IL-2 immunotherapy in chronically SIV-infected Rhesus Macaques

BACKGROUND: Despite inducing a sustained increase in CD4+ T cell counts, intermittent recombinant IL-2 (rIL-2) therapy did not confer a better clinical outcome in HIV-infected patients enrolled in large phase III clinical trials ESPRIT and SILCAAT. Several hypotheses were evoked to explain these discrepancies. Here, we investigated the impact of low and high doses of IL-2 in Rhesus macaques of Chinese origin infected with SIVmac251 in the absence of antiretroviral therapy (ART). RESULTS: We demonstrated that rIL-2 induced a dose dependent expansion of CD4+ and CD8+ T cells without affecting viral load. rIL-2 increased CD4 and CD8 Treg cells as defined by the expression of CD25(high)FoxP3(+)CD127(low). We also showed that rIL-2 modulated spontaneous and Fas-mediated CD4(+) and CD8(+) T cell apoptosis. The higher dose exhibited a dramatic pro-apoptotic effect on both CD4(+) and CD8(+) T cell populations. Finally, all the animals treated with rIL-2 developed a wasting syndrome in the month following treatment simultaneously to a dramatic decrease of circulating effector T cells. CONCLUSION: These data contribute to the understanding of the homeostatic and dosage effects of IL-2 in the context of SIV/HIV infection

The anti-caspase inhibitor Q-VD-OPH prevents AIDS disease progression in SIV-infected rhesus macaques

Apoptosis has been proposed as a key mechanism responsible for CD4+ T cell depletion and immune dysfunction during HIV infection. We demonstrated that Q-VD-OPH, a caspase inhibitor, inhibits spontaneous and activation-induced death of T cells from SIV-infected rhesus macaques (RMs). When administered during the acute phase of infection, Q-VD-OPH was associated with (a) reduced levels of T cell death, (b) preservation of CD4+/CD8+ T cell ratio in lymphoid organs and in the gut, (c) maintenance of memory CD4+ T cells, and (d) increased specific CD4+ T cell response associated with the expression of cytotoxic molecules. Although therapy was limited to the acute phase of infection, Q-VD-OPH-treated RMs showed lower levels of both viral load and cell-associated SIV DNA as compared with control SIV-infected RMs throughout the chronic phase of infection, and prevented the development of AIDS. Overall, our data demonstrate that Q-VD-OPH injection in SIV-infected RMs may represent an adjunctive therapeutic agent to control HIV infection and delaying disease progression to AIDS.This article is dedicated to the memory of Bruno Hurtrel. We also thank Jean-Claude Ameisen for his initial support. We acknowledge Celine Gommet (Institut Pasteur) for her expertise in the follow-up of our primate cohort. We also acknowledge Francois Villinger, who performed TRIM5a polymorphism. ML and JG were supported by fellowships from ANRS. RS thanks Fundacao para a Ciencia e a Tecnologia (FCT) for Investigator FCT Grant IF/00021/2014. This study was supported by research funding from ANRS and CIHR (MOP-133476) to JE. VR is supported by a fellowship from FCT (code SFRH/BD/64064/2009). JE thanks the Canada Research Chair program for financial assistance

Abortive T Follicular Helper Development Is Associated with a Defective Humoral Response in Leishmania infantum-Infected Macaques

Leishmania infantum causes a chronic infectious disease named visceral leishmaniasis (VL). We employed a non-human primate model to monitor immune parameters over time and gain new insights into the disease. Rhesus macaques were infected with L. infantum and the T helper and B cell immunological profiles characterized during acute and chronic phases of infection. Parasite detection in visceral compartments during the acute phase was associated with differentiation of effector memory CD4 T cells and increased levels of Th1 transcripts. At the chronic phase, parasites colonized novel lymphoid niches concomitant with increased expression of IL10. Despite the occurrence of hypergammaglobulinemia, the production of parasite-specific IgG was poor, being confined to the acute phase and positively correlated with the frequency of an activated memory splenic B cell population. We noticed the expansion of a splenic CD4 T cell population expressing CXCR5 and Bcl-6 during acute infection that was associated with the differentiation of the activated memory B cell population. Moreover, the number of splenic germinal centers peaked at one month after infection, hence paralleling the production of specific IgG. However, at chronic infection these populations contracted impacting the production of parasite-specific IgG. Our study provides new insights into the immune events taking place in a physiologically relevant host and a mechanistic basis for the inefficient humoral response during VL. © 2014 Rodrigues et al.This work was supported by an ANR (Agence Nationale de la Recherche) grant (LeishApo) and the Seven Framework Programme (KINDReD) to JE. JE thanks the Canada Research Chair program for financial assistance. VR is supported by a doctoral fellowship from FCT (Fundação para a Ciência e Tecnologia); code SFRH/BD/64064/2009. RS is supported by Programa Ciência – financed by Programa Operacional Potencial Humano POPH – QREN– Tipologia 4.2 –Promocao do Emprego Cientıfico, co-funded by Fundo Social Europeu and National funding from Ministry of Science, Technology and Higher Education (MCTES). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Inflammatory Potential of Four Different Phases of Calcium Pyrophosphate Relies on NF-κB Activation and MAPK Pathways

