TREM1/DAP12 based novel multiple chain CAR-T cells targeting DLL3 show robust anti-tumour efficacy for small cell lung cancer.

Small cell lung cancer (SCLC), recognized as the most aggressive subtype of lung cancer, presents an extremely poor prognosis. Currently, patients with small cell lung cancer face a significant dearth of effective alternative treatment options once they experience recurrence and progression after first-line therapy. Despite the promising efficacy of immunotherapy, particularly immune checkpoint inhibitors in non-small cell lung cancer (NSCLC) and various other tumours, its impact on significantly enhancing the prognosis of SCLC patients remains elusive. DLL3 has emerged as a compelling target for targeted therapy in SCLC due to its high expression on the membranes of SCLC and other neuroendocrine carcinoma cells, with minimal to no expression in normal cells. Our previous work led to the development of a novel multiple chain chimeric antigen receptor (CAR) leveraging the TREM1 receptor and DAP12, which efficiently activated T cells and conferred potent cell cytotoxicity. In this study, we have developed a DLL3-TREM1/DAP12 CAR-T (DLL3-DT CAR-T) therapy, demonstrating comparable anti-tumour efficacy against SCLC cells in vitro. In murine xenograft and patient-derived xenograft models, DLL3-DT CAR-T cells exhibited a more robust tumour eradication efficiency than second-generation DLL3-BBZ CAR-T cells. Furthermore, we observed elevated memory phenotypes, induced durable responses, and activation under antigen-presenting cells in DLL3-DT CAR-T cells. Collectively, these findings suggest that DLL3-DT CAR-T cells may offer a novel and potentially effective therapeutic strategy for treating DLL3-expressing SCLC and other solid tumours.

Activation of toll-like receptor 4/nuclear factor-kappa B signaling by triggering a receptor expressed on myeloid cells 1 promotes alveolar macrophage M1 polarization and exacerbates septic acute lung injury.

BACKGROUND: Septic acute lung injury (ALI) is a life-threatening condition commonly occurring in the intensive care unit. Inflammation is considered as the basic pathological response of septic ALI. Triggering receptor expressed on myeloid cells 1 (TREM1) is a member of the immunoglobulin superfamily receptors that regulates the inflammatory response. However, the role of TREM1 in septic ALI has not yet been reported. METHODS: Cell viability was tested using the MTT assay. TdT-mediated dUTP nick end labeling assay and flow cytometry were used for apoptosis. The level of protein was detected using western blot analysis. The levels of tumor necrosis factor-α and interleukin-1ß were assessed using enzyme-linked immunosorbent assay. The lactate dehydrogenase content was assessed using the assay kit. Myeloperoxidase activity was determined using an assay. Histology of lung tissue was further analyzed through hematoxylin-eosin staining. RESULTS: We found that TREM1 knockdown by transfection with si-TREM1 inhibited lipopolysaccharide (LPS)-induced cell apoptosis of alveolar macrophage cell line MH-S. The LPS stimulation caused M1 polarization of MH-S cells, which could be reversed by TREM1 knockdown. In vivo assays proved that si-TREM1 injection improved lung injury and inflammation of cecal ligation and puncture-induced ALI in mice. In addition, TREM1 knockdown suppressed the activation of toll-like receptor 4/nuclear factor-kappa B signaling, implying the involvement of TLR4 in the effects of TREM1 in response to LPS stimulation. CONCLUSIONS: This study examined the proinflammatory role of TREM1 in septic ALI and its regulatory effect on alveolar macrophage polarization. These results suggest that TREM1 could potentially serve as a therapeutic target in the prevention and treatment of ALI.

TREM1: Activation, signaling, cancer and therapy.

Triggering receptor expressed on myeloid cells 1 (TREM1) is a cell surface receptor expressed on neutrophils, monocytes and some tissue macrophages, where it functions as an immunoregulator that controls myeloid cell responses. The activation of TREM1 is suggested to be an upregulation-based, ligands-induced and structural multimerization-mediated process, in which damage- and pathogen-associated molecular patterns play important roles. Activated TREM1 initiates an array of downstream signaling pathways that ultimately result in the production of pro-inflammatory cytokines and chemokines, whereby it functions as an amplifier of inflammation and is implicated in the pathogenesis of many inflammation-associated diseases. Over the past decade, there has been growing evidence for the involvement of TREM1 overactivation in tumor stroma inflammation and cancer progression. Indeed, it was shown that TREM1 promotes tumor progression, immunosuppression, and resistance to therapy by activating tumor-infiltrating myeloid cells. TREM1-deficiency or blockade provide protection against tumors and reverse the resistance to anti-PD-1/PD-L1 therapy and arginine-deprivation therapy in preclinical models. Here, we first review the structure, activation modes and signaling pathways of TREM1 and emphasize the role of soluble TREM1 as a biomarker of infection and cancer. We then focus on the role of TREM1 in cancer and systematically summarize its expression patterns, upregulation mechanisms and functions in tumor development and progression. Lastly, we discuss the therapeutic prospects of TREM1 inhibition, via effective pharmacological inhibitors, in treating cancer and other diseases.

