Macrophage Inflammatory Response Research Articles

Ferroptosis Is Crucial for Cisplatin Induced Sertoli Cell Injury via N6-Methyladenosine Dependent Manner.

This study aimed to investigate the effect of the N6-methyladenosine (m6A) dependent ferroptosis on cisplatininduced Sertoli cell injury. A cisplatin exposure mouse model was established by intraperitoneal injection of cisplatin in our study. TM4 cell lines was used for in vitro study. Ferroptosis was detected according to metabolomic analysis and a series of assays, including malondialdehyde, glutathione, and glutathione disulfide concentration detection, 2',7'-dichlorodihydrofluorescein diacetate and BODIPY 581/591 C11 probe detection, and transmission electron microscope imaging. Key ferroptosis-related genes were identified via transcriptomic analysis, western blot and immunohistochemistry. The m6A modification was demonstrated via m6A RNA immunoprecipitation and luciferase reporter assays. Immune cell infiltration was detected by mass cytometry, and verified by flow cytometry and immunofluorescence. Ferroptosis, but not other types of programmed cell death, is a significant phenomenon in cisplatin-induced testis damage and Sertoli cell loss. Ferroptosis induced by cisplatin in Sertoli cell/TM4 cell is GPX4 independent but is regulated by SLC7A11 and ALOX12. Both SLC7A11 and ALOX12 are regulated via m6A dependent manner by METTL3. Furthermore, overexpressed ALOX12-12HETE pathway may result in macrophage polarization and inflammatory response in cisplatin exposure testis. Cisplatin-induced Sertoli cell injury via ferroptosis and promoted ferroptosis in an m6A dependent manner. m6A modification of both SLC7A11 and ALOX12 mRNA could result in ferroptosis in our in vitro model. Further, overexpressed ALOX12 can cause more production of 12-HETE, which may be responsible for testis inflammation caused by cisplatin.

Activation of murine macrophages by membrane proteins from Tritrichomonas foetus grown on iron- and calcium-rich conditions.

Tritrichomonas foetus is a protozoan parasite that causes a venereal disease in cattle limiting reproduction by abortions and sterility. The immune response against this parasite is poorly understood. Since the iron and calcium ions are important regulators of the microenvironment of the urogenital tract in cattle, we decided to evaluate the role of these divalent cations on the antigenicity of membrane proteins of T. foetus on macrophage activation as one of the first inflammatory responses towards this pathogen. Colorimetric methods and ELISA were used to detect the nitric oxide and oxygen peroxide production and expression of cytokines in culture supernatant from macrophage incubated with membrane proteins from T. foetus cultured in iron- and calcium-rich conditions. qRT-PCR assays were used to evaluate the transcript expression of genes involved in the inflammatory response on the macrophages. The membrane proteins used for in vitro stimulation caused the up-regulation of the iNOS and NOX-2 genes as well as the generation of NO and H2 O2 in murine macrophages on a dependent way of the metal concentrations. Additionally, after stimulation, macrophages showed a considerable rise in pro-inflammatory cytokines and a downregulation of anti-inflammatory cytokines, as well as up-regulation in the transcription of the TLR4 and MyD88 genes. These data suggest that membrane proteins of T. foetus induced by iron and calcium can activate an inflammatory specific macrophage response via TLR4/MyD88 signalling pathway.

A loss of function mutation in SOCS2 results in increased inflammatory response of macrophages to TLR ligands and Staphylococcus aureus.

