Tim-4 Inhibits NO Generation by Murine Macrophages

Macrophages and tertiary lymphoid structures as indicators of prognosis and therapeutic response in cancer patients

Tertiary lymphoid structures (TLS) can reflect cancer prognosis and clinical outcomes in various tumour tissues. Tumour-associated macrophages (TAMs) are indispensable components of the tumour microenvironment and play crucial roles in tumour development and immunotherapy. TAMs are associated with TLS induction via the modulation of the T cell response, which is a major component of the TLS. Despite their important roles in cancer immunology, the subtypes of TAMs that influence TLS and their correlation with prognosis are not completely understood. Here, we provide novel insights into the role of TAMs in regulating TLS formation. Furthermore, we discuss the prognostic value of these TAM subtypes and TLS, as well as the current antitumour therapies for inducing TLS. This study highlights an entirely new field of TLS regulation that may lead to the development of an innovative perspective on immunotherapy for cancer treatment.

Inflammatory Cell Dynamics after Murine Femoral Artery Wire Injury: A Multi-Parameter Flow Cytometry-Based Analysis

An acute inflammatory response following arterial surgery for atherosclerosis, such as balloon angioplasty, stenting, and surgical bypass, is an important driver of neointimal hyperplasia after arterial injury, which leads to recurrent ischemia. However, a comprehensive understanding of the dynamics of the inflammatory infiltrate in the remodeling artery is difficult to attain due to the shortcomings of conventional methods such as immunofluorescence. We developed a 15-parameter flow cytometry method to quantitate leukocytes and 13 leukocyte subtypes in murine arteries at 4 time points after femoral artery wire injury. Live leukocyte numbers peaked at 7 days, which preceded the peak neointimal hyperplasia lesion at 28 days. Neutrophils were the most abundant early infiltrate, followed by monocytes and macrophages. Eosinophils were elevated after 1 day, while natural killer and dendritic cells gradually infiltrated over the first 7 days; all decreased between 7 and 14 days. Lymphocytes began accumulating at 3 days and peaked at 7 days. Immunofluorescence of arterial sections demonstrated similar temporal trends of CD45+ and F4/80+ cells. This method allows for the simultaneous quantitation of multiple leukocyte subtypes from small tissue samples of injured murine arteries and identifies the CD64+Tim4+ macrophage phenotype as being potentially important in the first 7 days post-injury.

T-cell immunoglobulin- and mucin-domain-containing molecule-4 maintains adipose tissue homeostasis by orchestrating M2 macrophage polarization via nuclear factor kappa B pathway

Obesity is generally associated with low-grade inflammation. Adipose tissue macrophages (ATMs) orchestrate metabolic inflammation. The classical (M1-like) or alternative (M2-like) activation of ATMs is functionally coupled with the metabolic status of fat tissues. It has been found that T-cell immunoglobulin- and mucin-domain-containing molecule-4 (Tim-4) inhibits inflammation by regulating macrophages. However, the exact role of Tim-4 in macrophage polarization and obesity remains unknown. Here, we identified Tim-4 as a critical switch governing macrophage M1/M2 polarization and energy homeostasis. Tim-4 deletion led to spontaneous obesity in elder mice and promoted obesity severity of db/db mice. Obesity microenvironment enhanced the expression of Tim-4 in white adipose tissue and ATMs. In vitro, we detected an increase in M1-like cells and decrease in M2-like cells in both peritoneal macrophages and bone marrow-derived macrophages from Tim-4 knockout mice. Mechanistically, we demonstrated that Tim-4 promoted M2-like macrophages polarization via suppressing nuclear factor kappa B (NF-κB) signaling pathway. In addition, we found that Tim-4 promoted TLR4 internalization, which might contribute to regulation of NF-κB signaling. Collectively, these results indicated that Tim-4 maintained adipose tissue homeostasis by regulating macrophage polarization via NF-κB pathway, which would provide a new target for obesity intervention.

Novel Roles of the Tim Family in Immune Regulation and Autoimmune Diseases

T cell Ig and mucin domain (Tim) protein family members were identified to be important regulators of the immune response. As their name indicates, Tim proteins were originally considered a T cell-specific markers, and they mainly regulate the responses of T helper cells. However, accumulating evidence indicates that Tims are also expressed on antigen-presenting cells (APCs), such as monocytes, macrophages, dendritic cells (DCs) and B cells, and even plays various roles in natural killer cells (NKs) and mast cells. In recent years, the expression and function of Tims on different cells and the identification of new ligands for the Tim family have suggested that the Tim family plays a crucial role in immune regulation. In addition, the relationship between Tim family gene polymorphisms and susceptibility to several autoimmune diseases has expanded our knowledge of the role of Tim proteins in immune regulation. In this review, we discuss how the Tim family affects immunomodulatory function and the potential role of the Tim family in typical autoimmune diseases, including multiple sclerosis (MS), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and type 1 diabetes (T1D). A deeper understanding of the immunoregulatory mechanism of the Tim family might provide new insights into the clinical diagnosis and treatment of autoimmune diseases.