FOXM1 network in association with TREM1 suppression regulates NET formation in diabetic foot ulcers.

Diabetic foot ulcers (DFU) are a serious complication of diabetes mellitus and associated with reduced quality of life and high mortality rate. DFUs are characterized by a deregulated immune response with decreased neutrophils due to loss of the transcription factor, FOXM1. Diabetes primes neutrophils to form neutrophil extracellular traps (NETs), contributing to tissue damage and impaired healing. However, the role of FOXM1 in priming diabetic neutrophils to undergo NET formation remains unknown. Here, we found that FOXM1 regulates reactive oxygen species (ROS) levels in neutrophils and inhibition of FOXM1 results in increased ROS leading to NET formation. Next generation sequencing revealed that TREM1 promoted the recruitment of FOXM1+ neutrophils and reversed effects of diabetes and promoted wound healing in vivo. Moreover, we found that TREM1 expression correlated with clinical healing outcomes of DFUs, indicating TREM1 may serve as a useful biomarker or a potential therapeutic target. Our findings highlight the clinical relevance of TREM1, and indicates FOXM1 pathway as a novel regulator of NET formation during diabetic wound healing, revealing new therapeutic strategies to promote healing in DFUs.

Influence of trem-1 gene polymorphisms on cytokine levels during malaria by Plasmodium vivax in a frontier area of the Brazilian Amazon.

BACKGROUND: The immunopathology during malaria depends on the level of inflammatory response generated. In this scenario, the TREM-1 has been associated with the severity of infectious diseases and could play an important role in the inflammatory course of malaria. We aimed to describe the allelic and genotypic frequency of four polymorphisms in the trem-1 gene in Plasmodium vivax-infected patients and to verify the association of these polymorphisms with clinical and immunological factors in a frontier area of the Brazilian Amazon. METHODS: We included 76 individuals infected with P. vivax and 144 healthy controls living in the municipality of Oiapoque, Amapá, Brazil. The levels of TNF-α, IL-10, IL-2, IL-4, IL-5, and IFN-γ were measured by flow cytometry, while IL-6, sTREM-1, and antibodies against PvMSP-119 were evaluated by ELISA. The SNPs were genotyped by qPCR technique. Polymorphisms analysis, allelic and genotype, frequencies, and HWE calculation were determined by x2 test in R Software. The association between the parasitemia, gametocytes, antibodies, cytokines, and sTREM-1 with the genotypes of malaria and control groups was performed using the Kruskal-Wallis test, these analyzes were conducted in SPSS Software, at 5% significance level. RESULTS: All SNPs were successfully genotyped. Allelic and genotypic distribution was in Hardy-Weinberg Equilibrium. Furthermore, several associations were identified between malaria and control groups, with increased levels of IL-5, IL-6, IL-10, TNF-α, and IFN-γ in the infected individuals with rs6910730A, rs2234237T, rs2234246T, rs4711668C alleles compared to the homozygous wild-type and heterozygous genotypes of the controls (p-value < 0.05). No association was found for these SNPs and the levels of IL-2, and sTREM-1. CONCLUSIONS: The SNPs on the trem-1 gene are associated with the effector molecules of the innate immunity and may contribute to the identification and effective participation of trem-1 in the modulation of the immune response. This association may be essential for the establishment of immunization strategies against malaria.

TREM-1 as a Marker of Multiple Organ Failure in Cardiac Surgery.