Background: Calcium pyrophosphate (CPP) microcrystal deposition is associated with wide clinical phenotypes, including acute and chronic arthritis, that are interleukin 1β (IL-1β)-driven. Two CPP microcrystals, namely monoclinic and triclinic CPP dihydrates (m- and t-CPPD), have been identified in human tissues in different proportions according to clinical features. m-CPP tetrahydrate beta (m-CPPTβ) and amorphous CPP (a-CPP) phases are considered as m- and t-CPPD crystal precursors in vitro.Objectives: We aimed to decipher the inflammatory properties of the three crystalline phases and one amorphous CPP phase and the intracellular pathways involved.Methods: The four synthesized CPP phases and monosodium urate crystals (MSU, as a control) were used in vitro to stimulate the human monocytic leukemia THP-1 cell line or bone marrow-derived macrophages (BMDM) isolated from WT or NLRP3 KO mice. The gene expression of pro- and anti-inflammatory cytokines was evaluated by quantitative PCR; IL-1β, IL-6 and IL-8 production by ELISA; and mitogen-activated protein kinase (MAPK) activation by immunoblot analysis. NF-κB activation was determined in THP-1 cells containing a reporter plasmid. In vivo, the inflammatory potential of CPP phases was assessed with the murine air pouch model via cell analysis and production of IL-1β and CXCL1 in the exudate. The role of NF-κB was determined by a pharmacological approach, both in vivo and in vitro.Results:In vitro, IL-1β production induced by m- and t-CPPD and m-CPPTβ crystals was NLRP3 inflammasome dependent. m-CPPD crystals were the most inflammatory by inducing a faster and higher production and gene expression of IL-1β, IL-6, and IL-8 than t-CPPD, m-CPPTβ and MSU crystals. The a-CPP phase did not show an inflammatory property. Accordingly, m-CPPD crystals led to stronger activation of NF-κB, p38, extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) MAPKs. Inhibition of NF-κB completely abrogated IL-1β and IL-8 synthesis and secretion induced by all CPP crystals. Also, inhibition of JNK and ERK1/2 MAPKs decreased both IL-1β secretion and NF-κB activation induced by CPP crystals. In vivo, IL-1β and CXCL1 production and neutrophil infiltration induced by m-CPPD crystals were greatly decreased by NF-κB inhibitor treatment.Conclusion: Our results suggest that the inflammatory potential of different CPP crystals relies on their ability to activate the MAPK-dependent NF-κB pathway. Studies are ongoing to investigate the underlying mechanisms

Gout and pseudo-gout-related crystals promote GLUT1-mediated glycolysis that governs NLRP3 and interleukin-1β activation on macrophages

