Innate Immunity最新文献

Neutrophils play a pivotal role in the host immune system, serving as the frontline defense against microbial infections. They eradicate pathogens through diverse mechanisms, encompassing degranulation, phagocytosis, and the release of reactive oxygen species. Moreover, they are acknowledged as crucial contributors to chronic inflammatory pathological processes, including conditions such as cancer and autoimmune diseases. An expanding body of research suggests that neutrophils, harnessing their innate immune characteristics, possess the potential to serve as carriers for therapeutic agents or be directly employed in disease treatment. This underscores their potential as a cell therapy platform for future applications. Consequently, we systematically investigate the potential applications of neutrophils in this review, with a primary emphasis on elucidating the research advancements in utilizing neutrophils, including those derived from stem cells, for therapeutic interventions in various diseases.

Background: Acute Lung Injuries (ALI) are a severe consequence of influenza-induced cytokine storm that can cause respiratory failure and death. It has been demonstrated that Toll-like Receptor 4 (TLR4) is involved in cytokine storm and that TLR4^-/- mice are protected against ALI. Therefore, TLR4 is a prime target for protection against ALI. FP12 is a known TLR4 antagonist that reduces TLR4-dependent immune activation and it is a promising lead compound for the treatment of innate immunity related pathologies.

Objectives: We present here the preclinical development of FP12 as an anti-inflammatory lead compound acting on influenza-induced ALI.

Methods: In vitro: We pre-treated THP-1 cells with FP12 (10 μM) for 0.5 h, then exposed to LPS (100 ng/ml) for 0 to 16 h. In some experiments, cells were simultaneously incubated with FP12 and LPS, or FP12 was added 30 min after LPS. Cytokine levels were measured by Western blot and ELISA assays. In vivo: WT C57BL/6J mice were infected with mouse-adapted influenza virus (PR8). Two days after infection, mice received either vehicle, FP7 (200 µg/mouse), or FP12 (200 µg/mouse) once daily (Day 2 to Day 6). Mice were monitored daily for survival for 14 days. Data were collected through histological staining, qRT-PCR, and ELISA assay.

Results: FP12 treatment inhibited both LPS- and HMGB1-induced TLR4 intracellular pathways (MyD88 and TRIF) leading to significantly reduced levels of a variety of proinflammatory cytokines including Type I interferon (IFN-β), highlighting its effectiveness in controlling proinflammatory protein production and reducing inflammation. FP12 protected mice therapeutically from influenza virus-induced lethality and reduced both cytokine gene expression and High Mobility Group Box 1 (HMGB1) levels in the lungs as well as ALI.

Conclusion: FP12 can antagonize TLR4 activation in vitro and protects mice from severe influenza infection, most likely by reducing the TLR4-dependent cytokine storm mediated by danger-associated molecular patterns (DAMPs).

ObjectiveTo investigate the important active sites within the NTFs to affect the in vitro interaction of oxidized low-density lipoprotein (ox-LDL) with its receptor, OLR1.MethodsSimulation analysis online was performed to generate various OLR1 chimeras, truncation mutants, and site-specific mutations. They were transfected in COS-7 cells and subjected to ox-LDL stimulations to observe the different reactions. Immunoprecipitation-mass spectrometry (IP-MS) was performed to show what proteins combined with OLR1 mutants in reaction to ox-LDL. Lipid uptake in human monocytes (THP-1) originated foam cells overexpressing somatic mutant of OLR1 were also determined. Further studies focusing on these regions were conducted using truncation mutants and site-specific mutants such as G43A, V44A, L45A, C46A, and L47A.ResultsAmino acids within the TM were highly conserved, spanning amino acids 35 to 57. The induction of intracellular p-ERK1/2 in response to ox-LDL stimulation was highly promoted in Chimera 3 possessing the TM from OLR1 like OLR1/WT (p < 0.05). Sequence alignment revealed two conserved regions within the TM of OLR1, Leu45-Cys46-Leu47 and Val55-Leu56-Gly57. Western blot showed that most of the TM changes ablated ERK1/2 activation in response to ox-LDL stimulation (p < 0.05). One human somatic mutation at L45F revealed significantly lower p-ERK1/2 levels with enhanced intake of ox-LDL in THP-1-derived foam cells than the control cells (p < 0.05). L45A and C46A molecular complexes were identified. After ox-LDL stimulation, these underlined interactions with keratins, namely KRT2 and KRT6A.ConclusionThese findings emphasize the vital role of the TM in the interactions between OLR1 and ox-LDL and point to an exciting possibility that signal transduction induced by ox-LDL through its receptor OLR1 may involve complex interactions with cytoskeletal proteins.

