARS-CoV-2 variants was stereotypical.

High concentration of soluble E-cadherin (E-cad) was previously found in sera from Q fever patients. Here, BeWo cells which express a high concentration of E-cad were used as anin vitromodel to investigate the expression and function of E-cad in response to infection byCoxiella burnetii, the etiological agent of Q fever. Infection of BeWo cells withC. burnetiileads to a decrease in the number of BeWo cells expressing E-cad at their membrane. A shedding of soluble E-cad was associated with the post-infection decrease of membrane-bound E-cad. The modulation of E-cad expression requires bacterial viability and was not found with heat-inactivatedC. burnetii. Moreover, the intracytoplasmic cell concentration of β-catenin (β-cat), a ligand of E-cad, was reduced after bacterial infection, suggesting that the bacterium induces modulation of the E-cad/β-cat signaling pathway andCDH1andCTNNB1genes transcription. Finally, several genes operating the canonical Wnt-Frizzled/β-cat pathway were overexpressed in cells infected withC. burnetii. This was particularly evident with the highly virulent strain ofC. burnetii, Guiana. Our data demonstrate that infection of BeWo cells by liveC. burnetiimodulates the E-cad/β-cat signaling pathway.

Background Observations of vertical transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection from mother to fetus have recently been described in the literature. However, the consequences of such transmission, whether fetal or neonatal, are poorly understood. Methods From a case of in utero fetal death at 24+2 weeks of gestation that occurred 7 days after the diagnosis of symptomatic SARS-CoV-2 infection in the mother, we isolated the incriminating virus by immunochemistry and molecular techniques in several fetal tissues, with a variant analysis of the SARS-CoV-2 genome. Results The fetal demise could be explained by the presence of placental histological lesions, such as histiocytic intervillositis and trophoblastic necrosis, in addition to fetal tissue damage. We observed mild fetal growth retardation and visceral damage to the liver, causing hepatocellular damage and hemosiderosis. To the best of our knowledge, this is the first report in the literature of fetal demise secondary to maternal–fetal transmission of SARSCoV- 2 with a congenital infection and a pathological description of placental and fetal tissue damage. Conclusions SARS-CoV-2 was identified in both specimens using 3 independent techniques (immunochemistry, real-time quantitative polymerase chain reaction, and realtime digital polymerase chain reaction). Furthermore, the incriminating variant has been identified.

An increasing number of studies have provided strong evidence that gut microbiota interact with the immune system and stimulate various mechanisms involved in the pathogenesis of auto-immune diseases such as Systemic Lupus Erythematosus (SLE). Indeed, gut microbiota could be a source of diagnostic and prognostic biomarkers but also hold the promise to discover novel therapeutic strategies. Thus far, specific SLE microbial signatures have not yet been clearly identified with alteration patterns that may vary between human and animal studies. In this study, a comparative analysis of a clinically well-characterized cohort of adult patients with SLE showed reduced biodiversity, a lower Firmicutes/Bacteroidetes (F/B) ratio, and six differentially abundant taxa compared with healthy controls. An unsupervised clustering of patients with SLE patients identified a subgroup of patients with a stronger alteration of their gut microbiota. Interestingly, this clustering was strongly correlated with the disease activity assessed with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score (p = 0.03, odd ratio = 15) and the identification of specific alterations involving the F/B ratio and some different taxa. Then, the gut microbiota of pristane-induced lupus and control mice were analyzed for comparison with our human data. Among the six differentially abundant taxa of the human disease signature, five were common with our murine model. Finally, an exhaustive cross-species comparison between our data and previous human and murine SLE studies revealed a core-set of gut microbiome species that might constitute biomarker panels relevant for future validation studies.

