STING Targeting in Lung Diseases.

The cGAS-STING pathway displays important functions in the regulation of innate and adaptive immunity following the detection of microbial and host-derived DNA. Here, we briefly summarize biological functions of STING and review recent literature highlighting its important contribution in the context of respiratory diseases. Over the last years, tremendous progress has been made in our understanding of STING activation, which has favored the development of STING agonists or antagonists with potential therapeutic benefits. Antagonists might alleviate STING-associated chronic inflammation and autoimmunity. Furthermore, pharmacological activation of STING displays strong antiviral properties, as recently shown in the context of SARS-CoV-2 infection. STING agonists also elicit potent stimulatory activities when used as an adjuvant promoting antitumor responses and vaccines efficacy.

Protective Role of the Nucleic Acid Sensor STING in Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is the most common and severe type of interstitial lung disease for which current treatments display limited efficacy. IPF is largely driven by host-derived danger signals released upon recurrent local tissue damage. Here we explored the roles of self-DNA and stimulator of interferon genes (STING), a protein belonging to an intracellular DNA sensing pathway that leads to type I and/or type III interferon (IFN) production upon activation. Using a mouse model of IPF, we report that STING deficiency leads to exacerbated pulmonary fibrosis with increased collagen deposition in the lungs and excessive remodeling factors expression. We further show that STING-mediated protection does not rely on type I IFN signaling nor on IL-17A or TGF-ß modulation but is associated with dysregulated neutrophils. Together, our data support an unprecedented immunoregulatory function of STING in lung fibrosis.

Self-DNA release and STING-dependent sensing drives inflammation to cigarette smoke in mice.

Cigarette smoke exposure is a leading cause of chronic obstructive pulmonary disease (COPD), a major health issue characterized by airway inflammation with fibrosis and emphysema. Here we demonstrate that acute exposure to cigarette smoke causes respiratory barrier damage with the release of self-dsDNA in mice. This triggers the DNA sensor cGAS (cyclic GMP-AMP synthase) and stimulator of interferon genes (STING), driving type I interferon (IFN I) dependent lung inflammation, which are attenuated in cGAS, STING or type I interferon receptor (IFNAR) deficient mice. Therefore, we demonstrate a critical role of self-dsDNA release and of the cGAS-STING-type I interferon pathway upon cigarette smoke-induced damage, which may lead to therapeutic targets in COPD.

Mechanism of splenic cell death and host mortality in a Plasmodium yoelii malaria model.

Malaria is a fatal disease that displays a spectrum of symptoms and severity, which are determined by complex host-parasite interactions. It has been difficult to study the effects of parasite strains on disease severity in human infections, but the mechanisms leading to specific disease phenotypes can be investigated using strains of rodent malaria parasites that cause different disease symptoms in inbred mice. Using a unique mouse malaria model, here we investigated the mechanisms of splenic cell death and their relationship to control of parasitemia and host mortality. C57BL/6 mice infected with Plasmodium yoelii nigeriensis N67C display high levels of pro-inflammatory cytokines and chemokines (IL-6, IFN-γ, TNF-α, CXCL1, and CCL2) and extensive splenic damage with dramatic reduction of splenic cell populations. These disease phenotypes were rescued in RAG2-/-, IFN-γ-/-, or T cell depleted mice, suggesting IFN-γ and T cell mediated disease mechanisms. Additionally, apoptosis was one of the major pathways involved in splenic cell death, which coincides with the peaks of pro-inflammatory cytokines. Our results demonstrate the critical roles of T cells and IFN-γ in mediating splenic cell apoptosis, parasitemia control, and host lethality and thus may provide important insights for preventing/reducing morbidity associated with severe malaria in humans.

Evaluating the effects of refined carbohydrate and fat diets with acute ethanol consumption using a mouse model of alcoholic liver injury.

