Neutrophil Influx Research Articles

Acute airway inflammation following controlled biodiesel exhaust exposure in healthy subjects

BackgroundExposure to standard petrodiesel exhaust is linked to adverse health effects. Moreover, there is a mounting request to replace fossil-based fuels with renewable and sustainable alternatives and, therefore, rapeseed methyl ester (RME) and other biofuels have been introduced. However, recent toxicological research has indicated that biodiesel exhaust may also induce adverse health-related events.AimTo determine whether exposure to 100% RME biodiesel (BD100) exhaust would cause an acute airway neutrophilic recruitment in humans.MethodsFourteen healthy subjects underwent exposure to diluted BD100 exhaust and filtered air for 1-h, in a blinded, random fashion. Bronchoscopy with endobronchial mucosal biopsies, bronchial wash (BW) and bronchoalveolar lavage (BAL) was performed six hours after exposure. Differential cell counts and inflammatory markers were determined in the supernatant and biopsies were stained immunohistochemically.ResultsCompared with filtered air, BD100 exhaust exposure increased bronchial mucosal endothelial P-selectin adhesion molecule expression, as well as neutrophil, mast cell and CD68 + macrophage numbers. An increased influx of neutrophils and machrophages was also seen in BW.ConclusionExposure to biodiesel exhaust was associated with an acute airway inflammation that appeared similar to preceding petrodiesel exposure studies. The present findings, together with the recently reported adverse cardiovascular effects after similar biodiesel exposure, indicate that biodiesel is not free of toxicity and may affect human health.

MPO interacts with hRSV particles, contributing to the virucidal effects of NETs against clinical and laboratory hRSV isolates

Human Respiratory syncytial virus (hRSV) mainly affects immunosuppressed patients requiring hospitalization. No specific treatment is financially accessible, and available vaccines do not cover all risk groups. During hRSV infection, there is a robust neutrophilic influx into the airways. hRSV-activated neutrophils release substantial neutrophil extracellular traps (NETs) in lung tissue, comprising DNA, histones, cytosolic, and granular proteins. NETs form mucus buildup in the lungs, compromising respiratory capacity and neutralizing viral particles. Understanding responsible NETs molecules requires improvement. We evaluated NETs interacting with hRSV particles and their contribution to anti-hRSV NET effects. Immunoblotting, immunoprecipitation, and peptide sequencing assays confirmed hRSV binding to a 50–75 kDa NET protein, Myeloperoxidase (MPO). MPO, a microbicide enzyme in NETs, interacts with hRSV, likely at F0 protein (site IV) on the viral surface. Additionally, MPO (32 μM) and NETs (0.4 μg/mL) reduced in vitro replication of clinical (hRSV A and B) and laboratory (Long) hRSV isolates by approximately 30 %, reversible by selective MPO inhibitor (PF-06281355; 48 μM). Thus, MPO contributes to virucidal NET effects on diverse hRSV strains, enhancing comprehension of NETs' role in infection and aiding treatment strategies for respiratory diseases.

Disruption of the C5a/C5aR1 axis confers protection against hookworm infection in lung.

Hookworms are soil-transmitted parasitic nematodes that penetrate the host skin before migrating to the lungs. With an estimated 500-700 million people infected worldwide, hookworm infections are a neglected tropical disease and a significant cause of morbidity, particularly in children, pregnant women, and immunocompromised individuals. Although there is ample evidence that complement activation is pivotal to elicit a protective host immune response against invasive pathogens, its role in hookworm infection remains insufficiently explored. Here, we investigated the complement anaphylatoxin, C5a, during the early lung stage of infection with Nippostrongylus brasiliensis in C57BL/6J wild type and C5aR1-/- mice. Despite the previously reported ability of lung larvae to evade complement activation, C5a was detectable locally in lung tissue and bronchoalveolar lavages. Surprisingly, C5aR1 presence directly contributed to the pathogenicity of hookworm infection. The burden of viable parasites in the lungs was mitigated in C5aR1-/- mice, compared to C57BL/6J mice 48 hours post-infection. Additionally, C5aR1-/- mice showed significantly reduced lung injury, lower cytokine release, attenuated alveolar hemorrhage, and limited alveolar-capillary barrier disruption. Neutrophils were the most abundant and highest C5aR1-expressing cell type in the alveolar space after infection. Deficiency of C5aR1 reduced the influx of neutrophils, monocytes, and eosinophils to the pulmonary airways. RNA sequencing of alveolar neutrophils revealed C5aR1-dependent regulation of the novel nuclear protein, DEDD2. In conclusion, our findings highlight the impact of C5aR1 signaling in neutrophils during hookworm infection uncovering an unexpected downside of complement activation in parasitic infection.