Due to the role of macrophages in glomerular inflammation, macrophage surface molecules such as CD163 and CD11b represent attractive biomarkers for monitoring Lupus Nephritis (LN). We hypothesize that their urinary levels may reflect kidney disease activity. Here, we first analyzed the levels of urinary soluble CD163 (U-sCD163) and CD11b (U-sCD11b) in a cohort of 40 patients with LN including 23 with active disease. U-sCD163 levels were significantly elevated in active LN and correlated with the renal activity score, in contrast to U-sCD11b. Then, we developed the pristane induced LN mouse model to analyze, in a longitudinal way, the evolution of U-sCD163 levels according to the glomerular inflammation progression and response to treatment. We showed an increase of U-sCD163 levels associated with glomerular immune-complex deposits on mouse kidney biopsies at an early stage of the disease and a correlation with inflammatory markers including interferon-α, C-reactive protein and tumor necrosis factor-α. In addition, we showed that U-sCD163 levels decreased following efficient hydroxychloroquine treatment. Altogether our results led us to conclude that U-sCD163 represent a non-invasive biomarker for LN reflecting glomerular inflammation. Although prospective study in patients with LN, active or not, are necessary, U-sCD163 could be proposed to monitor response to treatment.

International audience; Circadian rhythms are present in almost all living organisms, and their activity relies on molecular clocks. In prokaryotes, a functional molecular clock has been defined only in cyanobacteria. Here, we investigated the presence of circadian rhythms in non-cyanobacterial prokaryotes. The bioinformatic approach was used to identify a homologue of KaiC (circadian gene in cyanobacteria) in Escherichia coli. Then, strains of E. coli (wild type and mutants) were grown on blood agar, and sampling was made every 3 h for 24 h at constant conditions. Gene expression was determined by qRT-PCR, and the rhythmicity was analyzed using the Cosinor model. We identified RadA as a KaiC homologue in E. coli. Expression of radA showed a circadian rhythm persisting at least 3 days, with a peak in the morning. The circadian expression of other E. coli genes was also observed. Gene circadian oscillations were lost in radA mutants of E. coli. This study provides evidence of molecular clock gene expression in E. coli with a circadian rhythm. Such a finding paves the way for new perspectives in antibacterial treatment.

Biological rhythms are important regulators of immune functions. In intensive care unit (ICU), sepsis is known to be associated with rhythm disruption. Our objectives were to determine factors associated with rhythm disruption of the body temperature and to assess the relationship between temperature and mortality in septic shock patients; In a cohort of septic shock, we recorded body temperature over a 24-h period on day 2 after ICU admission. For each patient, the temperature rhythmicity was assessed by defining period and amplitude, and the adjusted average (mesor) of the temperature by sinusoidal regression and cosinor analysis. Analyses were performed to assess factors associated with the three temperature parameters (period, amplitude, and mesor) and mortality. 162 septic shocks were enrolled. The multivariate analysis demonstrates that the period of temperature was associated with gender (women, coefficient −2.2 h, p = 0.031) and acetaminophen use (coefficient −4.3 h, p = 0.002). The mesor was associated with SOFA score (coefficient −0.05 °C per SOFA point, p = 0.046), procalcitonin (coefficient 0.001 °C per ng/mL, p = 0.005), and hydrocortisone use (coefficient −0.5 °C, p = 0.002). The amplitude was associated with the dialysis (coefficient −0.5 °C, p = 0.002). Mortality at day 28 was associated with lower mesor (adjusted hazard ratio 0.50, 95% CI 0.28 to 0.90; p = 0.02), and higher amplitude (adjusted hazard ratio 5.48, 95% CI 1.66 to 18.12; p = 0.005) of temperature. Many factors, such as therapeutics, influence the body temperature during septic shock. Lower mesor and higher amplitude were associated with mortality and could be considered prognostic markers in ICU. In the age of artificial intelligence, the incorporation of such data in an automated scoring alert could compete with physicians to identify high-risk patients during septic shock.

