Increased CD86 but Not CD80 and PD-L1 Expression on Liver CD68+ Cells during Chronic HBV Infection

Immunological Tolerance in Liver Transplant Recipients: Putative Involvement of Neuroendocrine-Immune Interactions

The transplantation world changed significantly following the introduction of immunosuppressants, with millions of people saved. Several physicians have noted that liver recipients that do not take their medication for different reasons became tolerant regarding kidney, heart, and lung transplantations at higher frequencies. Most studies have attempted to explain this phenomenon through unique immunological mechanisms and the fact that the hepatic environment is continuously exposed to high levels of pathogen-associated molecular patterns (PAMPs) or non-pathogenic microorganism-associated molecular patterns (MAMPs) from commensal flora. These components are highly inflammatory in the periphery but tolerated in the liver as part of the normal components that arrive via the hepatic portal vein. These immunological mechanisms are discussed herein based on current evidence, although we hypothesize the participation of neuroendocrine-immune pathways, which have played a relevant role in autoimmune diseases. Cells found in the liver present receptors for several cytokines, hormones, peptides, and neurotransmitters that would allow for system crosstalk. Furthermore, the liver is innervated by the autonomic system and may, thus, be influenced by the parasympathetic and sympathetic systems. This review therefore seeks to discuss classical immunological hepatic tolerance mechanisms and hypothesizes the possible participation of the neuroendocrine-immune system based on the current literature.

Human macrophages and monocyte-derived dendritic cells stimulate the proliferation of endothelial cells through midkine production

The cytokine midkine (MK) is a growth factor that is involved in different physiological processes including tissue repair, inflammation, the development of different types of cancer and the proliferation of endothelial cells. The production of MK by primary human macrophages and monocyte-derived dendritic cells (MDDCs) was never described. We investigated whether MK is produced by primary human monocytes, macrophages and MDDCs and the capacity of macrophages and MDDCs to modulate the proliferation of endothelial cells through MK production. The TLR stimulation of human monocytes, macrophages and MDDCs induced an average of ≈200-fold increase in MK mRNA and the production of an average of 78.2, 62, 179 pg/ml MK by monocytes, macrophages and MDDCs respectively (p < 0.05). MK production was supported by its detection in CD11c+ cells, CLEC4C+ cells and CD68+ cells in biopsies of human tonsils showing reactive lymphoid follicular hyperplasia. JSH-23, which selectively inhibits NF-κB activity, decreased the TLR-induced production of MK in PMBCs, macrophages and MDDCs compared to the control (p < 0.05). The inhibition of MK production by macrophages and MDDCs using anti-MK siRNA decreased the capacity of their supernatants to stimulate the proliferation of endothelial cells (p = 0.01 and 0.04 respectively). This is the first study demonstrating that the cytokine MK is produced by primary human macrophages and MDDCs upon TLR triggering, and that these cells can stimulate endothelial cell proliferation through MK production. Our results also suggest that NF-κB plays a potential role in the production of MK in macrophages and MDDCs upon TLR stimulation. The production of MK by macrophages and MDDCs and the fact that these cells can enhance the proliferation of endothelial cells by producing MK are novel immunological phenomena that have potentially important therapeutic implications.

The Liver and the Hepatic Immune Response in Trypanosoma cruzi Infection, a Historical and Updated View

Chagas disease was described more than a century ago and, despite great efforts to understand the underlying mechanisms that lead to cardiac and digestive manifestations in chronic patients, much remains to be clarified. The disease is found beyond Latin America, including Japan, the USA, France, Spain, and Australia, and is caused by the protozoan Trypanosoma cruzi. Dr. Carlos Chagas described Chagas disease in 1909 in Brazil, and hepatomegaly was among the clinical signs observed. Currently, hepatomegaly is cited in most papers published which either study acutely infected patients or experimental models, and we know that the parasite can infect multiple cell types in the liver, especially Kupffer cells and dendritic cells. Moreover, liver damage is more pronounced in cases of oral infection, which is mainly found in the Amazon region. However, the importance of liver involvement, including the hepatic immune response, in disease progression does not receive much attention. In this review, we present the very first paper published approaching the liver's participation in the infection, as well as subsequent papers published in the last century, up to and including our recently published results. We propose that, after infection, activated peripheral T lymphocytes reach the liver and induce a shift to a pro-inflammatory ambient environment. Thus, there is an immunological integration and cooperation between peripheral and hepatic immunity, contributing to disease control.