Objective Macrophage activation by monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals mediates an interleukin (IL)-1β-dependent inflammation during gout and pseudo-gout flare, respectively. Since metabolic reprogramming of macrophages goes along with inflammatory responses dependently on stimuli and tissue environment, we aimed to decipher the role of glycolysis and oxidative phosphorylation in the IL-1β-induced microcrystal response. Methods Briefly, an in vitro study (metabolomics and real-time extracellular flux analysis) on MSU and CPP crystal-stimulated macrophages was performed to demonstrate the metabolic phenotype of macrophages. Then, the role of aerobic glycolysis in IL-1β production was evaluated, as well in vitro as in vivo using 18F-fluorodeoxyglucose positron emission tomography imaging and glucose uptake assay, and molecular approach of glucose transporter 1 (GLUT1) inhibition. Results We observed that MSU and CPP crystals led to a metabolic rewiring toward the aerobic glycolysis pathway explained by an increase in GLUT1 plasma membrane expression and glucose uptake on macrophages. Also, neutrophils isolated from human synovial fluid during gout flare expressed GLUT1 at their plasma membrane more frequently than neutrophils isolated from bloodstream. Both glucose deprivation and treatment with either 2-deoxyglucose or GLUT1 inhibitor suppressed crystal-induced NLRP3 activation and IL-1β production, and microcrystal inflammation in vivo. Conclusion In conclusion, we demonstrated that GLUT1-mediated glucose uptake is instrumental during the inflammatory IL-1β response induced by MSU and CPP crystals. These findings open new therapeutic paths to modulate crystal-related inflammation

HIV/SIV Infection Primes Monocytes and Dendritic Cells for Apoptosis

Subversion or exacerbation of antigen-presenting cells (APC) death modulates host/pathogen equilibrium. We demonstrated during in vitro differentiation of monocyte-derived macrophages and monocyte-derived dendritic cells (DCs) that HIV sensitizes the cells to undergo apoptosis in response to TRAIL and FasL, respectively. In addition, we found that HIV-1 increased the levels of pro-apoptotic Bax and Bak molecules and decreased the levels of anti-apoptotic Mcl-1 and FLIP proteins. To assess the relevance of these observations in the context of an experimental model of HIV infection, we investigated the death of APC during pathogenic SIV-infection in rhesus macaques (RMs). We demonstrated increased apoptosis, during the acute phase, of both peripheral blood DCs and monocytes (CD14+) from SIV+RMs, associated with a dysregulation in the balance of pro- and anti-apoptotic molecules. Caspase-inhibitor and death receptors antagonists prevented apoptosis of APCs from SIV+RMs. Furthermore, increased levels of FasL in the sera of pathogenic SIV+RMs were detected, compared to non-pathogenic SIV infection of African green monkey. We suggest that inappropriate apoptosis of antigen-presenting cells may contribute to dysregulation of cellular immunity early in the process of HIV/SIV infection

Editorial: “The Host-Microbiome Interplay in Colorectal Cancer”

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in male and the second in female, according to the World Health Organization. The risk factors to develop CRC include genetic, age, lifestyle/environmental factors (smoking, diet) and obesity; however, the exact cause of CRC is still unknown. Recent advances place the gut microbiome as a key player in the CRC development and progression as well as on the success for the disease treatment. In fact, multi-cohort studies involving geographically diverse populations have revealed distinct and reproducible changes in the microbiota composition in CRC patients and along CRC progression compared to non-CRC controls (Thomas et al., 2019; Wirbel et al., 2019; Yachida et al., 2019). Mechanistically, oncogenic properties of specific bacteria (so called oncomicrobes) have been attributed to bacterial toxins or virulence factors (Lopez et al., 2021). For example, host cell-DNA binding of the secondary metabolite colibactin produced by pks+ Eschericia coli induces DNA damage and consequently mutagenesis in intestinal epithelial cells (IECs) (Nougayrède et al., 2006; Pleguezuelos-Manzano et al., 2020) that promote tumorigenesis (Arthur et al., 2012). Enterotoxigenic Bacteroides fragilis strains producing the BF toxin can trigger a cascade of signaling pathways that lead to chronic intestinal inflammation (Th-17-dependent colitis), tissue injury and CRC tumorigenesis (Wu et al., 2009; Thiele Orberg et al., 2017; Cheng et al., 2020). Fusobacterium nucleatum, a bacterial species often found enriched in CRC cases, can induce oncogenic inflammatory responses and attenuate anti-tumor immunity via expressing FadA and Fap2 adhesins (Rubinstein et al., 2013; Kostic et al., 2014; Gur et al., 2015). In this context, this Research Topic aimed to highlight original manuscripts identifying new microbes with oncogenic properties or new cellular mechanisms associated to CRC initiation, promotion and development that could be used as novel tools for the prevention or treatment of CRC.The work of editors related to this research topic received financial support from: Spanish project RTI2018-098288-B-I00 financed by MCIN/AEI/10.13039/501100011033/FEDER “Una manera de hacer Europa” (GC), NIH R01-AI079145 (C-GL) and NIH R03-CA249111 (IT)

Microbial-Driven Immunological Memory and Its Potential Role in Microbiome Editing for the Prevention of Colorectal Cancer.

