A different TIPE of immune homeostasis

Beta-Cell Tipe1 Orchestrates Insulin Secretion and Cell Proliferation by Promoting Gαs/cAMP Signaling via USP5

Inadequate β-cell mass and insulin secretion are essential for the development of type 2 diabetes (T2D). TNF-α-induced protein 8-like 1 (Tipe1) plays a crucial role in multiple diseases, however, a specific role in T2D pathogenesis remains largely unexplored. Herein, Tipe1 as a key regulator in T2D, contributing to the maintenance of β cell homeostasis is identified. The results show that the β-cell-specific knockout of Tipe1 (termed Ins2-Tipe1BKO) aggravated diabetic phenotypes in db/db mice or in mice with high-fat diet-induced diabetes. Notably, Tipe1 improves β cell mass and function, a process that depends on Gαs, the α subunit of the G-stimulating protein. Mechanistically, Tipe1 inhibited the K48-linked ubiquitination degradation of Gαs by recruiting the deubiquitinase USP5. Consequently, Gαs or cAMP agonists almost completely restored the dysfunction of β cells observed in Ins2-Tipe1BKO mice. The findings characterize Tipe1 as a regulator of β cell function through the Gαs/cAMP pathway, suggesting that Tipe1 may emerge as a novel target for T2D intervention.

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.

Tnfa , Il6 , Cxcl1 , and Adam8 Genes Are the Early Markers After Mouse Tail Intervertebral Disc Injury

OBJECTIVES

The early molecular events after intervertebral disc injury remain unclear. In this study, we aimed to compare inflammatory markers from 1 day to 4 wks after injury to have a comprehensive understanding of the intervertebral disc response to injury.

DESIGN

Mouse tail intervertebral disc injury was induced by a needle puncture. Inflammatory marker gene expression and morphological changes were recorded at 1 day, 1 wk, and 4 wks after injury.

RESULTS

Tnfa , Il6 , and Cxcl1 gene expression peaked at day 1 post-needle puncture of the mouse intervertebral disc, Adam8 gene expression peaked at 1-wk time point, while Tipe2 gene expression was upregulated at week 4 postinjury. F4/80 positive cells, likely to be macrophages, are present as early as day 1 in the injured intervertebral discs and consistently present at week 4 postinjury. Loss of Safranin O staining and increased histological scores of the injured intervertebral discs are consistent with progressive degeneration after injury.

CONCLUSIONS

Inflammatory cytokines including Tnfa precede Tipe2 , suggesting that Tipe2 is likely induced by Tnfa . Upregulation of Adam8 and Cxcl1 gene expression persisted at week 4, suggesting that they play a role in the transition to chronic phase of intervertebral disc degeneration.

Research progress of TIPE2 in immune-related diseases

The tumor necrosis factor α-induced protein 8 (TNFAIP8) family, which consists of TNFAIP8 (TIPE), TNFAIP8L1 (TIPE1), TNFAIP8L2 (TIPE2) and TNFAIP8L3 (TIPE3), has recently emerged as a regulatory factor involved in immune response and tumorigenesis. Among its members, TIPE2 acts as a negative regulator of both innate and adaptive immunity, playing a crucial role in maintaining immune homeostasis by negatively regulating T cell receptor (TCR) and toll-like receptor (TLR) signal transduction. Immune homeostasis is an indispensable characteristic of the immune system, which prevents harmful inflammatory reactions and ensures the proper functioning of the body. A large number of studies have shown that abnormal TIPE2 expression exists in a variety of inflammation-related diseases such as asthma, colitis, and systemic lupus erythematosus, highlighting the importance of comprehending its function for the prevention and treatment of immune-related conditions. This review aims to provide an overview of the in vivo distribution and expression of TIPE2, its regulatory role in central and peripheral immune-related diseases, and the underlying mechanisms that govern its function in the inflammatory response. By delving into these aspects, a deeper understanding of the role and functionality of TIPE2 in inflammatory responses can be achieved.