Alcoholism is a multifactorial and complex disorder responsible for 5.9% of deaths worldwide. Excessive consumption of ethanol (Et-OH) induces alcoholic liver disease (ALD), a condition comprising a spectrum of clinical signs and morphological changes, ranging from fatty liver (steatosis) to more severe forms of chronic liver injury. Secondary cofactors, such as nutritional and hepatotoxic comorbid conditions, can also contribute to liver disease development. Here we investigated the effects in the progression of ALD following short-term exposure to diet high in refined carbohydrates (HC), a high-sugar and -butter (HSB) hypercaloric diet and acute Et-OH consumption. HSB diet increased the body weight (BW) and adiposity independently of acute Et-OH consumption. HC diet did not affect BW but increased the adiposity, while acute Et-OH alone did not affect BW and adiposity. All groups of mice developed steatosis except the control group. Exposure to acute Et-OH and HSB diet increased the number of neutrophils and macrophages, and apoptosis in the liver. This combination also increased the number of circulating neutrophils and reduced mononuclear cells in the blood. Thus, short-term exposure to HSB diet and acute Et-OH intake is linked to increased liver injury. These findings offer important clues to understand the hepatic injuries associated with short exposure to hypercaloric diets and acute Et-OH.

Suppressor of cytokine signaling 2 (SOCS2) contributes to encephalitis in a model of Herpes infection in mice.

The most severe manifestation of Herpes Simplex Type 1 virus (HSV-1) infection is encephalitis characterized by arousal impairment and seizures that can evolve to coma and death. Previous studies reported the involvement of suppressor of cytokine signaling (SOCS) proteins, specifically SOCS1 and SOCS3, in HSV-1 infection, suggesting that other members of this family could be involved in the immune response against HSV-1. No previous study has reported the role of SOCS2 in HSV-1 infection. In the current study, C57BL/6 wild-type mice (WT) and mice deficient in SOCS2 gene (SOCS2-/-) were subjected to intracranial inoculation with 102 plaque forming units (PFU) of HSV-1. Survival curve, neuroinflammatory parameters and neuropathology were evaluated. Infected SOCS2-/- mice had increased survival in comparison with infected WT animals. This better outcome was associated with reduced leukocyte infiltration, concentration of cytokines, and structural changes in the brain. SOCS2 seems to play a detrimental role in HSV-1 encephalitis. Moreover, the control of neuroinflammatory response in HSV-1 infection was of paramount importance to clinical outcome.

Platelet Activating Factor (PAF) Receptor Deletion or Antagonism Attenuates Severe HSV-1 Meningoencephalitis.

Herpes simplex virus type 1 (HSV-1) is a human pathogen that may cause severe encephalitis. The exacerbated immune response against the virus contributes to the disease severity and death. Platelet activating factor (PAF) is a mediator capable of inducing increase in vascular permeability, production of cytokines on endothelial cells and leukocytes. We aimed to investigate the activation of PAF receptor (PAFR) and its contribution to the severity of the inflammatory response in the brain following HSV-1 infection. C57BL/6 wild-type (WT) and PAFR deficient (PAFR-/-) mice were inoculated intracranially with 104 plaque-forming units (PFU) of HSV-1. Visualization of leukocyte recruitment was performed using intravital microscopy. Cells infiltration in the brain tissue were analyzed by flow cytometry. Brain was removed for chemokine assessment by ELISA and for histopathological analysis. The pharmacological inhibition by the PAFR antagonist UK-74,505 was also analyzed. In PAFR-/- mice, there was delayed lethality but no difference in viral load. Histopathological analysis of infected PAFR-/- mice showed that brain lesions were less severe when compared to their WT counterparts. Moreover, PAFR-/- mice showed less TCD4+, TCD8+ and macrophages in brain tissue. This reduction of the presence of leukocytes in parenchyma may be mechanistically explained by a decrease in leukocytes rolling and adhesion. PAFR-/- mice also presented a reduction of the chemokine CXCL9 in the brain. In addition, by antagonizing PAFR, survival of C57BL/6 infected mice increased. Altogether, our data suggest that PAFR plays a role in the pathogenesis of experimental HSV-1 meningoencephalitis, and its blockade prevents severe disease manifestation.