Over the last several years, many advances have been made in understanding the role of bacteria in the pathogenesis of gastrointestinal cancers. Beginning with Helicobacter pylori being recognized as the first bacterial carcinogen and the causative agent of most gastric cancers, more recent studies have examined the role of enteric microbes in colorectal cancer. In the digestive tract, these communities are numerous and have a complex interrelationship with local immune/inflammatory responses that impact the health of the host. As modifying the microbiome in the stomach has decreased the risk of gastric cancer, modifying the distal microbiome may decrease the risk of colorectal cancers. To date, very few studies have considered the notion that mucosal lymphocyte-dependent immune memory may confound attempts to change the microbial components in these communities. The goal of this review is to consider some of the factors impacting host-microbial interactions that affect colorectal cancer and raise questions about how immune memory responses to the local microbial consortium affect any attempt to modify the composition of the intestinal microbiome

Mechanisms of Calcium Pyrophosphate Crystal-induced Inflammation

International audienceHydrated calcium pyrophosphate (CPP) crystal deposition occurs in hyaline and fibrocartilage. Monoclinic and triclinic dihydrated phases, m-CPPD and t-CPPD respectively, are the two phases of CPP crystals identified in human joints and synovial fluids. They are associated with different clinical manifestations including asymptomatic, self-resolving acute arthritis, destructive arthropathies and severe osteoarthritis (1). CPP crystal-induced inflammation is driven mainly by interleukin (IL)-1β production (2). IL-1β activation is a two-step process: a first signal stimulates pro-IL-1β synthesis and the second signal IL-1β maturation and secretion that depend on caspase 1 and NLRP3 inflammasome activation. How different CPPD crystal phases stimulate inflammatory responses remains not understood. We assessed, in vitro, the inflammatory properties of four synthetic CPP phases [m-CPPD, t-CPPD, amorphous CPP (a-CPP) and m-CPPT (tetrahydrate) beta] using human monocyte cell line (THP-1) and mouse bone marrow-derived macrophages. CPP crystals displayed different inflammatory potential: m-CPPD crystals were the most phlogistic one whereas a-CPP and m-CPPT phases induced mild inflammation response. CPP crystal-induced IL-1β production was dependent of NLRP3 inflammasome activation which occurred through several mechanisms. CPP crystal-induced potassium efflux preceded ROS induction and mitochondrial disturbance and was independent of P2X7 channel. Better characterization of cytosolic potassium regulation will permit to identify new therapeutic pathways in microcrystal-related inflammation

Reduced Oxidative Burst by Primed Neutrophils in the Elderly Individuals Is Associated With Increased Levels of the CD16(bright)/CD62L(dim) Immunosuppressive Subset

International audienceThe aim of our study was to analyze polymorphonuclear neutrophil (PMN) functions in elderly individuals compared with those in healthy young participants, directly in whole blood to avoid issues with data interpretation related to cell isolation procedures. Despite the presence of increased circulating levels of proinflammatory cytokines, resting PMNs from the elderly individuals were not activated as shown by normal CD62L and CD11b expression at the PMN surface and normal constitutive reactive oxygen species (ROS) production. However, suboptimal stimulation induced modulations of CD62L and CD11b expression, which positively correlated with the interleukin-6 circulating level, suggesting a possible in vivo preactivation of old PMNs by this cytokine. In addition, PMN phagocytosis of opsonized Escherichia Coli was decreased in elderly individuals. Furthermore, upon preincubation of elderly whole-blood samples with tumor necrosis factor-a or Toll Receptor agonists, we observed a reduced PMN oxidative burst in response to formyl peptides. Elderly participants also exhibited an increased percentage of the immunosuppressive CD16(bright)/CD62L(dim) PMN subpopulation, which was characterized by a lower phagocytic index and a reduced ROS production compared with the CD16(bright)/CD62L(bright) subset. Thus, the reduced phagocytosis and ROS production associated with an expansion of immunosuppressive CD16(bright)/CD62L(dim) PMN subpopulation might be involved in the increased susceptibility to bacterial and fungal infections with old age