BACKGROUND AND AIMS During COVID-19, the renal impairment is the most frequent after lung impairment and is associated of poor prognosis particularly in the intensive care unit (ICU). In this work, we aim to assess the incidence of acute kidney injury (AKI) in COVID-19-related acute respiratory distress syndrome (ARDS) patients, the existence of an early renal dysfunction and its prognosis, and its specificity compared with patients with non-COVID ARDS. METHOD This a prospective and multicentric study led in four ICUs. Patients of 18 years and older in ICU with invasive mechanical ventilation for ARDS were enrolled. Precise evaluation of renal dysfunction markers, including urinary protein electrophoresis, was performed within 24 h after the onset of mechanical ventilation. RESULTS From March 2020 to September 2021, 131 patients in ICU for ARDS were enrolled, 98 COVID-19 ARDS and 33 ARDS from other causes. There was more tubular profile in COVID-19 patients (68% versus 24%; P = .001) and a more mixed, tubular and glomerular profile in non-COVID-19 patients (29% versus 14%; P = .001). COVID-19 patients displayed an important tubular proteinuria, tended to display more AKI (49% versus 31%; P = .07), and had a longer duration of mechanical ventilation (18 versus 10 days; P = .002) and longer ICU length of stay (23 versus 15 days; P = .013). In COVID-19 patients, tubular proteinuria was associated with poor renal prognosis with a significant association with the onset of KDIGO ≥ 2 AKI. CONCLUSION COVID-19 ARDS patients had a specific renal impairment with tubular dysfunction, which appeared to be of poor prognosis on kidney and disease evolution.

Vγ9Vδ2 T cells play a key role in the innate immune response to viral infections, including SARS-CoV-1 and 2, and are activated through butyrophilin (BTN)-3A. Here, the objectives were to: 1) characterize the effects of SARS-CoV-2 infection on the number, phenotype, and activation of Vγ9Vδ2 T cells in infected patients, and 2) assess the effects of in vitro SARS-CoV-2 infection on the expression of BTN3A and its impact on the activation and response of Vγ9Vδ2 T cells to an anti-BTN3A antibody. Blood Vγ9Vδ2 T cells decreased in clinically mild SARS-CoV-2 infections compared to healthy volunteers (HV). This decrease was maintained up to 28 days and in the recovery period. Terminally differentiated Vγ9Vδ2 T cells tend to be enriched on the day of diagnosis, 28 days after and during the recovery period compared to HV. Furthermore, these cells showed cytotoxic and inflammatory activities as shown by TNFα, IFNγ and CD107a/b increase following anti-BTN3A activation. Moreover, BTN3A upregulation and Vγ9Vδ2 T cell infiltration were observed in a lung biopsy from a fatal SARS-CoV-2 infection, as compared to HV. In vitro, SARS-CoV-2 infection significantly increased BTN3A expression in macrophages and lung cell lines. The activation via BTN3A enhanced the anti-SARS-CoV-2 Vγ9Vδ2 T cells cytotoxicity and IFN-γ and TNFα in SARS-CoV-2 infected patient. Increasing concentrations of anti-BTN3A were accompanied by an inhibition of viral replication. Altogether, these data suggest that Vγ9Vδ2 T cells are important in the immune response against SARS-CoV-2 infection and that activation by an anti-BTN3A antibody may enhance their response.KEY POINTSSARS-CoV-2 mediates upregulation of the key receptor of Vγ9Vδ2 T cells BTN3A on lung tissues and cell lines as well as monocytesDuring SARS-CoV-2 infection, Vγ9Vδ2 are differentiated and efficiently degranulate and secrete cytokines upon activation with BTN3A mAb

Although epidemiologic research has demonstrated significant differences in incidence and outcomes of sepsis according to sex, their underlying biological mechanisms are poorly understood. Here, we studied the influence of hormonal status by comparing in vivo cardiac performances measured by MRI in non-ovariectomized and ovariectomized septic female rats. Control and ovariectomized rats were randomly allocated to the following groups: sham, sepsis and sepsis plus landiolol. Sepsis was induced by caecum ligation and punction (CLP). Landiolol, a short-acting selective β1-adrenergic blocker improving the in vivo cardiac performance of septic male rats was perfused continuously after sepsis induction. Cardiac MRI was carried out 18 h after induction of sepsis to assess in vivo cardiac function. Capillary permeability was evaluated by Evans Blue administration and measurement of its tissue extravasation. Variation in myocardial gene and protein expression was also assessed by qPCR and western-blot in the left ventricular tissue. Sepsis reduced indexed stroke volume, cardiac index and indexed end-diastolic volume compared to sham group in ovariectomized females whereas it had no effect in control females. This was associated with an overexpression of JAK2 expression and STAT3 phosphorylation on Ser727 site, and an inhibition of the adrenergic pathways in OVR females. Landiolol increased the indexed stroke volume by reversing the indexed end-diastolic volume reduction after sepsis in ovariectomized females, while it decreased indexed stroke volume and cardiac index in control. This was supported by an overexpression of genes involved in calcium influx in OVR females while an inactivation of the β-adrenergic and a calcium efflux pathway was observed in control females. Sepsis decreased in vivo cardiac performances in ovariectomized females but not in control females, presumably associated with a more pronounced inflammation, inhibition of the adrenergic pathway and calcium efflux defects. Administration of landiolol prevents this cardiac dysfunction in ovariectomized females with a probable activation of calcium influx, while it has deleterious effects in control females in which calcium efflux pathways were down-regulated.

