Triggering Receptor Expressed on Myeloid Cells in Cutaneous Melanoma

TREM2 as a Potential Immune-Related Biomarker of Prognosis in Patients with Skin Cutaneous Melanoma Microenvironment

Background

The skin cutaneous melanoma (SKCM) is a devastating form of skin cancer triggered by genetic and environmental factors, and the incidence of SKCM has rapidly increased in recent years. Immune infiltration of the tumor microenvironment is positively associated with overall survival in many tumors. Triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane receptor of the immunoglobulin superfamily and a crucial signaling hub for multiple pathological pathways that mediate immunity. Although numerous evidences suggest a crucial role for TREM2 in tumorigenesis of some tumors, no systematic SKCM analysis of TREM2 is available. Mehods. The relationship between TREM2 expression and diagnostic and prognostic value of SKCM patients via using The Cancer Genome Atlas (TCGA) data. The expression level of TREM2 and clinical characteristic correlation in SKCM patients were assessed by the Wilcoxon rank sum test. The cox regression methods, Kaplan-Meier (KM), and log-rank test were used to assess the impact of TREM2 expression on the overall survival (OS). Furthermore, the Gene Set Enrichment Analysis (GSEA) and TIMER were performed to evaluate the enrichment pathways and potential functions and quantify the immune cell infiltration level for TREM2 expression.

Results

The TREM2 in SKCM sample expression levels was significantly higher than in normal tissues. Moreover, this expression level of TREM2 was also associated with the BMI of SKCM patients. KM overall survival analysis and OS curve displayed that a high-level TREM2 expression was significantly correlated with a better SKCM prognosis of patients as compared with a low level of TREM2 expression. The GSEA analysis also revealed that TREM2 was associated with immune functions, such as neutrophil activation.

Conclusion

TREM2 played a crucial role in SKCM, which might be a prognostic biomarker and correlated with immune infifiltrates in SKCM patients.

Identification of Long Noncoding RNAs Involved in Eyelid Pigmentation of Hereford Cattle

Several ocular pathologies in cattle, such as ocular squamous cell carcinoma and infectious keratoconjunctivitis, have been associated with low pigmentation of the eyelids. The main objective of this study was to analyze the transcriptome of eyelid skin in Hereford cattle using strand-specific RNA sequencing technology to characterize and identify long noncoding RNAs (lncRNAs). We compared the expression of lncRNAs between pigmented and unpigmented eyelids and analyzed the interaction of lncRNAs and putative target genes to reveal the genetic basis underlying eyelid pigmentation in cattle. We predicted 4,937 putative lncRNAs mapped to the bovine reference genome, enriching the catalog of lncRNAs in Bos taurus. We found 27 differentially expressed lncRNAs between pigmented and unpigmented eyelids, suggesting their involvement in eyelid pigmentation. In addition, we revealed potential links between some significant differentially expressed lncRNAs and target mRNAs involved in the immune response and pigmentation. Overall, this study expands the catalog of lncRNAs in cattle and contributes to a better understanding of the biology of eyelid pigmentation.

Plasma Concentrations of sTREM-1 as Markers for Systemic Adverse Reactions in Subjects Treated With Weekly Rifapentine and Isoniazid for Latent Tuberculosis Infection

Background

A regimen of once-weekly rifapentine plus isoniazid for 3 months (3HP) is an effective treatment for subjects with latent tuberculosis infection; however, no reliable biomarker exists for predicting systemic adverse reactions (SARs) to 3HP treatment.

Methods

This prospective, multi-center study evaluated the plasma concentrations of soluble triggering receptors expressed on myeloid cells (sTREM)-1 and sTREM-2 in subjects undergoing 3HP treatment and examined the associations between these biomarkers and SARs.

Results

This study enrolled 80 consecutive subjects receiving 3HP treatment, 25 of whom had SARs and 55 of whom did not. Subjects with SARs presented higher concentrations of sTREM-1 at baseline than those without SARs (240.1 ± 19.1 vs. 176.7 ± 9.4 pg/mL, P = 0.001). The area under the receiver operating characteristic curves revealed that day 1 plasma levels of sTREM-1 (0.708, 95% CI, 0.584–0.833, P = 0.003) and sTREM-2 (0.343, 95% CI, 0.227–0.459, P = 0.025) as well as the sTREM-1/sTREM-2 ratio (0.748, 95% CI, 0.638–0.858, P = 0.001) had modest discriminative power pertaining to the development of SARs. An sTREM-1 level exceeding the cut-off value (>187.4 pg/mL) (hazard ratio [HR], 6.15; 95% CI 1.67–22.70, P = 0.006) and a sTREM-2 below the cut-off value (<237.2 pg/mL) (HR, 4.46; 95% CI 1.41–14.1, P = 0.011) were independent predictors of SARs after controlling for other variables.