Gene expression profiling reveals host defense strategies for restricting Candida albicans invasion and gastritis to the limiting ridge of the murine stomach.

Candida albicans is a fungal constituent of the human gastrointestinal microbiota that can tolerate acidic environments like the stomach, where it can be associated with ulcers and chronic gastritis. In mice, C. albicans induces gastritis without concurrent intestinal inflammation, suggesting that the stomach is particularly prone to fungal infection. We previously showed that C. albicans invasion in the limiting ridge does not extend to or elicit an inflammatory response in the adjacent glandular region, indicating regionalized gastritis in the murine stomach. However, the molecular pathways involved in the host response to C. albicans specifically in the limiting ridge have not been investigated. Here, we found that gastric dysbiosis was associated with C. albicans limiting ridge colonization and gastritis. We isolated the limiting ridge and evaluated the expression of over 90 genes involved in mucosal responses. C. albicans infection triggered a type 3 immune response marked by elevated Il17a, Il17f, Il1b, Tnf, and Il36g, as well as an upregulation of Il12a, Il4, Il10, and l13. Chemokine gene induction (including Ccl2, Ccl3, Ccl4, Ccl1l, Cxcl1, Cxcl2, Cxcl9, and Cxcl10) coincided with an influx of neutrophils, monocytes/macrophages, and eosinophils. Hyphal invasion caused tissue damage, epithelial remodeling, and upregulation of genes linked to epithelium signaling and antimicrobial responses in the limiting ridge. Our findings support a need for continued exploration into the interactions between the immunological milieu, the host microbiota, and clinical interventions such as the use of antibiotics and immunotherapeutic agents and their collective impact on invasive candidiasis risk.

Increased Circulating Extracellular Superoxide Dismutase Attenuates Platelet-Neutrophil Interactions.

Acute respiratory distress syndrome (ARDS) is a serious illness accounting for 10% of ICU admissions and high mortality of 31-45% with a paucity of pharmacologic treatment options. Dysregulated inflammation and oxidative stress are hallmark features of ARDS. We previously showed that transgenic mice expressing a naturally occurring polymorphism of the antioxidant enzyme extracellular superoxide dismutase (EC-SOD), are protected against Staphylococcus aureus (S. aureus) pneumonia, acute lung injury, and pulmonary neutrophilia. In this mouse strain, an R213G amino acid substitution leads to lower tissue binding affinity and elevated alveolar and plasma EC-SOD levels, though the redox-regulated mechanisms responsible for protection against S. aureus are not yet elucidated. Neutrophils are recruited to the areas of injury and inflammation, in part by activated platelets, which contain multiple redox-sensitive targets. Thus, we hypothesize that increased circulating EC-SOD due to the EC-SOD R213G variant protects against S. aureus pneumonia by reducing platelet activation and subsequent neutrophil recruitment to the lung. We demonstrate that, compared to WT mice with S. aureus pneumonia, platelet activation, formation of platelet-neutrophil aggregates (PNAs), and influx of neutrophils and PNAs into the lung are decreased in the infected R213G mice. Furthermore, pre-treatment with a MnTE-2-PyP SOD mimetic protects against S. aureus-induced platelet activation, pulmonary neutrophilia, and acute lung injury. Our data highlight the redox regulation of platelet activation as a driver of S. aureus-induced acute lung injury.

Abstract 4138606: Toll-like Receptor 4 Signaling Establishes Trained Innate Immunity Through Interferon-Mediated Epigenetic Modifications Leading to Cardioprotection in a Stress-induced Cardiomyopathy Model