TIPE-2 ameliorates inflammatory bowel disease in mice via inhibiting STAT3 and NF-kB activation

TIPE-2 has been identified as a negative regulator of both innate and adaptive immunity and is involved in several inflammatory diseases. However, the immune inhibition mechanism of TIPE-2 involved in inflammatory bowel disease has not been well studied. Therefore, the aim of this study was to investigate whether TIPE-2 improved experimental colitis by reducing high levels of inflammation in the intestine. Lentivirus encoding TIPE-2 was administered to mice by intrarectal injection after colitis induction. Histological analysis was used to analyze sections of the intestine. Protein expression induced by STAT3 and NF-κB signaling was analyzed by western blot. We found that TIPE-2 reduced the colitis activity index score and the histological score of the intestine. TIPE-2 also decreased inflammatory cytokine levels in the intestine. Additionally, TIPE-2 inhibited STAT3 and NF-kB activation. These results suggested that TIPE-2 might attenuate inflammation of colitis via inhibiting of STAT3 and NF-kB activation.

TIPE2 knockout reduces myocardial cell damage by inhibiting IFN-γ-mediated ferroptosis

Acute rejection of the transplanted heart is mediated by oxidative programmed cell death through the synergistic effects of the innate and adaptive immune systems. However, the role of ferroptosis, a newly discovered form of oxidative cell death, has not been widely evaluated. Tumor necrosis factor-α-induced protein-8 like 2 (TNFAIP8L2), also known as TIPE2, is required for maintaining immune homeostasis. To characterize the role of TIPE2 in mediating heart allografts, BALB/c hearts were transplanted into C57BL/6 wild-type (WT) and TIPE2^-/- recipient mice. In TIPE2^-/- recipient mice, allograft injury in BALB/c allograft hearts was significantly reduced through the inhibition of allograft ferroptosis. On day 3 and day 6 post-transplantation, the numbers of CD3⁺, CD4⁺, and CD8⁺ cells among splenocytes and draining lymph node cells were significantly decreased, and the activation of CD4⁺ and CD8⁺ cells in grafts was decreased in TIPE2^-/- recipient mice compared with WT mice. Moreover, CD4⁺ and CD8⁺ T cells in TIPE2^-/- recipient mice were characterized by deficient capacities for interferon-γ (IFN-γ) production through the TBK1 signaling axis and increased glutathione peroxidase 4 (GPX4). In cell experiments, treatment with IFN-γ enhanced ferroptosis-specific lipid peroxidation in myocardial cells and correlated inversely with GPX4 expression. Mechanistically, IFN-γ administration decreased the expression of GPX4 by inhibiting MEK/ERK phosphorylation. In summary, our findings demonstrated that TIPE2 deficiency inhibits T-cell production of IFN-γ to reduce ferroptosis in allografts by restraining lipid peroxidation.

Beneficial Effects of Gracillin From Rhizoma Paridis Against Gastric Carcinoma via the Potential TIPE2-Mediated Induction of Endogenous Apoptosis and Inhibition of Migration in BGC823 Cells

Tumor necrosis factor-α inducible protein-8 (TIPE2), initially recognized as a negative immune regulator, exerts an important role in suppressing the progression of numerous cancers. In our previous investigation, we found that TIPE2 expression displayed a decrease or absence in gastric tumor tissue, and the overexpression of TIPE2 suppressed the growth of gastric cancer tumors and cells, demonstrating that TIPE2 could be a potential medicinal target for gastric cancer treatment. However, it’s seldomly reported that several medicinal agents or candidates targeted TIPE2 for treating diseases, including gastric cancer. To identify the candidate targeting TIPE2 to fight against gastric cancer, several extractions from traditional natural medicinal plants with anti-tumor functions were employed to screen the active compounds according to bioassay-guided isolation. Interestingly, gracillin, a component from the ethyl acetate extraction of Rhizoma Paridis, was identified to induce the expression of TIPE2 and inhibit the cell proliferation in gastric cancer BGC-823 cells. Furthermore, the underlying mechanisms that restrain gastric cancer were evaluated by clone formation, EdU staining, flow cytometry, and other assays. Meanwhile, the role of TIPE2 in the anti-tumor effect of gracillin was elucidated via the use of siTIPE2 RNA. It was determined that gracillin could fight against gastric cancer cells by inhibiting the cell proliferation participated by the PI3K/AKT pathway and cell cycle arrest, suppressing the EMT pathway-regulating cell migration, and inducing bcl2-associated mitochondrial apoptosis. Additionally, TIPE2 maybe contribute to the benefits of gracillin. These results of the present study are an important step toward the medicinal development of gracillin, and are also of use in understanding the effect of TIPE2 as a potential tumor target.