Systemic inflammatory response syndrome (SIRS) frequently accompanies early postoperative period after cardiac surgery and in some cases is complicated by multiple organ failure (MOF). Inherited variation in the innate immune response genes (e.g., TREM1) is among the major factors determining the development of SIRS and the risk of MOF. This research was aimed to study whether the polymorphisms within the TREM1 gene are associated with MOF after the coronary artery bypass graft (CABG) surgery. Here we enrolled 592 patients who underwent CABG surgery in the Research Institute for Complex Issues of Cardiovascular Diseases (Kemerovo, Russia) and documented 28 cases of MOF. Genotyping was performed by allele-specific PCR using TaqMan probes. In addition, we measured serum soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) using enzyme-linked immunosorbent assay. Five polymorphisms (rs1817537, rs2234246, rs3804277, rs7768162 andrs4711668) within the TREM1 gene were significantly associated with MOF. Patients with MOF had higher serum sTREM-1 as compared with those without MOF at both pre- and post-intervention stages. Serum sTREM-1 was associated with the rs1817537,rs2234246 and rs3804277 polymorphisms within the TREM1 gene. Minor alleles within the TREM1 gene define the level of serum sTREM-1 and are associated with MOF after CABG surgery.

MiR-206 may regulate mitochondrial ROS contribute to the progression of Myocardial infarction via TREM1.

Myocardial infarction (MI) is a leading cause of mortality. To better understand its molecular and cellular mechanisms, we used bioinformatic tools and molecular experiments to explore the pathogenesis and prognostic markers. Differential gene expression analysis was conducted using GSE60993 and GSE66360 datasets. Hub genes were identified through pathway enrichment analysis and PPI network construction, and four hub genes (AQP9, MMP9, FPR1, and TREM1) were evaluated for their predictive performance using AUC and qRT-PCR. miR-206 was identified as a potential regulator of TREM1. Finally, miR-206 was found to induce EC senescence and ER stress through upregulating mitochondrial ROS levels via TREM1. These findings may contribute to understanding the pathogenesis of MI and identifying potential prognostic markers.

The associations between plasma soluble Trem1 and neurological diseases: a Mendelian randomization study.

BACKGROUND: Triggering receptor expressed on myeloid cell 1 (Trem1) is an important regulator of cellular inflammatory responses. Neuroinflammation is a common thread across various neurological diseases. Soluble Trem1 (sTrem1) in plasma is associated with the development of central nervous system disorders. However, the extent of any causative effects of plasma sTrem1 on the risk of these disorders is still unclear. METHOD: Genetic variants for plasma sTrem1 levels were selected as instrumental variables. Summary-level statistics of neurological disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), epilepsy, cerebrovascular diseases, and migraine were collected from genome-wide association studies (GWASs). Whether plasma sTrem1 was causally associated with neurological disorders was assessed using a two-sample Mendelian randomization (MR) analysis, with false discovery rate (FDR)-adjusted methods applied. RESULTS: We inferred suggestive association of higher plasma sTrem1 with the risk of AD (odds ratio [OR] per one standard deviation [SD] increase = 1.064, 95% CI 1.012-1.119, P = 0.014, PFDR = 0.056). Moreover, there was significant association between plasma sTrem1 level and the risk of epilepsy (OR per one SD increase = 1.044, 95% CI 1.016-1.072, P = 0.002, PFDR = 0.032), with a modest statistical power of 41%. Null associations were found for plasma sTrem1 with other neurological diseases and their subtypes. CONCLUSIONS: Taken together, this study indicates suggestive association between plasma sTrem1 and AD. Moreover, higher plasma sTrem1 was associated with the increased risk of epilepsy. The findings support the hypothesis that sTrem1 may be a vital element on the causal pathway to AD and epilepsy.

Persistent DNA damage and oncogenic stress-induced Trem1 promotes leukemia in mice.

The immune receptor TREM1 (Triggering receptor expressed on myeloid cells 1) is a master regulator of inflammatory response. Compelling evidence suggests important pathological roles for TREM1 in various types of solid tumors. However, the role of TREM1 in hematologic malignancies is not known. Our previous study demonstrated that TREM1 cooperates with diminished DNA damage response to induce expansion of pre-leukemic hematopoietic stem cells (HSC) in mice deficient for the Fanconi anemia gene Fanca. Here we investigated TREM1 in leukemogenesis using mouse models of the DNA repair-deficient Fanca-/- and the oncogenic MLL-AF9 or KrasG12D. We found that Trem1 was highly expressed in preleukemic HSC and leukemia stem cells (LSC). By selective deletion of the Trem1 gene in the hematopoietic compartment, we showed that ablation of Trem1 reduced leukemogenic activity of the pre-leukemic HSC and LSC in mice. Trem1 was required for the proliferation of the pre-leukemic HSC and LSC. Further analysis revealed that Trem1 expression in preleukemic HSC and LSC was associated with persistent DNA damage, prolonged oncogenic stress, and a strong inflammatory signature. Targeting several top Trem1 inflammatory signatures inhibited the proliferation of pre-leukemic HSC and LSC. Collectively, our observations uncover previously unknown expression and function of TREM1 in malignant stem cells, and identify TREM1 as a driver of leukemogenesis.