Introduction: The mechanisms responsible for establishing preconditioning-induced cardioprotection remain unknown. We have shown that a high dose of isoproterenol (ISO) induces cardioprotection against a second ISO dose in mice. The durability of protection and the lack of an innate immune response suggests trained immunity as a novel cardioprotective mechanism. Hypothesis: We hypothesize that cardioprotection is conferred through trained immunity, by interferon signaling downstream of necrotic cardiac material-mediated Toll-like receptor 4 (TLR4) activation. Methods: Wild-type C57BL/6J mice were intraperitoneally injected with TLR agonists or diluent, and challenged with 300 mg/kg ISO 7 days later. Mice were assessed by 2-D echocardiography, serum cardiac troponin levels, flow cytometry immune cell counts, and Multiome (single nuclei RNA+ATAC) sequencing. Results: The TLR4 agonist lipopolysaccharide (LPS) induced cardioprotection against ISO injury, with mice having enhanced survival (P=0.049) and no changes in cardiac troponin levels (P>0.99), cardiac neutrophil influx (P>0.99) or left ventricular motion (P=0.057) relative to baseline values before injury. Treating LPS-injected mice with β-glucan reversed the effects of LPS on immune cells and abolished cardioprotection. Multiome analysis of genes linked to chromatin peaks with increased accessibility in LPS+vehicle (protected) compared to LPS+β-glucan and diluent control (non-protected) hearts revealed the interferon pathway to be up-regulated across all major cell types. Modulation of interferon signaling with monoclonal antibodies against type 1+2 interferon receptors abolished cardioprotection in LPS-treated mice, whereas pre-treatment with recombinant type 1+2 interferons induced cardioprotection. Importantly, interferon-treated hearts shared similar chromatin accessibility features and enriched transcription factor motifs, including interferon-specific motifs, with LPS-protected hearts across cell types, particularly among non-cardiomyocytes. Conclusions: TLR4-induced interferon signaling is sufficient and in part necessary for cardioprotection against ISO injury. Moreover, our findings show that epigenetic modifications downstream of interferon signaling lead to cardioprotection consistent with trained innate immunity.

Reprogramming of epidermal keratinocytes by PITX1 transforms the cutaneous cellular landscape and promotes wound healing.

Cutaneous wound healing is a slow process that often terminates with permanent scarring while oral wounds, in contrast, regenerate damage faster. Unique molecular networks in epidermal and oral epithelial keratinocytes contribute to the tissue-specific response to wounding, but key factors that establish those networks and how the keratinocytes interact with their cellular environment remain to be elucidated. The transcription factor PITX1 is highly expressed in the oral epithelium but is undetectable in cutaneous keratinocytes. To delineate if PITX1 contributes to oral keratinocyte identity, cell-cell interactions, and the improved wound healing capabilities, we ectopically expressed PITX1 in the epidermis of murine skin. Using comparative analysis of murine skin and oral (buccal) mucosa with scRNA-seq and spatial transcriptomics, we found that PITX1 expression enhances epidermal keratinocyte migration, proliferation, and alters differentiation to a quasi-oral keratinocyte state. PITX1+ keratinocytes reprogram intercellular communication between skin-resident cells to mirror buccal tissue while also stimulating the influx of neutrophils that establish a pro-inflammatory environment. Furthermore, PITX1+ skin heals significantly faster than control skin via increased keratinocyte activation and migration and a tunable inflammatory environment. These results illustrate that PITX1 programs oral keratinocyte identity and cellular interactions while also revealing critical downstream networks that promote wound closure.

TLR7 deficiency alleviated myocardial ischemia reperfusion injury via regulating macrophage-neutrophil interaction

Abstract Background Toll-like receptor 7 (TLR7) is an intracellular innate immune receptor activated by single-stranded RNA. We previously reported that TLR7 could recognize RNA from dying cardiac cells and thereby deteriorating post myocardial infarction left ventricular remodeling. However, its effect on myocardial ischemia reperfusion (IR) injury is still unknown. Purpose In this study, we aimed to investigate the role of TLR7 in myocardial IR injury and the underlying mechanisms. Methods C57BL/6J wild type (WT) and TLR7 deficient (TLR7-/-) mice underwent left anterior descending artery occlusion for 30min followed by reperfusion. Myocardial infarct size was measured by Evan’s blue and TTC staining. mRNA expression levels of cytokines and phagocytosis-related receptors were detected by qPCR. TUNEL assay was conducted to determine apoptosis in the heart. Influx of neutrophils and macrophages in ischemic myocardium was analyzed by flow cytometry and Histone Cit3 was imaged to examine formation of neutrophils extracellular traps (NETs), cardiac function was evaluated by echocardiography during post-IR injury follow-up. Results TLR7 expression was up-regulated after IR injury in ischemic myocardium of WT mice. Compared to WT mice, fewer apoptotic cells and smaller infarct size (34±2% vs. 23±3% of area at risk, p<0.01) were observed in TLR7-/- mice at 24 hours post-IR, which was accompanied by reduced inflammatory cytokines (IL-1β: 110.5±14.1 vs. 54.8±13.7, p<0.05; TNF-α: 4.6±1.0 vs. 2.0±0.4, p<0.05) and increased anti-inflammatory factors (TNF-β: 2.9±0.3 vs. 8.6±2.6, p<0.05; IL-10: 14.2±2.1 vs. 32.3±8.8, p<0.05). Surprisingly, although the influx of neutrophils and macrophages increased to a similar extent in WT and TLR7-/- mice, the latter exhibited remarkably less NETs formation and enhanced macrophage phagocytosis in the infarct region. Moreover, TLR7 deficiency improved cardiac function, as indicated by increased left ventricular ejection fraction (LVEF) and fraction shortening (FS) at 56d post-IR. Conclusions TLR7 deficiency alleviates myocardial IR injury and improves cardiac function probably via enhancing macrophage clearance of NETs in the injured myocardium.TLR7 deficiency in cardiac functionTLR7 deficiency decreased NETs formation