IFN-γ plays a critical role in the immune response to bacterial infections. It is established that IFN-γ is mainly produced by NK/ILC1 cells and T cells, and most of papers have rejected the biologic reality of alternative sources for more than 20 years. Here, we are proposing to revisit this dogma and discuss the role of macrophage-derived IFN-γ in bacterial infections. Our hypothesis is based on a panel of publications and is recently revived by our results on placenta, a chimeric organ in which the immune response is tailored to protect the fetus from mother’s immune response. The culture of purified placental macrophages is associated with a production of IFN-γ that may contribute to fetal protection from bacterial infections before eliciting a Th1-like immune response potentially pathogenic for pregnancy. Hence, macrophage IFN-γ may be a novel actor of early crosstalk between innate and adaptive immunity in the context of host defense against bacterial infections.

Since December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2/2019-nCoV) has spread quickly worldwide, with more than 29 million cases and 920,000 deaths. Interestingly, coronaviruses were found to subvert and hijack the autophagic process to allow their viral replication. One of the spotlights had been focused on the autophagy inhibitors as a target mechanism effective in the inhibition of SARS-CoV-2 infection. Consequently, chloroquine (CQ) and hydroxychloroquine (HCQ), a derivative of CQ, was suggested as the first potentially be therapeutic strategies as they are known to be autophagy inhibitors. Then, they were used as therapeutics in SARS-CoV-2 infection along with remdesivir, for which the FDA approved emergency use authorization. Here, we investigated the antiviral activity and associated mechanism of GNS561, a small basic lipophilic molecule inhibitor of late-stage autophagy, against SARS-CoV-2. Our data indicated that GNS561 showed the highest antiviral effect for two SARS-CoV-2 strains compared to CQ and remdesivir. Focusing on the autophagy mechanism, we showed that GNS561, located in LAMP2-positive lysosomes, together with SARS-CoV-2, blocked autophagy by increasing the size of LC3-II spots and the accumulation of autophagic vacuoles in the cytoplasm with the presence of multilamellar bodies characteristic of a complexed autophagy. Finally, our study revealed that the combination of GNS561 and remdesivir was associated with a strong synergistic antiviral effect against SARS-CoV-2. Overall, our study highlights GNS561 as a powerful drug in SARS-CoV-2 infection and supports that the hypothesis that autophagy inhibitors could be an alternative strategy for SARS-CoV-2 infection.

International audience; Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease driven by complex interactions between genetics and environmental factors. SLE is characterised by breaking self-immune tolerance and autoantibody production that triggers inflammation and damage of multiple organs. Given the highly heterogeneous nature of SLE, the treatments currently used are still not satisfactory with considerable side effects, and the development of new therapies is a major health issue for better patient management. In this context, mouse models significantly contribute to our knowledge of the pathogenesis of SLE and are an invaluable tool for testing novel therapeutic targets. Here, we discuss the role of the most used SLE mouse models and their contribution to therapeutic improvement. Considering the complexity of developing targeted therapies for SLE, adjuvant therapies are also increasingly proposed. Indeed, murine and human studies have recently revealed that gut microbiota is a potential target and holds great promises for successful new SLE therapies. However, the mechanisms of gut microbiota dysbiosis in SLE remain unclear to date. In this review, we propose an inventory of existing studies investigating the relationship between gut microbiota dysbiosis and SLE to establish microbiome signature that may serve as a potential biomarker of the disease and its severity as well as a new potential therapy target. This approach may open new possibilities for early diagnosis, prevention and therapeutic perspectives of SLE based on gut microbiome.