T-Cell Immunoglobulin and Mucin Domain-Containing Protein-4 Is Critical for Kupffer Cell Homeostatic Function in the Activation and Resolution of Liver Ischemia Reperfusion Injury

BACKGROUND AND AIMS

Liver ischemia reperfusion injury (IRI) remains an unresolved clinical problem. This study dissected roles of liver-resident macrophage Kupffer cells (KCs), with a functional focus on efferocytosis receptor T-cell immunoglobulin and mucin domain-containing protein-4 (TIM-4), in both the activation and resolution of IRI in a murine liver partial warm ischemia model.

APPROACH AND RESULTS

Fluorescence-activated cell sorting results showed that TIM-4 was expressed exclusively by KCs, but not infiltrating macrophages (iMФs), in IR livers. Anti-TIM-4 antibody depleted TIM-4⁺ macrophages in vivo, resulting in either alleviation or deterioration of liver IRI, which was determined by the repopulation kinetics of the KC niche with CD11b⁺ macrophages. To determine the KC-specific function of TIM-4, we reconstituted clodronate-liposome-treated mice with exogenous wild-type or TIM-4-deficient KCs at either 0 hour or 24 hours postreperfusion. TIM-4 deficiency in KCs resulted in not only increases in the severity of liver IRI (at 6 hours postreperfusion), but also impairment of the inflammation resolution (at 7 days postreperfusion). In vitro analysis revealed that TIM-4 promoted KC efferocytosis to regulate their Toll-like receptor response by up-regulating IL-10 and down-regulating TNF-α productions.

CONCLUSIONS

TIM-4 is critical for KC homeostatic function in both the activation and resolution of liver IRI by efferocytosis.

Management of cell death in parasitic infections

For a long time, host cell death during parasitic infection has been considered a reflection of tissue damage, and often associated with disease pathogenesis. However, during their evolution, protozoan and helminth parasites have developed strategies to interfere with cell death so as to spread and survive in the infected host, thereby ascribing a more intriguing role to infection-associated cell death. In this review, we examine the mechanisms used by intracellular and extracellular parasites to respectively inhibit or trigger programmed cell death. We further dissect the role of the prototypical “eat-me signal” phosphatidylserine (PtdSer) which, by being exposed on the cell surface of damaged host cells as well as on some viable parasites via a process of apoptotic mimicry, leads to their recognition and up-take by the neighboring phagocytes. Although barely dissected so far, the engagement of different PtdSer receptors on macrophages, by shaping the host immune response, affects the overall infection outcome in models of both protozoan and helminth infections. In this scenario, further understanding of the molecular and cellular regulation of the PtdSer exposing cell-macrophage interaction might allow the identification of new therapeutic targets for the management of parasitic infection.

Tim-4 in Health and Disease: Friend or Foe?

T-cell immunoglobulin and mucin domain containing 4 (Tim-4) is a phosphatidylserine receptor and is selectively expressed on antigen presenting cells. Recently, Tim-4 was reported to be expressed on iNKT cells, B1 cells, and tumor cells, suggesting it has multiple biological functions. In this review, we mainly summarize the expression and regulation of Tim-4 in immune cells including T cells, macrophages, dendritic cells, NKT cells, B cells, and mast cells. The expression of Tim-4 in these cells implies that Tim-4 might participate in immune related diseases. Emerging evidence emphasizes a substantial role for Tim-4 in maintaining homeostasis by regulating various immune responses, including viral infection, allergy, autoimmunity, and tumor immunity. Here, we collectively evaluated the role of Tim-4 in health and diseases. This summary will be extremely useful to fully understand the function of Tim-4 in the pathogenesis of immune related diseases, which would provide novel clues for the diagnosis and treatment of diseases.

IL-6 promotes metastasis of non-small-cell lung cancer by up-regulating TIM-4 via NF-κB

OBJECTIVES

Interleukin-6 (IL-6) is critical for the development of non-small-cell lung cancer (NSCLC). Recently, we identified T-cell immunoglobulin domain and mucin domain 4 (TIM-4) as a new pro-growth player in NSCLC progression. However, the role of TIM-4 in IL-6-promoted NSCLC migration, invasion and epithelial-to-mesenchymal transition (EMT) remains unclear.