The role of suppressor of cytokine signaling (SOCS)2 in anti-infective bacterial immunity has been poorly investigated compared to other members of the SOCS family. We characterized the previously identified loss of function R96C point mutation of SOCS2 using a genome-edited mouse model that resumes the phenotype of Socs2 knockout mice. The response of macrophages to TLR-ligands and Staphylococcus aureus was examined. Conversely to previously published data using human monocyte-derived macrophages, the stimulation of bone-marrow-derived macrophages with various TLR ligands did not show any difference according to the SOCS2 variant. Upregulation of IL-6 and TNF-α pro-inflammatory cytokines production was only seen when the SOCS2 expression was promoted by the culture of macrophages in the presence of GM-CSF. Furthermore, we showed that the SOCS2 point mutation is associated with heightened STAT5 phosphorylation in a short time frame upon GM-CSF incubation. In mice, recruitment of neutrophil and F4/80int Ly6C+ inflammatory macrophage, as well as IFN-γ and IL-10 concentrations, are significantly increased upon S. aureus peritoneal infection. Altogether, these data support the idea that by lowering the pro-inflammatory environment, SOCS2 favors better control of bacterial burden during a systemic infection caused by S. aureus.

Astaxanthin targets IL-6 and alleviates the LPS-induced adverse inflammatory response of macrophages.

Numerous natural compounds are recognized for their anti-inflammatory properties attributed to antioxidant effects and the modulation of key inflammatory factors. Among them, astaxanthin (AST), a potent carotenoid antioxidant, remains relatively underexplored regarding its anti-inflammatory mechanisms and specific molecular targets. In this study, human monocytic leukemia cell-derived macrophages (THP-1) were selected as experimental cells, and lipopolysaccharides (LPS) served as inflammatory stimuli. Upon LPS treatment, the oxidative stress was significantly increased, accompanied by remarkable cellular damage. Moreover, LPSs escalated the expression of inflammation-related molecules. Our results demonstrate that AST intervention could effectively alleviate LPS-induced oxidative stress, facilitate cellular repair, and significantly attenuate inflammation. Further exploration of the anti-inflammatory mechanism revealed AST could substantially inhibit NF-κB translocation and activation, and mitigate inflammatory factor production by hindering NF-κB through the antioxidant mechanism. We further confirmed that AST exhibited protective effects against cell damage and reduced the injury from inflammatory cytokines by activating p53 and inhibiting STAT3. In addition, utilizing network pharmacology and in silico calculations based on molecular docking, molecular dynamics simulation, we identified interleukin-6 (IL-6) as a prominent core target of AST anti-inflammation, which was further validated by the RNA interference experiment. This IL-6 binding capacity actually enabled AST to curb the positive feedback loop of inflammatory factors, averting the onset of possible inflammatory storms. Therefore, this study offers a new possibility for the application and development of astaxanthin as a popular dietary supplement of anti-inflammatory or immunomodulatory function.

TREM2 in Regulating Macrophage Inflammatory Responses and Disease Pathogenesis

TREM2 in Regulating Macrophage Inflammatory Responses and Disease Pathogenesis

Adiponectin Resistance in Obesity: Adiponectin Leptin/Insulin Interaction.