IntroductionQ fever, a zoonosis caused by Coxiella burnetii, affects more males than females despite a similar level of exposure. A protective role of estradiol has been reported in mice, suggesting that sex hormones are involved in C. burnetii infection. We wondered whether the responses of monocytes and monocyte-derived macrophages (MDMs) to C. burnetii are influenced by sex hormones.Materials and MethodsThe bacterial intracellular fate in monocytes was studied using quantitative PCR, and monocyte cytokine production in response to C. burnetii was assessed using qRT-PCR and immunoassays. Before infection, MDMs from males and females were incubated with testosterone and estradiol, respectively.ResultsBacterial uptake and persistence were similar in monocytes from males and females but were slightly increased in male MDMs. The expression of inflammatory genes, including those encoding TNF and CXCL10, was higher in MDMs from females than in MDMs from males infected by C. burnetii. Adding testosterone to male MDMs amplified their immunoregulatory properties, including increased expression of IL10 and TGFB genes and TGF-β production in response to C. burnetii. In contrast, adding estradiol to MDMs from females had no effect on their inflammatory profile.ConclusionThe stronger inflammatory profile of macrophages from females may have a protective role, likely under estrogen control, while testosterone may affect disease progression by promoting an anti-inflammatory response. This finding may have consequences for personalized management of patients with Q fever.

COVID-19 is the biggest pandemic the world has seen this century. Alongside the respiratory damage observed in patients with severe forms of the disease, gastrointestinal symptoms have been frequently reported. These symptoms (e.g., diarrhoea), sometimes precede the development of respiratory tract illnesses, as if the digestive tract was a major target during early SARS-CoV-2 dissemination. We hypothesize that in patients carrying intestinal SARS-CoV-2, the virus may trigger epithelial barrier damage through the disruption of E-cadherin (E-cad) adherens junctions, thereby contributing to the overall gastrointestinal symptoms of COVID-19. Here, we use an intestinal Caco-2 cell line of human origin which expresses the viral receptor/co-receptor as well as the membrane anchored cell surface adhesion protein E-cad to investigate the expression of E-cad after exposure to SARS-CoV-2. We found that the expression of

Vimentin is a type III intermediate filament protein, widely expressed in mesenchymal cells. Mainly located in the cytoplasm, vimentin can also appear at extracellular locations, where it may interact with bacterial or viral pathogens. In this study, we aimed at investigating the implication of vimentin in SARS-CoV-2 viral entry and the consequences on viral replication and cellular response. We showed that upon infection, vimentin was upregulated at the cell surface, where it interacts with ACE2 for SARS-CoV-2 entry. We demonstrated a direct interaction between SARS-CoV-2 spike protein, ACE2, and vimentin in epithelial cells. Inhibition of cell-surface vimentin availability resulted in reduced viral entry and cytopathogenic effects. Finally, we showed that the expression of inflammatory cytokines and chemokines was modulated by vimentin-SARS-CoV-2 interaction. In conclusion, our data suggest that cell-surface vimentin acts as a co-receptor for SARS-CoV-2.

The etiological agent of COVID-19 SARS-CoV-2, is primarily a pulmonary-tropic coronavirus. Infection of alveolar pneumocytes by SARS-CoV-2 requires virus binding to the angiotensin I converting enzyme 2 (ACE2) monocarboxypeptidase. ACE2, present on the surface of many cell types, is known to be a regulator of blood pressure homeostasis through its ability to catalyze the proteolysis of Angiotensin II (Ang II) into Angiotensin-(1-7) [Ang-(1-7)]. We therefore hypothesized that SARS-CoV-2 could trigger variations of ACE2 expression and Ang II plasma concentration in SARS-CoV-2-infected patients. We report here, that circulating blood cells from COVID-19 patients express less ACE2 mRNA than cells from healthy volunteers. At the level of circulating cells, this ACE2 gene dysregulation mainly affects the monocytes, which also show a lower expression of membrane ACE2 protein. Moreover, soluble ACE2 (sACE2) plasma concentrations are lower in prolonged viral shedders than in healthy controls, while the concentration of sACE2 returns to normal levels in short viral shedders. In the plasma of prolonged viral shedders, we also found higher concentrations of Ang II and angiotensin I (Ang I). On the other hand, the plasma levels of Ang-(1-7) remains almost stable in prolonged viral shedders but seems insufficient to prevent the adverse effects of Ang II accumulation. Altogether, these data evidence that the SARS-CoV-2 may affect the expression of blood pressure regulators with possible harmful consequences on COVID-19 outcome.