MATERIALS AND METHODS

Expressions of TIM-4 and IL-6 were both evaluated by immunohistochemical staining in NSCLC tissues. Real-time quantitative PCR (qPCR), Western blot, flow cytometry and RT-PCR were performed to detect TIM-4 expression in NSCLC cells with IL-6 stimulation. The roles of TIM-4 in IL-6 promoting migration and invasion of NSCLC were detected by transwell assay. EMT-related markers were analysed by qPCR and Western blot in vitro, and metastasis was evaluated in BALB/c nude mice using lung cancer metastasis mouse model in vivo.

RESULTS

High IL-6 expression was identified as an independent predictive factor for TIM-4 expression in NSCLC tissues. NSCLC patients with TIM-4 and IL-6 double high expression showed the worst prognosis. IL-6 promoted TIM-4 expression in NSCLC cells depending on NF-κB signal pathway. Both TIM-4 and IL-6 promoted migration, invasion and EMT of NSCLC cells. Interestingly, TIM-4 knockdown reversed the role of IL-6 in NSCLC and IL-6 promoted metastasis of NSCLC by up-regulating TIM-4 via NF-κB.

CONCLUSIONS

TIM-4 involves in IL-6 promoted migration, invasion and EMT of NSCLC.

Association of Tim-4 expression in monocyte subtypes with clinical course and prognosis in acute ischemic stroke patients

Background: It has been proven that T cell immunoglobin and mucin domain (Tim)-4 and monocytes (Mo) are involved in regulation of immunity, which is important for the recovery of acute ischemic stroke (AIS).Methods: In this study, the expression of Tim-4 in both circulating Mo subtypes and plasma in 32 consecutive AIS patients and 32 control patients was assessed to determine their correlation with the clinical course and prognosis of AIS.Results: It was found that, compared to the control patients, the percentage of Tim-4 expression in overall Mo, classical Mo and non-classical Mo was significantly elevated after 2 and 5 days of stroke (p < 0.05), while it was promoted from 0 to 10 days of stoke in intermediate Mo (p < 0.05). Furthermore, Tim-4 expressions in non-classical Mo and intermediate Mo were obviously correlated with National Institutes of Health Stroke Scale (NIHSS) scores at 2 days of stroke (r = 0.351, p = 0.048; r = 0.358, p = 0.044, respectively). In poor outcome (PO) patients, the expression of Tim-4 in non-classical Mo was remarkably promoted at 2 days of stroke in comparison with non-PO patients (p < 0.05). More importantly, our results revealed a positive correlation between Tim-4 expression in non-classical Mo and interleukin (IL)-6 plasma levels in AIS patients without infection.Conclusion: In summary, our findings proved that Tim-4 expression in non-classical Mo could be an appropriate target for the prediction of the clinical course and prognosis in AIS patients.

Natural Inhibitors on Over-Activation of Microglia from Herbals

Neuroinflammation manifested by over-activation of microglial cells plays an essential role in neurodegenerative diseases. Short-term activation of microglia can be beneficial, but chronically activated microglia can aggravate neuronal dysfunction possibly by secreting potentially cytotoxic substances such as tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO), which can result in dysfunction and death of neurons. Therefore inhibiting over-activation of microglia and the production of cytotoxic intermediates may become an effective therapeutic approach for neuroinflammation. In this paper, we review our continuous research on natural inhibitors of over-activated microglia from traditional herbals, including flavonoids, lignans, sesquiterpene coumarins, and stilbenes.

Hepatic Ischemic Preconditioning Alleviates Ischemia-Reperfusion Injury by Decreasing TIM4 Expression

Ischemia-reperfusion injury (IRI) of the liver is a primary cause of post-liver-surgery complications and ischemic preconditioning (IPC) has been verified to protect against ischemia-reperfusion injury. TIM-4 activation plays an important role in macrophage mediated hepatic IRI. This study aimed to determine whether IPC protects against hepatic IRI through inhibiting TIM-4 activation. In this study, a model of warm liver ischemia (90 min) and reperfusion for 6 h was used. Mice were subjected to ischemia-reperfusion injury with or without ischemic preconditioning and TIM4 blocking antibody. Western blot was determined to detect the expression of TIM4 protein and mitochondrial apoptosis-related protein expression. Liver function was evaluated using the level of alanine transaminase (ALT) and aspartate transaminase (AST), cell apoptosis and pathological examination. We found that compared with the control group, ischemic preconditioning reduced IRI by decreasing hepatocyte apoptosis, ALT, AST, CD68 and CD3 positive cells, tissue myeloperoxidase activity(MPO), and downregulating TIM-4 expression. TIM4 blocking could reduce CD68 and CD3 positive cells in liver. Furthermore, activated monocytes transfusion significantly abolished the protect effect of IPC with increased hepatocyte apoptosis, ALT, AST, CD68 and CD3 positive cells while TIM-4 knockdown monocytes lost this effect. These results suggested that IPC protects against hepatic IRI by downregulating TIM-4 and indicated TIM-4 would be a novel therapeutic target to minimize IRI.