Pyoderma Gangrenosum Associated With Iatrogenic Interleukin 17A Blockade: A Report of Two Cases andaReview of the Literature.

Pyoderma gangrenosum (PG) is a rare necrotizing neutrophilic dermatosis driven by monokines and cytokines elaborated by monocytes and autoreactive T cells, respectively. Th1-mediated autoimmune disorders and myeloproliferative disease are among the potential disease associations. More recently, certain medications were implicated, including TNF-alpha inhibitors, rituximab, and IL-17A inhibitors, such as secukinumab, where the development of PG is held to represent a cutaneous immune adverse effect. We present two patients who developed an autoinflammatory syndrome resembling PG in the setting of drug therapy with agents exhibiting an IL-17A inhibitory effect. The drugs were erunumab in one and secukinumab in the other. One patient received the anti-calcitonin gene-related peptide targeted therapy, erenumab, for migraine prophylaxis. While this drug has not been previously implicated in the development of PG, it can cause IL-17A blockade. The other patient was on secukinumab, a monoclonal antibody that selectively targets IL-17A. We documented a microenvironment enriched in IL-17A, emphasizing that the blockade impacts the functionality of the receptor as opposed to a quantitative reduction in IL-17A production by T cells. Qualitative functional IL-17A blockade could result in a paradoxical increase in IL-23, a pro-inflammatory cytokine that may contribute to the influx of neutrophils pathogenetically implicated in PG.

Specialized Pro-Resolving Lipid Mediators Distinctly Modulate Silver Nanoparticle-Induced Pulmonary Inflammation in Healthy and Metabolic Syndrome Mouse Models.

Individuals with chronic diseases are more vulnerable to environmental inhalation exposures. Although metabolic syndrome (MetS) is increasingly common and is associated with susceptibility to inhalation exposures such as particulate air pollution, the underlying mechanisms remain unclear. In previous studies, we determined that, compared to a healthy mouse model, a mouse model of MetS exhibited increased pulmonary inflammation 24 h after exposure to AgNPs. This exacerbated response was associated with decreases in pulmonary levels of specific specialized pro-resolving mediators (SPMs). Supplementation with specific SPMs that are known to be dysregulated in MetS may alter particulate-induced inflammatory responses and be useful in treatment strategies. Our current study hypothesized that administration of resolvin E1 (RvE1), protectin D1 (PD1), or maresin (MaR1) following AgNP exposure will differentially regulate inflammatory responses. To examine this hypothesis, healthy and MetS mouse models were exposed to either a vehicle (control) or 50 μg of 20 nm AgNPs via oropharyngeal aspiration. They were then treated 24 h post-exposure with either a vehicle (control) or 400 ng of RvE1, PD1, or MaR1 via oropharyngeal aspiration. Endpoints of pulmonary inflammation and toxicity were evaluated three days following AgNP exposure. MetS mice that were exposed to AgNPs and received PBS treatment exhibited significantly exacerbated pulmonary inflammatory responses compared to healthy mice. In mice exposed to AgNPs and treated with RvE1, neutrophil infiltration was reduced in healthy mice and the exacerbated neutrophil levels were decreased in the MetS model. This decreased neutrophilia was associated with decreases in proinflammatory cytokines' gene and protein expression. Healthy mice treated with PD1 did not demonstrate alterations in AgNP-induced neutrophil levels compared to mice not receiving treat; however, exacerbated neutrophilia was reduced in the MetS model. These PD1 alterations were associated with decreases in proinflammatory cytokines, as well as elevated interleukin-10 (IL-10). Both mouse models receiving MaR1 treatment demonstrated reductions in AgNP-induced neutrophil influx. MaR1 treatment was associated with decreases in proinflammatory cytokines in both models and increases in the resolution inflammatory cytokine IL-10 in both models, which were enhanced in MetS mice. Inflammatory responses to particulate exposure may be treated using specific SPMs, some of which may benefit susceptible subpopulations.

