TIPE2 protein negatively regulates HBV-specific CD8+ T lymphocyte functions in humans

TIPE2: A Candidate for Targeting Antitumor Immunotherapy

TNF-α-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a recently discovered negative regulator of innate and adaptive immunity. TIPE2 is expressed in a wide range of tissues, both immune and nonimmune, and is implicated in the maintenance of immune homeostasis within the immune system. Furthermore, TIPE2 has been shown to play a pivotal role in the regulation of inflammation and the development of tumor. This review focuses on the structural characteristics, expression patterns, and functional roles of TIPE proteins, with a particular emphasis on the role and underlying mechanisms of TIPE2 in immune regulation and its involvement in different diseases. However, the current body of evidence is still limited in providing a comprehensive understanding of the complex role of TIPE2 in the human body, warranting further investigation to elucidate the possible mechanisms and functions of TIPE2 in diverse disease contexts.

TIPE2 deficiency prolongs mouse heart allograft survival by inhibiting immature DCs-induced Treg generation

It has been reported that deletion of tumor necrosis factor-α-induced protein-8 like 2 (TNFAIP8L2, TIPE2) facilitates the activation of T-cell receptors. However, the role of TIPE2 in T-cell-mediated acute transplant rejection remains unclear. To illustrate the underlying cellular mechanisms, we transplanted BALB/c hearts into C57BL/6 wild-type C57BL/6 mice or mice deficient for TIPE2 (TIPE2^-/-) and found that TIPE2^-/- recipient mice showed significantly prolonged survival of heart allografts and suppressed maturation of CD11c⁺ dendritic cells (DCs), which largely abolished the activation and proliferation of alloreactive T cells and their cytotoxic activity. TIPE2^-/- DCs increased CD4⁺Foxp3⁺CD127^- Treg generation, likely by inhibiting DCs maturation and CD80 and CD86 expression. Administration of anti-CD25 abolished the allograft survival induced by TIPE2 deficiency. Moreover, TIPE2 deficiency increased IL-10 production in T cells and in recipient serum and allografts. Mechanistic studies revealed that TIPE2^-/- restrained the maturation of DCs via inhibition of PI3K/AKT phosphorylation during alloantigen stimulation. Taken together, TIPE2 deficiency in recipient mice inhibited acute rejection by increasing Tregs generated by immature DCs. Thus, TIPE2 could be a therapeutic target for suppressing rejection in organ transplantation.

Microbial Metabolite 3-Indolepropionic Acid Mediates Immunosuppression

The microbial-derived metabolite, 3-indolepropionic acid (3-IPA), has been intensely studied since its origins were discovered in 2009; however, 3-IPA's role in immunosuppression has had limited attention. Untargeted metabolomic analyses of T-cell exhaustion and immunosuppression, represented by dysfunctional under-responsive CD8⁺ T cells, reveal a potential role of 3-IPA in these responses. T-cell exhaustion was examined via infection of two genetically related mouse strains, DBA/1J and DBA/2J, with lymphocytic choriomeningitis virus (LCMV) Clone 13 (Cl13). The different mouse strains produced disparate outcomes driven by their T-cell responses. Infected DBA/2J presented with exhausted T cells and persistent infection, and DBA/1J mice died one week after infection from cytotoxic T lymphocytes (CTLs)-mediated pulmonary failure. Metabolomics revealed over 70 metabolites were altered between the DBA/1J and DBA/2J models over the course of the infection, most of them in mice with a fatal outcome. Cognitive-driven prioritization combined with statistical significance and fold change were used to prioritize the metabolites. 3-IPA, a tryptophan-derived metabolite, was identified as a high-priority candidate for testing. To test its activity 3-IPA was added to the drinking water of the mouse models during LCMV Cl13 infection, with the results showing that 3-IPA allowed the mice to survive longer. This negative immune-modulation effect might be of interest for the modulation of CTL responses in events such as autoimmune diseases, type I diabetes or even COVID-19. Moreover, 3-IPA's bacterial origin raises the possibility of targeting the microbiome to enhance CTL responses in diseases such as cancer and chronic infection.

