Humoral pathways of innate immune regulation in granuloma formation.

The humoral arm of mammalian innate immunity regulates several molecular mechanisms involved in resistance to pathogens, inflammation, and tissue repair. Recent studies highlight the crucial role played by humoral mediators in granulomatous inflammation. However the molecular mechanisms linking the function of these soluble molecules to the initiation and maintenance of granulomas remain elusive. We propose that humoral innate immunity coordinates fundamental physiological processes in macrophages which, in turn, initiate activation and transformation events that enable granuloma formation. We discuss the involvement of humoral mediators in processes such as immune activation, phagocytosis, metabolism, and tissue remodeling, and how these can dictate macrophage functionality during granuloma formation. These advances present opportunities for discovering novel disease factors and developing targeted, more effective treatments for granulomatous diseases.

Profiling Bacteria in the Lungs of Patients with Severe Influenza Versus COVID-19 with or without Aspergillosis.

RATIONALE: The influence of the lung bacterial microbiome, including potential pathogens, in patients with influenza- or COVID-19-associated pulmonary aspergillosis (IAPA or CAPA) is yet to be explored. OBJECTIVES: To explore the composition of the lung bacterial microbiome and its association with viral and fungal infection, immunity and outcome in severe influenza versus COVID-19 with or without aspergillosis. METHODS: We performed a retrospective study in mechanically ventilated influenza and COVID-19 patients with or without invasive aspergillosis in whom bronchoalveolar lavage (BAL) for bacterial culture (with or without PCR) was obtained within two weeks after ICU admission. Additionally, 16S rRNA gene sequencing data and viral and bacterial load of BAL samples from a subset of these patients, and of patients requiring non-invasive ventilation, were analyzed. We integrated 16S rRNA gene sequencing data with existing immune parameter datasets. MEASUREMENTS AND MAIN RESULTS: Potential bacterial pathogens were detected in 20% (28/142) of influenza and 37% (104/281) of COVID-19 patients, while aspergillosis was detected in 38% (54/142) of influenza and 31% (86/281) of COVID-19 patients. A significant association between bacterial pathogens in BAL and 90-day mortality was found only in influenza patients, particularly IAPA patients. COVID-19 but not influenza patients showed increased pro-inflammatory pulmonary cytokine responses to bacterial pathogens. CONCLUSIONS: Aspergillosis is more frequently detected in lungs of severe influenza patients than bacterial pathogens. Detection of bacterial pathogens associates with worse outcome in influenza patients, particularly in those with IAPA, but not in COVID-19 patients. The immunological dynamics of tripartite viral-fungal-bacterial interactions deserve further investigation. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Deregulated immune cell recruitment orchestrated by c-MET impairs pulmonary inflammation and fibrosis.

BACKGROUND: Pulmonary fibrosis (PF) represents the pathologic end stage of several interstitial lung diseases (ILDs) associated with high morbidity and mortality rates. However, current treatments can only delay disease progression rather than provide a cure. The role of inflammation in PF progression is well-established, but new insights into immune regulation are fundamental for developing more efficient therapies. c-MET signaling has been implicated in the migratory capacity and effector functions of immune cells. Nevertheless, the role of this signaling pathway in the context of PF-associated lung diseases remains unexplored. METHODS: To determine the influence of c-MET in immune cells in the progression of pulmonary fibrosis, we used a conditional deletion of c-Met in immune cells. To induce pulmonary fibrosis mice were administered with bleomycin (BLM) intratracheally. Over the course of 21 days, mice were assessed for weight change, and after euthanasia at different timepoints, bronchoalveolar lavage fluid cells and lung tissue were assessed for inflammation and fibrosis. Furthermore, c-MET expression was assessed in cryobiopsy sections, bronchoalveolar lavage fluid cells samples and single cell RNA-sequencing dataset from human patients with distinct interstitial lung diseases. RESULTS: c-MET expression was induced in lung immune cells, specifically in T cells, interstitial macrophages, and neutrophils, during the inflammatory phase of BLM-induced PF mouse model. Deletion of c-Met in immune cells correlated with earlier weight recovery and improved survival of BLM-treated mice. Moreover, the deletion of c-Met in immune cells was associated with early recruitment of the immune cell populations, normally found to express c-MET, leading to a subsequent attenuation of the cytotoxic and proinflammatory environment. Consequently, the less extensive inflammatory response, possibly coupled with tissue repair, culminated in less exacerbated fibrotic lesions. Furthermore, c-MET expression was up-regulated in lung T cells from patients with fibrosing ILD, suggesting a potential involvement of c-MET in the development of fibrosing disease. CONCLUSIONS: These results highlight the critical contribution of c-MET signaling in immune cells to their enhanced uncontrolled recruitment and activation toward a proinflammatory and profibrotic phenotype, leading to the exacerbation of lung injury and consequent development of fibrosis.