Granulomas in Common Variable Immunodeficiency Display Different Histopathological Features Compared to Other Granulomatous Diseases

Granulomatous disease affects up to 20% of patients with Common Variable Immunodeficiency (CVID). Granulomas are comprised of highly activated immune cells, and emerge in response to antigenic triggers. In CVID granulomas however, the underlying pathophysiology is unclear and the specific trigger remains unknown. Granuloma formation in CVID is often compared to sarcoidosis, although clinical context and prognosis differ, suggesting a different pathogenesis. The aim of this study was to investigate if the cellular organization and proteomics of granulomas in CVID is different from other granulomatous diseases. Therefore, tissue slides from formaldehyde fixed paraffin embedded biopsies obtained from patients with CVID, sarcoidosis, tuberculosis and foreign-material induced pseudo-sarcoidosis were stained with hematoxylin and eosin and assessed for histopathological characteristics. Targeted spatial protein analysis was performed, and immune fluorescent multiplex assays were used to analyze the cellular organization. Histological analysis revealed that CVID granulomas were smaller, less circumscribed, with fewer multinucleated giant cells and minimal fibrosis compared to the other granulomatous diseases. Spatial protein analysis showed that granulomas in all diseases expressed CD68, CD11c, CD44, CD127, and PD-L1. However in CVID, reduced expression of the fibrosis-related protein fibronectin, but enrichment of CD163, CD3 and FAPα inside CVID granulomas was observed. Immunofluorescence analysis conformed a different cellular organization in CVID granulomas with increased influx of neutrophils, macrophages, T and B lymphocytes. In conclusion, granulomas in CVID display a different histological and cellular organization with increased influx of myeloid and lymphoid cells, compared to sarcoidosis, tuberculosis and pseudo-sarcoidosis, indicating a distinct pathogenesis underlying granuloma formation.

Postnatal supplementation with alarmins S100a8/a9 ameliorates malnutrition-induced neonate enteropathy in mice.

Malnutrition is linked to 45% of global childhood mortality, however, the impact of maternal malnutrition on the child's health remains elusive. Previous studies suggested that maternal malnutrition does not affect breast milk composition. Yet, malnourished children often develop a so-called environmental enteropathy, assumed to be triggered by frequent pathogen uptake and unfavorable gut colonization. Here, we show in a murine model that maternal malnutrition induces a persistent inflammatory gut dysfunction in the offspring that establishes during nursing and does not recover after weaning onto standard diet. Early intestinal influx of neutrophils, impaired postnatal development of gut-regulatory functions, and expansion of Enterobacteriaceae were hallmarks of this enteropathy. This gut phenotype resembled those developing under deficient S100a8/a9-supply via breast milk, which is a known key factor for the postnatal development of gut homeostasis. We could confirm that S100a8/a9 is lacking in the breast milk of malnourished mothers and the offspring's intestine. Nutritional supply of S100a8 to neonates of malnourished mothers abrogated the aberrant development of gut mucosal immunity and microbiota colonization and protected them lifelong against severe enteric infections and non-infectious bowel diseases. S100a8 supplementation after birth might be a promising measure to counteract deleterious imprinting of gut immunity by maternal malnutrition.

Fatty acid metabolism in neutrophils promotes lung damage and bacterial replication during tuberculosis.