The adiponectin (APN) levels in obesity are negatively correlated with chronic subclinical inflammation markers. The hypertrophic adipocytes cause obesity-linked insulin resistance and metabolic syndrome. Furthermore, macrophage polarization is a key determinant regulating adiponectin receptor (AdipoR1/R2) expression and differential adiponectin-mediated macrophage inflammatory responses in obese individuals. In addition to decrease in adiponectin concentrations, the decline in AdipoR1/R2 messenger ribonucleic acid (mRNA) expression leads to a decrement in adiponectin binding to cell membrane, and this turns into attenuation in the adiponectin effects. This is defined as APN resistance, and it is linked with insulin resistance in high-fat diet-fed subjects. The insulin-resistant group has a significantly higher leptin-to-APN ratio. The leptin-to-APN ratio is more than twofold higher in obese individuals. An increase in expression of AdipoRs restores insulin sensitivity and β-oxidation of fatty acids via triggering intracellular signal cascades. The ratio of high molecular weight to total APN is defined as the APN sensitivity index (ASI). This index is correlated to insulin sensitivity. Homeostasis model of assessment (HOMA)-APN and HOMA-estimated insulin resistance (HOMA-IR) are the most suitable methods to estimate the metabolic risk in metabolic syndrome. While morbidly obese patients display a significantly higher plasma leptin and soluble (s)E-selectin concentrations, leptin-to-APN ratio, there is a significant negative correlation between leptin-to-APN ratio and sP-selectin in obese patients. When comparing the metabolic dysregulated obese group with the metabolically healthy obese group, postprandial triglyceride clearance, insulin resistance, and leptin resistance are significantly delayed following the oral fat tolerance test in the first group. A neuropeptide, Spexin (SPX), is positively correlated with the quantitative insulin sensitivity check index (QUICKI) and APN. APN resistance together with insulin resistance forms a vicious cycle. Despite normal or high APN levels, an impaired post-receptor signaling due to adaptor protein-containing pleckstrin homology domain, phosphotyrosine-binding domain, and leucine zipper motif 1 (APPL1)/APPL2 may alter APN efficiency and activity. However, APPL2 blocks adiponectin signaling through AdipoR1 and AdipoR2 because of the competitive inhibition of APPL1. APPL1, the intracellular binding partner of AdipoRs, is also an important mediator of adiponectin-dependent insulin sensitization. The elevated adiponectin levels with adiponectin resistance are compensatory responses in the condition of an unusual discordance between insulin resistance and APN unresponsiveness. Hypothalamic recombinant adeno-associated virus (rAAV)-leptin (Lep) gene therapy reduces serum APN levels, and it is a more efficient strategy for long-term weight maintenance.

Immunotoxic, genotoxic, and endocrine disrupting impacts of polyamide microplastic particles and chemicals

Due to their exceptional properties and cost effectiveness, polyamides or nylons have emerged as widely used materials, revolutionizing diverse industries, including industrial 3D printing or additive manufacturing (AM). Powder-based AM technologies employ tonnes of polyamide microplastics to produce complex components every year. However, the lack of comprehensive toxicity assessment of particulate polyamides and polyamide-associated chemicals, especially in the light of the global microplastics crisis, calls for urgent action. This study investigated the physicochemical properties of polyamide-12 microplastics used in AM, and assessed a number of toxicity endpoints focusing on inflammation, immunometabolism, genotoxicity, aryl hydrocarbon receptor (AhR) activation, endocrine disruption, and cell morphology. Specifically, microplastics examination by means of field emission scanning electron microscopy revealed that work flow reuse of material created a fraction of smaller particles with an average size of 1–5 µm, a size range readily available for uptake by human cells. Moreover, chemical analysis by means of gas chromatography high-resolution mass spectrometry detected several polyamide-associated chemicals including starting material, plasticizer, thermal stabilizer/antioxidant, and migrating slip additive. Even if polyamide particles and chemicals did not induce an acute inflammatory response, repeated and prolonged exposure of human primary macrophages disclosed a steady increase in the levels of proinflammatory chemokine Interleukin-8 (IL-8/CXCL-8). Moreover, targeted metabolomics disclosed that polyamide particles modulated the kynurenine pathway and some of its key metabolites. The p53-responsive luciferase reporter gene assay showed that particles per se were able to activate p53, being indicative of a genotoxic stress. Polyamide-associated chemicals triggered moderate activation of AhR and elicited anti-androgenic activity. Finally, a high-throughput and non-targeted morphological profiling by Cell Painting assay outlined major sites of bioactivity of polyamide-associated chemicals and indicated putative mechanisms of toxicity in the cells. These findings reveal that the increasing use of polyamide microplastics may pose a potential health risk for the exposed individuals, and it merits more attention.