TIPE2 is a checkpoint of natural killer cell maturation and antitumor immunity

The maturation process of NK cells determines their functionality during which IL-15 plays a critical role. However, very few checkpoints specifically targeting this process have been discovered. Here, we report that TIPE2 expression gradually increased during NK cell ontogenesis correlating to their maturation stages in both mice and humans. NK-specific TIPE2 deficiency increased mature NK cells in mice, and these TIPE2-deficient NK cells exhibited enhanced activation, cytotoxicity, and IFN-γ production upon stimulation and enhanced response to IL-15 for maturation. Moreover, TIPE2 suppressed IL-15–triggered mTOR activity in both human and murine NK cells. Consequently, blocking mTOR constrained the effect of TIPE2 deficiency on NK cell maturation in response to IL-15. Last, NK-specific TIPE2-deficient mice were resistant to tumor growth in vivo. Our results uncover a potent checkpoint in NK cell maturation and antitumor immunity in both mice and humans, suggesting a promising approach of targeting TIPE2 for NK cell–based immunotherapies.

Microarray gene expression profiling provides insights into functions of TIPE2 in HBV-related apoptosis

Tumor necrosis factor-α-induced protein-8 like-2 (TNFAIP8L2, TIPE2), a member of TNFAIP8 family, functions as a regulator in inflammation. Our previous studies showed that TIPE2 can negatively regulate HBV-specific CD8⁺ T lymphocyte functions. But the effect of TIPE2 on the apoptosis of HBV-infected hepatocytes which is very important for eliminating viruses remains unclear. Using gene expression microarray analysis, we find that TIPE2 deficiency can regulate the expression of apoptotic genes in liver tissues from HBV hydrodynamic injection (HI) mouse model. TIPE2 protein was detected in TUNEL staining positive hepatocytes in HBV-infected C57 mice. Interestingly, the TIPE2 expressed hepatocytes were just the HBV infected cells. Furthermore, TIPE2 upregulates the mRNA levels of FasL, Bim and TNFRsF1b which promote cells death, when TIPE2 was transfected into HepG2 cells in vitro. As a result, TIPE2 overexpression cells showed a higher number of apoptotic cells and increased level of cleavage caspase3 compared to controls. Those results indicate that TIPE2 participates in HBV infection by regulating apoptosis of virus-infected hepatocytes.

Expression of TIPE family members in human colorectal cancer

The tumor necrosis factor α-induced protein 8 (TNFAIP8)-like (TIPE) protein family comprises four members, namely TNFAIP8, TIPE1, TIPE2 and TIPE3, which are involved in multiple processes in cancer. The current study aimed to investigate the expression patterns and potential clinical roles of the TIPE family members in human colorectal cancer (CRC). Paired tumor and adjacent tissue samples were collected from 49 patients with CRC, and the relative mRNA expression levels of the TIPE family members in these samples were evaluated by using reverse transcription-quantitative PCR, and the protein levels in five randomly selected pairs of tumor and adjacent tissue samples were detected by western blot analysis. The mRNA expression levels of the TIPE family members were significantly downregulated in CRC tumor tissues compared with those in the adjacent tissues; however, within each sample, TNFAIP8 and TIPE3 protein levels were only partially consistent with their mRNA levels. In addition, the mRNA expression levels between each pair of TIPE family members exhibited a positive linear relationship, and TIPE2 mRNA levels exhibited strong linear associations with those of TNFAIP8 and TIPE1. TNFAIP8 mRNA expression levels in tumor tissues were significantly associated with the tumor differentiation grade, and TIPE2 mRNA expression levels in tumor tissues were significantly associated with sex. TIPE1 and TIPE3 mRNA expression levels in tumor tissues exhibited no associations with patient clinicopathological characteristics. In addition, the mRNA expression patterns of the TIPE family members were analyzed using data from The Cancer Genome Atlas data set, and the results also demonstrated that TNFAIP8, TIPE2 and TIPE3 mRNA levels were downregulated in patients with colon adenocarcinoma compared with those in normal controls. These results provided evidence that the four members of the TIPE family may affect each other to mediate the carcinogenesis of CRC, and that TIPE2 may serve an important role in CRC.