Microbiome and the immune system are constantly shaping each other, in a mutual aim to thrive, defining the unstable equilibrium of the healthy individual. Microbiome is growingly involved in dysimmune conditions such as allergy, asthma, autoimmunity, and primary or acquired immune deficiencies. The current epidemics of allergic diseases and asthma has long been linked to the microbial environment through the hygiene hypothesis. Progress in the understanding of the microbiome-immune system crosstalk has unraveled a tight connection between microbial communities and the development of allergic diseases and asthma. Disruption of the microbiome affects the immune response of the host and paves the way for disease pathogenesis. Conversely, disease and therapeutic interventions affect microbial communities. We aimed at providing the reader with a view of the state-of-the art of microbiome – immune system crosstalk, with special focus on the loopholes giving potential grip to the pathogenesis of microbiome-related dysimmunity. Keywords: Microbiome, Mycobiome, Immune system, Dysbiosis, Allergy, Asthma, Atopy, Atopic dermatitis, Dendritic cell, Macrophage, Mast cell, Chronic rhinosinusitis

The infection of pregnant animals and women by Coxiella burnetii, an intracellular bacterium, compromises both maternal health and foetal development. The placenta is targeted by C. burnetii, as demonstrated by bacteriological and histological evidence. It now appears that placental strains of C. burnetii are highly virulent compared to reference strains and that placental injury involves different types of placental cells. Trophoblasts, the major placental cells, are largely infected by C. burnetii and may represent a replicating niche for the bacteria. The placenta also contains numerous immune cells, including macrophages, dendritic cells, and mast cells. Placental macrophages are infected and activated by C. burnetii in an unusual way of M1 polarisation associated with bacterial elimination. Placental mast cells eliminate bacteria through a mechanism including the release of extracellular actin filaments and antimicrobial peptides. In contrast, C. burnetii impairs the maturation of decidual dendritic cells, favouring bacterial pathogenicity. Our aim is to review C. burnetii infections of human placentas, paying special attention to both the action and function of the different cell types, immune cells, and trophoblasts targeted by C. burnetii in relation to foetal injury.

Macrophages are tissue immune cells involved in homeostasis and are considered as the first line of defense during bacterial infections. They are resident cells but may be recruited during inflammation and/or infection. Hence, their study is necessary not only to decipher innate immune mechanisms involved in bacterial infections but also to follow infected patients. Among the numerous functions of macrophages, their polarization into microbicidal or permissive cells has been an interesting concept to describe their responses to bacterial aggression. Numerous in vitro studies, including ours, have shown the ability of bacteria to induce different patterns of macrophage polarization. However, the studies of patients during infections have produced less convincing results. We propose in this review to take stock of the tools for studying the polarization of macrophages and to show their limits. We make recommendations for using macrophage polarization as a biomarker for measuring severity and response to treatment in bacterial infectious diseases.

Background Coronavirus disease 2019 (COVID-19) clinical expression is pleiomorphic, severity is related to age and comorbidities such as diabetes and hypertension, and pathophysiology involves aberrant immune activation and lymphopenia. We wondered if the myeloid compartment was affected during COVID-19 and if monocytes and macrophages could be infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods Monocytes and monocyte-derived macrophages (MDMs) from COVID-19 patients and controls were infected with SARS-CoV-2 and extensively investigated with immunofluorescence, viral RNA extraction and quantification, and total RNA extraction followed by reverse-transcription quantitative polymerase chain reaction using specific primers, supernatant cytokines (interleukins 6, 10, and 1β; interferon-β; transforming growth factor–β1, and tumor necrosis factor–α), and flow cytometry. The effect of M1- vs M2-type or no polarization prior to infection was assessed. Results SARS-CoV-2 efficiently infected monocytes and MDMs, but their infection is abortive. Infection was associated with immunoregulatory cytokines secretion and the induction of a macrophagic specific transcriptional program characterized by the upregulation of M2-type molecules. In vitro polarization did not account for permissivity to SARS-CoV-2, since M1- and M2-type MDMs were similarly infected. In COVID-19 patients, monocytes exhibited lower counts affecting all subsets, decreased expression of HLA-DR, and increased expression of CD163, irrespective of severity. Conclusions SARS-CoV-2 drives monocytes and macrophages to induce host immunoparalysis for the benefit of COVID-19 progression. SARS-CoV-2 infection of macrophages induces a specific M2 transcriptional program. In Covid-19 patients, monocyte subsets were decreased associated with up-expression of the immunoregulatory molecule CD163 suggesting that SARS-CoV-2 drives immune system for the benefit of Covid-19 disease progression.