The inhibition effect of caffeic acid on NOX/ROS-dependent macrophages M1-like polarization contributes to relieve the LPS-induced mice mastitis

The mammary gland is an adipose tissue containing not only adipocytes but also epithelial, endothelial, and immune cells. Epithelial cells and macrophages, as the integral components of the immune system, are on the front line of defense against infection. Our preliminary work proved that caffeic acid (CA) can effectively inhibit the inflammatory cascade of bovine mammary epithelial cells (BMEC) induced by lipopolysaccharide (LPS) and maintain cellular integrity and viability. Here, we investigated the therapeutic effect of CA on LPS-induced mice mastitis and explored its regulatory mechanism on macrophage inflammatory response induced by LPS in vitro. Firstly, the mice mastitis model was established by intramammary injection with 10 μg LPS, after which different CA doses (5, 10, 15 mg/kg) were administered. Then, the pathological section, myeloperoxidase (MPO) activity, proinflammatory factors and chemokines releasement, and redox state of mammary tissues were assessed, confirming CA's effectiveness on mice mastitis. In vitro, we validated the therapeutic relevance of CA in relieving LPS-induced RAW264.7 inflammatory and oxidative stress responses. Moreover, we further provided evidence that CA significantly reduced LPS-induced reactive oxygen species (ROS) generation via NADPH oxidase (NOX), which improved the imbalance relationship between nuclear factor kappa-B (NF-κB) and NF-E2 p45-related factor 2 (Nrf2) and led to a marked weakening of M1 polarization. The NOX-ROS signal inhibited by CA weakened the oxidative burst and neutrophil chemotaxis of macrophages, thus alleviating the immune cascade in mammary gland tissue and reducing the LPS-induced inflammatory damage. Collectively, CA would be a potential candidate or antibacterial synergist for curbing mastitis.

CTRP6 promotes the macrophage inflammatory response, and its deficiency attenuates LPS-induced inflammation

Macrophages play critical roles in inflammation and tissue homeostasis, and their functions are regulated by various autocrine, paracrine, and endocrine factors. We have previously shown that CTRP6, a secreted protein of the C1q family, targets both adipocytes and macrophages to promote obesity-linked inflammation. However, the gene programs and signaling pathways directly regulated by CTRP6 in macrophages remain unknown. Here, we combine transcriptomic and phosphoproteomic analyses to show that CTRP6 activates inflammatory gene programs and signaling pathways in mouse bone marrow-derived macrophages (BMDMs). Treatment of BMDMs with CTRP6 upregulated proinflammatory, and suppressed the antiinflammatory, gene expression. We also showed that CTRP6 activates p44/42-MAPK, p38-MAPK, and NF-κB signaling pathways to promote inflammatory cytokine secretion from BMDMs, and that pharmacologic inhibition of these signaling pathways markedly attenuated the effects of CTRP6. Pretreatment of BMDMs with CTRP6 also sensitized and potentiated the BMDMs response to lipopolysaccharide (LPS)-induced inflammatory signaling and cytokine secretion. Consistent with the metabolic phenotype of proinflammatory macrophages, CTRP6 treatment induced a shift toward aerobic glycolysis and lactate production, reduced oxidative metabolism, and elevated mitochondrial reactive oxygen species production in BMDMs. Importantly, in accordance with our invitro findings, BMDMs from CTRP6-deficient mice were less inflammatory at baseline and showed a marked suppression of LPS-induced inflammatory gene expression and cytokine secretion. Finally, loss of CTRP6 in mice also dampened LPS-induced inflammation and hypothermia. Collectively, our findings suggest that CTRP6 regulates and primes the macrophage response to inflammatory stimuli and thus may have a role in modulating tissue inflammatory tone in different physiological and disease contexts.