Mycobacterium tuberculosis (Mtb) infection induces a marked influx of neutrophils into the lungs, which intensifies the severity of tuberculosis (TB). The metabolic state of neutrophils significantly influences their functional response during inflammation and interaction with bacterial pathogens. However, the effect of Mtb infection on neutrophil metabolism and its consequent role in TB pathogenesis remain unclear. In this study, we examined the contribution of glycolysis and fatty acid metabolism on neutrophil responses to Mtb HN878 infection using ex-vivo assays and murine infection models. We discover that blocking glycolysis aggravates TB pathology, whereas inhibiting fatty acid oxidation (FAO) yields protective outcomes, including reduced weight loss, immunopathology, and bacterial burden in lung. Intriguingly, FAO inhibition preferentially disrupts the recruitment of a pathogen-permissive immature neutrophil population (Ly6Glo/dim), known to accumulate during TB. Targeting carnitine palmitoyl transferase 1a (Cpt1a)-a crucial enzyme in mitochondrial β-oxidation-either through chemical or genetic methods impairs neutrophils' ability to migrate to infection sites while also enhancing their antimicrobial function. Our findings illuminate the critical influence of neutrophil immunometabolism in TB pathogenesis, suggesting that manipulating fatty acid metabolism presents a novel avenue for host-directed TB therapies by modulating neutrophil functions.

The investigation of SNP in SOCS2 gene and its effect on milk yield, fat, protein, and somatic cell count in Awassi ewes.

Livestock farmers face financial losses every year because milk yield and components are severely affected by udder diseases. These udder infections attract the immune response from the host and lead to the influx of neutrophils into milk to fight infection and thus the number of somatic cell count (SCC) is increased. The SCC value of milk could be used as an important indicator in detecting clinical mastitis in dairy animals. Also, the milk yield and milk quality (e.g. fat) are negatively affected by the increased SCC. The SCC is used to estimate the somatic cell score (SCS)of the milk, which is used as an indirect measure to detect subclinical mastitis. Therefore, the purpose of this study was to investigate the presence of a significant SNP rs868996547, on the suppressor of cytokine signaling 2 gene (SOCS2) which is related to milk yield and milk quality in Awassi sheep. In this study, milk production data was obtained from 210 healthy Awassi ewes with different parties and ages. The general linear model (GLM) process analysis of variance (ANOVA) was used to determine fixed effects on milk traits. The DNA extraction was done using a blood DNA extraction kit from Qiagen. To validate the presence of SNP a customized SNP detection developed by Thermofisher Scientific was used. The presence of the SNP in the SOCS2 gene was detected with genotypes (C/T, T/T, and C/C) and T being the mutated allele and it had a significant (p < 0.015) effect on the milk yield (p < 0,015;0.091), fat (p < 0,001;0,003), fat/protein ratio (p < 0.001;0,037) and log10SCC value (p < 0,006;0,015) of Awassi ewes. However, the protein, total solid, and lactose percentages in the wild type and the mutated ewes found having no significant difference (P > 0.05). Our result showed the increase in SCC or SCS of the milk significantly affected the milk yield and composition. Parity and age had significant effects on ewes' milk yield (p < 0.001). In conclusion, we investigated the presence of SOCS2 gene of Awassi ewes in the study flock and its effect on milk yield, fat, and somatic cell count, and the change in milk composition and milk yield because of SCC.

Langerhans cells orchestrate apoptosis of DNA-damaged keratinocytes upon high-dose UVB skin exposure.

Ultraviolet (UV) irradiation of the skin causes mutations that can promote the development of melanoma and nonmelanoma skin cancer. High-dose UVB exposure triggers a vigorous skin reaction characterized by inflammation resulting in acute sunburn. This response includes the formation of sunburn cells and keratinocytes (KC) undergoing programmed cell death (apoptosis) when repair mechanisms of DNA damage are inadequate. The primary objective of this research was to clarify the involvement of Langerhans cells (LC) in the development of acute sunburn following intense UVB skin irradiation. To address this, we subjected the dorsal skin of mice to a single high-dose UVB exposure and analyzed the immediate immune response occurring within the skin tissue. Acute sunburn triggered an activation of LC, coinciding with a rapid influx of neutrophils that produced TNF-α. Furthermore, our investigation unveiled a marked increase in DNA-damaged KC and the subsequent induction of apoptosis in these cells. Importantly, we demonstrate a crucial link between the inflammatory cascade, the initiation of apoptosis in DNA-damaged KC, and the presence of LC in the skin. LC were observed to modulate the chemokine response in the skin following exposure to UVB, thereby affecting the trafficking of neutrophils. Skin lacking LC revealed diminished inflammation, contained fewer TNF-α-producing neutrophils, and due to the prevention of apoptosis induction, a lingering population of DNA-damaged KC, presumably carrying the risk of enduring genomic alterations. In summary, our results underscore the pivotal role of LC in preserving the homeostasis of UVB-irradiated skin. These findings contribute to a deeper understanding of the intricate mechanisms underlying acute sunburn responses and their implications for UV-induced skin cancer.