High-throughput matrix screening identifies synergistic and antagonistic antimalarial drug combinations.

Drug resistance in Plasmodium parasites is a constant threat. Novel therapeutics, especially new drug combinations, must be identified at a faster rate. In response to the urgent need for new antimalarial drug combinations we screened a large collection of approved and investigational drugs, tested 13,910 drug pairs, and identified many promising antimalarial drug combinations. The activity of known antimalarial drug regimens was confirmed and a myriad of new classes of positively interacting drug pairings were discovered. Network and clustering analyses reinforced established mechanistic relationships for known drug combinations and identified several novel mechanistic hypotheses. From eleven screens comprising >4,600 combinations per parasite strain (including duplicates) we further investigated interactions between approved antimalarials, calcium homeostasis modulators, and inhibitors of phosphatidylinositide 3-kinases (PI3K) and the mammalian target of rapamycin (mTOR). These studies highlight important targets and pathways and provide promising leads for clinically actionable antimalarial therapy.

Bone-Marrow-Resident NK Cells Prime Monocytes for Regulatory Function during Infection.

Tissue-infiltrating Ly6C(hi) monocytes play diverse roles in immunity, ranging from pathogen killing to immune regulation. How and where this diversity of function is imposed remains poorly understood. Here we show that during acute gastrointestinal infection, priming of monocytes for regulatory function preceded systemic inflammation and was initiated prior to bone marrow egress. Notably, natural killer (NK) cell-derived IFN-γ promoted a regulatory program in monocyte progenitors during development. Early bone marrow NK cell activation was controlled by systemic interleukin-12 (IL-12) produced by Batf3-dependent dendritic cells (DCs) in the mucosal-associated lymphoid tissue (MALT). This work challenges the paradigm that monocyte function is dominantly imposed by local signals after tissue recruitment, and instead proposes a sequential model of differentiation in which monocytes are pre-emptively educated during development in the bone marrow to promote their tissue-specific function.

Phosphatidylinositol 3-Kinase γ is required for the development of experimental cerebral malaria.

Experimental cerebral malaria (ECM) is characterized by a strong immune response, with leukocyte recruitment, blood-brain barrier breakdown and hemorrhage in the central nervous system. Phosphatidylinositol 3-kinase γ (PI3Kγ) is central in signaling diverse cellular functions. Using PI3Kγ-deficient mice (PI3Kγ-/-) and a specific PI3Kγ inhibitor, we investigated the relevance of PI3Kγ for the outcome and the neuroinflammatory process triggered by Plasmodium berghei ANKA (PbA) infection. Infected PI3Kγ-/- mice had greater survival despite similar parasitemia levels in comparison with infected wild type mice. Histopathological analysis demonstrated reduced hemorrhage, leukocyte accumulation and vascular obstruction in the brain of infected PI3Kγ-/- mice. PI3Kγ deficiency also presented lower microglial activation (Iba-1+ reactive microglia) and T cell cytotoxicity (Granzyme B expression) in the brain. Additionally, on day 6 post-infection, CD3+CD8+ T cells were significantly reduced in the brain of infected PI3Kγ-/- mice when compared to infected wild type mice. Furthermore, expression of CD44 in CD8+ T cell population in the brain tissue and levels of phospho-IkB-α in the whole brain were also markedly lower in infected PI3Kγ-/- mice when compared with infected wild type mice. Finally, AS605240, a specific PI3Kγ inhibitor, significantly delayed lethality in infected wild type mice. In brief, our results indicate a pivotal role for PI3Kγ in the pathogenesis of ECM.

Effects of tityustoxin on cerebral inflammatory response in young rats.