The preprogrammed anti-inflammatory phenotypes of CD11chigh macrophages by Streptococcus pneumoniae aminopeptidase N safeguard from allergic asthma

BackgroundEarly microbial exposure is associate with protective allergic asthma. We have previously demonstrated that Streptococcus pneumoniae aminopeptidase N (PepN), one of the pneumococcal components, inhibits ovalbumin (OVA) -induced airway inflammation in murine models of allergic asthma, but the underlying mechanism was incompletely determined.MethodsBALB/c mice were pretreated with the PepN protein and exposed intranasally to HDM allergen. The anti-inflammatory mechanisms were investigated using depletion and adoptive transfer experiments as well as transcriptome analysis and isolated lung CD11chigh macrophages.ResultsWe found pretreatment of mice with PepN promoted the proliferation of lung-resident F4/80+CD11chigh macrophages in situ but also mobilized bone marrow monocytes to infiltrate lung tissue that were then transformed into CD11high macrophages. PepN pre-programmed the macrophages during maturation to an anti-inflammatory phenotype by shaping the metabolic preference for oxidative phosphorylation (OXPHOS) and also inhibited the inflammatory response of macrophages by activating AMP-activated protein kinase. Furthermore, PepN treated macrophages also exhibited high-level costimulatory signaling molecules which directed the differentiation into Treg.ConclusionOur results demonstrated that the expansion of CD11chigh macrophages in lungs and the OXPHOS metabolic bias of macrophages are associated with reduced allergic airway inflammation after PepN exposure, which paves the way for its application in preventing allergic asthma.

Irisflorentin promotes bacterial phagocytosis and inhibits inflammatory responses in macrophages during bacterial infection

Bacterial infection remains a big concern in the patients of ICU, which is the main cause of life-threatening organ dysfunction, or even sepsis. The poor control of bacterial infection caused by antibiotic resistance, etc. or the overwhelming immune response are the most important patho genic factors in intensive care unit (ICU) patients. As main pathogens, antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), impose serious challenges during sepsis and require alternative therapeutic options. Irisflorentin (IFL) is one of the major bioactive compounds isolated from the roots of Belamcanda chinensis (Shegan). In this study, IFL could suppress inflammatory response induced by MRSA or a synthetic mimic of bacterial lipoprotein (Pam3CSK4). IFL treatment enhanced the ability of macrophages to phagocytose bacteria likely through up-regulating the expression of phagocytic receptors SR-A1 and FcγR2a. Furthermore, IFL inhibited Pam3CSK4-induced production of pro-inflammatory cytokines, including IL-6 and TNF-α in Raw 264.7 cells, mouse primary macrophages or dendritic cells. IFL treatment also inhibited heat-killed MRSA-induced secretion of IL-6 and TNF-α in mouse bone marrow-derived macrophages. Moreover, IFL attenuated M1 polarization of macrophages as indicated by the down-regulated expression of its polarization markers CD86 and iNOS. Mechanistically, IFL markedly decreased the Pam3CSK4-induced activation of ERK, JNK or p38 MAPK pathways in macrophages. Taken together, IFL may serve as a promising compound for the therapy of bacterial infection, particularly those caused by antibiotic-resistant bacteria, such as MRSA.

Serine metabolism in macrophage polarization.

Emerging studies have revealed that macrophages possess different dependences on the uptake, synthesis, and metabolism of serine for their activation and functionalization, necessitating our insight into how serine availability and utilization impact macrophage activation and inflammatory responses. This article summarizes the reports published domestically and internationally about the serine uptake, synthesis, and metabolic flux by the macrophages polarizing with distinct stimuli and under different pathologic conditions, and particularly analyzes how altered serine metabolism rewires the metabolic behaviors of polarizing macrophages and their genetic and epigenetic reprogramming. Macrophages dynamically change serine metabolism to orchestrate their anabolism, redox balance, mitochondrial function, epigenetics, and post-translation modification, and thus match the distinct needs for both classical and alternative activation. Serine metabolism coordinates multiple metabolic pathways to tailor macrophage polarization and their responses to different pathogenic attacks and thus holds the potential as therapeutic target for types of acute and chronic inflammatory diseases.

Characterization of outer membrane vesicles released by clinical isolates of Neisseria gonorrhoeae.