DJ-X-013 reduces LPS-induced inflammation, modulates Th17/ myeloid-derived suppressor cells, and alters NF-κB expression to ameliorate experimental colitis

ScopeInflammatory bowel disease (IBD) is a chronic intestinal inflammatory condition of unknown etiology, although recent evidence suggests that it is caused by an excessive immune response to mucosal antigens. We determined the anti-inflammatory properties of novel compound DJ-X-013 in vitro in lipopolysaccharide (LPS)-induced macrophages and in an in vivo dextran sodium sulfate (DSS)-induced model of colitis. Methods and resultsTo evaluate the anti-inflammatory properties of DJ-X-013, we used LPS-activated RAW 264.7 macrophages in vitro and a DSS-induced experimental model of colitis in vivo. We examine cellular morphology, and tissue architecture by histology, flow cytometry, RT-qPCR, multiplex, and immunoblot analysis to perform cellular and molecular studies. DJ-X-013 treatment altered cell morphology and expression of inflammatory cytokines in LPS-activated macrophages as compared to cells treated with LPS alone. DJ-X-013 also impeded the migration of RAW 264.7 macrophages by modulating cytoskeletal organization and suppressed the expression of NF-κB and inflammatory markers as compared to LPS alone. DJ-X-013 treatment improved body weight, and colon length and attenuated inflammation in the colon of DSS-induced colitis. Intriguingly, DSS-challenged mice treated with DJ-X-013 induced the numbers of myeloid-derived suppressor cells (MDSCs), dendritic cells (DCs), and natural killer T cells (NKT) in the colon lamina propria (LP) relative to DSS. DJ-X-013 also reduced the influx of neutrophils, TNF-α producing macrophages, restricted the number of Th17 cells, and suppressed inflammatory cytokines and NF-κB in the LP relative to DSS. ConclusionDJ-X-013 is proposed to be a therapeutic strategy for ameliorating inflammation and experimental colitis.

The Omega-6 Lipid pathway shift is associated with neutrophil influx and structural lung damage in early cysticfibrosis lung disease.

In cystic fibrosis (CF), an imbalanced lipid metabolism is associated with lung inflammation. Little is known about the role that specific lipid mediators (LMs) exert in CF lung inflammation, and whether their levels change during early disease progression. Therefore, we measured airway LM profiles of young CF patients, correlating these with disease-associated parameters. Levels of omega (ω)-3/6 PUFAs and their LM derivatives were determined in bronchoalveolar lavage fluid (BALF) of children with CF ages 1-5 using a targeted high-performance liquid chromatography-tandem mass spectrometry approach. Hierarchical clustering analysis was performed on relative LM levels. Individual relative LM levels were correlated with neutrophilic inflammation (BALF %Neu) and structural lung damage (PRAGMA-CF %Disease). Significant correlations were included in a backward multivariate linear regression model to identify the LMs that are best related to disease progression. A total of 65 BALF samples were analysed for ω-3/6 lipid content. LM profiles clustered into an arachidonic acid (AA)-enriched and a linoleic acid (LA)-enriched sample cluster. AA derivatives like 17-OH-DH-HETE, 5-HETE, 5,15-diHETE, 15-HETE, 15-KETE, LTB4 and 6-trans-LTB4 positively correlated with BALF %Neu and/or PRAGMA %Dis. Contrastingly, 9-HoTrE and the LA derivatives 9-HoDE, 9(10)-EpOME, 9(10)-DiHOME, 13-HoDE, 13-oxoODE and 12(13)-EpOME negatively correlated with BALF %Neu and/or PRAGMA %Dis. 6-trans-LTB4 was the strongest predictor for BALF %Neu. 5-HETE and 15-KETE contributed most to PRAGMA %Dis prediction. Our data provide more insight into the lung lipidome of infants with CF, and show that a shift from LA derivatives to AA derivatives in BALF associates with early CF lung disease progression.

NOCICEPTOR NEURONS CONTROL POLLUTION-MEDIATED NEUTROPHILIC ASTHMA.