Fungal and host protein persulfidation are functionally correlated and modulate both virulence and antifungal response.

Aspergillus fumigatus is a human fungal pathogen that can cause devastating pulmonary infections, termed "aspergilloses," in individuals suffering immune imbalances or underlying lung conditions. As rapid adaptation to stress is crucial for the outcome of the host-pathogen interplay, here we investigated the role of the versatile posttranslational modification (PTM) persulfidation for both fungal virulence and antifungal host defense. We show that an A. fumigatus mutant with low persulfidation levels is more susceptible to host-mediated killing and displays reduced virulence in murine models of infection. Additionally, we found that a single nucleotide polymorphism (SNP) in the human gene encoding cystathionine γ-lyase (CTH) causes a reduction in cellular persulfidation and correlates with a predisposition of hematopoietic stem cell transplant recipients to invasive pulmonary aspergillosis (IPA), as correct levels of persulfidation are required for optimal antifungal activity of recipients' lung resident host cells. Importantly, the levels of host persulfidation determine the levels of fungal persulfidation, ultimately reflecting a host-pathogen functional correlation and highlighting a potential new therapeutic target for the treatment of aspergillosis.

MAVS Expression in Alveolar Macrophages Is Essential for Host Resistance against Aspergillus fumigatus.

Our recent data demonstrate a critical role of the RIG-I-like receptor family in regulating antifungal immunity against Aspergillus fumigatus in a murine model. However, the importance of this pathway in humans and the cell types that use this innate immune receptor family to detect A. fumigatus remain unresolved. In this study, using patients who underwent hematopoietic stem cell transplantation, we demonstrate that a polymorphism in human MAVS present in the donor genome was associated with the incidence of invasive pulmonary aspergillosis. Moreover, in a separate cohort of confirmed invasive pulmonary aspergillosis patients, polymorphisms in the IFIH1 gene alter the inflammatory response, including IFN-responsive chemokines. Returning to our murine model, we now demonstrate that CD11c+ Siglec F+ alveolar macrophages require Mavs expression to maintain host resistance against A. fumigatus. Our data support the role of MAVS signaling in mediating antifungal immunity in both mice and humans at least in part through the role of MAVS-dependent signaling in alveolar macrophages.

Recognition of DHN-melanin by a C-type lectin receptor is required for immunity to Aspergillus.

Resistance to infection is critically dependent on the ability of pattern recognition receptors to recognize microbial invasion and induce protective immune responses. One such family of receptors are the C-type lectins, which are central to antifungal immunity. These receptors activate key effector mechanisms upon recognition of conserved fungal cell-wall carbohydrates. However, several other immunologically active fungal ligands have been described; these include melanin, for which the mechanism of recognition is hitherto undefined. Here we identify a C-type lectin receptor, melanin-sensing C-type lectin receptor (MelLec), that has an essential role in antifungal immunity through recognition of the naphthalene-diol unit of 1,8-dihydroxynaphthalene (DHN)-melanin. MelLec recognizes melanin in conidial spores of Aspergillus fumigatus as well as in other DHN-melanized fungi. MelLec is ubiquitously expressed by CD31+ endothelial cells in mice, and is also expressed by a sub-population of these cells that co-express epithelial cell adhesion molecule and are detected only in the lung and the liver. In mouse models, MelLec was required for protection against disseminated infection with A. fumigatus. In humans, MelLec is also expressed by myeloid cells, and we identified a single nucleotide polymorphism of this receptor that negatively affected myeloid inflammatory responses and significantly increased the susceptibility of stem-cell transplant recipients to disseminated Aspergillus infections. MelLec therefore recognizes an immunologically active component commonly found on fungi and has an essential role in protective antifungal immunity in both mice and humans.