CoVID-19 is an unprecedented epidemic, globally challenging health systems, societies, and economy. Its diagnosis relies on molecular methods, with drawbacks revealed by current use as mass screening. Monocyte CD169 upregulation has been reported as a marker of viral infections, we evaluated a flow cytometry three-color rapid assay of whole blood monocyte CD169 for CoVID-19 screening.Outpatients (n=177) with confirmed CoVID-19 infection, comprising 80 early-stage (≤14 days after symptom onset), 71 late-stage (≥15 days), and 26 asymptomatic patients received whole blood CD169 testing in parallel with SARS-CoV-2 RT-PCR. Upregulation of monocyte CD169 without polymorphonuclear neutrophil CD64 changes was the primary endpoint. Sensitivity was 98% and 100% in early-stage and asymptomatic patients respectively, specificity was 50% and 84%. Rapid whole blood monocyte CD169 evaluation was highly sensitive when compared with RT-PCR, especially in early-stage, asymptomatic patients whose RT-PCR tests were not yet positive.Diagnostic accuracy, easy finger prick sampling and minimal time-to-result (15-30 minutes) rank whole blood monocyte CD169 upregulation as a potential screening and diagnostic support for CoVID-19. Secondary endpoints were neutrophil CD64 upregulation as a marker of bacterial infections and monocyte HLA-DR downregulation as a surrogate of immune fitness, both assisting with adequate and rapid management of non-CoVID cases.

Since December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2/2019-nCoV) has spread quickly worldwide, with more than 29 million cases and 920,000 deaths. Interestingly, coronaviruses were found to subvert and hijack the autophagic process to allow their viral replication. One of the spotlights had been focused on the autophagy inhibitors as a target mechanism effective in the inhibition of SARS-CoV-2 infection. Consequently, chloroquine (CQ) and hydroxychloroquine (HCQ), a derivative of CQ, was suggested as the first potentially be therapeutic strategies as they are known to be autophagy inhibitors. Then, they were used as therapeutics in SARS-CoV-2 infection along with remdesivir, for which the FDA approved emergency use authorization. Here, we investigated the antiviral activity and associated mechanism of GNS561, a small basic lipophilic molecule inhibitor of late-stage autophagy, against SARS-CoV-2. Our data indicated that GNS561 showed the highest antiviral effect for two SARS-CoV-2 strains compared to CQ and remdesivir. Focusing on the autophagy mechanism, we showed that GNS561, located in LAMP2-positive lysosomes, together with SARS-CoV-2, blocked autophagy by increasing the size of LC3-II spots and the accumulation of autophagic vacuoles in the cytoplasm with the presence of multilamellar bodies characteristic of a complexed autophagy. Finally, our study revealed that the combination of GNS561 and remdesivir was associated with a strong synergistic antiviral effect against SARS-CoV-2. Overall, our study highlights GNS561 as a powerful drug in SARS-CoV-2 infection and supports that the hypothesis that autophagy inhibitors could be an alternative strategy for SARS-CoV-2 infection.