Tumor necrosis factor α‑induced protein 8‑like 2 contributes to penehyclidine hydrochloride pretreatment against lipopolysaccharide‑induced acute lung injury in a mouse model

The aim of the present study was to investigate the effect of penehyclidine hydrochloride (PHC) pretreatment on mice with lipopolysaccharide (LPS)‑induced acute lung injury (ALI) and its possible underlying mechanisms. Mice were randomly separated into six groups: i) Sham group; ii) LPS group; iii) LPS + PHC group; iv) tumor necrosis factor a‑induced protein 8‑like protein 2 (TIPE2) group; v) LPS + TIPE2 group; and vi) LPS + TIPE2 + PHC group. The ALI model was induced using LPS through intratracheal injection. The mice received adenovirus gene to induce the overexpression of TIPE2. After mice were sacrificed, lung injury indices were assessed, and arterial blood, bronchoalveolar lavage fluid and lung tissues were collected for subsequent assays. Expression levels of related proteins were detected by using western blotting. It was found that compared with the sham group, the mice treated with LPS showed increased lung injury and dysfunctions of gas exchange. However, these trends were significantly ameliorated in the LPS + PHC group. Evaluation of protein expression in lung tissues showed that the increased expression of nuclear NF‑κB p65 and p‑c‑Jun N‑terminal kinase (JNK) induced by LPS were suppressed in the LPS + PHC group and the expression of TIPE2 was increased. The mice that received adenovirus gene to induce TIPE2 overexpression could also showed protective effects compared with the mice in the LPS group. However, the expression of TIPE2 decreased rather than increased in LPS group. In the mice pretreated with PHC, the expression of TIPE2 increased in mice with LPS‑induced ALI. To conclude, PHC pretreatment could inhibit the occurrence of inflammation and apoptosis in LPS‑induced ALI. This process may be related to the activation of TIPE2 and the inhibition of NF‑κB and JNK signaling pathway in the lungs of mice.

TNFAIP8 Regulates Intestinal Epithelial Cell Differentiation and May Alter Terminal Differentiation of Secretory Progenitors

The intestine is a highly proliferative dynamic environment that relies on constant self-renewal of the intestinal epithelium to maintain homeostasis. Tumor necrosis factor-alpha-induced protein 8 (TNFAIP8 or TIPE0) is a regulator of PI3K-mediated signaling. By binding to PIP2 and PIP3, TIPE family members locally activate PI3K activity while globally inhibiting PI3K activity through sequestration of membranous PIP2. Single-cell RNA sequencing survey of Tipe0-/- small intestine was used to investigate the role of TIPE0 in intestinal differentiation. Tipe0-/- intestinal cells were shown to shift towards an undifferentiated state, with the notable exception of goblet cells. Additionally, three possible novel regulators of terminal cell fate decisions in the secretory lineage were identified: Nupr1, Kdm4a, and Gatad1. We propose that these novel regulators drive changes involved in goblet cell (Nupr1) or tuft cell (Kdm4a and Gatad1) fate commitment and that TIPE0 may play a role in orchestrating terminal differentiation.

Protective Effect of Dexmedetomidine on Acute Lung Injury via the Upregulation of Tumour Necrosis Factor-α-Induced Protein-8-like 2 in Septic Mice