Inflammation Is a Histological Characteristic of Skeletal Muscle in Chronic Limb Threatening Ischemia.

BACKGROUND: The loss of skeletal muscle is a prognostic factor in several diseases including in patients with chronic limb threatening ischemia (CLTI). Patients with CLTI also have a lower skeletal mass and area when compared to those with claudication. However, there are no currently available data regarding the histological characteristics of core muscles in patients with CLTI. This study aims to determine the differences in core skeletal muscles between patients with claudication and those with CLTI. The second aim is to evaluate the differences in myokines, which are molecules secreted by skeletal muscle, between patients with claudication and those with CLTI. METHODS: An observational, prospective study was conducted from January 2018 to July 2022 involving consecutive patients with peripheral arterial disease (PAD). The clinical characteristics were registered. In PAD patients with surgical indication for common femoral artery approach, samples of sartorius skeletal muscle (and not from the limb muscles directly involved in the ischemic process) were collected. The samples were submitted to histological characterization on hematoxylin-eosin and to immunohistochemical analysis to detect CD45+ leukocytes and CD163+ macrophages. The extent of the inflammatory cells (leukocytes and macrophages) was semiquantitatively assessed using a 0-to-4 grade scale as follows: absent (0†), mild (†), moderate (††), severe (†††), and very severe (††††). Serum levels of myokines: irisin, myostatin, IL-8, and lL-6 were determined with multiplex bead-based immunoassay. RESULTS: 119 patients (mean age: 67.58 ± 9.60 years old, 79.80% males) 64 with claudication and 54 with CLTI were enrolled in the study. No differences were registered between patients with claudication and those with CLTI on age, gender, cardiovascular risk factors, and medication, except on smoking habits. There was a significantly higher prevalence of smokers and a higher smoking load in the claudication group. Samples of sartorius skeletal muscle from 40 patients (14 with claudication and 26 with CLTI) were submitted to histological analysis. No differences were found in skeletal muscle fibers preservation, trauma, or hemorrhage (on hematoxylin-eosin staining). However, in the immunohistochemistry study, we found more inflammatory cells CD45+ leukocytes in patients with CLTI when compared to those with claudication [CD45+ ≥ moderate (††): claudication (n = 14): 4; 28.57%; CLTI (n = 25): 16; 64.00%; P = 0.034]. Patients with CLTI also had higher tissue levels of CD163+ macrophages, but this difference was not significant [CD163+ ≥ moderate (††): claudication (n = 13): 7; 53.85%; CLTI (n = 27): 21; 77.78%; P = 0.122]. The serum levels of the myokines, irisin, and myostatin were below the lower limit of detection, in the majority of patients, so no valid results were obtained. However, patients with CLTI had a higher serum level of Interleukin (IL)-6 and IL-8. CONCLUSIONS: CLTI patients exhibit increased quantities of leukocytes in their sartorius muscle, as well as elevated serum levels of myokines IL-8 and IL-6. Inflamed skeletal muscle can contribute to the loss of muscle mass and account for the lower density of skeletal muscle observed in CLTI. Additionally, inflamed skeletal muscle may contribute to the development of systemic inflammation through the secretion of pro-inflammatory cytokines into the systemic circulation. Halting the inflammatory process could eventually improve the prognosis of CLTI patients.

Higher Levels of Cytokines in Patients with Chronic Limb-Threatening Ischemia.