Conclusions

Plasma sTREM-1 and sTREM-2 levels are useful biomarkers for predicting SARs during 3HP treatment.

Clinical trial government

NCT04655794

Analysis of the Prognostic Value and Potential Molecular Mechanisms of TREM-1 Overexpression in Papillary Thyroid Cancer via Bioinformatics Methods

BACKGROUND

Triggering receptor expressed on myeloid cells-1 (TREM-1) has been reported as a biomarker in many cancers. However, the biological function of TREM-1 in papillary thyroid carcinoma (PTC) remains unknown.

METHODS

We obtained TREM-1 expression data from The Cancer Genome Atlas (TCGA) database. Enrichment analysis of coexpressed genes and TREM-1 methylation analysis were performed via LinkedOmics. The correlations between TREM-1 and immune infiltrates were investigated via ESTIMATE, TIMER and TISIDB. We analyzed the association of TREM-1 expression with pan-cancer overall survival via Gene Expression Profiling Interactive Analysis (GEPIA).

RESULTS

TREM-1 has lower methylation levels and higher expression levels in PTC tissues compared to normal tissues. TREM-1 expression is significantly associated with poor prognosis, advanced T classification, advanced N classification, and an increased incidence of BRCA2 and BRAF mutations. Genes coexpressed with TREM-1 primarily participate in immune-related pathways. TREM-1 expression is positively correlated with immune infiltration, tumor progression and poor overall survival across cancers.

CONCLUSIONS

TREM-1 is a good prognostic and diagnostic biomarker in PTC. TREM-1 may promote thyroid cancer progression through immune-related pathways. Methylation may act as an upstream regulator of TREM-1 expression and biological function. Additionally, TREM-1 has broad prognostic value in a pan-cancer cohort.

TREM-1 and TREM-2 Expression on Blood Monocytes Could Help Predict Survival in High-Grade Glioma Patients

Objective

In recent years, the role of the modern inflammatory markers TREM-1 (triggering receptors expressed on myeloid cells) and HMGB1 (high mobility group box 1 protein) in tumorigenesis has begun to be studied. Their role in gliomas is not clear. The aim of our study was to find the role of inflammation in gliomas. Patients and Methods. In 63 adult patients with gliomas and 31 healthy controls, the expressions of TREM-1 and TREM-2 on CD14⁺ blood cells (method: flow cytometry) and the levels of soluble sTREM-1, HMGB1, IL-6, and IL-10 (Elisa tests) were analyzed.

Results

Cox proportional hazard analysis showed that a TREM-1/TREM-2 ratio was associated with reduced overall survival (HR = 1.001, P = 0.023). Patients with a TREM-1/TREM-2 ratio above 125 survived significantly shorter than patients with a TREM-1/TREM-2 ratio below 125. The percentage of CD14⁺ TREM-1⁺ cells was strongly associated with a plasma IL-6/IL-10 ratio (positively) and with IL-10 (negatively). Conversely, we found a higher percentage of CD14⁺ TREM-2⁺ monocytes in better surviving patients; these cells could downregulate the exaggerated inflammation and potentiate the phagocytosis in the tumor. The serum levels of HMGB1 negatively correlated with the percentage of CD14⁺ TREM-1⁺ cells and with the TREM-1/TREM-2 ratio. The positive correlation between the serum levels of a late proinflammatory cytokine HMGB1 with the percentage of TREM2⁺ CD14⁺ monocytes can be explained as an effort for suppression of systemic inflammation by anti-inflammatory acting CD14⁺ TREM-2⁺ cells.

Conclusion

We showed that the TREM-1/TREM-2 ratio (expression on the surface of blood monocytes) could help predict prognosis in patients with gliomas, especially in high-grade gliomas, and that systemic inflammation has an impact on the patient's overall survival. This is the first study that showed that TREM expression on monocytes in peripheral blood could help predict prognosis in patients with gliomas.