The aim of the present study was to investigate whether TIPE2 participates in the protective actions of dexmedetomidine (DEX) in a mouse model of sepsis-induced acute lung injury (ALI). We administered TIPE2 adeno-associated virus (AAV-TIPE2) intratracheally into the lungs of mice. Control mice were infected with an adeno-associated virus expressing no transgene. Three weeks later, an animal model of caecal ligation-perforation (CLP)-induced sepsis was established. DEX was administered intravenously 30 min after CLP. Twenty-four hours after sepsis, lung injury was assayed by lung histology, the ratio of polymorphonuclear leukocytes (PMNs) to total cells in the bronchoalveolar lavage fluid (BALF), myeloperoxidase (MPO) activity, BALF protein content and the lung wet-to-dry (W/D) weight ratio. Proinflammatory factor levels in the BALF of mice were measured. The protein expression levels in lung tissues were analysed by Western blotting. The results showed that DEX treatment markedly mitigated sepsis-induced lung injury, which was characterized by the deterioration of histopathology, histologic scores, the W/D weight ratio and total protein levels in the BALF. Moreover, DEX markedly attenuated sepsis-induced lung inflammation, as evidenced by the decrease in the number of PMNs in the BALF, lung MPO activity and proinflammatory cytokines in the BALF. In addition, DEX dramatically prevented sepsis-induced pulmonary cell apoptosis in mice, as reflected by decreases in the number of TUNEL-positive cells, the protein expression of cleaved caspase-9 and cleaved caspase 3 and the Bax/Bcl-2 ratio. In addition, evaluation of protein expression showed that DEX blocked sepsis-activated JNK phosphorylation and NF-κB p65 nuclear translocation. Similar results were also observed in the TIPE2 overexpression group. Our study demonstrated that DEX inhibits acute inflammation and apoptosis in a murine model of sepsis-stimulated ALI via the upregulation of TIPE2 and the suppression of the activation of the NF-κB and JNK signalling pathways.

Tumor Necrosis Factor-α-Induced Protein 8-Like 2 Negatively Regulates Innate Immunity Against RNA Virus by Targeting RIG-I in Macrophages

A systematic and flexible immunoregulatory network is required to ensure the proper outcome of antiviral immune signaling and maintain homeostasis during viral infection. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2), a novel immunoregulatory protein, has been extensively studied in inflammatory response, apoptosis, and cancer. However, the function of TIPE2 in antiviral innate immunity is poorly clarified. In this study, we reported that the expression of TIPE2 declined at the early period and then climbed up in macrophages under RNA virus stimulation. Knockout of TIPE2 in the macrophages enhanced the antiviral capacity and facilitated type I interferon (IFN) signaling after RNA viral infection both in vitro and in vivo. Consistently, overexpression of TIPE2 inhibited the production of type I IFNs and pro-inflammatory cytokines, and thus promoted the viral infection. Moreover, TIPE2 restrained the activation of TBK1 and IRF3 in the retinoic acid inducible gene-I (RIG-I)-like receptors (RLR) signaling pathway by directly interacting with retinoic acid inducible gene-I (RIG-I). Taken together, our results suggested that TIPE2 suppresses the type I IFN response induced by RNA virus by targeting RIG-I and blocking the activation of downstream signaling. These findings will provide new insights to reveal the immunological function of TIPE2 and may help to develop new strategies for the clinical treatment of RNA viral infections.

A novel prognostic factor TIPE2 inhibits cell proliferation and promotes apoptosis in pancreatic ductal adenocarcinoma (PDAC)

Background: Tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a newly discovered negative immune regulator. Studies have shown that TIPE2 causes significant malignant biological effects and is differentially expressed in various malignant tumors. However, the expression and roles of TIPE2 in pancreatic ductal adenocarcinoma (PDAC) are largely unknown. Materials and Methods: The expression of TIPE2 in PDAC tissues was assessed by immunohistochemistry, qPCR and western blot analysis and related clinicopathological parameters including survival time were analyzed. After overexpression of TIPE2, cell proliferation and apoptosis analysis were conducted, and the associated underlying molecular mechanism was also explored. Results: In the present study, TIPE2 was upregulated in early PDAC tissues, and TIPE2 expression decreased as the tumor progressed (P<0.001). TIPE2 expression was negatively associated with tumor size, TNM stage and metastasis of lymph nodes. Furthermore, as an independent risk factor, TIPE2 could be used to predict the survival of patients with PDAC (P=0.035). TIPE2 overexpression significantly suppressed the viability, proliferation and induced apoptosis of PDAC cells by inhibiting survivin and increasing the activity of caspase3/7. Conclusions: For the first time, this study demonstrated that TIPE2 is an independent prognostic factor in PDAC. TIPE2 inhibited the proliferation and induced apoptosis via regulating survivin/caspase3/7 signaling pathway. These results indicated that TIPE2 is a potential biomarker for predicting the prognosis of PDAC patients and plays a pivotal role in the progression of PDAC.