To date, the Covid-19 pandemic affected more than 18 million individuals and caused more than 690, 000 deaths. Its clinical expression is pleiomorphic and severity is related to age and comorbidities such as diabetes and hypertension. The pathophysiology of the disease relies on aberrant activation of immune system and lymphopenia that has been recognized as a prognosis marker. We wondered if the myeloid compartment was affected in Covid-19 and if monocytes and macrophages could be infected by SARS-CoV-2. We show here that SARS-CoV-2 efficiently infects monocytes and macrophages without any cytopathic effect. Infection was associated with the secretion of immunoregulatory cytokines (IL-6, IL-10, TGF-β) and the induction of a macrophagic specific transcriptional program characterized by the upregulation of M2-type molecules. In addition, we found that in vitro macrophage polarization did not account for the permissivity to SARS-CoV-2, since M1-and M2-type macrophages were similarly infected. Finally, in a cohort of 76 Covid-19 patients ranging from mild to severe clinical expression, all circulating monocyte subsets were decreased, likely related to massive emigration into tissues. Monocytes from Covid-19 patients exhibited decreased expression of HLA-DR and increased expression of CD163, irrespective of the clinical status. Hence, SARS-CoV-2 drives circulating monocytes and macrophages inducing immunoparalysis of the host for the benefit of Covid-19 disease progression.

Placental macrophages are a heterogenous population of immune cells present throughout pregnancy. They are essential for maintenance of the homeostatic placenta environment and host defense against infections. The characterization of placental macrophages as well as their activation have been limited for a long time by the lack of convenient tools. The emergence of unbiased methods makes it possible to reappraise the study of placental macrophages. In this review, we discuss the diversity and the functions of placental macrophages to better understand their dysfunctions during placental infections., Graphical abstract Schematic representation of the maternal and fetal parts of the placenta villi. Decidual macrophages are localized in the decidual at the maternal part, whereas Hofbauer cells are present in the fetal part in the intervillous space.Image 1, Highlights • Placental macrophage populations exhibit heterogeneity in terms of fetal/maternal origin and phenotype. • Placental macrophages combine metabolic and immunological functions that enable placenta development and maternal immune tolerance. • The role of placental macrophages in infectious diseases remains obscure opening fascinating heuristic and therapeutic perspectives.

One quarter of all cancers are linked to infectious diseases. The link between viral infection and cancer has been widely studied, but few reports have focused on the carcinogenic role of bacterial infection. Nonetheless

Background Circadian clock alterations were poorly reported in trauma patients, although they have a critical role in human physiology. Core body temperature is a clinical variable regulated by the circadian clock. Our objective was to identify the circadian temperature disruption in trauma patients and to determine whether these disruptions were associated with the 28-day mortality rate. Methods A retrospective and observational single-center cohort study was conducted. All adult severe trauma patients admitted to the intensive care unit of Aix Marseille University, North Hospital, from November 2013 to February 2018, were evaluated. The variations of core body temperature for each patient were analyzed between days 2 and 3 after intensive care unit admission. Core body temperature variations were defined by three parameters: mesor, amplitude, and period. A logistic regression model was used to determine the variables influencing these three parameters. A survival analysis was performed assessing the association between core body temperature rhythm disruption and 28-day mortality rate. A post hoc subgroup analysis focused on the patients with head trauma. Results Among the 1584 screened patients, 248 were included in this study. The period differed from 24 h in 177 (71%) patients. The mesor value (°C) was associated with body mass index and ketamine use. Amplitude (°C) was associated with ketamine use only. The 28-day mortality rate was 18%. For all trauma patients, age, body mass index, intracranial hypertension, and amplitude were independent risk factors. The patients with a mesor value p 0.6 °C (p p = 0.001 and HR = 4.73, 95% CI [1.38–16.22], p = 0.01). Conclusions Our results highlight an association between core body temperature circadian alteration and 28-day mortality rate. This association was more pronounced in the head trauma patients than in the non-head trauma patients. Further studies are needed to show a causal link and consider possible interventions.

Additional file 4 Four examples of central core body temperature rhythm modelling. The dark lines represent the sinusoidal approximation of the Cosinor analysis from the set of temperature data (grey dots). Period, Mesor, and Amplitude of the temperature are respectively for trauma A: 6.4 hours, 38.7°C, 0.35°C; trauma B: 13.3 hours, 37.8°C, 0.38°C; trauma C: 24.0 hours, 37.6°C, 0.30°C; trauma D: 41.3 hours, 37.6°C, 0.62 °C.