BACKGROUND: Inflammation is a key element in the initiation and progression of peripheral arterial disease (PAD). Understanding the impact of inflammatory molecules, as cytokines in PAD could help us to improve the prognosis of these patients. The main goal of this study was to compare the serum level of cytokines between patients with claudication to those with chronic limb-threatening ischemia (CLTI). The second objective was to evaluate the relationship between the levels of cytokines and death or amputation rate. METHODS: An observational, single-center, and prospective study was conducted from January 2018 to July 2022. The study was approved by the ethical commission of the Local Hospital (75/2017). Patients with PAD, suggested by the clinical history and objective examination and confirmed with ankle-brachial index, attending vascular surgery consultations of the first author were included. The following exclusion criteria were applied: i) bedridden individuals or subjects who refused to participate in the protocol; ii) diseases responsible for body composition changes or proinflammatory state; iii) recent diet change, iv) active malignancy, v) autoimmune disease, vi) active infection, vii) chronic renal failure (glomerular filtration rate <30 mL/min/1.73 m2), or viii) heart failure in the past 3 months. This cohort was observed at admission, 3, 6, and 12 months. A panel of 27 cytokines was determined with ELISA, at baseline. RESULTS: We included 119 subjects (mean age: 67.58 ± 9.60 years old; 79.80% males), 65 patients with claudication and 54 with CLTI. From the 27 cytokines analyzed, patients with CLTI, when compared to those with claudication, had a higher serum level of 11 cytokines: IL1ra, IL-6, IL-8, IL12 p70, G-CSF, IP-10, MCP-1, MIP-1α, PDGF-ß, RANTES, and TNF-α. From the group of patients with CLTI those who underwent a major amputation had a higher serum level of FGF-basic [median = 49.04; interquartile range = 37.03-52.49; versus median = 33.04; interquartile range = 28.60-38.98; P = 0.001]. CONCLUSIONS: Patients with CLTI have higher serum level of inflammatory cytokines, which may have role in the prognosis of these patients.

Evaluation of Echinacea purpurea Extracts as Immunostimulants: Impact on Macrophage Activation.

Echinacea purpurea has been traditionally used to strengthen the immune system. Therefore, herein, we investigated the potential of E. purpurea aqueous extracts (AEs) obtained from flowers (F), leaves (L), or roots (R) as an immune booster in human primary monocyte-derived macrophages (hMDMs). Additionally, to identify the main class of compounds (phenolic/carboxylic acids vs. alkylamides) responsible for the bioactivity, the three AEs were fractioned by semi-preparative high-performance liquid chromatography (HPLC). The AEs and the isolated phenolic/carboxylic acidic fractions were not cytotoxic for hMDMs for all tested concentrations, as confirmed by the metabolic activity and DNA content assays. Moreover, AE drastically induced the production of the interleukin (IL)-6 and tumor necrosis factor (TNF)-α, with a minimal effect on IL-1ß and prostaglandin E2 (PGE2), supporting their potential for macrophage activation. Interestingly, in the presence of the phenolic/carboxylic acidic fractions, this efficacy considerably decreased, suggesting a complementary effect between compounds. AE also triggered the phosphorylation of the extracellular signal-regulated kinase (ERK) 1/2 and p38 signaling pathways and upregulated the cyclooxygenase (COX)-2 expression in hMDMs. Overall, AE-F was demonstrated to be the most powerful immunostimulant extract that can be related to their higher number in identified bioactive compounds compared to AE-L and AE-R. These results highlight the efficiency of E. purpurea AE to enhance the function of a key cell type of the immune system and their potential as immunostimulant formulations for patients with a compromised immune system due to certain diseases (e.g., acquired immunodeficiencies) and treatments (e.g., chemotherapy).

Multicentric Study on the Clinical Mycology Capacity and Access to Antifungal Treatment in Portugal.