The enigmatic role of TIPE2 in asthma

Unlike other members of the tumor necrosis factor (TNF)-α-induced protein 8 (TNFAIP8/TIPE) family that play a carcinogenic role and regulate apoptosis, TNFAIP8-like 2 (TIPE2) can not only maintain immune homeostasis but also regulate inflammation. TIPE2 mainly restrains the activation of T cell receptor (TCR) and Toll-like receptors (TLR), regulating its downstream signaling pathways, thereby regulating inflammation. Interestingly, TIPE2 is abnormally expressed in many inflammatory diseases and may promote or inhibit inflammation in different diseases. This review summarizes the molecular target and cellular function of TIPE2 in immune cells and inflammatory diseases and the underlying mechanism by which TIPE2 regulates inflammation. The function and mechanism of TIPE2 in asthma is also explained in detail. TIPE2 is abnormally expressed in asthma and participates in the pathogenesis of different phenotypes of asthma through regulating multiple inflammatory cells' activity and function. Considering the indispensable role of TIPE2 in asthma, TIPE2 may be an effective therapeutic target in asthma. However, the available data are insufficient to provide a full understanding of the complex role of TIPE2 in human asthma. Further study is still necessary to explore the possible mechanism and functions of TIPE2 in different asthma phenotypes.

TIPE2 as a potential therapeutic target in chronic viral hepatitis

Tumor necrosis factor-α-induced protein-8 like-2 (TIPE2) is a novel negative regulator of innate and adaptive immune responses by binding to caspase-8. The binding of TIPE2 and caspase-8 can inhibit the activity of activating protein-1(AP-1) and nuclear factor-κB (NF-κB), ultimately promoting Fas-induced apoptosis in immune cells. Therefore, TIPE2-caspase-8-NF-κB signaling might serve as a biomarker and a potential target for therapeutic intervention. Areas covered: This review summarizes the biological functions of TIPE2 in the regulation of immune homeostasis and the underlying mechanism by which TIPE2 is regulated in the human immune response. The molecular pathway of TIPE2-caspase-8 signaling in chronic infections of hepatitis B virus and hepatitis C virus is also explained. Expert opinion: Considering the essential role of TIPE2 in linking immunity and inflammation, this protein may be a promising therapeutic target in chronic viral hepatitis. However, studies are necessary to elucidate the molecular mechanism of TIPE2 in the immunogenesis of viral hepatitis and to develop potential interventions for breaking immune tolerance in chronic hepatitis B virus infection. Additional studies are required to understand how TIPE2 binds to caspase-8.

TIPE Family of Proteins and Its Implications in Different Chronic Diseases

The tumor necrosis factor-α-induced protein 8-like (TIPE/TNFAIP8) family is a recently identified family of proteins that is strongly associated with the regulation of immunity and tumorigenesis. This family is comprised of four members, namely, tumor necrosis factor-α-induced protein 8 (TIPE/TNFAIP8), tumor necrosis factor-α-induced protein 8-like 1 (TIPE1/TNFAIP8L1), tumor necrosis factor-α-induced protein 8-like 2 (TIPE2/TNFAIP8L2), and tumor necrosis factor-α-induced protein 8-like 3 (TIPE3/TNFAIP8L3). Although the proteins of this family were initially described as regulators of tumorigenesis, inflammation, and cell death, they are also found to be involved in the regulation of autophagy and the transfer of lipid secondary messengers, besides contributing to immune function and homeostasis. Interestingly, despite the existence of a significant sequence homology among the four members of this family, they are involved in different biological activities and also exhibit remarkable variability of expression. Furthermore, this family of proteins is highly deregulated in different human cancers and various chronic diseases. This review summarizes the vivid role of the TIPE family of proteins and its association with various signaling cascades in diverse chronic diseases.