Comparative transcriptomics in human COPD reveals dysregulated genes uniquely expressed in ferrets.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a progressive lung disease with poor treatment options. However, most mouse models of COPD produce a primarily emphysematous disease not recapitulating clinically meaningful COPD features like chronic bronchitis. METHODS: Wild-type ferrets (Mustela putorius furo) were divided randomly into two groups: whole body cigarette smoke exposure and air controls. Ferrets were exposed to smoke from 1R6F research cigarettes, twice daily for six months. RNA-sequencing was performed on RNA isolated from lung tissue. Comparative transcriptomics analyses of COPD in ferrets, mice, and humans were done to find the uniquely expressed genes. Further, Real-time PCR was performed to confirmed RNA-Seq data on multiple selected genes. RESULTS: RNA-sequence analysis identified 420 differentially expressed genes (DEGs) that were associated with the development of COPD in ferrets. By comparative analysis, we identified 25 DEGs that are uniquely expressed in ferrets and humans, but not mice. Among DEGs, a number were related to mucociliary clearance (NEK-6, HAS1, and KL), while others have been correlated with abnormal lung function (IL-18), inflammation (TREM1, CTSB), or oxidative stress (SRX1, AHRR). Multiple cellular pathways were aberrantly altered in the COPD ferret model, including pathways associated with COPD pathogenesis in humans. Validation of these selected unique DEGs using real-time PCR demonstrated > absolute 2-fold changes in mRNA versus air controls, consistent with RNA-seq analysis. CONCLUSION: Cigarette smoke-induced COPD in ferrets modulates gene expression consistent with human COPD and suggests that the ferret model may be uniquely well suited for the study of aspects of the disease.

Design of the lentivirus-driven sustained LR12 delivery system for TREM-1 inhibition for palliating atherosclerosis.

Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) has been a potential target in the management of pathophysiology and clinical sequelae of atherosclerosis. LR12 peptide effectively blocks ligand-TREM-1 interaction; however, the short half-life of LR12 is a major hurdle in its translational application in atherosclerosis management warranting new methods for sustained bioavailability in clinical applications. The present study reports a novel method of packing the coding sequence of LR12 in a lentiviral system to ensure a sustained expression and bioavailability for effective TREM-1 inhibition. Lentivirus vector systems (LV-LR12 and LV-SP) for the expression of LR12 peptide and SP (scrambled peptide) were successfully designed, constructed, and tested in vitro in smooth muscle cells (SMCs). Viral amounts obtained were 703.6 ± 145.12 and 609.3 ± 145.93 ng/ml p24 for LV-LR12 and LV-SP, respectively which correspond to ~ 107 IFU/ml for both vectors. Dot blot assay revealed significantly increased expression of LR12-FLAG and SP-FLAG in 125 µg total protein which was doubled in 250 µg protein with respect to un-transduced SMCs suggesting the sustained release of LR12/SP as confirmed by ELISA. Cellular expression of LR12-FLAG and SP-FLAG displayed 8.44-fold and 7.55-fold increase, respectively compared to the control SMCs. The findings demonstrated a promising strategy for packing the LR12 coding sequence in lentiviral vector for TREM-1 inhibition for the management of atherosclerosis and other inflammatory diseases.

The relationship between vitamin D receptor gene and TREM-1 gene polymorphisms and the susceptibility and prognosis of neonatal sepsis.