The success of the clinical management of invasive fungal diseases (IFD) is highly dependent on suitable tools for timely and accurate diagnosis for effective treatment. An in-depth analysis of the ability of European institutions to promptly and accurately diagnose IFD was previously conducted to identify limitations and aspects to improve. Here, we evaluated and discussed the specific case of Portugal, for which, to our knowledge, there are no reports describing the national mycological diagnostic capacity and access to antifungal treatment. Data from 16 Portuguese medical institutions were collected via an online electronic case report form covering different parameters, including institution profile, self-perceived IFD incidence, target patients, diagnostic methods and reagents, and available antifungals. The majority of participating institutions (69%) reported a low-very low incidence of IFD, with Candida spp. indicated as the most relevant fungal pathogen, followed by Aspergillus spp. and Cryptococcus spp. All institutions had access to culture and microscopy, whereas 94 and 88% were able to run antigen-detection assays and molecular tests, respectively. All of the institutions capable of providing antifungal therapy declared to have access to at least one antifungal. However, echinocandins were only available at 85% of the sites. Therapeutic drug monitoring (TDM) was reported to remain a very restricted practice in Portugal, being available in 19% of the institutions, with the TDM of itraconazole and posaconazole performed in only 6% of them. Importantly, several of these resources are outsourced to external entities. Except for TDM, Portugal appears to be well-prepared concerning the overall capacity to diagnose and treat IFD. Future efforts should focus on promoting the widespread availability of TDM and improved access to multiple classes of antifungals, to further improve patient outcomes.

Enhanced Sensitivity in Optical Sensors through Self-Image Theory and Graphene Oxide Coating.

This paper presents an approach to enhancing sensitivity in optical sensors by integrating self-image theory and graphene oxide coating. The sensor is specifically engineered to quantitatively assess glucose concentrations in aqueous solutions that simulate the spectrum of glucose levels typically encountered in human saliva. Prior to sensor fabrication, the theoretical self-image points were rigorously validated using Multiphysics COMSOL 6.0 software. Subsequently, the sensor was fabricated to a length corresponding to the second self-image point (29.12 mm) and coated with an 80 µm/mL graphene oxide film using the Layer-by-Layer technique. The sensor characterization in refractive index demonstrated a wavelength sensitivity of 200 ± 6 nm/RIU. Comparative evaluations of uncoated and graphene oxide-coated sensors applied to measure glucose in solutions ranging from 25 to 200 mg/dL showed an eightfold sensitivity improvement with one bilayer of Polyethyleneimine/graphene. The final graphene oxide-based sensor exhibited a sensitivity of 10.403 ± 0.004 pm/(mg/dL) and demonstrated stability with a low standard deviation of 0.46 pm/min and a maximum theoretical resolution of 1.90 mg/dL.

Intramacrophage lipid accumulation compromises T cell responses and is associated with impaired drug therapy against visceral leishmaniasis.

Under perturbing conditions such as infection with Leishmania, a protozoan parasite living within the phagosomes in mammalian macrophages, cellular and organellar structures, and metabolism are dynamically regulated for neutralizing the pressure of parasitism. However, how modulations of the host cell metabolic pathways support Leishmania infection remains unknown. Herein, we report that lipid accumulation heightens the susceptibility of mice to L. donovani infection and promotes resistance to first-line anti-leishmanial drugs. Despite being pro-inflammatory, the in vitro generated uninfected lipid-laden macrophages (LLMs) or adipose-tissue macrophages (ATMs) display lower levels of reactive oxygen and nitrogen species. Upon infection, LLMs secrete higher IL-10 and lower IL-12p70 cytokines, inhibiting CD4+ T cell activation and Th1 response suggesting a key modulatory role for intramacrophage lipid accumulation in anti-leishmanial host defence. We, therefore, examined this causal relationship between lipids and immunomodulation using an in vivo high-fat diet (HFD) mouse model. HFD increased the susceptibility to L. donovani infection accompanied by a defective CD4+ Th1 and CD8+ T cell response. The white adipose tissue of HFD mice displays increased susceptibility to L. donovani infection with the preferential infection of F4/80+ CD11b+ CD11c+ macrophages with higher levels of neutral lipids reserve. The HFD increased resistance to a first-line anti-leishmanial drug associated with a defective adaptive immune response. These data demonstrate that the accumulation of neutral lipids contributes to susceptibility to visceral leishmaniasis hindering host-protective immune response and reducing the efficacy of antiparasitic drug therapies.