In Vivo and In Vitro Characterization of Primary Human Liver Macrophages and Their Inflammatory State

Liver macrophages (LMs) play a central role in acute and chronic liver pathologies. Investigation of these processes in humans as well as the development of diagnostic tools and new therapeutic strategies require in vitro models that closely resemble the in vivo situation. In our study, we sought to gain further insight into the role of LMs in different liver pathologies and into their characteristics after isolation from liver tissue. For this purpose, LMs were characterized in human liver tissue sections using immunohistochemistry and bioinformatic image analysis. Isolated cells were characterized in suspension using FACS analyses and in culture using immunofluorescence staining and laser scanning microscopy as well as functional assays. The majority of our investigated liver tissues were characterized by anti-inflammatory LMs which showed a homogeneous distribution and increased cell numbers in correlation with chronic liver injuries. In contrast, pro-inflammatory LMs appeared as temporary and locally restricted reactions. Detailed characterization of isolated macrophages revealed a complex disease dependent pattern of LMs consisting of pro- and anti-inflammatory macrophages of different origins, regulatory macrophages and monocytes. Our study showed that in most cases the macrophage pattern can be transferred in adherent cultures. The observed exceptions were restricted to LMs with pro-inflammatory characteristics.

Near-Infrared-II Nanoparticles for Cancer Imaging of Immune Checkpoint Programmed Death-Ligand 1 and Photodynamic/Immune Therapy

Development of second near-infrared (NIR-II) nanoparticles (NPs) with high biocompatibility, low toxicity, and high singlet oxygen quantum yield (Φ_Δ) to prevent tumor recurrence is highly desirable in molecular imaging and photodynamic/immune combination therapy. Here, theranostic photosensitizer BODIPY (BDP)-I-N-anti-PD-L1 NPs were developed by encapsulating the photosensitizer BDP-I-N with amphipathic poly(styrene-co-chloromethylstyrene)-graft-poly(ethylene glycol) nanocarriers through self-assembly functionalization with programmed cell death-ligand 1 (PD-L1) monoclonal antibody. These NPs exhibit highly intensive luminescence in the NIR-II window (1000-1700 nm) to real-time imaging of immune checkpoint PD-L1, high singlet oxygen quantum yield (Φ_Δ = 73%), and an eliminating effect of primary cancers. The NPs also allow for profiling PD-L1 expression as well as accumulating in MC38 tumor and enabling molecular imaging in vivo. Upon an 808 nm laser excitation, the targeted NPs produce an emission wavelength above 1200 nm to image a tumor to a normal tissue signal ratio (T/NT) at an approximate value of 14.1. Moreover, the MC38 tumors in mice are eliminated by combining photodynamic therapy and immunotherapy within 30 days, with no tumor recurrence within a period of 40 days. In addition, the tumors do not grow in the rechallenged mice within 7 days of inoculation. Such a strategy shows a durable immune memory effect against tumor rechallenging without toxic side effects to major organs.

The regulatory role of microRNA-mRNA co-expression in hepatitis B virus-associated acute liver failure

INTRODUCTION AND OBJECTIVES

Acute liver failure (ALF) is a dramatic disorder requiring intensive care. MicroRNAs (miRNAs) have been identified to play important roles in ALF. This study was performed to identify miRNA-mRNA co-expression network after ALF to investigate the molecule mechanism underlying the pathogenesis of ALF.

MATERIALS AND METHODS

The microarray dataset GSE62030 and GSE62029 were downloaded from Gene Expression Omnibus database. Overlapping differentially expressed miRNAs (DEmiRNAs) and genes (DEGs) were identified in liver tissues from patients with hepatitis B virus (HBV)-associated ALF in comparison with normal tissues from donors. Gene enrichment analysis was performed. Key pathways associated with the DEGs were identified. The miRNA-mRNA regulatory network was constructed.

