Multiple organ dysfunction is the most severe outcome of sepsis progression and is highly correlated with a worse prognosis. Excessive neutrophil extracellular traps (NETs) are critical players in ...the development of organ failure during sepsis. Therefore, interventions targeting NET release would likely effectively prevent NET-based organ injury associated with this disease. Herein, we demonstrate that the pore-forming protein gasdermin D (GSDMD) is active in neutrophils from septic humans and mice and plays a crucial role in NET release. Inhibition of GSDMD with disulfiram or genic deletion abrogated NET formation, reducing multiple organ dysfunction and sepsis lethality. Mechanistically, we demonstrate that during sepsis, activation of the caspase-11/GSDMD pathway controls NET release by neutrophils during sepsis. In summary, our findings uncover a novel therapeutic use for disulfiram and suggest that GSDMD is a therapeutic target to improve sepsis treatment.
Neutrophil extracellular traps (NETs) are innate defense mechanisms that are also implicated in the pathogenesis of organ dysfunction. However, the role of NETs in pediatric sepsis is unknown.
Infant ...(2 weeks old) and adult (6 weeks old) mice were submitted to sepsis by intraperitoneal (i.p.) injection of bacteria suspension or lipopolysaccharide (LPS). Neutrophil infiltration, bacteremia, organ injury, and concentrations of cytokine, NETs, and DNase in the plasma were measured. Production of reactive oxygen and nitrogen species and release of NETs by neutrophils were also evaluated. To investigate the functional role of NETs, mice undergoing sepsis were treated with antibiotic plus rhDNase and the survival, organ injury, and levels of inflammatory markers and NETs were determined. Blood samples from pediatric and adult sepsis patients were collected and the concentrations of NETs measured.
Infant C57BL/6 mice subjected to sepsis or LPS-induced endotoxemia produced significantly higher levels of NETs than the adult mice. Moreover, compared to that of the adult mice, this outcome was accompanied by increased organ injury and production of inflammatory cytokines. The increased NETs were associated with elevated expression of Padi4 and histone H3 citrullination in the neutrophils. Furthermore, treatment of infant septic mice with rhDNase or a PAD-4 inhibitor markedly attenuated sepsis. Importantly, pediatric septic patients had high levels of NETs, and the severity of pediatric sepsis was positively correlated with the level of NETs.
This study reveals a hitherto unrecognized mechanism of pediatric sepsis susceptibility and suggests that NETs represents a potential target to improve clinical outcomes of sepsis.
Countries worldwide have confirmed a staggering number of COVID-19 cases, and it is now clear that no country is immune to the SARS-CoV-2 infection. Resource-poor countries with weaker health systems ...are struggling with epidemics of their own and are now in a more uncertain situation with this rapidly spreading infection. Frontline healthcare workers are succumbing to the infection in their efforts to save lives. There is an urgency to develop treatments for COVID-19, yet there is limited clinical data on the efficacy of potential drug treatments. Countries worldwide implemented a stay-at-home order to “flatten the curve” and relieve the pressure on the health system, but it is uncertain how this will unfold after the economy reopens. Trehalose, a natural glucose disaccharide, is known to impair viral function through the autophagy system. Here, we propose trehalose as a potential preventative treatment for SARS-CoV-2 infection and transmission.
Neutrophil extracellular traps (NETs) are cell-extruded DNA strands coated with neutrophils' nuclear proteins and enzymes from cytotoxic granules, produced by NETosis, a cell death pathway. They ...perform an important defensive role in innate immunity, but their increased production and/or inefficient degradation expose new antigens, such as DNA or citrullinated histone peptides, triggering autoimmunity. This study aimed to access possible associations between serum NETs levels with epidemiological, clinical, and serological data from a well-characterized SLE Brazilian patients’ cohort. NET levels were evaluated in one hundred seventy serum samples of patients with Systemic Lupus Erythematosus (SLE) using an Immunoassay. Univariate and multivariate binary logistic regression used clinical patients' data as independent variables. Parametric and non-parametric tests compared log10 base serum NET levels transformed between patients' groups. SLE patients were also dichotomized into “High serum NET levels” and “Low serum NET levels” groups. All analyses were performed in R language 4.1.2, and p < 0.05 were considered significant. Increased susceptibility for high serum NET levels was observed in SLE patients with Raynaud's phenomenon (OR = 2.30, 95 % CI = 1.06–5.21 and p = 0.039), independently of any other risk factor. Also, SLE patients with Raynaud's phenomenon presented higher mean NET serum levels (mean = −0.13 vs. −0.51, p = 0.01). In addition, higher mean NET serum levels were associated with glomerulonephritis (mean = -0.45 vs. −0.12, p = 0.03). Ultimately, the SLEDAI index scored higher in the high NETs serum levels group (median = 2.0 vs. 0.0, p = 6 × 10−3). The formation of NETs might be implicated in Raynaud's phenomenon, glomerulonephritis, and disease index score in SLE patients. Our results highlight the importance of serum NET levels as a possible therapeutical target to modulate the clinical course of SLE.
