Pentraxin 3 Inhibits Complement-driven Macrophage Activation to Restrain Granuloma Formation in Sarcoidosis.

Rationale: Sarcoidosis is a multisystemic inflammatory disease characterized by the formation of granulomas in response to persistent stimuli. The long pentraxin PTX3 (pentraxin 3) has emerged as a component of humoral innate immunity with essential functions in the resolution of inflammation, but its role during granuloma formation is unknown. Objectives: To evaluate PTX3 as a modulator of pathogenic signals involved in granuloma formation and inflammation in sarcoidosis. Methods: Peripheral blood mononuclear cells obtained from patients with sarcoidosis harboring loss-of-function genetic variants and gene-deleted mice were used to assess the role of PTX3 in experimental models of granuloma formation in vitro and in vivo. The identified mechanisms of granulomatous inflammation were further evaluated in tissue and BAL samples and correlated with the disease course. Measurements and Main Results: We have identified a molecular link between PTX3 deficiency and the pathogenic amplification of complement activation to promote granuloma formation. Mechanistically, PTX3 deficiency licensed the complement component C5a-mediated activation of the metabolic checkpoint kinase mTORC1 (mammalian target of rapamycin complex 1) and the reprogramming of macrophages toward increased glycolysis to foster their proliferation and aggregation. This process sustained the further recruitment of granuloma-promoting immune cells and the associated proinflammatory microenvironment and influenced the clinical course of the disease. Conclusions: Our results identify PTX3 as a pivotal molecule that regulates complement-mediated signaling cues in macrophages to restrain granulomatous inflammation and highlight the therapeutic potential of this signaling axis in targeting granuloma formation in sarcoidosis.

Neuraminidase and SIGLEC15 modulate the host defense against pulmonary aspergillosis.

Influenza-associated pulmonary aspergillosis (IAPA) has been reported increasingly since the advent of use of neuraminidase (NA) inhibitors following the 2009 influenza pandemic. We hypothesize that blocking host NA modulates the immune response against Aspergillus fumigatus. We demonstrate that NA influences the host response against A. fumigatus in vitro and that oseltamivir increases the susceptibility of mice to pulmonary aspergillosis. Oseltamivir impairs the mouse splenocyte and human peripheral blood mononuclear cell (PBMC) killing capacity of A. fumigatus, and adding NA restores this defect in PBMCs. Furthermore, the sialic acid-binding receptor SIGLEC15 is upregulated in PBMCs stimulated with A. fumigatus. Silencing of SIGLEC15 decrease PBMC killing of A. fumigatus. We provide evidence that host NA activity and sialic acid recognition are important for anti-Aspergillus defense. NA inhibitors might predispose individuals with severe influenza to invasive aspergillosis. These data shed light on the pathogenesis of invasive fungal infections and may identify potential therapeutic targets.

Biofunctionalized Liposomes to Monitor Rheumatoid Arthritis Regression Stimulated by Interleukin-23 Neutralization.

Even after the revolution of rheumatoid arthritis (RA) treatment with biologic agents, this debilitating disease remains a major clinical problem. The outstanding outcomes of the systemic administration of antibodies (Abs) are narrowed by the risk of serious side effects and limited efficacy due to their short half-life. Interleukin-23 (IL-23) is a crucial pro-inflammatory cytokine involved in inflammation that potently enhances the generation of T-helper type-17 (Th17) cells. Hence, in this work, anti-IL-23 Abs are immobilized at the surface of liposomes to increase their therapeutic efficacy, being gold nanoparticles (AuNPs) incorporated to allow monitoring the biodistribution of the liposomes after systemic administration as well as due to their anti-inflammatory and antioxidant effects. A stable monodispersed liposomes' suspension with around 130 nm is produced and efficiently biofunctionalized with anti-IL-23 Abs. IL-23 capture and neutralization capacity are confirmed using activated macrophages. Biological assays demonstrate their hemocompatibility and cytocompatibility with human articular chondrocytes, macrophages, and endothelial cells. Moreover, the neutralization of IL-23 by the biofunctionalized liposomes efficiently decreases the production of IL-17A by peripheral blood mononuclear cells of healthy donors and RA patients who are activated to Th17 differentiation. Therefore, the developed formulation may be a promising strategy to treat RA.

Phagosomal removal of fungal melanin reprograms macrophage metabolism to promote antifungal immunity.

In response to infection, macrophages adapt their metabolism rapidly to enhance glycolysis and fuel specialized antimicrobial effector functions. Here we show that fungal melanin is an essential molecule required for the metabolic rewiring of macrophages during infection with the fungal pathogen Aspergillus fumigatus. Using pharmacological and genetic tools, we reveal a molecular link between calcium sequestration by melanin inside the phagosome and induction of glycolysis required for efficient innate immune responses. By remodeling the intracellular calcium machinery and impairing signaling via calmodulin, melanin drives an immunometabolic signaling axis towards glycolysis with activation of hypoxia-inducible factor 1 subunit alpha (HIF-1α) and phagosomal recruitment of mammalian target of rapamycin (mTOR). These data demonstrate a pivotal mechanism in the immunometabolic regulation of macrophages during fungal infection and highlight the metabolic repurposing of immune cells as a potential therapeutic strategy.