The immune and sensory nervous systems, having evolved together, use a shared language of receptors and transmitters to maintain homeostasis by responding to external and internal disruptions. Although beneficial in many cases, neurons can exacerbate inflammation during allergic reactions, such as asthma. Our research modeled asthma aggravated by pollution, exposing mice to ambient PM2.5 particles and ovalbumin. This exposure significantly increased bronchoalveolar lavage fluid neutrophils and γδ T cells compared to exposure to ovalbumin alone. We normalized airway inflammation and lung neutrophil levels by silencing nociceptor neurons at inflammation's peak using intranasal QX-314 or ablating TRPV1-expressing neurons. Additionally, we observed heightened sensitivity in chemical-sensing TRPA1 channels in neurons from pollution-exacerbated asthmatic mice. Elevated levels of artemin were detected in the bronchoalveolar lavage fluid from pollution-exposed mice, with artemin levels normalizing in mice with ablated nociceptor neurons. Upon exposure PM2.5 particles, alveolar macrophages expressing pollution-sensing aryl hydrocarbon receptors, were identified as the source of artemin. This molecule enhanced TRPA1 responsiveness and increased neutrophil influx, providing a novel mechanism by which lung-innervating neurons respond to air pollution and suggesting a potential therapeutic target for controlling neutrophilic airway inflammation in asthma, a clinically intractable condition.

A lactobacilli-based inhaled live biotherapeutic product attenuates pulmonary neutrophilic inflammation

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of prematurity. Exposure to noxious stimuli such as hyperoxia, volutrauma, and infection in infancy can have long-reaching impacts on lung health and predispose towards the development of conditions such as chronic obstructive pulmonary disease (COPD) in adulthood. BPD and COPD are both marked by lung tissue degradation, neutrophil influx, and decreased lung function. Both diseases also express a change in microbial signature characterized by firmicute depletion. However, the relationship between pulmonary bacteria and the mechanisms of downstream disease development has yet to be elucidated. We hypothesized that murine models of BPD would show heightened acetylated proline-glycine-proline (Ac-PGP) pathway and neutrophil activity, and through gain- and loss-of-function studies we show that Ac-PGP plays a critical role in driving BPD development. We further test a inhaled live biotherapeutic (LBP) using active Lactobacillus strains in in vitro and in vivo models of BPD and COPD. The Lactobacillus-based LBP is effective in improving lung structure and function, mitigating neutrophil influx, and reducing a broad swath of pro-inflammatory markers in these models of chronic pulmonary disease via the MMP-9/PGP (matrix metalloproteinase/proline-glycine-proline) pathway. Inhaled LBPs show promise in addressing common pathways of disease progression that in the future can be targeted in a variety of chronic lung diseases.

Repeated stress to the skin amplifies neutrophil infiltration in a keratin 17- and PKCα-dependent manner.

Neutrophils are the first immune cells to reach inflamed sites and contribute to the pathogenesis of chronic inflammatory skin diseases. Yet, little is known about the pattern of neutrophil infiltration in inflamed skin in vivo and the mechanisms mediating their recruitment. Here, we provide insight into the dynamics of neutrophil infiltration in skin in response to acute or repeated inflammatory stress, highlighting a novel keratinocyte- and keratin 17 (K17)-dependent mechanism that regulates neutrophil recruitment to inflamed skin. We used the phorbol ester TPA and UVB, alone or in combination, to induce sterile inflammation in mouse skin. A single TPA treatment results in a neutrophil influx in the dermis that peaks at 12 h and resolves within 24 h. A subsequent TPA treatment or a UVB challenge, when applied 24 h but not 48 h later, accelerates, amplifies, and prolongs neutrophil infiltration. This transient amplification response (TAR) is mediated by local signals in inflamed skin, can be recapitulated in ex vivo culture, and involves the K17-dependent sustainment of protein kinase Cα (PKCα) activity and release of chemoattractants by stressed keratinocytes. K17 binds RACK1, a scaffold protein essential for PKCα activity. The N-terminal head domain of K17 is crucial for its association with RACK1 and regulation of PKCα activity. Analysis of RNAseq data reveals a signature consistent with TAR and PKCα activation in inflammatory skin diseases. These findings uncover a novel, keratin-dependent mechanism that amplifies neutrophil recruitment in skin under stress, with direct implications for inflammatory skin disorders.