Accidents caused by scorpion stings, mainly affecting children, are considered an important cause of morbidity and mortality in tropical countries. Clinical studies demonstrate the relevant role of systemic inflammatory events in scorpion envenoming. However, remains poorly understood whether the major lethal component in Tityus serrulatus venom, tityustoxin (TsTX), is able to induce inflammatory responses in the cerebral microcirculation. In this study, we systematically examined leukocyte recruitment into the CNS in response to TsTX injection. Accordingly, developing rats were subjected to a subcutaneous (s.c.) injection of TsTX (0.75mg/kg), and leukocyte recruitment (i.e., 4, 8 and 12h after injection) and TNF-α levels were evaluated. Rats injected with TsTX presented a significant increase in leukocyte rolling and adhesion and higher levels of TNF-α at all time points studied, compared to the control group. Altogether, this work demonstrates the triggering of neuroimmunological mechanisms induced by TsTX injection in young rats.

Absence of CCR5 increases neutrophil recruitment in severe herpetic encephalitis.

BACKGROUND: The neuroinflammatory response aimed at clearance of herpes simplex virus-1 (HSV-1) plays a key role in the pathogenesis of neuroaxonal damage in herpetic encephalitis. Leukocytes activated in an adaptive immune response access brain tissue by passing through the blood-brain barrier. The chemokine CCL5/RANTES is involved in recruitment of these cells to the brain acting via the receptors CCR1, CCR3 and mainly CCR5. Here, we evaluated the role of CCR5 on traffic of leukocytes in the brain microvasculature, cellular and cytokines profile in a severe form of herpetic encephalitis. RESULTS: Wild type and mice lacking CCR5 (CCR5-/-) were inoculated intracerebrally with 104 PFU of neurotropic HSV-1. We evaluated the traffic of leukocytes in the brain microvasculature using intravital microscopy and the profile of cytokines by Enzyme-Linked Immunosorbent Assay at 1 day post infection. Flow cytometry and histopathological analyses were also carried out in brain tissue. Absence of CCR5 leads to lower viral load and an increased leukocyte adhesion in brain microvasculature, predominantly of neutrophils (CD11+ Ly6G+ cells). Moreover, there was a significant increase in the levels of MIP-1/CCL2, RANTES/CCL5, KC/CXCL1 and MIG/CXCL9 in the brain of infected CCR5-/- mice. CONCLUSIONS: These results suggest that the absence of CCR5 may boost the immune response with a high neutrophil recruitment which most likely helps in viral clearance. Nonetheless, the elevated immune response may be detrimental to the host.

The role of platelet-activating factor receptor (PAFR) in lung pathology during experimental malaria.

Malaria-associated lung pathology has been a neglected area in the study of malaria complications. Platelet-activating factor (PAF) is an inflammatory mediator involved in lung inflammation. Using mice lacking the PAF receptor (PAFR(-/-)) we investigated the relevance of signaling through the PAFR for the lung inflammatory process triggered by Plasmodium berghei ANKA (PbA) strain infection. In PAFR(-/-) mice, pulmonary inflammation was markedly reduced as demonstrated by histology, production of certain pro-inflammatory mediators, accumulation of macrophage and CD8+ T cells in the lung parenchyma and the virtual absence of changes in vascular permeability. Therefore, PAFR activation is crucial in the pathogenesis of pulmonary damage associated with PbA infection in C57Bl/6 mice.

[The portrayal of malaria in the works of João Guimarães Rosa]. / As representações da malária na obra de João Guimarães Rosa.

The article discusses the historical, scientific and literary aspects of malaria, with an emphasis on images of the disease in the work of the writer João Guimarães Rosa. The main reference for this study is the short story "Sarapalha," which is featured in the book entitled Sagarana. The author's medical training together with his experiences in the hinterlands of the country is the subject matter for the work, with stories of the harsh reality of life in the outback. A highlight of the story is the narrative of malaria in the language of the outback, though with absolute medical and scientific precision.

As representações da malária na obra de João Guimarães Rosa / The portrayal of malaria in the works of João Guimarães Rosa

O artigo aborda fatores históricos, científicos e literários da malária, com ênfase nas imagens da doença na obra do escritor João Guimarães Rosa. A principal referência para este estudo é o conto "Sarapalha", presente no livro Sagarana. A formação médica do autor somada a suas experiências no interior do país serve de subsídio para a obra, com histórias vivenciadas na rudeza do sertão. Um ponto de destaque no conto é a narrativa da malária na linguagem do sertão, mas com absoluta fidedignidade médico-científica.