Inflammation and Loss of Skeletal Muscle Mass in Chronic Limb Threatening Ischemia.

BACKGROUND: Lower extremity peripheral arterial disease (PAD) is an atherosclerotic disease of the lower extremities. Atherosclerosis, inflammation, and sarcopenia are independently associated and potentiate each other. Inflammation is deeply involved in the formation and progression of atherosclerosis and is also involved in the pathophysiology of sarcopenia. Sarcopenia is defined as low muscle mass, with low muscle strength. This study aims to determine the differences in skeletal muscle characteristics and in inflammatory parameters between patients with claudication and with chronic limb threatening ischemia (CLTI). METHODS: An observational, prospective study in patients with PAD was conducted from January 2018 to December 2020. The clinical characteristics and the cardiovascular risk factors were prospectively registered. The inflammatory parameters determined were: positive acute phase proteins (C-reactive Protein- CRP- and fibrinogen) and negative acute phase proteins albumin, total cholesterol and high-density lipoprotein (HDL). The skeletal muscle area and density were quantified with a computed topography (CT) scan. The strength was determined with a Jamar® hydraulic hand dynamometer. RESULTS: A total of 116 patients (mean age: 67.65 ± 9.53 years-old) 64% with claudication and 46% with CLTI were enrolled in the study. No differences were registered between patients with claudication and CLTI on age, cardiovascular risk factors (hypertension, dyslipidemia, diabetes mellitus, and smoking habits) and medication. There was a higher prevalence of men in the claudication group (88.89% vs. 71.70%, P = 0.019). Analyzing the inflammatory parameters, we noted that patients with CLTI had increased serum levels of positive acute phase proteins: CRP (37.53 ± 46.61 mg/L vs. 9.18 ± 26.12 mg/L, P = 0.000), and fibrinogen (466.18 ± 208.07 mg/dL vs. 317.37 ± 79.42 mg/dL, P = 0.000). CLTI patients had decreased negative acute phase proteins: albumin (3.53 ± 0.85 g/dL vs. 3.91 ± 0.72 g/dL, P = 0.001), total cholesterol (145.41 ± 38.59 mg/dL vs. 161.84 ± 34.94 mg/dL, P = 0.013) and HDL (38.70 ± 12.19 mg/dL vs. 51.31 ± 15.85 mg/dL, P = 0.000). We noted that patients with CLTI had lower skeletal muscle area and mass (14,349.77 ± 3,036.60 mm2 vs. 15,690.56 ± 3,183.97 mm2P = 0.013; 10.11 ± 17.03HU vs. 18.02 ± 13.63HU P = 0.013). After adjusting for the variable sex, the association between skeletal muscle density and CLTI persisted (r (97) = -0.232, P = 0.021). The groups did not differ in strength (patients with claudication: 25.39 ± 8.23 Kgf vs. CLTI: 25.17 ± 11.95 Kgf P = 0.910). CONCLUSIONS: CLTI patients have decreased skeletal muscle mass and a systemic inflammation status. Recognizing the deleterious triad of atherosclerosis, inflammation and loss of skeletal mass patients with CLTI is an opportunity to improve medical therapy and to perform a timely intervention to stop this vicious cycle.

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.