TIPE3 protein promotes breast cancer metastasis through activating AKT and NF-κB signaling pathways

TIPE3 (TNFAIP8L3) is the transfer protein of phosphoinositide second messengers that promote cancer. Its role in breast cancer has not been evaluated. We report here that TIPE3 protein was significantly upregulated in human breast cancer tissues as compared with adjacent non-tumor tissues from the same patients. The level of TIPE3 protein in invasive ductal carcinoma was significant higher than that in ductal carcinoma in situ (DCIS), and the level of TIPE3 in lymphatic metastasized carcinoma was higher than that in invasive ductal carcinoma from the same patients. Additionally, the level of TIPE3 protein was positively correlated with the level of human epidermal growth factor receptor 2 (HER-2), and TIPE3 expression was significantly higher in high-invasive breast cancer cell lines than that in low-invasive cell lines. Importantly, TIPE3 knockdown in breast cancer cells inhibited cell proliferation, migration, and invasion in vitro, whereas TIPE3 overexpression had the opposite effect. In mice, TIPE3 expression significantly promoted the metastasis of breast cancer cells. TIPE3 expression also increased the level of MMP2 and uPA, and the activation of the AKT and NF-κB signaling pathways. These results demonstrate that TIPE3 may promote breast cancer growth and metastasis through AKT and NF-κB, and may serve as a potential biomarker for breast cancer metastasis.

Increased expression of TIPE2 in alternatively activated macrophages is associated with eosinophilic inflammation and disease severity in chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a multifactorial disorder characterized by exaggerated local immune responses. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is a novel protein with potential immune modulating function. The expression and function of TIPE2 in human airway diseases are unclear.

METHODS

The expression of TIPE2 in sinonasal mucosal samples was assessed by means of quantitative reverse transcript-polymerse chain reaction, immunohistochemistry, and Western blotting. The human monocytic/macrophage cell line, THP-1 cells, was stimulated with various cytokines. Computed tomography (CT) scan images, endoscopic findings, and symptoms were scored.

RESULTS

Compared with non-eosinophilic polyps and control mucosa, the mRNA and protein expression of TIPE2 was significantly upregulated in eosinophilic polyps, with a further increase in those with asthma. The number of CD68⁺ CD163⁺ alternatively activated (M2) macrophages was increased in eosinophilic polyps. TIPE2 was mainly expressed by M2 macrophages in sinonasal mucosa and its expression was upregulated in M2 macrophages in eosinophilic polyps. Interleukin (IL)-4 and IL-13, but not interferon (IFN)-γ or IL-17A, induced TIPE2 expression in differentiated THP-1 cells. The mRNA levels of IL-4 and IL-13 correlated with the mRNA levels of TIPE2 and M2 macrophage markers in sinonasal mucosa. Importantly, the number of TIPE2⁺ cells, particularly TIPE2⁺ CD163⁺ CD68⁺ M2 macrophages, correlated positively with the number of eosinophils and total inflammatory cells in sinonasal mucosa, as well as disease duration, CT scores, hyposmia scores, and polyp size in CRSwNP.

CONCLUSION

The T-helper 2 milieu is able to induce TIPE2 expression in macrophages. TIPE2-positive M2 macrophages potentially contribute to eosinophilic inflammation and disease progression in CRSwNP.

Clinical Significance of TIPE2 Protein Upregulation in Non-Hodgkin's Lymphoma

Non-Hodgkin's lymphoma (NHL), which includes diffuse large B-cell lymphoma (DLBCL) and peripheral T-cell lymphoma, is a refractory malignant tumor originated from the lymphatic system. TNFAIP8L2 (TIPE2 or tumor necrosis-alpha-induced protein-8 like 2) is a negative regulator for inflammation and an inhibitor for carcinogenesis. However, whether TIPE2 plays a role in lymphomagenesis is unknown. In this study, we determined TIPE2 expression in NHL by immunohistochemistry and investigated its clinicopathological significance in DLBCL. We found that TIPE2 expression was upregulated in both DLBCL and peripheral T-cell lymphoma. But the expression of TIPE2 in T lymphomas was weaker than that in DLBCL. Interestingly, among DLBCL, TIPE2 expression was significantly stronger in the germinal center B-cell (GCB) type than in the non-GCB type. These results suggest that the expression of TIPE2 protein could be a predictor of better prognosis for DLBCL.

Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is associated with immune phases of patients with chronic hepatitis B

Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is a newly negative immune regulator but its role in different immune phases of patients with chronic hepatitis B (CHB) is unknown. We determined the mRNA levels of TIPE2, interleukin-6, interleukin-10, tumor necrosis factors-α and interferon-γ in peripheral blood mononuclear cells from 205 naïve treated CHB patients and 15 healthy controls by quantitative real time polymerase chain reaction. Intrahepatic TIPE2 protein was also determined using immunohistochemistry staining. The TIPE2 mRNA level in CHB patients was significantly higher than that in healthy controls. Moreover, the TIPE2 mRNA level in immune clearance (IC) phases was significantly higher than that in immune tolerance (IT) phase; whereas TIPE2 mRNA in HBeAg negative hepatitis (ENH) was obviously higher than low replication (LR) phase. Furthermore, the optional cut off values of 2.02 and 1.59 for TIPE2 mRNA level have strong power in identifying IC and ENH from IT and LR. In addition, intrahepatic TIPE2 protein was predominantly located in hepatocyte plasma and correlated with hepatic inflammatory and fibrosis. Multivariate analysis showed tumor necrosis factors-α, interferon-γ and HBV DNA load were independently correlated with TIPE2 level. In conclusion, TIPE2 might be associated to the immune clearance of patients with chronic hepatitis B.

Adenovirus-mediated TIPE2 overexpression inhibits gastric cancer metastasis via reversal of epithelial-mesenchymal transition

Tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 (TNFAIP8L2; also termed TIPE2) has been shown to be involved in both the immune-negative modulation and cancer. We previously found that TIPE2 is lost in human gastric cancer, and TIPE2 restoration suppresses gastric cancer growth by induction of apoptosis and impairment of protein kinase B (PKB/AKT) and extracellular signal-regulated kinase-1/2 (ERK1/2) signaling. However, its correlation with epithelial-mesenchymal transition (EMT) in gastric cancer is largely elusive. In the present report, we carried out a gain-of-function study in AGS and HGC-27 human gastric cancer cells by adenovirus-mediated human TIPE2 gene transfer (AdVTIPE2). We then examined the effects of AdVTIPE2 on in vitro migration and invasion of AGS and HGC-27 tumor cells by wound-healing assay and Transwell invasion assay, respectively. We also investigated the effects of AdVTIPE2 on in vivo lung metastasis of AGS and HGC-27 tumor cells by intravenous (i.v.) injection in athymic BALB/c nude mice. We demonstrated that AdVTIPE2 remarkably suppressed the migratory, invasive and metastatic potential of AGS and HGC-27 tumor cells in vitro and in vivo in BALB/c nude mouse model. Mechanistically, AdVTIPE2 obviously upregulated E-cadherin epithelial marker in AGS and HGC-27 tumor cells, whereas it downregulated N-cadherin and Vimentin mesenchymal markers, Snail1, Snail2/Slug and Zeb1 EMT-inducing transcription factors (EMT-TFs), and tripartite motif-containing 29 (TRIM29) and phosphatase regenerating liver 3 (PRL-3) gastric cancer-specific metastasis markers. Importantly, glycogen synthase kinase-3β (GSK-3β) inhibitor VIII and 26S proteasome inhibitor MG132 assays revealed that TIPE2 downregulated Snail1 and Snail2/Slug in a GSK-3β- and proteasome-dependent manner possibly by impairing AKT signaling. Our data provided the first evidence that TIPE2 inhibits gastric cancer cell migration, invasion and metastasis very probably via reversal of EMT, revealing that TIPE2 may be a novel therapeutic target for human gastric cancer EMT and metastasis.