RESULTS

Total 42 DEmiRNAs and 523 DEGs were identified in liver tissues from patients with HBV-associated ALF. Gene ontology and pathways enrichment analysis showed upregulated DEGs were related to immune responses, inflammation, and infection, and downregulated DEGs were associated with amino acids, secondary metabolites and xenobiotics metabolism. In miRNA-mRNA co-expression network, DEGs were regulated by at least one DEmiRNA and transcription factor. Further analysis showed DEmiRNAs, including has-miR-55-5p, has-miR-193b-5p, has-miR-200b-3p, and has-miR-3175 were associated with amino acid metabolism, drug metabolism and detoxication, and signaling pathways including mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/AKT, Ras, and Rap1.

CONCLUSIONS

These miRNA-mRNA pairs and changed profiles were associated with and might be responsible for the impairment of detoxification and metabolism induced by HBV-associated ALF.

Human Liver Macrophage Subsets Defined by CD32

Human liver myeloid cells are imperfectly defined, but it is broadly agreed that cells of stellate appearance in situ, expressing the markers CD11b and CD68, are the liver's resident macrophages, classically termed Kupffer cells. Recent investigations using single cell RNA sequencing and unsupervised clustering algorithms suggest there are two populations of cells with the characteristics of tissue macrophages in human liver. We therefore analyzed dissociated human liver tissue using the markers CD11b and CD68 to define macrophage-like cells and found within this population two subsets that differ in their expression of multiple surface markers. These subsets were FACS-sorted based on CD32 expression, and gene expression analysis identified them with human liver myeloid cell subsets that were previously defined by two independent single cell RNA sequencing studies. Using qRT-PCR we found that the two subsets differed in the expression of genes associated with T cell activation and immunosuppression, suggesting distinct roles in T cell tolerance. In addition, one subset expressed two markers, CD1C and CD11c, more often seen on classical dendritic cells. Criteria used to distinguish macrophages from dendritic cells in other tissues may need to be revised in the human liver.

The reduction in CD8+PD-1+ T cells in liver histological tissue is related to Pegylated IFN-α therapy outcomes in chronic hepatitis B patients

BACKGROUND

Antiviral therapy is recommended for patients with immune-active chronic hepatitis B (CHB) to decrease the risk of liver-related complications. However, the outcomes of the pegylated IFN-α (PEG-IFN-α) therapy vary among CHB patients. We aimed to identify factors that can influence the outcomes in CHB patients who received antiviral PEG-IFN-α monotherapy.

METHODS

Thirty-two CHB patients who received PEG-IFN-α monotherapy were enrolled in this study. All of the patients underwent two liver biopsies at baseline and 6 months after the initiation of the therapy. CD8⁺ T cells, CD4⁺ T cells, CD68⁺ mononuclear cells, and PD-1 levels in the 64 liver biopsy specimens were examined via immunofluorescence.

RESULTS

The overall median frequency of CD8⁺ T cells in the liver tissues of 32 CHB patients significantly decreased at 6 months after the therapy initiation (p < 0.01). In the FIER (fibrosis and inflammation response with HBeAg seroconversion) group, CD8⁺PD-1⁺ T cells significantly decreased at 6 months (p < 0.05), while CD8⁺PD-1^- T cells had no significant difference. On the contrary, in the FIENR (no fibrosis and inflammation response and HBeAg seroconversion) group, CD8⁺PD-1^- T cells significantly decreased after 6 months of PEG-IFN-α treatment (p < 0.05), while CD8⁺PD-1⁺ T cells had no significant difference. In addition, the levels of CD68⁺ mononuclear cells in the FIER group showed an overall increasing trend after treatment (p < 0.05).

CONCLUSIONS

The changes in the levels of CD8⁺PD-1⁺ T cells and CD68⁺ mononuclear cells may be related to the response to PEG-IFN-α therapy.