PTX3 Polymorphisms Influence Cytomegalovirus Reactivation After Stem-Cell Transplantation.

Background: Reactivation of latent human cytomegalovirus (CMV) in patients undergoing allogeneic stem-cell transplantation (HSCT) predisposes to several clinical complications and is therefore a major cause of morbidity and mortality. Although pentraxin-3 (PTX3) has been previously described to bind both human and murine CMV and mediate several host antiviral mechanisms, whether genetic variation in the PTX3 locus influences the risk of CMV infection is currently unknown. Methods: To dissect the contribution of genetic variation within PTX3 to the development of CMV infection, we analyzed described loss-of-function variants at the PTX3 locus in 394 recipients of HSCT and their corresponding donors and assessed the associated risk of CMV reactivation. Results: We report that the donor, but not recipient, h2/h2 haplotype in PTX3 increased the risk of CMV reactivation after 24 months following transplantation, with a significant effect on survival. Among recipients with h2/h2 donors, CMV seropositive patients as well as those receiving grafts from unrelated donors, regardless of the CMV serostatus, were more prone to develop viral reactivation after transplantation. Most importantly, the h2/h2 haplotype was demonstrated to display an influence toward risk of CMV reactivation comparable to that conferred by the unrelated status of the donor alone. Conclusions: Our findings demonstrate the important contribution of genetic variation in donor PTX3 to the risk of CMV reactivation in patients undergoing HSCT, highlighting a promising prognostic value of donor PTX3 to predict risk of CMV reactivation in this clinical setting.

Host Genetic Signatures of Susceptibility to Fungal Disease.

Our relative inability to predict the development of fungal disease and its clinical outcome raises fundamental questions about its actual pathogenesis. Several clinical risk factors are described to predispose to fungal disease, particularly in immunocompromised and severely ill patients. However, these alone do not entirely explain why, under comparable clinical conditions, only some patients develop infection. Recent clinical and epidemiological studies have reported an expanding number of monogenic defects and common polymorphisms associated with fungal disease. By directly implicating genetic variation in the functional regulation of immune mediators and interacting pathways, these studies have provided critical insights into the human immunobiology of fungal disease. Most of the common genetic defects reported were described or suggested to impair fungal recognition by the innate immune system. Here, we review common genetic variation in pattern recognition receptors and its impact on the immune response against the two major fungal pathogens Candida albicans and Aspergillus fumigatus. In addition, we discuss potential strategies and opportunities for the clinical translation of genetic information in the field of medical mycology. These approaches are expected to transfigure current clinical practice by unleashing an unprecedented ability to personalize prophylaxis, therapy and monitoring for fungal disease.

Metabolic Regulation of Innate Immunity to Fungal Infection.

In recent years, the renewed interest in immune cell metabolism has driven the emergence of a research field aimed at studying the role of metabolic processes during innate and adaptive immune responses. Although the specific requirements of myeloid cells after the canonical lipopolysaccharide/TLR4 stimulation have been extensively addressed, recent evidence suggests that this model may not represent a universally accurate metabolic blueprint. Instead, different microbial stimuli, pathogens, or tissue microenvironments trigger specific and complex metabolic rewiring of myeloid cells. This chapter aims to provide an overview of the metabolic heterogeneity in activated myeloid cells during fungal disease. Directions for future research in dissecting the uniqueness of metabolic signatures during fungal infection are suggested to ultimately provide new tailored diagnostic and therapeutic interventions.

Evaluation of Bronchoalveolar Lavage Fluid Cytokines as Biomarkers for Invasive Pulmonary Aspergillosis in At-Risk Patients.

Background: Invasive pulmonary aspergillosis (IPA) is an infection that primarily affects immunocompromised hosts, including hematological patients and stem-cell transplant recipients. The diagnosis of IPA remains challenging, making desirable the availability of new specific biomarkers. High-throughput methods now allow us to interrogate the immune system for multiple markers of inflammation with enhanced resolution. Methods: To determine whether a signature of alveolar cytokines could be associated with the development of IPA and used as a diagnostic biomarker, we performed a nested case-control study involving 113 patients at-risk. Results: Among the 32 analytes tested, IL-1ß, IL-6, IL-8, IL-17A, IL-23, and TNFα were significantly increased among patients with IPA, defining two clusters able to accurately differentiate cases of infection from controls. Genetic variants previously reported to confer increased risk of IPA compromised the production of specific cytokines and impaired their discriminatory potential toward infection. Collectively, our data indicated that IL-8 was the best performing cytokine, with alveolar levels ≥904 pg/mL predicting IPA with elevated sensitivity (90%), specificity (73%), and negative predictive value (88%). Conclusions: These findings highlight the existence of a specific profile of alveolar cytokines, with IL-8 being the dominant discriminator, which might be useful in supporting current diagnostic approaches for IPA.