Expression and roles of TIPE2 in autoimmune hepatitis

Tumor necrosis factor, alpha-induced protein 8-like 2 (TIPE2) is associated with the development of hepatic inflammatory diseases. However, to date, the possible role of TIPE2 in autoimmune hepatitis (AIH) has not been reported. The present study aimed to investigate the expression of TIPE2 in peripheral blood mononuclear cells (PBMCs) of mice with AIH. Furthermore, the liver function, pro-inflammatory cytokine production and hepatic histopathology were examined in TIPE2-deficient mice in order to evaluate whether TIPE2 is involved in the pathogenesis of AIH. A murine model of AIH was induced by treatment with concanavalin A (ConA). The expression of TIPE family members in the PBMCs was examined using reverse-transcription quantitative polymerase chain reaction analysis, while the protein expression of TIPE2 was additionally detected by western blot analysis. The activity of alanine amiotransferase (ALT) and aspartate aminotransferase (AST) in the serum was measured on an automated chemical analyzer to assess liver function. The serum levels of tumor necrosis factor-α, interleukin (IL)-6 and IL-12 were measured using commercial ELISA kits. Hematoxylin and eosin staining was performed to assess hepatic histopathology. The results showed that the expression of TIPE2 was significantly decreased in the mice with AIH. Following ConA-induced AIH, TIPE2-deficient mice had significantly increased serum ALT and AST levels, enhanced production of pro-inflammatory cytokines, as well as more severe hepatic inflammation compared with the wild-type mice. In conclusion, the present study demonstrated, for the first time, that TIPE2 is involved in the pathogenesis of AIH. TIPE2 prevents liver dysfunction and inhibits deleterious inflammatory immune responses after AIH and may therefore serve as a novel agent for the treatment of AIH.

Hepatitis C virus promotes hepatocellular carcinogenesis by targeting TIPE2, a new regulator of DNA damage response

Infection of hepatitis C virus (HCV) is associated with primary hepatocellular carcinoma (HCC). However, its underlying molecular mechanisms remain enigmatic. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2), a new negative regulator of immunity, plays significant roles in modulating inflammation and tumorigenesis. We hypothesized that TIPE2 might be involved in the development of HCV-induced HCC. To test this hypothesis, the expression of TIPE2 was determined by Western blot in the tumor and pericarcinomatous tissues collected from ten HCV-positive HCC patients; the interaction between TIPE2 and HCV-encoded non-structural proteins was analyzed by immunoprecipitation and immunofluorescence assays, and tumorigenesis and its mechanisms were studied in cell models and nude mice. Our results demonstrated that the expression of TIPE2 was significantly reduced in HCC tissues compared to that in the paracarcinoma tissues. HCV-encoded non-structural protein NS5A could specifically interact with TIPE2 and induce its degradation. Downregulation of TIPE2 by shRNA in cell lines increased genomic DNA damage and promoted cell colony formation in vitro and tumorigenesis in nude mice. In contrast, overexpression of TIPE2 had an opposite effect. Downregulation of TIPE2 by NS5A is associated with genomic DNA instability and HCV-induced HCC development. Thus, TIPE2 may be a new therapeutic target for the treatment of HCV-associated HCC.

Tumor necrosis factor α-induced protein 8-like 1 promotes apoptosis by regulating B-cell leukemia/lymphoma-2 family proteins in RAW264.7 cells