Pathogenetic Mechanisms of T Cell Dysfunction in Chronic HBV Infection and Related Therapeutic Approaches

A great effort of research has been devoted in the last few years to developing new anti-HBV therapies of finite duration that also provide effective sustained control of virus replication and antigen production. Among the potential therapeutic strategies, immune-modulation represents a promising option to cure HBV infection and the adaptive immune response is a rational target for novel therapeutic interventions, in consideration of the key role played by T cells in the control of virus infections. HBV-specific T cells are severely dysfunctional in chronic HBV infection as a result of several inhibitory mechanisms which are simultaneously active within the chronically inflamed liver. Indeed, the liver is a tolerogenic organ harboring different non-parenchymal cell populations which can serve as antigen presenting cells (APC) but are poorly efficient in effector T cell priming, with propensity to induce T cell tolerance rather than T cell activation, because of a poor expression of co-stimulatory molecules, up-regulation of the co-inhibitory ligands PD-L1 and PD-L2 upon IFN stimulation, and production of immune regulatory cytokines, such as IL10 and TGF-β. They include resident dendritic cells (DCs), comprising myeloid and plasmacytoid DCs, liver sinusoidal endothelial cells (LSECs), Kupffer cells (KCs), hepatic stellate cells (HSCs) as well as the hepatocytes themselves. Additional regulatory mechanisms which contribute to T cell attrition in the chronically infected liver are the high levels of soluble mediators, such as arginase, indoleamine 2,3-dioxygenase (IDO) and suppressive cytokines, the up-regulation of inhibitory checkpoint receptor/ligand pairs, the expansion of regulatory cells, such as CD4+FOXp3+ Treg cells, myeloid-derived suppressor cells and NK cells. This review will deal with the interactions between immune cells and liver environment discussing the different mechanisms which contribute to T cell dysfunction in chronic hepatitis B, some of which are specifically activated in HBV infection and others which are instead common to chronic inflammatory liver diseases in general. Therapeutic interventions targeting dysregulated pathways and cellular functions will be also delineated.

Immune-related adverse reactions in the hepatobiliary system: second-generation check-point inhibitors highlight diverse histological changes

AIMS

Immune check-point inhibitors are known to cause immune-mediated adverse liver injury, but our knowledge is mainly based on cases treated with ipilimumab or nivolumab.

METHODS AND RESULTS

Clinicopathological features of 10 patients with hepatobiliary adverse reactions caused by second-generation drugs, pembrolizumab (n = 6) and atezolizumab (n = 4), were reviewed. Liver dysfunction developed during a median period of 3.5 weeks after administration of the check-point inhibitor (3 days-1 year). Antinuclear antibodies were detected in two patients at a low titre (1/80), and serum IgG concentrations were also only mildly elevated in two patients. Liver biopsies showed panlobular hepatitis (n = 5), cholangiopathic changes (n = 2), granulomatous injury (n = 2) and bland cholestasis (n = 1). Two cases of cholangiopathy (both pembrolizumab-treated) showed diffuse sclerosing cholangitis on imaging, and one also presented lymphocytic cholangitis resembling primary biliary cholangitis on biopsy. In two atezolizumab-treated cases, Küpffer cells were hyperplastic and aggregated, forming microgranulomas. Confluent necrosis and eosinophilic or plasma cell infiltration were rare. On immunostaining, the ratio of CD8⁺ /CD4⁺ cells was 12.2 ± 5.1, which was significantly higher than that in autoimmune hepatitis (2.7 ± 1.1; P < 0.001) or idiosyncratic drug-induced liver injury (5.0 ± 1.1; P = 0.014). All patients responded to steroid therapy, but it was less effective in patients with sclerosing cholangitis.

CONCLUSIONS

Pembrolizumab and atezolizumab manifested not only lobular hepatitis but also sclerosing cholangitis, lymphocytic duct injury and granulomatous hepatitis, probably representing various impaired cellular functions in CD8⁺ lymphocytes and macrophages due to blockage of PD-1-PD-L1 interaction.