OBJECTIVE: The objective of this was to study the relationship between vitamin D receptor (VDR) and triggering receptor expressed on myeloid cells 1 (TREM-1) gene single-nucleotide polymorphisms (SNP) and neonatal sepsis susceptibility and prognosis. METHODS: The blood of 150 neonatal sepsis patients and 150 normal neonates was collected, and genomic DNA was extracted. Sanger sequencing was used to analyze the genotypes of VDR rs739837 and TREM-1 rs2234246. RESULTS: Vitamin D receptor rs739837 locus GT, TT genotype, dominant model, and recessive model were all protective factors for sepsis (0 < OR < 1, p < 0.05). The risk of sepsis in carriers of the rs739837 G allele was 0.65 times that of the rs739837 T allele (95% CI: 0.50-0.83, p < 0.001), CT, TT, dominant model, and recessive model at rs2234246 were risk factors for sepsis (OR > 1, p < 0.05). The risk of sepsis in carriers of the rs739837 T allele was 1.38 times that of carriers of the C allele (95% CI: 1.16-1.61, p < 0.001). The polymorphisms of VDR gene rs739837 and TREM-1 gene rs2234246 were not significantly correlated with the survival of patients with neonatal sepsis (p > 0.05). CONCLUSION: Vitamin D receptor gene rs739837 locus G>T is associated with a reduction in the risk of neonatal sepsis, TREM-1 rs2234246 C>T is associated with the increased risk of neonatal sepsis, but none of them was significantly associated with the prognosis of neonatal sepsis.

TREM (Triggering Receptor Expressed on Myeloid Cells)-1 Inhibition Attenuates Neuroinflammation via PKC (Protein Kinase C) δ/CARD9 (Caspase Recruitment Domain Family Member 9) Signaling Pathway After Intracerebral Hemorrhage in Mice.

Background and Purpose: Intracerebral hemorrhage (ICH) is a devastating subtype of stroke with high mortality and disability. Inflammatory response promotes secondary brain injury after ICH. TREM (triggering receptor expressed on myeloid cells)-1 is a key regulator of inflammation. The aim of this study was to evaluate the role of TREM-1 in neuroinflammatory response after ICH in mice. Methods: CD1 mice (n=275) were used in this study. Mice were subjected to ICH by autologous blood injection. TREM-1 knockout CRISPR was administered intracerebroventricularly to evaluate the role of TREM-1 after ICH. A selective TREM-1 inhibitor, LP17, was administered intranasally 2 hours after ICH. To elucidate TREM-1 signaling pathway, CARD9 (caspase recruitment domain family member 9) activation CRISPR was administered with LP17 and TREM-1 activating anti-mouse TREM-1 monoclonal antibody (mAb) was administered with Rottlerin, a specific PKC (protein kinase C) δ inhibitor. Lastly, to evaluate the role of HMGB1 (high-mobility group box 1) in TREM-1 mediated microglia activation, glycyrrhizin, an inhibitor of HMBG1 was administered with TREM-1 activating mAb. Neurobehavioral test, brain water content, Western blot, immunofluorescence staining, and coimmunoprecipitation was performed. Results: TREM-1 knockout reduced ICH-induced neurobehavioral deficits and neuroinflammatory response. The temporal expression of HMGB1, TREM-1, PKC δ, and CARD9 increased after ICH. TREM-1 was expressed on microglia. Intranasal administration of LP17 significantly decreased brain edema and improved neurobehavioral outcomes at 24 and 72 hours after ICH. LP17 promoted M2 microglia polarization and reduced proinflammatory cytokines after ICH, which was reversed with CARD9 activation CRISPR. TREM-1 mAb increased neurobehavior deficits, proinflammatory cytokines, and reduced M2 microglia after ICH, which was reversed with Rottlerin. HMBG1 interaction with TREM-1 increased after ICH, and glycyrrhizin reduced neuroinflammation and promoted M2 microglia which was reversed with TREM-1 mAb. Conclusions: This study demonstrated that TREM-1 enhanced neuroinflammation by modulating microglia polarization after ICH, and this regulation was partly mediated via PKC δ/CARD9 signaling pathway and increased HMGB1 activation of TREM-1.

HBV upregulated triggering receptor expressed on myeloid cells-1 (TREM-1) expression on monocytes participated in disease progression through NF-Kb pathway.

The triggering receptor expressed on myeloid cells-1 (TREM-1) signal is related to the continuous amplification of inflammatory pathway. However, it is not clear whether and how HBV can regulated the expression of TREM-1 on monocyte participated in the progression of liver disease. Here, we showed that the expression of TREM-1 on monocyte subsets were increased significantly in HBV related liver cirrhosis group compared with chronic infected group and healthy control group. HBsAg and HBeAg could up-regulated TREM-1 on monocyte by NF-KB pathway, and at least last for 72 h. Increased TREM-1 on monocyte might associated with high level of inflammatory cytokine (TNF-a, IL-1ß and IL-6) and the activation of LX-2 cells. Bioinformatics analysis showed that the high expression of TREM-1 was related to the poor prognosis of hepatocellular carcinoma (HCC). The level of TREM-1 might help to predict the progression of HBV infected liver disease and treat target to prevent fibrosis progression.