The article discusses the historical, scientific and literary aspects of malaria, with an emphasis on images of the disease in the work of the writer João Guimarães Rosa. The main reference for this study is the short story "Sarapalha," which is featured in the book entitled Sagarana. The author's medical training together with his experiences in the hinterlands of the country is the subject matter for the work, with stories of the harsh reality of life in the outback. A highlight of the story is the narrative of malaria in the language of the outback, though with absolute medical and scientific precision.

Dengue-3 encephalitis promotes anxiety-like behavior in mice.

Dengue virus is a human pathogen that may cause meningoencephalitis and other neurological syndromes. The current study investigated anxiety-like behavior and expression of proinflammatory cytokines and pro-apoptotic caspase-3 in the hippocampus of C57BL/6 mice infected with non-adapted Dengue virus 3 genotype I (DENV-3) inoculated intracranially with 4×10(3) (plaque-forming unit) PFU. Anxiety-like behavior was assessed in control and DENV-3 infected mice using the elevated plus maze. The open field test was performed to evaluate locomotor activity. Histopathological changes in CA regions of the hippocampus were assessed by haematoxylin and eosin staining. Immunoreactive and protein levels of cleaved caspase-3 were also analyzed in the hippocampus. The mRNA expression of IL-6 and TNF-α in the hippocampus were estimated by quantitative real time (polymerase chain reaction) PCR. All procedures were conducted on day 5 post-infection. We found that DENV-3 infected mice presented higher levels of anxiety in comparison with controls (p≤0.05). No difference in motor activity was found between groups (p=0.77). The infection was followed by a significant increase of TNF-α and IL-6 mRNA expression in the hippocampus (p≤0.05). Histological analysis demonstrated meningoencephalitis with formation of perivascular cuffs, infiltration of immune cells and loss of neurons at CA regions of hippocampus. Numerous caspase-3 positive neurons were visualized at CA areas in DENV-3 infected mice. Marked increase of cleaved caspase-3 levels were observed after infection. This study described anxiety-like behavior, hippocampal inflammation and neuronal apoptosis associated with DENV-3 infection in the central nervous system.

Platelet-activating factor receptor is essential for the development of experimental cerebral malaria.

Cerebral malaria is a severe form of the disease that may result, in part, from an overt inflammatory response during infection by Plasmodium falciparum. The understanding of the pathogenesis of cerebral malaria may aid in the development of better therapeutic strategies for patients. The immune response in cerebral malaria involves elevation of circulating levels of cytokines and chemokines associated with leukocyte accumulation and breakdown of the blood-brain barrier in the central nervous system. Platelet-activating factor (PAF) is a mediator of inflammation shown to orchestrate inflammatory processes, including recruitment of leukocytes and increase of vascular permeability. Using mice lacking the PAF receptor (PAFR(-/-)), we investigated the relevance of this molecule for the outcome and the neuroinflammatory process triggered by P. berghei ANKA, an experimental model of cerebral malaria. In PAFR(-/-) mice, lethality was markedly delayed and brain inflammation was significantly reduced, as demonstrated by histology, accumulation, and activation of CD8(+) T cells, changes in vascular permeability and activation of caspase-3 on endothelial cells and leukocytes. Similarly, treatment with the PAFR antagonist UK-74,505 delayed lethality. Taken together, the results suggest that PAFR signaling is crucial for the development of experimental cerebral malaria. Mechanistically, PAFR activation is crucial for the cascade of events leading to changes in vascular permeability, accumulation, and activation of CD8(+) T cells and apoptosis of leukocytes and endothelial cells.