Although the newly identified protein tumor necrosis factor α-induced protein 8-like 1 (TNFAIP8L1), also known as TIPE1, has been reported to be able to induce apoptosis in human hepatocellular carcinoma cells, the involvement of TIPE1 in apoptosis remains to be elucidated. The present study investigated the pro-apoptotic effect of TIPE1 in an murine macrophage cell line, RAW264.7. The cell apoptosis rate was detected by flow cytometry. The results revealed that overexpressed TIPE1 could directly enhance the apoptosis and the cisplatin-induced cell death of RAW264.7 cells in vitro. Meanwhile, TIPE1 overexpression could suppress tumor growth in vivo. Furthermore, western blotting revealed that overexpressed TIPE1 could upregulate the expression of B-cell leukemia/lymphoma (Bcl)-2 associated X protein (Bax), Bcl-2 interacting killer (Bik) and p53 upregulated modulator of apoptosis (Puma), and activate the mitogen activated protein kinases (MAPKs) signaling pathway. However, western blotting demonstrated that inhibitors of the MAPKs pathway could not decrease the expression of Bax, Bik or Puma. These results indicated that TIPE1 could promote the apoptosis of RAW264.7 cells by upregulating the pro-apoptotic members of the Bcl-2 family of proteins, and that the MAPKs signaling pathway was not involved in the pro-apoptotic effect of TIPE1.

Decreased expression of TIPE2 contributes to the hyperreactivity of monocyte to Toll-like receptor ligands in primary biliary cirrhosis

BACKGROUND AND AIM

Previous studies have shown differential TIPE2 expression in several autoimmune diseases. However, the expression levels of TIPE2 in primary biliary cirrhosis (PBC) remained unclear. The purposes of this study were to evaluate TIPE2 expression levels in patients with PBC and further investigate its role in PBC pathogenesis.

METHODS

A total of 40 PBC patients and 44 healthy controls were included in the present study. Quantitative reverse-transcription polymerase chain reaction and western blotting were used to determine the differences in mRNA and protein expression levels of TIPE2. The correlations of TIPE2 expression levels and clinical characteristics, inflammatory cytokines, and ursodeoxycholic acid treatment were also assessed. Besides, the influence of TIPE2 on the reactivity of monocyte to Toll-like receptor ligands was further analyzed.

RESULTS

The expression levels of TIPE2 were significantly decreased in PBC patients compared with normal controls (P < 0.01). The expression levels of TIPE2 were negatively correlated with alanine aminotransferase (r = -0.40, P = 0.01), alkaline phosphatase (r = -0.36, P = 0.02), gamma glutamyl transpeptidase (r = -0.53, P < 0.01), tumor necrosis factor (TNF)-α (r = -0.332, P = 0.03), interleukin (IL)-1β (r = -0.386, P = 0.01), and IL-8 (r = -0.366, P = 0.02) levels in sera from PBC patients. TIPE2 expression level could be significantly increased after ursodeoxycholic acid treatment (P < 0.01). The production of TNF-α, IL-1β, and IL-8 by monocytes from PBC patients after stimulation with lipopolysaccharide and lipoteichoic acid was significantly increased when TIPE2 was knocked down. Furthermore, TIPE2 knockdown could promote activation of nuclear factor-κB pathways through increasing phosphorylation and degradation of IκB in peripheral blood monocytes from PBC patients.

CONCLUSION

The present study reported that insufficient expression of TIPE2 might be involved in the hyperreactivity of monocyte to Toll-like receptor ligands in PBC.

Adenovirus-directed expression of TIPE2 suppresses gastric cancer growth via induction of apoptosis and inhibition of AKT and ERK1/2 signaling