The gut microbiome plays a crucial role in shaping immune responses, and its connection to immunity has never been more relevant than in the COVID-19 era. The interaction between gut microbes and the immune system, known as microbiome-immunity crosstalk, influences both how the body responds to infections and how well it recovers. COVID-19, whether in its acute phase or lingering as long COVID, has been linked to disturbances in the gut microbiome. During infection, many patients experience dysbiosis-an imbalance in gut bacteria-that can contribute to immune dysfunction and excessive inflammation. This imbalance may not only worsen the severity of the disease but also prolong recovery, leading to persistent symptoms like fatigue, brain fog, and digestive issues. Long COVID, in particular, has been associated with ongoing immune dysregulation, where the body's defense system remains in a state of heightened activation, causing chronic inflammation. Given the strong link between gut health and immunity, there is growing interest in strategies to restore microbial balance. Synbiotics-combinations of probiotics (beneficial bacteria) and prebiotics (nutrients that support them)-are being explored as a potential therapeutic approach. By replenishing beneficial gut microbes, synbiotics may help regulate immune responses, reduce inflammation, and support overall recovery from COVID-19. Emerging research suggests that improving gut health could enhance the body's ability to fight infections and recover more efficiently. As we continue to understand the long-term impact of COVID-19, focusing on the gut microbiome offers a promising path forward. Supporting a balanced and diverse microbiome through diet, lifestyle, and targeted interventions like synbiotics may provide a natural way to strengthen immunity and improve health outcomes in both acute and long COVID cases.

Background: To determine whether (i) altered levels of acute-phase response (APR)-, inflammation-, and extracellular matrix (ECM)-related proteins in the amniotic fluid (AF) were associated with spontaneous preterm delivery (SPTD) in asymptomatic women with midtrimester short cervix (SCX) and (ii) if SPTD risk severity was related to the expression levels of inflammation-related proteins in the AF. Methods: This retrospective cohort study included 70 singleton pregnant women diagnosed with a SCX (<25 mm) at 17-25 weeks, who were subjected to amniocentesis to exclude intraamniotic inflammation (IAI; defined as AF interleukin [IL]-6 ≥ 2.6 ng/mL). APR (i.e., hepcidin, kallistatin, MBL, pentraxin-2, RBP4, and serpin A1), inflammatory (i.e., IL-6, IL-8, and resistin), and ECM-related (i.e., lumican, MMP-8, TGFBI, and uPA) molecules were assayed in the AF by ELISA. The primary outcome measure was SPTD at <34 weeks. The levels of each identified dysregulated inflammatory mediator were divided into quartiles to assess the correlation between their AF expression profiles and SPTD risk severity. Results: Multivariable Firth logistic regression analyses revealed that elevated AF levels of IL-6, IL-8, kallistatin, pentraxin-2, resistin, and serpin A1, and IAI presence were independently associated with SPTD at <34 weeks after adjusting for baseline covariates. The areas under the curves of the aforementioned mediators ranged from 0.67 to 0.79 for outcome prediction. The odds of SPTD at <34 weeks, even after adjusting for confounders, significantly increased with each increasing quartile of baseline AF levels of IL-6/8, pentraxin-2, and resistin. Conclusions: APR (kallistatin, pentraxin-2, and serpin A1)- and inflammation (IL-6/8 and resistin)-, but not ECM-related mediators in the AF are involved in SPTD development in asymptomatic women with a midtrimester SCX. In particular, SPTD risk (especially risk severity) is associated with the degree of the inflammatory response in the AF, as categorized by inflammatory protein expression profiles, as well as IAI presence.