The sexually transmitted pathogen Neisseria gonorrhoeae releases membrane vesicles including outer membrane vesicles (OMVs) during infections. OMVs traffic outer membrane molecules, such as the porin PorB and lipo-oligosaccharide (LOS), into host innate immune cells, eliciting programmed cell death pathways, and inflammation. Little is known, however, about the proteome and LOS content of OMVs released by clinical strains isolated from different infection sites, and whether these vesicles similarly activate immune responses. Here, we characterized OMVs from four N. gonorrhoeae isolates and determined their size, abundance, proteome, LOS content, and activation of inflammatory responses in macrophages. The overall proteome of the OMVs was conserved between the four different isolates, which included major outer membrane and periplasm proteins. Despite this, we observed differences in the rate of OMV biogenesis and the relative abundance of membrane proteins and LOS. Consequently, OMVs from clinical isolates induced varying rates of macrophage cell death and the secretion of interleukin-1 family members, such as IL-1αandIL-1β. Overall, these findings demonstrate that clinical isolates of N. gonorrhoeae utilize membrane vesicles to release proteins and lipids, which affects innate immune responses.

Age-Associated KLF9 Enhances the Inflammatory Response of Alveolar Macrophages Via Regulating TLR2 Expression.

Staphylococcus aureus pneumonia is a severe infection in infant and young children. Toll-like receptor 2 (TLR2)-mediated inflammation plays essential roles in S. aureus pneumonia. Krueppel-like factor 9 (KLF9) is a transcriptional factor participating in multiple cellular aspects including inflammation. In this study, the potential roles of KLF9 in S. aureus pneumonia were evaluated. The expression of KLF9 in peripheral blood mononuclear cells (PBMCs) from healthy donors with different ages and in alveolar macrophages from mice with different ages was measured. Pam3CK4-induced expression of inflammatory cytokines was compared in alveolar macrophages from young and old mice and in wild-type (WT) and KLF9-deficient macrophages. The survival rate, body weight loss, lung pathology were compared between WT and KLF9-deficient mice after S. aureus infection. The TLR2 expression was compared between WT and KLF9-deficient macrophages after Pam3CK4 treatment. Decreased expression of KLF9 was detected in PBMCs from elder donor and in macrophages from old mice. Impaired expression of pro-inflammatory cytokines was observed in macrophages from old mice and KLF9-deficient macrophages after Pam3CK4 treatment. KLF9-deficient mice had elevated survival rate, decreased lung injury after S. aureus infection. Decreased expression of TLR2 was detected in KLF9-deficient macrophages and overexpression of TLR2 rescued the impaired expression of inflammatory cytokines in KLF9-deficient macrophages. KLF9 regulated inflammatory responses in macrophages through TLR2.

Pulsed ultrasound promotes secretion of anti-inflammatory extracellular vesicles from skeletal myotubes via elevation of intracellular calcium level.

The regulation of inflammatory responses is an important intervention in biological function and macrophages play an essential role during inflammation. Skeletal muscle is the largest organ in the human body and releases various factors which mediate anti-inflammatory/immune modulatory effects. Recently, the roles of extracellular vesicles (EVs) from a large variety of cells are reported. In particular, EVs released from skeletal muscle are attracting attention due to their therapeutic effects on dysfunctional organs and tissues. Also, ultrasound (US) promotes release of EVs from skeletal muscle. In this study, we investigated the output parameters and mechanisms of US-induced EV release enhancement and the potential of US-treated skeletal muscle-derived EVs in the regulation of inflammatory responses in macrophages. High-intensity US (3.0 W/cm2) irradiation increased EV secretion from C2C12 murine muscle cells via elevating intracellular Ca2+ level without negative effects. Moreover, US-induced EVs suppressed expression levels of pro-inflammatory factors in macrophages. miRNA sequencing analysis revealed that miR-206-3p and miR-378a-3p were especially abundant in skeletal myotube-derived EVs. In this study we demonstrated that high-intensity US promotes the release of anti-inflammatory EVs from skeletal myotubes and exert anti-inflammatory effects on macrophages.