Definition of the Chemical and Immunological Signals Involved in Drug-Induced Liver Injury

Idiosyncratic drug-induced liver injury (iDILI), which is rare and often recognized only late in drug development, poses a major public health concern and impediment to drug development due to its high rate of morbidity and mortality. The mechanisms of DILI are not completely understood; both non-immune- and immune-mediated mechanisms have been proposed. Non-immune-mediated mechanisms including direct damage to hepatocytes, mitochondrial toxicity, interference with transporters, and alteration of bile ducts are well-known to be associated with drugs such as acetaminophen and diclofenac; whereas immune-mediated mechanisms involving activation of both adaptive and innate immune cells and the interactions of these cells with parenchymal cells have been proposed. The chemical signals involved in activation of both innate and adaptive immune responses are discussed with respect to recent scientific advances. In addition, the immunological signals including cytokine and chemokines that are involved in promoting liver injury are also reviewed. Finally, we discuss how liver tolerance and regeneration can have profound impact on the pathogenesis of iDILI. Continuous research in developing in vitro systems incorporating immune cells with liver cells and animal models with impaired liver tolerance will provide an opportunity for improved prediction and prevention of immune-mediated iDILI.

Functional aspects, phenotypic heterogeneity, and tissue immune response of macrophages in infectious diseases

Macrophages are a functionally heterogeneous group of cells with specialized functions depending not only on their subgroup but also on the function of the organ or tissue in which the cells are located. The concept of macrophage phenotypic heterogeneity has been investigated since the 1980s, and more recent studies have identified a diverse spectrum of phenotypic subpopulations. Several types of macrophages play a central role in the response to infectious agents and, along with other components of the immune system, determine the clinical outcome of major infectious diseases. Here, we review the functions of various macrophage phenotypic subpopulations, the concept of macrophage polarization, and the influence of these cells on the evolution of infections. In addition, we emphasize their role in the immune response in vivo and in situ, as well as the molecular effectors and signaling mechanisms used by these cells. Furthermore, we highlight the mechanisms of immune evasion triggered by infectious agents to counter the actions of macrophages and their consequences. Our aim here is to provide an overview of the role of macrophages in the pathogenesis of critical transmissible diseases and discuss how elucidation of this relationship could enhance our understanding of the host-pathogen association in organ-specific immune responses.

Recent Findings in the Regulation of Programmed Death Ligand 1 Expression

With the recent approvals for the application of monoclonal antibodies that target the well-characterized immune checkpoints, immune therapy shows great potential against both solid and hematologic tumors. The use of these therapeutic monoclonal antibodies elicits inspiring clinical results with durable objective responses and improvements in overall survival. Agents targeting programmed cell death protein 1 (PD-1; also known as PDCD1) and its ligand (PD-L1) achieve a great success in immune checkpoints therapy. However, the majority of patients fail to respond to PD-1/PD-L1 axis inhibitors. Expression of PD-L1 on the membrane of tumor and immune cells has been shown to be associated with enhanced objective response rates to PD-1/PD-L1 inhibition. Thus, an improved understanding of how PD-L1 expression is regulated will enable us to better define its role as a predictive marker. In this review, we summarize recent findings in the regulation of PD-L1 expression.

Chronic Hepatitis C Virus Infection Impairs M1 Macrophage Differentiation and Contributes to CD8+ T-Cell Dysfunction

Chronic hepatitis C virus (HCV) infection causes generalized CD8+ T cell impairment, not limited to HCV-specific CD8+ T-cells. Liver-infiltrating monocyte-derived macrophages (MDMs) contribute to the local micro-environment and can interact with and influence cells routinely trafficking through the liver, including CD8+ T-cells. MDMs can be polarized into M1 (classically activated) and M2a, M2b, and M2c (alternatively activated) phenotypes that perform pro- and anti-inflammatory functions, respectively. The impact of chronic HCV infection on MDM subset functions is not known. Our results show that M1 cells generated from chronic HCV patients acquire M2 characteristics, such as increased CD86 expression and IL-10 secretion, compared to uninfected controls. In contrast, M2 subsets from HCV-infected individuals acquired M1-like features by secreting more IL-12 and IFN-γ. The severity of liver disease was also associated with altered macrophage subset differentiation. In co-cultures with autologous CD8+ T-cells from controls, M1 macrophages alone significantly increased CD8+ T cell IFN-γ expression in a cytokine-independent and cell-contact-dependent manner. However, M1 macrophages from HCV-infected individuals significantly decreased IFN-γ expression in CD8+ T-cells. Therefore, altered M1 macrophage differentiation in chronic HCV infection may contribute to observed CD8+ T-cell dysfunction. Understanding the immunological perturbations in chronic HCV infection will lead to the identification of therapeutic targets to restore immune function in HCV+ individuals, and aid in the mitigation of associated negative clinical outcomes.