Tim-4 protects mice against lipopolysaccharide-induced endotoxic shock by suppressing the NF-κB signaling pathway

Endotoxic shock is the primary cause of morbidity and mortality in hospital patients, creating an urgent need to explore the mechanisms involved in sepsis. Our previous studies showed that T-cell immunoglobulin- and mucin-domain-containing molecule-4 (Tim-4) attenuated the inflammatory response through regulating the functions of macrophages. However, the mechanism by which Tim-4 does this has not been fully elucidated. In this study, we found that Tim-4 expression was increased in lipopolysaccharide (LPS)-induced endotoxic shock. Interestingly, the survival rate of mice in the Tim-4 overexpression group was higher than that of the control group after LPS administration. To investigate the function of Tim-4 in LPS-induced inflammation, we further demonstrated that Tim-4 attenuated LPS-induced endotoxic shock by inhibiting cytokine production by macrophages. Blocking expression of Tim-4 and nuclear factor-kappa B (NF-κB) signal inhibition showed that Tim-4 inhibited cytokine production via NF-κB signaling pathway. This study indicates that Tim-4 may exert its immune modulation by regulating inflammatory factor secretion and might act as a novel potential target for inflammatory diseases, especially endotoxic shock.

Stauntoside B inhibits macrophage activation by inhibiting NF-κB and ERK MAPK signalling

Inflammation is a defensive reaction of body to resist foreign invasion. However, it has been demonstrated that excessive and continuous inflammatory responses contribute to various inflammatory diseases, including rheumatoid arthritis. Nuclear factor-κB (NF-κB) regulates the expression of an array of inflammatory mediators, cytokines and chemokine genes in activated macrophages. Therefore, NF-κB has become an attractive drug target for controlling inflammation. In this study, stauntoside B, a C21 steroidal glycosides compound isolated from a Chinese medicine Cynanchi Stauntonii, was for the first time found to suppress macrophage activation induced by lipopolysaccharide (LPS) in RAW264.7 cells and rat primary peritoneal macrophages and could be a potent NF-κB inhibitor. The results showed that stauntoside B significantly reduced the release of inflammatory mediators in activated RAW264.7 cells and rat peritoneal macrophages, including nitric oxide (NO) and prostaglandin E2 (PGE2). The mRNA expressions of pro-inflammatory mediators and cytokines, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), microsomal prostaglandin synthetase-1 (mPGES-1), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and monocyte chemoattractant protein-1 (MCP-1) as well as the production of TNF-α and IL-6 were also inhibited by stauntoside B. Mechanistic investigation implies that the anti-inflammatory activity of stauntoside B could result from the suppression of LPS-induced IKKα/β activation, IκBα phosphorylation, p65 (ser536) NF-κB phosphorylation, and ERK MAPK activation by stauntoside B treatment in activated macrophages. Meanwhile, stauntoside B could induce apoptosis in LPS-activated macrophages. The current study suggests stauntoside B being a valuable candidate drug for the treatment of inflammatory diseases, especially for NF-κB activation associated inflammatory diseases.

TIM-4 promotes the growth of non-small-cell lung cancer in a RGD motif-dependent manner

BACKGROUND

T-cell immunoglobulin domain and mucin domain 4 (TIM-4) is exclusively expressed in antigen-presenting cells and involved in immune regulation. However, the role of TIM-4 expressed in tumour cells remains completely unknown.

METHODS

Immunohistochemistry staining was used to examine TIM-4 or Ki-67 expression in tumour tissues. Real-time PCR or RT-PCR was performed to detect TIM-4 mRNA expression. Lung cancer cell growth and proliferation were conducted by CCK-8 assay and EdU staining. Cell cycle progression was analysed by flow cytometry. The PCNA and cell cycle-related proteins were verified by western blot. Co-IP assay was used to identify the interaction of TIM-4 and integrin αvβ3. The efficacy of TIM-4 in vivo was evaluated using xenograft tumour model.

RESULTS

The expression of TIM-4 in non-small-cell lung cancer (NSCLC) tissues was significantly higher than that of the adjacent tissues. Enhanced TIM-4 expression was negatively correlated with histological differentiation of lung carcinoma and lifespan of patients. Overexpression of TIM-4 promoted lung cancer cell growth and proliferation, and upregulated the expression of PCNA, cyclin A, cyclin B1 and cyclin D1, accompanied by accumulation of lung cancer cells in S phase. Interestingly, Arg-Gly-Asp (RGD) motif mutation abolished the effect of TIM-4 on lung cancer cells, which was further verified by tumour xenografts in mice. Furthermore, we found that TIM-4 interacted with αvβ3 integrin through RGD motif.

CONCLUSIONS

This finding suggests that TIM-4 might be a potential biomarker for NSCLC that promotes lung cancer progression by RGD motif.