Tumor necrosis factor (TNF)-α-induced protein 8-like 2 (TNFAIP8L2/TIPE2) as a novel anti-inflammatory factor plays an important role in maintaining immune homeostasis. Recently, TIPE2 has been shown to inhibit hepatocarcinoma growth and metastasis through targeting Ras and Rac1. However, its effects in human cancers are poorly understood. In the present study, we analyzed TIPE2 mRNA expression in a panel of human gastric cancer cells (AGS, HGC-27 and SGC-7901) and then examined the cell-autonomous effects of adenovirus-mediated human TIPE2 gene transfer (AdVTIPE2) on AGS and HGC-27 human gastric cancer cells. We found that compared with the GES-1 normal human gastric mucous epithelial cells, human TIPE2 was lost in the AGS, HGC-27 and SGC-7901 gastric cancer cells. Adenovirus-mediated human TIPE2 overexpression significantly inhibited AGS and HGC-27 gastric cancer cell growth and induced AGS and HGC-27 tumor cell apoptosis in vitro. Furthermore, AdVTIPE2 treatment obviously suppressed the growth of AGS gastric cancer subcutaneously xenografted tumors implanted in athymic BALB/c nude mice in vivo. Mechanistically, AdVTIPE2 exhibited marked effects on the upregulation of Bax, cleaved Caspase-9, cleaved Caspase-3, cleaved poly ADP ribose polymerase as well as the downregulation of B-cell lymphoma (Bcl)-XL, phosphorylated-protein kinase B (p-PKB/AKT), phosphorylated-extracellular signal-regulated kinase 1/2 (p-ERK1/2) in AGS gastric cancer cells in vitro and in vivo. Collectively, AdVTIPE2 suppressed gastric cancer growth very possibly by the activation of intrinsic apoptotic pathway and the attenuation of AKT and ERK1/2 signaling. Thus, our data indicated that TIPE2 may be a novel potential therapeutic target for human gastric cancer.

TIPE2 mRNA Level in PBMCs Serves as a Novel Biomarker for Predicting Short-Term Mortality of Acute-on-Chronic Hepatitis B Liver Failure: A Prospective Single-Center Study

It remains difficult to accurately predicate short-term mortality of acute-on-chronic hepatitis B liver failure (ACHBLF). Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is a novel identified negative regulator of immune response and we have previously demonstrated TIPE2 play an essential role in the pathogenesis of ACHBLF. We therefore aimed to evaluate the diagnosis value of TIPE2 mRNA in peripheral blood mononuclear cells (PBMCs) for predicting 3-month mortality of ACHBLF patients. This prospective study consisted of 108 ACHBLF patients from March 2009 to May 2013 as training cohort and 63 ACHBLF patients from June 2013 to December 2014 as validation cohort. Forty-two patients with chronic hepatitis B (CHB) and 22 healthy volunteers were also included as controls. The mRNA level of TIPE2 in PBMCs was determined using quantitative real-time polymerase chain reaction. Univariate analysis and Cox proportional hazard regression analysis were performed to identify independent risk factors to 3-month mortality. Area under the receptor operating characteristic curve (AUROC) was performed to assess diagnostic value of TIPE2 mRNA in training and validation cohort. The level of TIPE2 mRNA was significantly higher in ACHBLF patients (median (interquartile): 6.5 [3.7, 9.6]) compared with CHB (2.3 [1.6, 3.7]) and healthy controls (0.4 [0.3, 0.6]; both P < 0.05). Cox proportional hazards regression analyses showed 5 independent risk factors associated with 3-month mortality of ACHBLF: white blood cells (HR = 1.058, 95% CI: 1.023-1.095), spontaneous bacterial peritonitis (HR = 2.541, 95% CI: 1.378-4.686), hepatic encephalopathy (HR = 1.848, 95% CI: 1.028-3.321), model for end-stage liver diseases (MELD) score (HR = 1.062, 95% CI: 1.009-1.118), and TIPE2 mRNA (HR = 1.081, 95% CI: 1.009-1.159). An optimal cut-off point 6.54 of TIPE2 mRNA showed sensitivity of 74.63%, specificity of 90.24%, positive predictive value of 92.5%, and negative predictive value of 67.3% for predicting 3-month mortality in training cohort. Furthermore, TIPE2 mRNA plus MELD performed better than MELD alone for predicting 3-month mortality in training (AUROC, 0.853 vs 0.722, P < 0.05) and validation cohort (AUROC, 0.909 vs 0.717, P < 0.001). TIPE2 mRNA level might be a novel biomarker in predicting 3-month mortality of ACHBLF. Combination of TIPE2 mRNA and MELD would improve the diagnostic value of MELD alone in predicting 3-month mortality of patients with ACHBLF.