Positive allosteric modulation of indoleamine 2,3-dioxygenase 1 restrains neuroinflammation.

l-tryptophan (Trp), an essential amino acid for mammals, is the precursor of a wide array of immunomodulatory metabolites produced by the kynurenine and serotonin pathways. The kynurenine pathway is a paramount source of several immunoregulatory metabolites, including l-kynurenine (Kyn), the main product of indoleamine 2,3-dioxygenase 1 (IDO1) that catalyzes the rate-limiting step of the pathway. In the serotonin pathway, the metabolite N-acetylserotonin (NAS) has been shown to possess antioxidant, antiinflammatory, and neuroprotective properties in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). However, little is known about the exact mode of action of the serotonin metabolite and the possible interplay between the 2 Trp metabolic pathways. Prompted by the discovery that NAS neuroprotective effects in EAE are abrogated in mice lacking IDO1 expression, we investigated the NAS mode of action in neuroinflammation. We found that NAS directly binds IDO1 and acts as a positive allosteric modulator (PAM) of the IDO1 enzyme in vitro and in vivo. As a result, increased Kyn will activate the ligand-activated transcription factor aryl hydrocarbon receptor and, consequently, antiinflammatory and immunoregulatory effects. Because NAS also increased IDO1 activity in peripheral blood mononuclear cells of a significant proportion of MS patients, our data may set the basis for the development of IDO1 PAMs as first-in-class drugs in autoimmune/neuroinflammatory diseases.

Immunohistochemical identification of a malignant catarrhal fever virus in cattle with renal diseases from Paraná state, Southern Brazil: a retrospective epidemiological study.

Malignant catarrhal fever (MCF) is a viral infectious disease caused by specific members of the Macavirus genus that are referred to as the MCF virus (MCFV) complex group. This study determined the prevalence of MCFV-associated infections in cattle within the mesoregions of the state of Paraná, Southern Brazil, by analyzing the histopathologic patterns of renal lesions in association with positive immunoreactivity to intralesional antigens of MCFV. Intracytoplasmic MCFV antigens were identified in 41.7% (48/115) of the kidneys of cattle evaluated. Lymphocytic interstitial nephritis, vascular degeneration, and ballooning degeneration of the renal tubules were the principal histopathological findings associated with positive immunoreactivity to MCFV. The results indicate that MCFV infections are endemic within the state of Paraná and suggest that the kidney can be of diagnostic value in suspected cases of MCF-associated infections in cattle. Furthermore, the utilization of an in situ diagnostic technique resulted in the detection of a greater number of cases of infections by MCFV than previously identified using other diagnostic methods. Additionally, degenerative vascular lesions of the kidney should be considered during the establishment of a histological diagnosis of MCFV-induced infections in cattle in the absence of fibrinoid change or necrotizing vasculitis.

Lung microbiota predict invasive pulmonary aspergillosis and its outcome in immunocompromised patients.

RATIONALE: Recent studies have revealed that the lung microbiota of critically ill patients is altered and predicts clinical outcomes. The incidence of invasive fungal infections, namely, invasive pulmonary aspergillosis (IPA), in immunocompromised patients is increasing, but the clinical significance of variations in lung bacterial communities is unknown. OBJECTIVES: To define the contribution of the lung microbiota to the development and course of IPA. METHODS AND MEASUREMENTS: We performed an observational cohort study to characterise the lung microbiota in 104 immunocompromised patients using bacterial 16S ribosomal RNA gene sequencing on bronchoalveolar lavage samples sampled on clinical suspicion of infection. Associations between lung dysbiosis in IPA and pulmonary immunity were evaluated by quantifying alveolar cytokines and chemokines and immune cells. The contribution of microbial signatures to patient outcome was assessed by estimating overall survival. MAIN RESULTS: Patients diagnosed with IPA displayed a decreased alpha diversity, driven by a markedly increased abundance of the Staphylococcus, Escherichia, Paraclostridium and Finegoldia genera and a decreased proportion of the Prevotella and Veillonella genera. The overall composition of the lung microbiome was influenced by the neutrophil counts and associated with differential levels of alveolar cytokines. Importantly, the degree of bacterial diversity at the onset of IPA predicted the survival of infected patients. CONCLUSIONS: Our results reveal the lung microbiota as an understudied source of clinical variation in patients at risk of IPA and highlight its potential as a diagnostic and therapeutic target in the context of respiratory fungal diseases.

Targeting immunometabolism in host-directed therapies to fungal disease.

