Immunoglobulin-Like Transcript 5 Inhibits Macrophage-Mediated Bacterial Killing and Antigen Presentation During Sepsis

Immunoglobulin-like transcript 5 polarizes M2-like tumor-associated macrophages for immunosuppression in non-small cell lung cancer

Immune checkpoint inhibitors (ICIs) have shifted the treatment paradigm of non-small cell lung cancer (NSCLC) over the last decade. Despite notable therapeutic advancements in responders, the response rate remains limited owing to the immunosuppressive tumor microenvironment (TME). Therefore, to improve the efficacy of ICIs, it is essential to explore alternative targets or signals that mediate immunosuppression. Immunoglobulin-like transcript (ILT) 5 is a negative regulator of immune activation in myeloid cells. However, the expression and function of ILT5 in NSCLC remain unknown. Here, we found that ILT5 was highly expressed in tumor-associated macrophages (TAMs) of NSCLC tissues and predicted poor patient survival. Functionally, ILT5 induces the M2-like polarization of TAMs, which subsequently decreases the density of T cells, and increases FOXP3+T cell accumulation, leading to an immunosuppressive TME. The combination of ILT5 expression with M2-like TAM density is a more reliable biomarker of patient survival than ILT5 expression alone. ILT5 knockout mitigates the reprogramming of TAM and T cell subsets toward immunosuppressive phenotypes and inhibits tumor growth in vivo. These findings highlight that ILT5 is a potential immunotherapeutic target and a promising prognostic biomarker for NSCLC.

CLPs-miR-103a-2-5p inhibits proliferation and promotes cell apoptosis in AML cells by targeting LILRB3 and Nrf2/HO-1 axis, regulating CD8 + T cell response

BACKGROUND

LILRB3, a member of the leukocyte immunoglobulin-like receptor B (LILRB) family, has immunosuppressive functions and directly regulates cancer development, which indicates that LILRB3 is an attractive target for cancer diagnosis and therapy. Novel therapeutic treatments for acute myeloid leukemia (AML) are urgent and important, and RNA therapeutics including microRNAs (miRNAs) could be an effective option. Here, we investigate the role of dysregulated miRNA targeting LILRB3 in the AML microenvironment.

METHODS

Potential miRNAs binding to the 3'-untranslated region (3'-UTR) of the LILRB3 mRNA were predicted by bioinformatics websites. Then, we screened miRNAs targeting LILRB3 by quantitative real-time PCR, and the dual luciferase reporter assay. The expression of LILRB3 and microRNA (miR)-103a-2-5p in AML were determined and then their interactions were also analyzed. In vitro, the effects of miR-103a-2-5p were determined by CCK8, colony formation assay, and transwell assay, while cell apoptosis and cell cycle were analyzed by flow cytometry. Cationic liposomes (CLPs) were used for the delivery of miR-103a-2-5p in the AML mouse model, which was to validate the potential roles of miR-103a-2-5p in vivo.

RESULTS

LILRB3 was upregulated in AML cells while miR-103a-2-5p was dramatically downregulated. Thus, a negative correlation was found between them. MiR-103a-2-5p directly targeted LILRB3 in AML cells. Overexpressed miR-103a-2-5p significantly suppressed the mRNA and protein levels of LILRB3, thereby inhibiting AML cell growth and reducing CD8 + T cell apoptosis. In addition, overexpressed miR-103a-2-5p reduced both the relative expression of Nrf2/HO-1 pathway-related proteins and the ratio of GSH/ROS, leading to the excessive intracellular ROS that may promote AML cell apoptosis. In the mouse model, the delivery of miR-103a-2-5p through CLPs could inhibit tumor growth.

CONCLUSIONS

MiR-103a-2-5p serves as a tumor suppressor that could inhibit AML cell proliferation and promote their apoptosis by downregulating LILRB3 expression, suppressing the Nrf2/HO-1 axis, and reducing the ratio of GSH/ROS. Besides, our findings indicate that miR-103a-2-5p may enhance the CD8 + T cell response by inhibiting LILRB3 expression. Therefore, the delivery of miR-103a-2-5p through CLPs could be useful for the treatment of AML.