Display omitted
Sepsis is one of the main causes of mortality in hospitalized patients. Despite the recent technical advances and the development of novel generation of antibiotics, severe sepsis ...remains a major clinical and scientific challenge in modern medicine. Unsuccessful efforts have been dedicated to the search of therapeutic options to treat the deleterious inflammatory components of sepsis. Recent findings on neuronal networks controlling immunity raised expectations for novel therapeutic strategies to promote the regulation of sterile inflammation, such as autoimmune diseases. Interesting studies have dissected the anatomical constituents of the so-called “cholinergic anti-inflammatory pathway”, suggesting that electrical vagus nerve stimulation and pharmacological activation of beta-2 adrenergic and alpha-7 nicotinic receptors could be alternative strategies for improving inflammatory conditions. However, the literature on infectious diseases, such as sepsis, is still controversial and, therefore, the real therapeutic potential of this neuroimmune pathway is not well defined. In this review, we will discuss the beneficial and detrimental effects of neural manipulation in sepsis, which depend on the multiple variables of the immune system and the nature of the infection. These observations suggest future critical studies to validate the clinical implications of vagal parasympathetic signaling in sepsis treatment.
Sepsis-surviving adult individuals commonly develop immunosuppression and increased susceptibility to secondary infections, an outcome mediated by the axis IL-33/ILC2s/M2 macrophages/Tregs. ...Nonetheless, the long-term immune consequences of paediatric sepsis are indeterminate. We sought to investigate the role of age in the genesis of immunosuppression following sepsis.
Here, we compared the frequency of Tregs, the activation of the IL-33/ILC2s axis in M2 macrophages and the DNA methylation of epithelial lung cells from post-septic infant and adult mice. Likewise, sepsis-surviving mice were inoculated intranasally with Pseudomonas aeruginosa or by subcutaneous inoculation of the B16 melanoma cell line. Finally, blood samples from sepsis-surviving patients were collected and the concentration of IL-33 and Tregs frequency were assessed.
In contrast to 6-week-old mice, 2-week-old mice were resistant to secondary infection and did not show impairment in tumour controls upon melanoma challenge. Mechanistically, increased IL-33 levels, Tregs expansion, and activation of ILC2s and M2-macrophages were observed in 6-week-old but not 2-week-old post-septic mice. Moreover, impaired IL-33 production in 2-week-old post-septic mice was associated with increased DNA methylation in lung epithelial cells. Notably, IL-33 treatment boosted the expansion of Tregs and induced immunosuppression in 2-week-old mice. Clinically, adults but not paediatric post-septic patients exhibited higher counts of Tregs and seral IL-33 levels.
These findings demonstrate a crucial and age-dependent role for IL-33 in post-sepsis immunosuppression. Thus, a better understanding of this process may lead to differential treatments for adult and paediatric sepsis.
It is well established that sepsis induces vascular hyporesponsiveness to vasoconstrictors. Perivascular adipose tissue (PVAT) displays anti-contractile action in various blood vessels. We ...hypothesized that sepsis would increase the anti-contractile effect of PVAT aggravating sepsis-induced vasoplegia. Male Wistar Hannover rats were subjected to lethal sepsis by cecal ligation and puncture (CLP) method. Aorta or PVAT were collected for functional or biochemical assays 6 h after CLP surgery. Functional experiments showed that sepsis increased the anti-contractile action of PVAT in both endothelium-intact and endothelium-denuded aortas. Carboxy-PTIO, L-NAME and ODQ reversed the hypocontractility mediated by PVAT in aortas from septic rats. Inhibition of nNOS and iNOS with 7-nitroindazole and 1400 W attenuated PVAT-mediated hypocontractility during sepsis. Similar results were found in the presence of indomethacin and Ro1138452, a selective prostacyclin IP receptor antagonist. However, neither tiron nor catalase affected phenylephrine-induced contraction in aortas from septic rats. Increased levels of superoxide anion (O2•-) and 6-keto-prostaglandin F1α (stable product of prostacyclin) were detected in PVAT from septic rats. In situ quantification of reactive oxygen species and nitric oxide (NO) using fluorescent dyes revealed increased levels of both in PVAT from septic rats. The novelty of our study is that PVAT contributes to sepsis-induced vasoplegia by releasing NO and prostacyclin. These findings suggested that signaling pathways in PVAT may be considered as potential novel pharmacological therapeutic targets during sepsis-induced vasoplegia.