Exosomes in the serum of Acute Myeloid Leukemia patients induce dendritic cell tolerance: Implications for immunotherapy

Exosomes may represent an interesting antigenic pulse for new forms of anti-tumor immunotherapy. We evaluated exosomes from serum of patients with acute myeloid leukemia (AML) as an antigenic source for dendritic cells (DC) and the effects upon antitumor cytotoxicity, assessed by the percentage of specific lysis of K562 leukemic cells in co-cultures. Surprisingly, incubation of exosomes with DCs decreased lysis of K562, which may correspond to a mechanism of tumor evasion in vivo. However, when immature DCs were pulsed with exosomes purified from K562 culture supernatants, the lysis of target cells was notably enhanced, associated with a substantial increase in the expression of the maturation marker CD83. Thus, the development of vaccines using patients' exosomes would probably add no benefits to the treatment of AML; alternately, exosomes from cultured cells may represent an effective way for maturing DCs into a cytotoxic phenotype, without the immunosuppression observed with patients' exosomes.

The immunological function of extracellular vesicles in hepatitis B virus-infected hepatocytes

Hepatitis B virus (HBV) generates large amounts of complete and incomplete viral particles. Except for the virion, which acts as infectious particles, the function of those particles remains elusive. Extracellular vesicles (EVs) have been revealed to have biological functions. The EVs which size are less than 100 nm in diameter, were collected from HBV infected-patients. These vesicles contain, complete and incomplete virions, and exosomes, which have been recently shown to be critical as intercellular communicators. Here, the effects of the exosome, the complete, and the incomplete particles on the target cells were investigated. These particles are endocytosed by monocyte/macrophages and function primarily to upregulate PD-L1. The functions and composition of the EVs were affected by nucleotide reverse transcriptase inhibitors (NRTIs), suggesting that the EVs are involved in the pathogenesis of HBV hepatitis and clinical course of those patients treated by NRTIs.

Liver macrophages: Friend or foe during hepatitis B infection?

The Hepatitis B virus chronically infects the liver of 250 million people worldwide. Over the past decades, major advances have been made in the understanding of Hepatitis B virus life cycle in hepatocytes. Beside these parenchymal cells, the liver also contains resident and infiltrating myeloid cells involved in immune responses to pathogens and much less is known about their interplay with Hepatitis B virus. In this review, we summarized and discussed the current knowledge of the role of liver macrophages (including Kupffer cells and liver monocyte-derived macrophages), in HBV infection. While it is still unclear if liver macrophages play a role in the establishment and persistence of HBV infection, several studies disclosed data suggesting that HBV would favour liver macrophage anti-inflammatory phenotypes and thereby increase liver tolerance. In addition, alternatively activated liver macrophages might also play in the long term a key role in hepatitis B-associated pathogenesis, especially through the activation of hepatic stellate cells. Therapies aiming at a transient activation of pro-inflammatory liver macrophages should therefore be considered for the treatment of chronic HBV infection.

CD80 Regulates Th17 Cell Differentiation in Coxsackie Virus B3-Induced Acute Myocarditis

The cluster of differentiation protein complex, CD80/CD86, regulates Th1/Th2 differentiation in autoimmune disease. In order to establish the effects of CD80/CD86 on Th17 cell differentiation in acute viral myocarditis (VMC), we infected C57BL/6 mice with Coxsackie virus B3 (CVB3) and examined the effects of the treatment with anti-CD80/CD86 monoclonal antibodies (mAbs) on Th17 cell differentiation in vivo. The effects of anti-CD80/CD86 mAbs on Th17 cell differentiation were further evaluated in vitro. The treatment with anti-CD80 mAb induced marked suppression of Th17 cell differentiation and ROR-γt mRNA expression, whereas anti-CD86 mAb alone had no effect, both in vivo and in vitro. Our finding that CD80 regulates Th17 differentiation supports the potential utility of anti-CD80 mAb as an effective new immunotherapeutic target in acute VMC.