Research progress of B subfamily of leucocyte immunoglobulin-like receptors in inflammation

Leucocyte immunoglobulin-like receptors subfamily B (LILRB) belongs to the type I transmembrane glycoproteins, which is the immunosuppressive receptor. LILRBs are widely expressed in bone marrow cells, hematopoietic stem cells, nerve cells and other body cells. Studies have found that LILRBs receptor can bind to a variety of ligands and has a variety of biological functions such as regulating inflammatory response, immune tolerance and cell differentiation. Inflammatory reaction plays a vital role in resisting microorganisms. The function of inhibitory immune receptors can recognize the signs of infection and promote the function of anti-microbial effect. The inflammatory response must be strictly regulated to prevent excessive inflammation and tissue damage. Therefore, it is of general interest to understand the role of LILRBs in the inflammatory response. Because they can inhibit the anti-microbial response of neutrophils, some human pathogens use these receptors to escape immunity. This article reviews the biological role of LILRBs in the inflammatory response. We focus on the known ligands of LILRBs, their different roles after binding with ligands, and how these receptors help to form neutrophil responses during infection. Recent studies have shown that LILRBs recruit phosphatases through intracellular tyrosine-based immunoreceptor inhibitory motifs to negatively regulate immune activation, thereby transmitting inflammation-related signals, suggesting that LILRBs may be an ideal target for the treatment of inflammatory diseases. Here, we describe in detail the regulation of LILRBs on the inflammatory response, its signal transduction mode in inflammation, and the progress in the treatment of inflammatory diseases, providing a reference for further research.

Leukocyte Immunoglobulin-like Receptor A5 Deletion Aggravates the Pathogenesis of Pseudomonas aeruginosa Keratitis by Promoting Proinflammatory Cytokines

PURPOSE

The purpose of this study was to assess the role of leukocyte immunoglobulin-like receptor A5 (LILRA5) in regulating bacterial infection and corneal inflammation.

METHODS

The human corneal tissue microarray data set GSE58291 from Gene Expression Omnibus was downloaded. Then, the differentially expressed genes, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Gene Set Enrichment Analysis, and the immune infiltration analysis were conducted. We constructed the Pseudomonas aeruginosa ( P. aeruginosa ) keratitis mice model using wild-type and LILRA5-deficient mice. The results of the bioinformatics analysis were verified by the cell in vitro and animal in vivo experiments.

RESULTS

This study revealed that LILRA5 is substantially expressed in human keratitis and regulates the immune response negatively. Neutrophils were identified as the core fraction of immune cells in keratitis. After P. aeruginosa infection, neutrophils lacking LILRA5 induced elevated levels of proinflammatory cytokines and toll-like receptor 4. LILRA5 deficiency exacerbated the severity of the infection and the production of proinflammatory cytokines in mice.

CONCLUSIONS

LILRA5 was discovered as an immunosuppressive regulator in P. aeruginosa keratitis, highlighting its significance in activated immune responses.

Correlation of HMGB1, TLR2 and TLR4 with left ventricular diastolic dysfunction in sepsis patients

Left ventricular diastolic dysfunction (LVDD) is a common consequence of sepsis due to dysregulated inflammatory responses. Here we aim to investigate high mobility group box 1 (HMGB1), toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) as serum biomarkers to assess LVDD risk of patients with sepsis. We recruited 120 patients with sepsis, among which 52 had ultrasonically confirmed LVDD and 68 were without LVDD. Blood samples were collected, and enzyme-linked immunosorbent assay (ELISA) was used to analyse levels of HMGB1, TLR2 and TLR4 in serum. Multivariate analysis was performed to assess the odds ratio of the serum biomarkers. Spearman's correlation analysis was conducted to evaluate the correlation between the serum biomarkers to B-type natriuretic peptide (BNP) and cardiac troponin I (cTnl) levels and the ratios of early diastolic mitral inflow velocity to early diastolic mitral annulus velocity (E/e' ratios) in ultrasound. Receiver operating curve was used to measure the sensitivity and specificity of HMGB1, TLR2 and TLR4 individually and in combination as diagnostic markers. Elevated HMGB1, TLR2 and TLR4 had significant values in predicting LVDD suggested by high odds ratio (all P < .05). A significant correlation was found between these values and cTnl, the current gold standard for LVDD analysis. HMGB1, TLR2 and TLR4 also showed a high diagnostic sensitivity and specificity in ROC analysis. HMGB1, TLR2 and TLR4 are potentially valuable in predicting LVDD risk among patients with sepsis, providing additional tools with the capability of potentially assisting the clinical management of patients with sepsis.

