PDL1 expression on monocytes is associated with plasma cytokines in Tuberculosis and HIV

The imbalance of circulating PD-L1-expressing non-classical/ classical monocytes is involved in immunocompromised host related pulmonary opportunistic infection

The application of biological therapy and glucocorticoids in Auto-immune diseases (AID) patients will cause immunocompromised host (ICH) prone to infection. And monocytes play a key role in both innate and adaptive immune responses. We aimed to investigate the changes of circulating monocyte subsets in AID or AID-ICH patients with pulmonary infection. The subgroups and PD-L1 expression of monocytes were measured by flow cytometry in healthy individuals (HC), new-onset AID patients (AID cohort) and AID-ICH patients with pulmonary opportunistic infection (AID-ICH cohort). Flow cytometry analysis was used to determine the distribution of monocyte subsets, including classical monocytes (CL, CD14++CD16-), intermediate monocytes (ITM, CD14++CD16+) and non-classical monocytes (NC, CD14+/-CD16++), as well as the dynamic change of PD-L1 + cluster among monocyte subsets. Among total monocyte, AID-ICH displayed decreased CL subset along with increased NC subset compared to HCs and AID. Regarding PD-L1 + monocytes, although CL subset constituted the majority of that in HCs, AIDs and AID-ICHs, imbalance of NC/CL within PD-L1 + monocytes was only noticed in AID-ICHs (P < 0.05). Furthermore, when AID subjects were developed into immunocompromised status (ICH), PD-L1 + cluster in CL was minorly decreased (P > 0.05). Clinically, the lower ratio of PD-L1 + cluster among CL subset (P < 0.05) and the less differentiated CL in PD-L1 + monocytes (P < 0.05) was more likely to leaded to disease progression. The imbalance of circulating NC/CL subset was remarkable in immunocompromised host with pulmonary opportunistic infection, especially involvement of PD-L1+ cluster, which served as a potential biomarker in clinical practice.

Epstein Barr Virus (EBV) Latent Membrane Protein 1 (LMP-1) Regulates Functional Markers in Intermediate and Non-Classical Monocytes

Background: The Epstein-Barr virus (EBV) infects more than 90 percent of the human population. In pediatric patients, the innate immune response against EBV primary infection plays a key role. Monocytes and macrophages can have distinct functions depending on the microenvironment surrounding them. At least three monocyte subpopulations can be differentiated depending on membrane protein expression: classical (C, CD14++CD16-), intermediate (I, CD14++CD16+), and non-classical (NC, CD14+CD16++). They also modulate T and B lymphocyte activation/inhibition through the expression of costimulatory molecules such as CD80, CD86, and PD-L1. Yet, little is known about monocytes' role in EBV infection. Methods: Peripheral blood and tonsil biopsies of EBV primary infected (PI) patients, healthy carriers (HCs), and patients undergoing reactivation (R) were studied. Results: Classical monocytes prevailed in all infectious statuses. Tonsillar CD163 positively correlated with CD163 expression in NC monocytes in HCs. PD-L1+ cells in the tonsil positively correlated with PD-L1 expression in NC monocytes. LMP-1 viral latent protein presented a positive correlation with PD-L1, CD163, and CD206 expression in the NC subpopulation. Conclusions: Our results evidence the predominant role of I and NC monocytes' response against EBV infection. Furthermore, the viral oncoprotein LMP-1 could be involved in the expression of regulatory proteins in I and NC monocytes.

A causal relationship between distinct immune features and acute or chronic pancreatitis: results from a mendelian randomization analysis

OBJECTIVES

This study aimed to thoroughly examining the causal link between immune traits and four types of pancreatitis, using mendelian randomization.

METHODS

Data on 731 immune traits were collected from the genome-wide association study (GWAS) database as exposure. Information regarding acute pancreatitis (AP), alcohol-induced acute pancreatitis (AAP), chronic pancreatitis (CP), and alcohol-induced chronic pancreatitis (ACP) were acquired from the FinnGen Consortium as outcomes. Mendelian randomization (MR) using inverse variance weighting (IVW) evaluated the links between immune traits and pancreatitis. We evaluated the robustness of the IVW results through sensitivity analyses and validated them using meta-analysis with AP and CP data from the UK Biobank in the GWAS catalog.

RESULTS

A total of 36 immune traits showed significant associations with susceptibility of four types of pancreatitis, including AP (7 traits), AAP (8 traits), CP (14 traits), and ACP (7 traits). Twenty characteristics were found to be potential risk factors for pancreatitis, identified in B Cells (5 traits), conventional dendritic cells (cDCs, 2 traits), maturation stage of T cells (2 traits), monocytes (2 traits), myeloid cells (2 traits), T cells, B cells, natural killer cells (TBNK, 2 traits), and regulatory T cells (Treg cells, 5 traits). Multiple sensitivity analyses confirmed the validity of the findings. Meta-analysis confirmed a solid causal relationship between CX3CR1 on CD14- CD16-of monocyte panel and the susceptibility of CP.