Fungal infections affect over a billion people and are responsible for more than 1.5 million deaths each year. Despite progress in diagnostic and therapeutic approaches, the management of severe fungal infections remains a challenge. Recently, the reprogramming of cellular metabolism has emerged as a central mechanism through which the effector functions of immune cells are supported to promote antifungal activity. An improved understanding of the immunometabolic signatures that orchestrate antifungal immunity, together with the dissection of the mechanisms that underlie heterogeneity in individual immune responses, may therefore unveil new targets amenable to adjunctive host-directed therapies. In this review, we highlight recent advances in the metabolic regulation of host-fungus interactions and antifungal immune responses, and outline targetable pathways and mechanisms with promising therapeutic potential.

Tryptophan catabolites from microbiota engage aryl hydrocarbon receptor and balance mucosal reactivity via interleukin-22.

Endogenous tryptophan (Trp) metabolites have an important role in mammalian gut immune homeostasis, yet the potential contribution of Trp metabolites from resident microbiota has never been addressed experimentally. Here, we describe a metabolic pathway whereby Trp metabolites from the microbiota balance mucosal reactivity in mice. Switching from sugar to Trp as an energy source (e.g., under conditions of unrestricted Trp availability), highly adaptive lactobacilli are expanded and produce an aryl hydrocarbon receptor (AhR) ligand-indole-3-aldehyde-that contributes to AhR-dependent Il22 transcription. The resulting IL-22-dependent balanced mucosal response allows for survival of mixed microbial communities yet provides colonization resistance to the fungus Candida albicans and mucosal protection from inflammation. Thus, the microbiota-AhR axis might represent an important strategy pursued by coevolutive commensalism for fine tuning host mucosal reactivity contingent on Trp catabolism.

Association of Skeletal Muscle and Cardiovascular Risk Factors in Patients with Lower Extremity Arterial Disease.

BACKGROUND: Sarcopenia is defined as low muscle mass, with low muscle strength or low physical performance. The skeletal muscle mass (or density) and strength are inversely associated with cardiovascular risk factors. We aim to determine the relationship between skeletal muscle characteristics (strength, mass, area), and cardiovascular risk factors in a population with lower extremity artery disease (LEAD). METHODS: An observational, prospective study including patients with LEAD was conducted from January 2018 to December 2020. The cardiovascular risk factors and anthropometric measurements were prospectively registered. The skeletal muscle characteristics (area, density/mass and strength) were analysed. The skeletal muscle area and density were quantified with a CT scan. The strength was determined with a Jamar® hydraulic hand dynamometer. RESULTS: A total of 96 patients with LEAD with 67.70 ± 10.11 years-old were enrolled in the study. The most prevalent cardiovascular risk factor was hypertension, followed by dyslipidemia and diabetes. Patients with diabetes had a lower handgrip strength and skeletal muscle density, when compared with patients without diabetes (strength: 19.67 ± 9.98 kgf vs. 26.79 ± 11.80 kgf, P = 0.002 and skeletal muscle density: 10.58 ± 17.61 HU vs. 18.17 ± 15.33 HU, P = 0.032). There was a trend for the association between the presence of cardiovascular risk factors (hypertension and dyslipidemia) and a decrease in skeletal muscle density and strength (density: hypertension: 13.46 ± 16.74 HU vs. 20.38 ± 11.63 HU P=0.055; dyslipidemia: 13.57 ± 17.16 HU vs. 17.74 ± 13.00 HU P= 0.315; strength- hypertension: 22.55 ± 10.08 kgf vs. 27.58 ± 15.11 P= 0.073; dyslipidemia: 22.80 ± 10.52 kgf vs. 25.28 ± 13.14 kgf P= 0.315). Interestingly, we found that smokers had a favorable skeletal muscle characteristic, which could be explained by the higher prevalence of diabetes in nonsmokers. CONCLUSIONS: The indicators of skeletal muscle dysfunction (strength and density) are associated to the presence of diabetes in patients with LEAD. Therapeutic strategies to improve the skeletal muscle characteristics could have a role in improving LEAD risk factors, particularly diabetes.