Bronchial cell pyroptosis and IL-17 respectively contribute- to the pathogenesis of steroid-insensitive asthma. In this study, we aim to explore the relationship between bronchial cell pyroptosis and Th17 in airway inflammation of steroid-insensitive asthma. The steroid-insensitive asthma model of mice was induced by toluene diisocyanate (TDI), which was also intraperitoneally injected with NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inhibitor MCC950. The bronchial epithelial cell pyroptosis was identified in morphology by transmission electron microscope. Protein expressions of pyroptosis cytokines (pro-Caspase-1, Caspase-1 p20, pro-GSDMD, cleaved-GSDMD and HMGB1), IL-17A, IL-17F and phosphorylated STAT3 (p-STAT3) in lung tissues were assessed by western blotting. Th17 in lung tissues was measured by flow cytometry. IL-17A + and p-STAT3 + cells in airway were identified by immunohistochemistry. In steroid-insensitive asthma mice, bronchial epithelial cell pyroptosis was confirmed in morphology using transmission electron microscope. Compared with controls, the protein expressions of Caspase-1 p20, cleaved-GSDMD and HMGB1 in lung tissues were increased in mice with steroid-insensitive asthma, which could be attenuated by MCC950. Th17 cells precentage and proteins expressions of p-STAT3, IL-17A and IL-17F were also increased in lung of steroid-insensitive asthmatic mice, which were also attenuated by MCC950. Similarly, the counts of IL-17A + cell and p-STAT3 + cell were more in airway of steroid-insensitive asthmatic mice than controls, and was attenuated by MCC950. In conclusion, bronchial epithelial cell pyroptosis could promote Th17 inflammation in airway of steroid-insensitive asthma mouse, which will provide further understanding on the interaction between innate immunity and acquired immunity in the pathogenesis of steroid-insensitive asthma.

BackgroundFour influenza pandemics have occurred during the past 100 years, and new variants of influenza viruses will continue to emerge. The nasal mucosa acts as the primary site of exposure to influenza A virus (IAV) infection, but viral recognition and host immune responses in the nasal mucosa are still poorly understood.ObjectivesThis study aimed to evaluate the utility of non-invasive nasopharyngeal swabs for longitudinal monitoring of mucosal immune responses in pigs experimentally challenged with two swine-adapted and one human-adapted IAV. By tracking antiviral immune responses from disease onset to recovery, we sought to assess the feasibility of this method for capturing dynamic changes in viral load and host responses across different IAV strains.MethodsForty-two IAV-negative pigs were divided into four groups and housed separately for infection studies. Viral and host RNA from nasopharyngeal swabs was analyzed using microfluidic qPCR, while statistical analysis was performed with a Bayesian approach in R. Additionally, immunohistochemical staining was used to assess MUC5AC expression in the nasal mucosa of infected pigs.ResultsRNA was successfully isolated from nasopharyngeal swabs, enabling gene expression analysis to monitor innate immune responses to IAV infection. A classical innate antiviral immune response was demonstrated after the three virus infections including expression of pattern recognition receptors (PRRs), transcription factors, interferons (IFNs), interferon-stimulated genes (ISGs), cytokines, and chemokines. The kinetics and magnitude of immune responses varied between infections, with notable downregulation of mucins following infection with the Danish swine-adapted isolate. Further, the Danish isolate induced a fast but transient IFN-mediated response concurrent with high expression of cytokines and chemokines, while the other swine-adapted Mexican isolate induced a prolonged immune response of ISGs, cytokines, and chemokines.ConclusionThis study highlights the significance of highly translational nasopharyngeal swabs as a non-invasive method for assessing mucosal antiviral immune responses. Utilizing microfluidic mRNA analysis, we gained valuable insights into antiviral mucosal responses across 216 swab samples collected from viral inoculation through recovery in three distinct influenza virus infections.