CONCLUSIONS

Our MR study identified immune traits causally linked to acute and chronic pancreatitis, offering new insights for early clinical intervention and immune cell-targeted therapies.

Absence of PD-L1 signaling hinders macrophage defense against Mycobacterium tuberculosis via upregulating STAT3/IL-6 pathway

The blockade of programmed death-ligand 1 (PD-L1) pathway has been clinically used in cancer immunotherapy, while its effects on infectious diseases remain elusive. Roles of PD-L1 signaling in the macrophage-mediated innate immune defense against M.tb is unclear. In this study, the outcomes of tuberculosis (TB) in wild-type (WT) mice treated with anti-PD-1/PD-L1 therapy and macrophage-specific Pdl1-knockout (Pdl1ΔΜΦ) mice were compared. Treatment with anti-PD-L1 or anti-PD-1 benefited protection against M.tb infection in WT mice, while Pdl1ΔΜΦ mice exhibited the increased susceptibility to M.tb infection. Mechanistically, the absence of PD-L1 signaling impaired M.tb killing by macrophages. Furthermore, elevated STAT3 activation was found in PD-L1-deficient macrophages, leading to increased interleukin (IL)-6 production and reduced inducible nitric oxide synthase (iNOS) expression. Inhibiting STAT3 phosphorylation partially impeded the increase in IL-6 production and restored iNOS expression in these PD-L1-deficient cells. These findings provide valuable insights into the complexity and mechanisms underlying anti-PD-L1 therapy in the context of tuberculosis.

Protein Expression of TLR2, TLR4, and TLR9 on Monocytes in TB, HIV, and TB/HIV

Toll-like receptors (TLRs) have a critical role in recognizing pathogenic patterns and initiating immune responses against TB and HIV. Previously, studies described the gene expression of TLRs in patients with TB and HIV. Here, we demonstrated TLRs protein expressions and their association with clinical status and plasma markers in TB, HIV, and TB/HIV coinfection. The phenotyping of TLR2, TLR4, and TLR9 on CD14+ monocytes and their subsets were determined by multicolor flow cytometry. Host plasma biomarkers and microbial indices were measured using Luminex Multiplex assay and standard of care tools, respectively. TLR2 expression significantly enhanced in TB, slightly increased in HIV but slightly reduced in TB/HIV coinfection compared to apparently health controls (HC). On the other hand, TLR4 expression was significantly increased in TB, HIV, and TB/HIV compared to HC. Expression of TLR4 was equally enhanced on classical and intermediate monocytes while higher TLR2 expression on intermediate than classical monocytes. TLR4 had a positive correlation pattern with plasma biomarkers while TLR2 had an inverse correlation pattern. TLR4 is associated with disease severity while TLR2 is with the immune-competent status of patients. Our findings demonstrated that the pattern of TLR expression is disease as well as monocyte subset specific and distinct factors drive these differences.

Extracellular vesicles recovered from plasma of severe dengue patients induce CD4+ T cell suppression through PD-L1/PD-1 interaction

IMPORTANCE

Severe dengue manifestations caused by the dengue virus are a global health problem. Studies suggest that severe dengue disease depends on uncontrolled immune cell activation, and excessive inflammation adds to the pathogenesis of severe dengue disease. Therefore, it is important to understand the process that triggers the uncontrolled activation of the immune cells. The change in immune response in mild to severe dengue may be due to direct virus-to-cell interaction or it could be a contact-independent process through the extracellular vesicles (EVs) released from infected cells. The importance of circulating EVs in the context of dengue virus infection and pathogenesis remains unexplored. Therefore, understanding the possible biological function of circulating EVs may help to delineate the role of EVs in the progression of disease. Our present study highlights that EVs from plasma of severe dengue patients can have immunosuppressive properties on CD4+ T cells which may contribute to T cell suppression and may contribute to dengue disease progression.

Early innate cell interactions with Mycobacterium tuberculosis in protection and pathology of tuberculosis

Tuberculosis (TB) remains a significant global health challenge, claiming the lives of up to 1.5 million individuals annually. TB is caused by the human pathogen Mycobacterium tuberculosis (Mtb), which primarily infects innate immune cells in the lungs. These immune cells play a critical role in the host defense against Mtb infection, influencing the inflammatory environment in the lungs, and facilitating the development of adaptive immunity. However, Mtb exploits and manipulates innate immune cells, using them as favorable niche for replication. Unfortunately, our understanding of the early interactions between Mtb and innate effector cells remains limited. This review underscores the interactions between Mtb and various innate immune cells, such as macrophages, dendritic cells, granulocytes, NK cells, innate lymphocytes-iNKT and ILCs. In addition, the contribution of alveolar epithelial cell and endothelial cells that constitutes the mucosal barrier in TB immunity will be discussed. Gaining insights into the early cellular basis of immune reactions to Mtb infection is crucial for our understanding of Mtb resistance and disease tolerance mechanisms. We argue that a better understanding of the early host-pathogen interactions could inform on future vaccination approaches and devise intervention strategies.