Hypoxia and Matrix Metalloproteinase 13-Responsive Hydrogel Microspheres Alleviate Osteoarthritis Progression In Vivo.

The occurrence of osteoarthritis (OA) is highly associated with the inflammatory hypoxic microenvironment. Yet currently no attention has been paid to fabricating hypoxia-responsive platforms for OA treatment. Herein, an injectable hydrogel microsphere system (HAM-SA@HCQ) focusing on the hypoxic inflamed joint is prepared with methacrylate-modified sulfonated azocalix[4]arene (SAC4A-MA), methacrylated hyaluronic acid (HA-MA), and dithiol-terminated matrix metalloproteinase 13 (MMP-13) sensitive peptide via a microfluidic device and photo crosslinking technique, followed by encapsulation of the anti-inflammatory drug hydroxychloroquine (HCQ) through host-guest interaction. Owing to the hydrophobic deep cavity, phenolic units, and azo bonds of SAC4A-MA, the hydrogel microspheres show strong drug loading capacity, prominent reactive oxygen species (ROS) scavenging capability, and specific hypoxia-responsive drug release ability. In the OA tissue microenvironment, the hydrogel microspheres undergo degradation by excessive MMP-13 and release HCQ under the hypoxia condition, which synergizes with the ROS-scavenging calixarene to inhibit the inflammatory response of macrophages. After being injected into the OA-inflamed joint, the HAM-SA@HCQ can significantly attenuate the oxidative stress, downregulate the expression of hypoxia-induced factor-1α and inflammatory cytokines, and prevent the cartilage from being destroyed.

Nicotinamide mononucleotide as a therapeutic agent to alleviate multi-organ failure in sepsis

BackgroundSepsis-caused multi-organ failure remains the major cause of morbidity and mortality in intensive care units with limited therapeutics. Nicotinamide mononucleotide (NMN), a precursor of nicotinamide adenine dinucleotide (NAD+), has been recently reported to be protective in sepsis; however, its therapeutic effects remain to be determined. This study sought to investigate the therapeutic effects of NMN in septic organ failure and its underlying mechanisms.MethodsSepsis was induced by feces-injection-in-peritoneum in mice. NMN was given after an hour of sepsis onset. Cultured neutrophils, macrophages and endothelial cells were incubated with various agents.ResultsWe demonstrate that administration of NMN elevated NAD+ levels and reduced serum lactate levels, oxidative stress, inflammation, and caspase-3 activity in multiple organs of septic mice, which correlated with the attenuation of heart dysfunction, pulmonary microvascular permeability, liver injury, and kidney dysfunction, leading to lower mortality. The therapeutic effects of NMN were associated with lower bacterial burden in blood, and less ROS production in septic mice. NMN improved bacterial phagocytosis and bactericidal activity of macrophages and neutrophils while reducing the lipopolysaccharides-induced inflammatory response of macrophages. In cultured endothelial cells, NMN mitigated mitochondrial dysfunction, inflammation, apoptosis, and barrier dysfunction induced by septic conditions, all of which were offset by SIRT3 inhibition.ConclusionNAD+ repletion with NMN prevents mitochondrial dysfunction and restrains bacterial dissemination while limiting inflammatory damage through SIRT3 signaling in sepsis. Thus, NMN may represent a therapeutic option for sepsis.