Use of machine learning-based integration to develop a monocyte differentiation-related signature for improving prognosis in patients with sepsis

BACKGROUND

Although significant advances have been made in intensive care medicine and antibacterial treatment, sepsis is still a common disease with high mortality. The condition of sepsis patients changes rapidly, and each hour of delay in the administration of appropriate antibiotic treatment can lead to a 4-7% increase in fatality. Therefore, early diagnosis and intervention may help improve the prognosis of patients with sepsis.

METHODS

We obtained single-cell sequencing data from 12 patients. This included 14,622 cells from four patients with bacterial infectious sepsis and eight patients with sepsis admitted to the ICU for other various reasons. Monocyte differentiation trajectories were analyzed using the "monocle" software, and differentiation-related genes were identified. Based on the expression of differentiation-related genes, 99 machine-learning combinations of prognostic signatures were obtained, and risk scores were calculated for all patients. The "scissor" software was used to associate high-risk and low-risk patients with individual cells. The "cellchat" software was used to demonstrate the regulatory relationships between high-risk and low-risk cells in a cellular communication network. The diagnostic value and prognostic predictive value of Enah/Vasp-like (EVL) were determined. Clinical validation of the results was performed with 40 samples. The "CBNplot" software based on Bayesian network inference was used to construct EVL regulatory networks.

RESULTS

We systematically analyzed three cell states during monocyte differentiation. The differential analysis identified 166 monocyte differentiation-related genes. Among the 99 machine-learning combinations of prognostic signatures constructed, the Lasso + CoxBoost signature with 17 genes showed the best prognostic prediction performance. The highest percentage of high-risk cells was found in state one. Cell communication analysis demonstrated regulatory networks between high-risk and low-risk cell subpopulations and other immune cells. We then determined the diagnostic and prognostic value of EVL stabilization in multiple external datasets. Experiments with clinical samples demonstrated the accuracy of this analysis. Finally, Bayesian network inference revealed potential network mechanisms of EVL regulation.

CONCLUSIONS

Monocyte differentiation-related prognostic signatures based on the Lasso + CoxBoost combination were able to accurately predict the prognostic status of patients with sepsis. In addition, low EVL expression was associated with poor prognosis in sepsis.

Transcriptome Analysis Reveals a Two-Gene Signature Links to Motor Progression and Alterations of Immune Cells in Parkinson's Disease

BACKGROUND

The motor impairment in Parkinson's disease (PD) can be managed but effective treatments for stopping or slowing the disease process are lacking. The advent of transcriptomics studies in PD shed light on the development of promising measures to predict disease progression and discover novel therapeutic strategies.

OBJECTIVE

To reveal the potential role of transcripts in the motor impairment progression of patients with PD via transcriptome analysis.

METHODS

We separately analyzed the differentially expressed genes (DEGs) between PD cases and healthy controls in two cohorts using whole blood bulk transcriptome data. Based on the intersection of DEGs, we established a prognostic signature by regularized regression and Cox proportional hazards analysis. We further performed immune cell analysis and single-cell RNA sequencing analysis to study the biological features of this signature.

RESULTS

We identified a two-gene-based prognostic signature that links to PD motor progression and the two-gene signature-derived risk score was associated with several types of immune cells in blood. Notably, the fraction of neutrophils increased 5% and CD4+ T cells decreased 7% in patients with high-risk scores compared to that in patients with low-risk scores, suggesting these two types of immune cells might play key roles in the prognosis of PD. We also observed the downregulated genes in PD patients with high-risk scores that enriched in PD-associated pathways from iPSC-derived dopaminergic neurons single-cell RNA sequencing analysis.

CONCLUSION

We identified a two-gene signature linked to the motor progression in PD, which provides new insights into the motor prognosis of PD.