Monocyte pathology in human tuberculosis is due to plasma milieu changes and aberrant STAT signalling

Monocyte-derived macrophages contribute centrally to immune protection in Mycobacterium tuberculosis infection and changes in monocyte phenotype characterize immunopathology in tuberculosis patients. Recent studies highlighted an important role of the plasma milieu in tuberculosis immunopathology. Here, we investigated monocyte pathology in patients with acute tuberculosis and determined tuberculosis plasma milieu effects on phenotype as well as cytokine signalling of reference monocytes. Patients with tuberculosis (n = 37) and asymptomatic contacts (controls n = 35) were recruited as part of a hospital-based study in the Ashanti region of Ghana. Multiplex flow cytometry phenotyping of monocyte immunopathology was performed and effects of individual blood plasma samples on reference monocytes prior to and during treatment were characterized. Concomitantly, cell signalling pathways were analysed to elucidate underlying mechanisms of plasma effects on monocytes. Multiplex flow cytometry visualization characterized changes in monocyte subpopulations and detected higher expression of CD40, CD64 and PD-L1 in monocytes from tuberculosis patients as compared to controls. Aberrant expression normalized during anti-mycobacterial treatment and also CD33 expression decreased markedly. Notably, higher CD33, CD40 and CD64 expression was induced in reference monocytes when cultured in the presence of plasma samples from tuberculosis patients as compared to controls. STAT signalling pathways were affected by the aberrant plasma milieu and higher levels of STAT3 and STAT5 phosphorylation was found in tuberculosis plasma-treated reference monocytes. Importantly, high pSTAT3 levels were associated with high CD33 expression and pSTAT5 correlated with CD40 as well as CD64 expression. These results suggested plasma milieu effects with potential implications on monocyte phenotype and function in acute tuberculosis.

CD300f signalling induces inhibitory human monocytes/macrophages

The CD300 glycoproteins are a family of related leucocyte surface molecules that regulate the immune response via their paired triggering and inhibitory receptors. Here we studied CD300f, an apoptotic cell receptor, and how it modulates the function of human monocytes and macrophages. We showed that CD300f signalling by crosslinking with anti-CD300f mAb (DCR-2) suppressed monocytes causing upregulation of the inhibitory molecule, CD274 (PD-L1) and their inhibition of T cell proliferation. Furthermore, CD300f signalling drove macrophages preferentially towards M2-type with upregulation of CD274, which was further enhanced by IL-4. CD300f signalling activates the PI3K/Akt pathway in monocytes. Inhibition of PI3K/Akt signalling resulting from CD300f crosslinking leads to downregulation of CD274 expression on monocytes. These findings highlight the potential use of CD300f blockade in cancer immune therapy to target immune suppressive macrophages in the tumour microenvironment, a known resistance mechanism to PD-1/PD-L1 checkpoint inhibitors.

Screening for diagnostic targets in tuberculosis and study on its pathogenic mechanism based on mRNA sequencing technology and miRNA-mRNA-pathway regulatory network

Purpose

Tuberculosis is common infectious diseases, characterized by infectivity, concealment and chronicity, and the early diagnosis is helpful to block the spread of tuberculosis and reduce the resistance of Mycobacterium tuberculosis to anti-tuberculosis drugs. At present, there are obvious limitations in the application of clinical detection methods used for the early diagnosis of tuberculosis. RNA sequencing (RNA-Seq) has become an economical and accurate gene sequencing method for quantifying transcripts and detecting unknown RNA species.

Methods

A peripheral blood mRNA sequencing was used to screen the differentially expressed genes between healthy people and tuberculosis patients. A protein-protein interaction (PPI) network of differentially expressed genes was constructed through Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. The potential diagnostic targets of tuberculosis were screened by the calculation of degree, betweenness and closeness in Cytoscape 3.9.1 software. Finally, the functional pathways and the molecular mechanism of tuberculosis were clarified in combination of the prediction results of key gene miRNAs, and by Gene Ontology (GO) enrichment analysis and the Kyoto Encyclopedia Genes and Genomes (KEGG) pathway annotation analysis.

Results

556 Differential genes of tuberculosis were screened out by mRNA sequencing. Six key genes (AKT1, TP53, EGF, ARF1, CD274 and PRKCZ) were screened as the potential diagnostic targets for tuberculosis by analyzing the PPI regulatory network and using three algorithms. Three pathways related to the pathogenesis of tuberculosis were identified by KEGG pathway analysis, and two key miRNAs (has-miR-150-5p and has-miR-25-3p) that might participate in the pathogenesis of tuberculosis were screened out by constructing a miRNA-mRNA pathway regulatory network.

Conclusion

Six key genes and two important miRNAs that could regulate them were screened out by mRNA sequencing. The 6 key genes and 2 important miRNAs may participate in the pathogenesis of infection and invasion of Mycobacterium tuberculosis through herpes simplex virus 1 infection, endocytosis and B cell receptor signaling pathways.