Sepsis is an overwhelming systemic inflammation resulting from an uncontrolled infection that causes extensive tissue damage, organ dysfunction and eventually death. A growing body of evidence ...indicates that impaired neutrophil migration to the site of infection is associated with poor outcome in sepsis. Here we show that galectin-3 (Gal-3), an endogenous glycan-binding protein, plays a critical role in sepsis outcome. We found that serum Gal-3 concentration increased in patients with septic shock and mice undergoing sepsis induced by cecal ligation and puncture (CLP). Mice deficient in Gal-3 (Gal-3 KO) are more resistant to sepsis induced by CLP, showing lower levels of biochemical markers and neutrophil infiltration for organ injury/dysfunction than those observed in wild-type mice (WT). Furthermore, Gal-3 KO mice show an increased number of neutrophils in the primary focus of infection and reduced bacterial loads in the peritoneal cavity, blood, and lungs. Mechanistically, blood neutrophils from septic mice show higher levels of surface-bound Gal-3 than neutrophils from naive mice. The deficiency of Gal-3 was associated with increased rolling and adhesion of these cells in mesenteric venules. Our results indicate that Gal-3, secreted during sepsis, inhibits neutrophil migration into the infectious focus, which promotes the bacterial spread and worsens the outcome of sepsis.
Intestinal mucositis is a common side effect of irinotecan-based anticancer regimens. Mucositis causes cell damage, bacterial/endotoxin translocation and production of cytokines including IL-1 and ...IL-18. These molecules and toll-like receptors (TLRs) activate a common signaling pathway that involves the Myeloid Differentiation adaptor protein, MyD88, whose role in intestinal mucositis is unknown. Then, we evaluated the involvement of TLRs and MyD88 in the pathogenesis of irinotecan-induced intestinal mucositis. MyD88-, TLR2- or TLR9-knockout mice and C57BL/6 (WT) mice were given either saline or irinotecan (75 mg/kg, i.p. for 4 days). On day 7, animal survival, diarrhea and bacteremia were assessed, and following euthanasia, samples of the ileum were obtained for morphometric analysis, myeloperoxidase (MPO) assay and measurement of pro-inflammatory markers. Irinotecan reduced the animal survival (50%) and induced a pronounced diarrhea, increased bacteremia, neutrophil accumulation in the intestinal tissue, intestinal damage and more than twofold increased expression of MyD88 (200%), TLR9 (400%), TRAF6 (236%), IL-1β (405%), IL-18 (365%), COX-2 (2,777%) and NF-κB (245%) in the WT animals when compared with saline-injected group (P<0.05). Genetic deletion of MyD88, TLR2 or TLR9 effectively controlled the signs of intestinal injury when compared with irinotecan-administered WT controls (P<0.05). In contrast to the MyD88-/- and TLR2-/- mice, the irinotecan-injected TLR9-/- mice showed a reduced survival, a marked diarrhea and an enhanced expression of IL-18 versus irinotecan-injected WT controls. Additionally, the expression of MyD88 was reduced in the TLR2-/- or TLR9-/- mice. This study shows a critical role of the MyD88-mediated TLR2 and TLR9 signaling in the pathogenesis of irinotecan-induced intestinal mucositis.
Coastal areas host some of the planet’s most productive ecosystems, providing life-sustaining ecological services and several benefits to humankind, while also being some of the most threatened areas ...(e.g., by globalization, climate change, and biological invasion). Salt marshes are coastal habitats with a key role in food and shelter provisioning, sediment deposition, nutrient cycling and carbon storage.
Spartina
spp. is a genus of grass halophytes which occurs in salt marshes worldwide, and includes species with different invasive potential. We evaluated the effect of climate change in the distribution and invasion potential of five
Spartina
species (
S. anglica
,
S. alterniflora
,
S. densiflora
,
S. patens
, and
S. maritima
) at a global scale. Species distribution models (SDMs) were applied on species occurrence data and atmospheric environmental predictors (WorldClim 2.1) to project potential changes in habitat suitability and associated changes in distribution and species co-occurrence until the end of the century, across four Shared Socioeconomic Pathway scenarios (i.e., SSP1-2.6 to SSP5-8.5). Projections showed a global trend for increasing species co-occurrence, with a general range expansion potentiated by increasing pathway severity. This study suggests that
Spartina
species can potentially benefit from climate change, predicting poleward expansions in the Northern Hemisphere for most species, with results pointing at increased conflict and invasion potential in Northern Europe and East Asian shorelines, already under strong invasive pressure.
S. anglica
is projected to remain a successful invader, with more severe scenarios likely favoring greater expansions.
S. alterniflora
exhibits very low expansion comparatively, despite exhibiting the same northward distribution shift. SSP1-2.6 produced the smallest change to species co-occurrence, suggesting a smaller potential for invasion-related conflicts, although still registering a potential net expansion for the Genus. Despite their limitations, SDMs can help establish general trends in climate change ecology and inform policymakers and environmental agents to ensure the correct management of these habitats and, ultimately, ecosystems.
PDF