Tumor-derived immunoglobulin like transcript 5 induces suppressive immunocyte infiltration in colorectal cancer

Infiltration of immunosuppressive cells in the tumor microenvironment (TME) induced colorectal cancer (CRC) progression and its resistance to immunotherapy. Identification of tumor-specific factors to modulate inhibitory immunocyte infiltration would provide alternative and novel targets for CRC immunotherapy. Immunoglobulin-like transcript (ILT) 5 is a negative regulator of myeloid cell activation. However, its expression and functional role in solid tumors is still unknown. Using human CRC tissues and cell lines, we found that ILT5 was highly expressed in CRC cells compared with normal colorectal epithelial cells. Enriched ILT5 in tumor cells was correlated with advanced tumor stages and poor patient survival. Our subsequent in vitro and in vivo studies revealed that tumor-derived ILT5 inhibited the infiltration of T cells, especially that of CD8⁺ T cells in the TME, creating suppressive T-cell contexture. Furthermore, ILT5 directed M2-like polarization of tumor-associated macrophages (TAMs). Inhibition of tumor-derived ILT5 restored the immunosuppressive T-cell and TAM contexture, and restricted CRC progression. Our findings identified ILT5 expression in solid tumor cells for the first time and raised ILT5 as a potential immunotarget and prognostic predictor in CRC.

Leukocyte Immunoglobulin-Like Receptors in Regulating the Immune Response in Infectious Diseases: A Window of Opportunity to Pathogen Persistence and a Sound Target in Therapeutics

Immunoregulatory receptors are essential for orchestrating an immune response as well as appropriate inflammation in infectious and non-communicable diseases. Among them, leukocyte immunoglobulin-like receptors (LILRs) consist of activating and inhibitory receptors that play an important role in regulating immune responses modulating the course of disease progression. On the one hand, inhibitory LILRs constitute a safe-guard system that mitigates the inflammatory response, allowing a prompt return to immune homeostasis. On the other hand, because of their unique capacity to attenuate immune responses, pathogens use inhibitory LILRs to evade immune recognition, thus facilitating their persistence within the host. Conversely, the engagement of activating LILRs triggers immune responses and the production of inflammatory mediators to fight microbes. However, their heightened activation could lead to an exacerbated immune response and persistent inflammation with major consequences on disease outcome and autoimmune disorders. Here, we review the genetic organisation, structure and ligands of LILRs as well as their role in regulating the immune response and inflammation. We also discuss the LILR-based strategies that pathogens use to evade immune responses. A better understanding of the contribution of LILRs to host-pathogen interactions is essential to define appropriate treatments to counteract the severity and/or persistence of pathogens in acute and chronic infectious diseases lacking efficient treatments.

OX40L/OX40 Signal Promotes IL-9 Production by Mucosal MAIT Cells During Helicobacter pylori Infection

Mucosal associated invariant T (MAIT) cells play a critical role in Helicobacter pylori (H. pylori)-induced gastritis by promoting mucosal inflammation and aggravating mucosal injuries (1, 2). However, the underlying mechanism and key molecules involved are still uncertain. Here we identified OX40, a co-stimulatory molecule mainly expressed on T cells, as a critical regulator to promote proliferation and IL-9 production by MAIT cells and facilitate mucosal inflammation in H. pylori-positive gastritis patients. Serum examination revealed an increased level of IL-9 in gastritis patients. Meanwhile, OX40 expression was increased in mucosal MAIT cells, and its ligand OX40L was also up-regulated in mucosal dendritic cells (DCs) of gastritis patients, compared with healthy controls. Further results demonstrated that activation of the OX40/OX40L pathway promoted IL-9 production by MAIT cells, and MAIT cells displayed a highly-activated phenotype after the cross-linking of OX40 and OX40L. Moreover, the level of IL-9 produced by MAIT cells was positively correlated with inflammatory indexes in the gastric mucosa, suggesting the potential role of IL-9-producing MAIT cells in mucosal inflammation. Taken together, we elucidated that OX40/OX40L axis promoted mucosal MAIT cell proliferation and IL-9 production in H. pylori-induced gastritis, which may provide potential targeting strategies for gastritis treatment.

Leukocyte immunoglobulin-like receptor subfamily B: therapeutic targets in cancer

Inhibitory leukocyte immunoglobulin-like receptors (LILRBs 1–5) transduce signals via intracellular immunoreceptor tyrosine-based inhibitory motifs that recruit phosphatases to negatively regulate immune activation. The activation of LILRB signaling in immune cells may contribute to immune evasion. In addition, the expression and signaling of LILRBs in cancer cells especially in certain hematologic malignant cells directly support cancer development. Certain LILRBs thus have dual roles in cancer biology—as immune checkpoint molecules and tumor-supporting factors. Here, we review the expression, ligands, signaling, and functions of LILRBs, as well as therapeutic development targeting them. LILRBs may represent attractive targets for cancer treatment, and antagonizing LILRB signaling may prove to be effective anti-cancer strategies.