CD86 Expression by Monocytes Influences an Immunomodulatory Profile in Asymptomatic Patients with Chronic Chagas Disease

In the chronic phase of Chagas disease, 60% of the patients develop the asymptomatic form known as indeterminate (IND). The remaining 30% of the patients develop a life-threatening form in which digestive and/or cardiac (CARD) alterations take place. The mechanisms underlying the development of severe forms of Chagas disease remain poorly understood. It is well known that interactions between immune cells such as monocytes and lymphocytes drive immune responses. Further, the co-stimulatory molecules CD80 and CD86 expressed by monocytes and subsets induce lymphocyte activation, thereby triggering cellular immune response. Here, we revealed, for the first time, the functional-phenotypic profile of monocytes subsets in Chagas disease. Using flow cytometry, we evaluated the effect of in vitro stimulation with Trypanosoma cruzi antigens on the expression of the co-stimulatory molecules CD80 and CD86 in different monocyte subsets of patients with IND and CARD clinical forms of Chagas disease. We also assessed the expression of toll-like receptor (TLR)-2, TLR-4, TLR-9, HLA-DR, IL-10, and IL-12 in the monocyte subsets and of CTLA-4 and CD28, ligands of CD80 and CD86, in T lymphocytes. CD86 expression in all monocyte subsets was higher in IND patients when compared with non-infected (NI) individuals. After stimulation with T. cruzi, these patients also showed a higher frequency of CD4⁺CTLA-4⁺ T lymphocytes than NI individuals. We found an association between CD80 and CD28, and between CD86 and CTLA-4 expression, with a high frequency of regulatory T (Treg) cells in IND patients. We proposed that CD86 may be involved in immunoregulation by its association with CTLA-4 in asymptomatic patients. CD86 and CTLA-4 interaction may influence Treg activation, and this could represent a new strategy to control inflammation and tissue damage.

Clinical Significance of Dynamics of Programmed Death Ligand-1 Expression on Circulating CD14+ Monocytes and CD19+ B Cells with the Progression of Hepatitis B Virus Infection

Programmed death-1 (PD-1) expression has been revealed to be upregulated on T cells and contributes to T cell exhaustion in patients with hepatitis B virus (HBV) infection. In this study, we investigated the dynamic expression of programmed death ligand-1 (PD-L1), the ligand of PD-1, on circulating CD14⁺ monocytes and CD19⁺ B cells of HBV-infected patients at the stages of chronic HBV (CHB) infection, liver cirrhosis (LC), and hepatocellular carcinoma (HCC), respectively. The results showed that compared with healthy controls, the levels of PD-L1 expression on CD14⁺ and CD19⁺ populations were both upregulated in CHB, LC, and HCC groups. Although there was no significant difference of PD-L1 expression on CD14⁺ population among three disease groups, further analysis demonstrated that the frequency of CD14⁺PD-L1⁺ population was negatively correlated with HBV DNA load, the levels of alanine aminotransaminase (ALT), and the levels of aspartate aminotransferase (AST), respectively, at CHB stage, while it did not present significant correlation with such parameters at LC stage and was only positively correlated with HBV DNA load at HCC stage. Similarly, the levels of PD-L1 expression on CD19⁺ population also did not present much difference among three disease groups. Intriguingly, the frequencies of CD19⁺PD-L1⁺ population at CHB and LCC stages were both positively correlated with the levels of ALT and AST, but they were not significantly correlated with HBV DNA load. Thereby, the current study elucidated the dynamics of PD-L1 expression on monocytes and B cells, along with the dynamic regulation of PD-1 on T cells, which had a close relationship during the progression of HBV infection. Collectively, our findings demonstrated that in the course of HBV infection development, PD-L1 expression on CD14⁺ monocytes and CD19⁺ B cells varied and significantly correlated with clinical parameters, which could be utilized as a potential clinical indicator.