HIV and HCV augments inflammatory responses through increased TREM-1 expression and signaling in Kupffer and Myeloid cells.

Chronic infection with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) affects an estimated 35 million and 75 million individuals worldwide, respectively. These viruses induce persistent inflammation which often drives the development or progression of organ-specific diseases and even cancer including Hepatocellular Carcinoma (HCC). In this study, we sought to examine inflammatory responses following HIV or HCV stimulation of macrophages or Kupffer cells (KCs), that may contribute to virus mediated inflammation and subsequent liver disease. KCs are liver-resident macrophages and reports have provided evidence that HIV can stimulate and infect them. In order to characterize HIV-intrinsic innate immune responses that may occur in the liver, we performed microarray analyses on KCs following HIV stimulation. Our data demonstrate that KCs upregulate several innate immune signaling pathways involved in inflammation, myeloid cell maturation, stellate cell activation, and Triggering Receptor Expressed on Myeloid cells 1 (TREM1) signaling. TREM1 is a member of the immunoglobulin superfamily of receptors and it is reported to be involved in systemic inflammatory responses due to its ability to amplify activation of host defense signaling pathways. Our data demonstrate that stimulation of KCs with HIV or HCV induces the upregulation of TREM1. Additionally, HIV viral proteins can upregulate expression of TREM1 mRNA through NF-кB signaling. Furthermore, activation of the TREM1 signaling pathway, with a targeted agonist, increased HIV or HCV-mediated inflammatory responses in macrophages due to enhanced activation of the ERK1/2 signaling cascade. Silencing TREM1 dampened inflammatory immune responses elicited by HIV or HCV stimulation. Finally, HIV and HCV infected patients exhibit higher expression and frequency of TREM1 and CD68 positive cells. Taken together, TREM1 induction by HIV contributes to chronic inflammation in the liver and targeting TREM1 signaling may be a therapeutic option to minimize HIV induced chronic inflammation.

TREM-1 isoforms in bacterial infections: to immune modulation and beyond.

The triggering receptor expressed on myeloid cells 1 (TREM-1) is an innate immunity receptor associated with the amplification of inflammation in sterile and non-sterile inflammatory disorders. Since its first description, the two isoforms of the receptor, membrane and soluble (mTREM-1 and sTREM-1, respectively) have been largely explored in the immunopathogenesis of several bacterial diseases and sepsis. The role of the receptor in these scenarios seems to be at least partly dependent on the source/type of bacteria, host and context. As uncontrolled inflammation is a result of several bacterial infections, the inhibition of the receptor has been considered as a promising approach to treat such conditions. Further, sTREM-1 has been explored as a biomarker for diagnosis and/or prognosis of several bacterial diseases. Therefore, this review aims to provide an updated insight into how the receptor influences and is influenced by bacterial infections, highlighting the advances regarding the use/manipulation of TREM-1 isoforms in biomedical research and clinical practice.

TREM-1 promoted apoptosis and inhibited autophagy in LPS-treated HK-2 cells through the NF-κB pathway.

Triggering receptor expressed by myeloid cells (TREM-1) is an amplifier of inflammatory responses triggered by bacterial or fungal infection. Soluble TREM-1 (sTREM-1) expression was found to be upregulated in sepsis-associated acute kidney injury (SA-AKI) and predicted to be a potential biomarker. However, the mechanism remains unclear. The human kidney-2 (HK-2) cell line was treated with lipopolysaccharide (LPS) and used to examine the potential roles of TREM-1 in apoptosis and autophagy. A cell viability assay was employed to assess the number of viable cells and as a measure of the proliferative index. The concentrations of sTREM-1, interleukin (IL)-1ß, tumor necrosis factor-α (TNFα) and IL-6 in cell-free culture supernatants were measured by enzyme-linked immunosorbent assay (ELISA). Western blot analysis was performed to analyze apoptosis, autophagy and the relevant signaling pathways. The results suggested that TREM-1 overexpression after LPS treatment decreased proliferation and increased apoptosis. The concentrations of sTREM-1, IL-1ß, TNFα and IL-6 in cell-free culture supernatants were increased in the TREM-1 overexpression group after LPS treatment. Expression of the antiapoptotic gene Bcl-2 was downregulated in the TREM-1 overexpression group, while that of the proapoptotic genes Bax, cleaved caspase-3 and cleaved caspase-9 was upregulated. Overexpression of TREM-1 downregulated expression of the autophagy genes Beclin-1, Atg-5 and LC3b and increased the gene expression of p62, which inhibits autophagy. Conversely, treatment with TREM-1-specific shRNA had the opposite effects. The nuclear factor-κB (NF-κB) signaling pathway (P-p65/p65 and P-IκBα/IκBα) in LPS-induced HK-2 cells was regulated by TREM-1. In summary, TREM-1 promoted apoptosis and inhibited autophagy in HK-2 cells in the context of LPS exposure potentially through the NF-κB pathway.