[Research progress on the relationship between triggering receptor expressed on myeloid cells 1 and 2 and malignant tumors]

Increasing scientific evidence supports the positive relationship between inflammation and cancer development. The immune response initiated by pattern recognition receptors is critical to triggering of tumor-associated inflammation. Triggering receptor expressed on myeloid cells (TREM) is an immunoglobulin of the super transmembrane glycoprotein family, which is mainly expressed on select groups of myeloid cells. The most important members of TREM comprise TREM-1 and TREM-2. Activation of TREM-1 and TREM-2 signaling is initiated upon binding of their ligands. Subsequently, cross-linking reactions of downstream effectors occur, resulting in inflammation regulation. Recently, the connection between TREM and malignant tumors has been widely noticed and studied. This review summarizes studies of association between TREM-1, TREM-2, and malignant tumors in the medical field to provide new ideas for study on the correlation between periodontitis and oral cavity cancer.

Triggering receptor expressed on myeloid cells in the pathogenesis of periodontitis: potential novel treatment strategies

INTRODUCTION

Periodontal diseases are polymicrobial inflammatory disorders of the tissue, ligament, and bone structures supporting teeth. Periodontitis (inflammation with corresponding loss of attachment) affects 40-50% of adults. Recently, members of the Triggering Receptor on Myeloid Cell (TREM) family have been studied to determine their relationship to these diseases. Areas covered: TREM-1 is a receptor expressed on the surface of PMNs, monocytes, macrophages, dendritic cells, vascular smooth muscle cells, and keratinocytes upregulated in the presence of periodontal inflammation. TREM-1 expression can be upregulated by oral bacterium Porphyromonas gingivalis that can be abrogated by a sub-antimicrobial dose of doxycycline. When cleaved from the cell surface, a soluble form of TREM-1 (sTREM-1) can be used as a biomarker of inflammation and might also provide a link between oral and systemic inflammation. While less understood, TREM-2 has a role in osteoclastogenesis which could contribute to the alveolar bone destruction seen in more advanced periodontitis. Expert commentary: Additional studies to simulate biofilm microenvironment in TREM research are warranted. Longitudinal studies determining TREM-1, sTREM-1, and TREM-2 levels in tissues over time and progression of periodontal diseases would provide valuable information in the role of TREM receptors as indicators of or contributors to the disease process.

Triggering receptor expressed on myeloid cells and 5'adenosine monophosphate-activated protein kinase in the inflammatory response: a potential therapeutic target

INTRODUCTION

The events in the cellular and molecular signaling triggered during inflammation mitigate tissue healing. The metabolic check-point control mediated by 5'-adenosine monophosphate-activated protein kinase (AMPK) is crucial for switching the cells into an activated state capable of mediating inflammatory events. The cell metabolism involved in the inflammatory response represents a potential therapeutic target for the pharmacologic management of inflammation. Areas covered: In this article, a critical review is presented on triggering receptor expressed on myeloid cell (TREM) receptors and their role in the inflammatory responses, as well as homeostasis between different TREM molecules and their regulation. Additionally, we discussed the relationship between TREM and AMPK to identify novel targets to limit the inflammatory response. Literature search was carried out from the National Library of Medicine's Medline database (using PubMed as the search engine) and Google Scholar and identified relevant studies up to 30 March 2016 using inflammation, TREM, AMPK, as the key words. Expert commentary: The prevention of phenotype switching of immune cells during inflammation by targeting AMPK and TREM-1 could be beneficial for developing novel management strategies for inflammation and associated complications.

TREM-1, HMGB1 and RAGE in the Shoulder Tendon: Dual Mechanisms for Inflammation Based on the Coincidence of Glenohumeral Arthritis

Rotator cuff injury (RCI) is a major musculoskeletal disorder in the adult population where inflammation and pain are major contributing factors. Coincidence of other clinical conditions like glenohumeral arthritis aggravates inflammation and delays the healing response. The mechanism and signaling factors underlying the sustenance of inflammation in the rotator cuff joint are largely unknown. The present article aims to elucidate the involvement of inflammatory molecule, TREM-1 (Triggering Receptors Expressed on Myeloid cells-1), and danger-associated molecular patterns (DAMPs), including high mobility group protein 1 (HMGB-1) and RAGE (receptor for advanced glycation end products), in the setting of RCI with respect to the severity of glenohumeral arthritis. Biceps tendons (15 specimens) from the shoulder and blood (11 samples) from patients with glenohumeral arthritis (Group-1, n = 4) and without glenohumeral arthritis (Group-2, n = 11) after RCI surgery were obtained for the study. Molecular and morphological alterations between the groups were compared using histology, immunofluorescence, RT-PCR and flow cytometry. MRI and histomorphology assessment revealed severe inflammation in Group-1 patients while in Group-2 ECM disorganization was prominent without any hallmarks of inflammation. A significant increase in TREM-1 expression in circulating neutrophils and monocytes was observed. Elevated levels of TREM-1, HMGB-1 and RAGE in Group-1 patients along with CD68⁺ and CD16⁺ cells confirmed DAMP-mediated inflammation. Expression of TREM-1 in the tendon of Group-2 patients even in the absence of immune cells presented a new population of TREM-expressing cells that were confirmed by real-time PCR analysis and immunofluorescence. Expression of HMGB-1 and RAGE in the biceps tendon from the shoulder of patients without glenohumeral arthritis implied TREM-1-mediated inflammation without involving immune cells, whereas in patients with glenohumeral arthritis, infiltration and the activation of the immune cells, primarily macrophages, release mediators to induce inflammation. This could be the reason for ECM disorganization without the classical signs of inflammation in patients without glenohumeral arthritis.