Behavioral investigation of mice with experimental autoimmune encephalomyelitis / Investigação comportamental de camundongos com encefalomielite autoimune experimental

Multiple sclerosis is a neuroinflammatory disease that results in serious neurological disability. Besides physical impairment, behavioral symptoms are also common in patients with multiple sclerosis. Experimental autoimmune encephalomyelitis (EAE) is considered to be a model of multiple sclerosis and mimics the main features of the disease, such as demyelination and motor impairment. In this work, we aimed to study behavioral parameters in animals with EAE using the MOG35-55 model in C57BL/6 mice. We analyzed memory and anxiety in animals using the elevated plus maze, the step down inhibitory avoidance task and the memory recognition test. No differences in any tests were found when comparing controls and animals induced with EAE. Therefore, we conclude that behavioral changes in animals with EAE induced with MOG35-55 are probably subtle or absent.

Esclerose múltipla é uma doença neuroinflamatória que resulta em séria incapacidade neurológica. Além do comprometimento físico, sintomas comportamentais também são comuns em pacientes com esclerose múltipla. A encefalomielite autoimune experimental (EAE) é considerada um modelo de esclerose múltipla e mimetiza as principais caracte-rísticas da doença, como a desmielinização e a fraqueza motora. Neste trabalho, objetivamos estudar parâmetros comportamentais em animais com EAE usando o modelo de MOG35-55 em camundongos C57BL/6. Analisamos memória e ansiedade em animais utilizando o labirinto em cruz elevado, o teste da esquiva inibitória e o teste de memória de reconhecimento. Nenhuma diferença em quaisquer dos testes foi encontrada comparando animais controles e animais induzidos com EAE. Assim, concluímos que alterações comportamentais em animais com EAE induzidos com MOG35-55 são provavelmente sutis ou ausentes.

Plasmodium berghei NK65 induces cerebral leukocyte recruitment in vivo: an intravital microscopic study.

Malaria is second only to tuberculosis as the leading cause of morbidity and mortality as a consequence of a single infectious agent. Much of the pathology of malaria arises from the inappropriate or excessive immune response mounted by the host in an attempt to eliminate the parasite. We here report the inflammatory changes observed in the cerebral microvasculature of C57BL/6 and BALB/c mice that had been inoculated with Plasmodium berghei NK65, a lethal strain of rodent malaria. Although no neurological signs were observed in experimentally infected mice, inflammation of the cerebral microvasculature was clearly evident. Histopathological analysis demonstrated that alterations in cerebral tissue were more intense in infected C57Bl/6 mice than in infected BALB/c animals. Intravital microscopic examination of the cerebral microvasculature revealed increased leukocyte rolling and adhesion in pial venules of infected mice compared with non-infected animals. The extravasation of Evans blue dye into the cerebral parenchyma was also elevated in infected mice in comparison with their non-infected counterparts. Additionally, protein levels of TNF-α, MIG/CXCL9, MCP-1/CCL2, MIP-1α/CCL3 and RANTES/CCL5 were up-regulated in brain samples derived from infected C57Bl/6 mice. Taken together, the data reported here illustrate the complex strain-dependent relationships between leukocyte recruitment, blood brain barrier permeability and chemokine production.

Role of IL-4 in an experimental model of encephalitis induced by intracranial inoculation of herpes simplex virus-1 (HSV-1).

Herpes simplex virus-1 (HSV-1) is a pathogen that may cause severe encephalitis in humans. In this study, we aimed to investigate the role of interleukin-4 (IL-4) in a model of HSV-1 brain infection. IL-4 knockout (IL-4-/-) and wild type (WT) C57BL/6 mice were inoculated with 10(4) plaque-forming units of HSV-1 by the intracranial route. Histopathologic analysis revealed a distinct profile of infiltrating cells at 3 days post-infection (dpi). Infected WT mice presented mononuclear inflammatory cells while IL-4-/- mice developed meningoencephalitis with predominance of neutrophils. IL-4-/- mice had diminished leukocyte adhesion at 3 dpi when compared to infected WT animals in intravital microscopy study. Conversely no differences were found in cerebral levels of CXCL1, CXCL9, CCL3, CCL5 and TNF-α between WT and IL-4-/- infected mice. IL-4 may play a role in the recruitment of cells into central nervous system in this acute model of severe encephalitis caused by HSV-1.