Enhancing silk fibroin structures and applications through angle-dependent Ar+ plasma treatment

This study tackles limitations of Silk Fibroin (SF), including availability of sites for modification. This is achieved by Direct Plasma Nanosynthesis (DPNS), an Ar+ bombardment method, to generate and modify nanostructures and nanoscale properties on the SF surface. SF samples were treated with DPNS at incidence angles of 45o and 60o, with specific ion dose and energy parameters (1 × 1018 ions/cm2 and 500 eV, respectively) maintained throughout the process. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) primarily underscored transformations in SF's nitrogenous components. Specifically, treatment produced a boost in C-NH2, particularly pronounced in the 45o-treated samples, suggesting changes were more superficial than alterations to the secondary structure.The DPNS treatment gave rise to periodic nanocone structures on the SF surface, with a scale increase correlated to a higher angle of incidence. This resulted in a decrease in surface stiffness and significant changes in the motility of J774 macrophages interacting with the transformed SF. Furthermore, the SF samples treated at a 60o incidence showcased a confinement effect, moderating the macrophages' motility, morphology, and inflammatory response. The DPNS-induced alterations not only mitigate SF's limitations but also affect cellular behavior, expanding potential for SF in biomaterials.

Pyrogenic and inflammatory mediators are produced by polarized M1 and M2 macrophages activated with D-dimer and SARS-CoV-2 spike immune complexes

Lung macrophages are the first line of defense against invading respiratory pathogens including SARS-CoV-2, yet activation of macrophage in the lungs can lead to hyperinflammatory immune response seen in severe COVID-19. Here we used human M1 and M2 polarized macrophages as a surrogate model of inflammatory and regulatory macrophages and explored whether immune complexes (IC) containing spike-specific IgG can trigger aberrant cytokine responses in macrophages in the lungs and associated lymph nodes. We show that IC of SARS-CoV-2 recombinant S protein coated with spike-specific monoclonal antibody induced production of Prostaglandin E2 (PGE2) in non-polarized (M0) and in M1 and M2-type polarized human macrophages only in the presence of D-dimer (DD), a fibrinogen degradation product, associated with coagulopathy in COVID-19. Importantly, an increase in PGE2 was also observed in macrophages activated with DD and IC of SARS-CoV-2 pseudovirions coated with plasma from hospitalized COVID-19 patients but not from healthy subjects. Overall, the levels of PGE2 in macrophages activated with DD and IC were as follows: M1≫M2>M0 and correlated with the levels of spike binding antibodies and not with neutralizing antibody titers. All three macrophage subsets produced similar levels of IL-6 following activation with DD+IC, however TNFα, IL-1β, and IL-10 cytokines were produced by M2 macrophages only. Our study suggests that high titers of spike or virion containing IC in the presence of coagulation byproducts (DD) can promote inflammatory response in macrophages in the lungs and associated lymph nodes and contribute to severe COVID-19.

VNS-mediated α7nAChR signaling promotes SPM synthesis via regulation of netrin-1 expression during LPS-induced ALI.

The α7 nicotinic acetylcholine receptor (α7nAChR) plays a crucial role in the cholinergic anti-inflammatory pathway (CAP) during sepsis-associated acute lung injury (ALI). Increasing evidence suggests that specialized pro-resolving mediators (SPMs) are important in resolving α7nAChR-mediated ALI resolution. Our study aims to elucidate the pivotal role of α7nAChR in the CAP during LPS-associated acute lung injury (ALI). By employing vagus nerve stimulation (VNS), we identified α7nAChR as the key CAP subunit in ALI mice, effectively reducing lung permeability and the release of inflammatory cytokines. We further investigated the alterations in SPMs regulated by α7nAChR, revealing a predominant synthesis of lipoxin A4 (LXA4). The significance of α7nAChR-netrin-1 pathway in governing SPM synthesis was confirmed through the use of netrin-1 knockout mice and siRNA-transfected macrophages. Additionally, our evaluation identified a synchronous alteration of LXA4 synthesis in the α7nAChR-netrin-1 pathway accompanied by 5-lipoxygenase (5-LOX), thereby confirming an ameliorative effect of LXA4 on lung injury and macrophage inflammatory response. Concurrently, inhibiting the function of LXA4 annulled the lung-protective effect of VNS. As a result, our findings reveal a novel anti-inflammatory pathway wherein VNS modulates netrin-1 expression via α7nAChR, ultimately leading to LXA4 synthesis and subsequent lung protection.