MicroRNA regulation postbleomycin due to the R213G extracellular superoxide dismutase variant is predicted to suppress inflammatory and immune pathways.

Oxidative stress is a key contributor to the development of dysregulated inflammation in acute lung injury (ALI). A naturally occurring single nucleotide polymorphism in the key extracellular antioxidant enzyme, extracellular superoxide dismutase (EC-SOD), results in an arginine to glycine substitution (R213G) that promotes resolution of inflammation and protection against bleomycin-induced ALI. Previously we found that mice harboring the R213G mutation in EC-SOD exhibit a transcriptomic profile consistent with a striking suppression of inflammatory and immune pathways 7 days postbleomycin. However, the alterations in noncoding regulatory RNAs in wild-type (WT) and R213G EC-SOD lungs have not been examined. Therefore, we used next-generation microRNA (miR) Sequencing of lung tissue to identify dysregulated miRs 7 days after bleomycin in WT and R213G mice. Differential expression analysis identified 92 WT and 235 R213G miRs uniquely dysregulated in their respective genotypes. Subsequent pathway analysis identified that these miRs were predicted to regulate approximately half of the differentially expressed genes previously identified. The gene targets of these altered miRs indicate suppression of immune and inflammatory pathways in the R213G mice versus activation of these pathways in WT mice. Triggering receptor expressed on myeloid cells 1 (TREM1) signaling was identified as the inflammatory pathway with the most striking difference between WT and R213G lungs. miR-486b-3p was identified as the most dysregulated miR predicted to regulate the TREM1 pathway. We validated the increase in TREM1 signaling using miR-486b-3p antagomir transfection. These findings indicate that differential miR regulation is predicted to regulate the inflammatory gene profile, contributing to the protection against ALI in R213G mice.

TREM-1-targeting LP17 attenuates cerebral ischemia-induced neuronal injury by inhibiting oxidative stress and pyroptosis.

Stroke ranks as the second leading cause of disability and death globally. Trigger receptors expressed on myeloid cells (TREM) -1 are responsible for the activation of the innate immune response and also play a critical role in inflammation. In this study, we reported the contribution of TREM-1 after ischemic damage in a rat middle cerebral artery occlusion (MCAO) model. This study also demonstrated that TREM-1 expression was upregulated following cerebral infarction in rats. TREM-1 inhibition was determined using its selective inhibitor, LP17, which indicated a neuroprotective effect on cerebral infarction damage. The findings revealed that inhibition of TREM-1 by administering LP17 improved cerebral damage and decreased ischemic areas and brain water contents. Moreover, LP17 decreased MCAO-induced microglial activation and neurodegeneration, evidenced by a reduction in the expression of microglial Iba-1 and FJ-B positive cells, and reversed neuronal loss. Besides, the contribution of LP17 to ischemic neuronal damage may be associated with a decrease in the production of pro-inflammatory cytokines, and enhanced production of anti-inflammatory cytokine IL-10. Both in vivo and in vitro studies showed that inhibiting TREM-1 attenuated ROS accumulation, lipid per-oxidation (LPO) contents such as malondialdehyde (MDA) and enhanced the superoxide dismutase (SOD) activity after ischemia. Inhibiting TREM-1 alleviated inflammation and pyroptosis found in MCAO rats. This was achieved through the inhibition of the levels of NLRP3, caspase-1, ASC (an apoptosis-associated speck-like protein containing a CARD) and gasdermin D. These results confirmed that inhibiting TREM-1 protects against ischemia-induced neuronal damage and alleviates microglial mediated neuro-inflammation by reducing oxidative stress and pyroptosis. Therefore, blocking TREM-1 expression provides an effective intervention for improving ischemic stroke.