Increased expression of triggering receptor expressed on myeloid cells 1 and 2 in inflamed human gingiva

BACKGROUND AND OBJECTIVE

Periodontitis is an infectious disease in which the host immune and inflammatory responses play essential roles in resistance to bacterial infection, as well as the induction of tissue destruction if the immune response is dysregulated. The triggering receptor expressed on myeloid cells (TREMs) modulates inflammatory and innate immune signaling. TREM-1 is considered as an amplifier of the immune response, while TREM-2 is a negative regulator that has yet to be explored in periodontal disease before. We hypothesized that TREMs participated in the innate immune responses during the pathogenesis of periodontitis. Therefore, the aim of this study was to evaluate TREM-1 and TREM-2 expression in the gingival tissues from patients with chronic periodontitis and healthy subjects as well as their correlation with clinical periodontal parameters. This study is the first to identify TREM-2 in periodontal tissue, as well as the protein expression changes of TREM-1 and TREM-2 in periodontal tissues.

MATERIAL AND METHODS

Gingival tissue sections were collected from 31 healthy subjects and 53 patients with chronic periodontitis. Immunohistochemistry and quantitative real-time polymerase chain reaction were employed to evaluate the protein and mRNA expression of these receptors in gingival tissues. The recorded clinical parameters were probing depth, clinical attachment loss, plaque index and bleeding on probing.

RESULTS

In addition to myeloid cells in gingival connective tissues, TREM-1 and TREM-2 were also found expressed in gingival epithelial cells. In particular, TREM-1 was detected in almost all gingival epithelium from both healthy and inflamed biopsies. The expression levels of TREM-1 and TREM-2 were significantly increased in the periodontitis group compared to the healthy group. Increased levels of these receptors are to be positively correlated with site-specific periodontal parameters.

CONCLUSION

The increased expression of TREM-1 and TREM-2 levels in periodontitis may confer diagnostic and potential therapeutic targets as well as indicating their association with the clinical severity of the disease.

Cutaneous expression of TREM, vitamin D receptor and HMGB1 in vitamin D deficiency

Signaling pathways of the vitamin D receptor (VDR) and the triggering receptor expressed on myeloid cells (TREM) have been independently implicated in the biology of numerous of cutaneous pathologies. There is substantial evidence for possible crosstalk between these pathways, though the relationship between VDR and TREMs remains unclear. In this study, we characterize the effects of vitamin D-deficiency and sufficiency on the cutaneous expression of TREM-1, TREM-2, VDR, HMGB1, and RAGE. Cutaneous tissue isolated from Yucatan microswine were immunohistochemically evaluated for epidermal expression of TREM-1, TREM-2, VDR, HMGB1, and RAGE. The swine were fed a vitamin D-deficient or vitamin D-sufficient diet to examine the role of vitamin D state on levels of these markers. In vitamin D-sufficient animals, keratinocytes exhibited elevated levels of TREM-1, TREM-2. Additionally, TREM-1 expression predominated in basal cells, whereas TREM-2 levels were higher in keratinocytes, regardless of vitamin D state. Levels of HMGB1 and RAGE did not differ by vitamin D state. VDR expression was consistently higher in the cytoplasm and nuclei of basal cells, when compared to keratinocytes. Our findings suggest a role of vitamin D in signaling of TREM pathways. Additionally, the TREM ratio may play a role in keratinocyte differentiation and should be explored further. Possible signaling crosstalk between these pathways has a potential role in progression of cutaneous malignancies and other inflammatory pathologies.