IntroductionRepeated injections of low-dose lipopolysaccharide (LPS preconditioning) augment the antibacterial activity of liver macrophages. In this study, a mouse model of acute kidney injury (AKI) induced by Staphylococcus aureus (S. aureus) bacteremia was used to investigate the effects of LPS preconditioning on renal macrophages.MethodsEight-week-old C57BL/6J mice were preconditioned with either low-dose LPS (5 μg/kg) or the vehicle for three consecutive days. Kidney immune cells were isolated, and the antibacterial activity of renal macrophages was assessed by pHrodo^TM-labeled S. aureus in vitro. Twenty-four hours after the last LPS injection, the mice were intravenously challenged with S. aureus (2 × 10⁷ CFU) and their renal function was evaluated to identify the changes.ResultsMouse renal macrophages exhibited a weak antibacterial activity against S. aureus compared with the liver and spleen macrophages. LPS preconditioning elevated the count of F4/80^low CD11b^high bone marrow-derived macrophages (BMDM) and augmented their antibacterial activities in the mouse kidney. It also enhanced the antibacterial activity of F4/80^high CD11b^low tissue-resident macrophages (TRM) without altering their abundance. LPS preconditioning lowered the bacterial propagation in the kidney in the challenged mice and ameliorated sepsis-associated AKI compared with the control. LPS preconditioning upregulated the CD80/CD206 expression (M1/M2) ratio in BMDMs in the kidney before bacterial challenge and reduced their M1/M2 ratio following S. aureus challenge compared with the control.ConclusionLPS preconditioning enhanced the antibacterial activity of the renal macrophages against S. aureus and suppressed the excessive activation of M1 macrophages following S. aureus challenge, resulting in the amelioration of AKI caused by S. aureus bacteremia.

High-molecular-weight kininogen (HK) is known to bind lipopolysaccharides (LPS) with high affinity and serves as a crucial LPS carrier in circulation, supporting endotoxemia. However, its role in host defense against Gram-negative bacterial infection remains unclear. Here we demonstrate that HK directly binds to Escherichia coli (E. coli) via LPS and rapidly localizes to sites of infection. HK-deficient mice (Kng1^-/-) showed increased susceptibility to infection, with increased bacterial dissemination, lung injury, and proinflammatory cytokine production. In contrast, endogenous expression of human HK in Kng1^-/- mice restored survival, limited bacterial spread, and reduced tissue damage. Mechanistically, HK promoted neutrophil antimicrobial responses by enhancing reactive oxygen species production and microbicidal activity. Consistently, liver-specific HK deficiency recapitulated the impaired bacterial clearance and reduced survival upon E. coli challenge, highlighting the importance of plasma HK. Together, these findings identify HK as a new soluble pattern recognition molecule that senses E. coli invasion and initiates neutrophil-mediated antimicrobial responses, revealing a previously unrecognized protective function of the contact system in innate immunity.

Malaria, a globally prevalent disease caused by Plasmodium species, significantly impacts the immune system, particularly affecting splenic function. This study investigates the therapeutic potential of Indigofera oblongifolia leaf extracts (IOLE) with silver nanoparticles (AgNPs) against Plasmodium chabaudi-induced splenic damage in a female C57BL/6 mice model. Fifty female mice were infected with P. chabaudi and subsequently treated with IOLE AgNPs or chloroquine phosphate. Histopathological and immunohistochemical analyses revealed that IOLE AgNPs effectively restored splenic architecture, reduced inflammatory markers, and improved immune responses compared to the control and chloroquine-treated groups. These findings suggest that IOLE AgNPs may offer a novel therapeutic approach to mitigate splenic dysfunction associated with malaria and provide comparative analysis between established therapies like chloroquine and innovative combination of traditional medical plant and modern nano technology.