MicroRNA-205-5p inhibits skin cancer cell proliferation and increase drug sensitivity by targeting TNFAIP8

Tumor necrosis factor-α-induced protein 8 (TNFAIP8) is a member of the TIPE/TNFAIP8 family which regulates tumor growth and survival. Our goal is to delineate the detailed oncogenic role of TNFAIP8 in skin cancer development and progression. Here we demonstrated that higher expression of TNFAIP8 is associated with basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma development in patient tissues. Induction of TNFAIP8 expression by TNFα or by ectopic expression of TNFAIP8 in SCC or melanoma cell lines resulted in increased cell growth/proliferation. Conversely, silencing of TNFAIP8 decreased cell survival/cell migration in skin cancer cells. We also showed that miR-205-5p targets the 3'UTR of TNFAIP8 and inhibits TNFAIP8 expression. Moreover, miR-205-5p downregulates TNFAIP8 mediated cellular autophagy, increased sensitivity towards the B-RAF^V600E mutant kinase inhibitor vemurafenib, and induced cell apoptosis in melanoma cells. Collectively our data indicate that miR-205-5p acts as a tumor suppressor in skin cancer by targeting TNFAIP8.

Dendritic cells transduced with TIPE-2 recombinant adenovirus induces T cells suppression

INTRODUCTION

TIPE-2 has been identified as a negative regulator of both innate and adaptive immunity and is involved in several inflammatory diseases. However, the role of immune suppression of dendritic cells (DCs) transduced with TIPE-2 has not been well studied.

METHODS

In this study, DCs were transduced with TIPE-2 recombinant adenovirus, and then were cocultured with allogeneic CD4+ or CD8 + T cells. The proliferation, cytokine production and activation marker levels of CD4+ or CD8 + T cell were detected.

RESULTS

The data demonstrated that T cell proliferation, cytokine production and activation marker levels were attenuated after treated with TIPE-2 transduced DCs.

CONCLUSIONS

These results suggested that TIPE-2 transduced DCs are capable of inducing allogeneic CD4+ or CD8 + T cell immune suppression, which provide a promising way for the therapeutical strategies of transplantation or autoimmune diseases.

TNFAIP8 drives metabolic reprogramming to promote prostate cancer cell proliferation

Tumor necrosis factor-α-induced protein 8 (TNFAIP8) is a member of TIPE/TNFAIP8 family, has been involved in the development and progression of various human cancers. We hypothesized that TNFAIP8 promotes prostate cancer (PCa) progression via regulation of oxidative phosphorylation (OXPHOS) and glycolysis. Ectopic expression of TNFAIP8 increased PCa cell proliferation/migration/spheroid formation by enhancing cell metabolic activities. Mechanistically, TNFAIP8 activated the PI3K-AKT pathway and up-regulated PCa cell survival. TNFAIP8 was also found to regulate the expression of glucose metabolizing enzymes, enhancing glucose consumption, and endogenous ATP production. Treatment with a glycolysis inhibitor, 2-deoxyglucose (2-DG), reduced TNFAIP8 mediated glucose consumption, ATP production, spheroid formation, and PCa cell migration. By maintaining mitochondrial membrane potential, TNFAIP8 increased OXPHOS and glycolysis. Moreover, TNFAIP8 modulates the production of glycolytic metabolites in PCa cells. Collectively, our data suggest that TNFAIP8 exerts its oncogenic effects by enhancing glucose metabolism and by facilitating metabolic reprogramming in PCa cells. Therefore, TNFAIP8 may be a biomarker associated with prostate cancer and indicate a potential therapeutic target.

Novel anti-inflammatory actions of TIPE2 in human primary amnion and myometrial cells

Inflammation plays a pivotal role in the terminal process of human labor and delivery, including myometrial contractions and membrane rupture. TNF-alpha-induced protein 8-like-2 (TIPE2) is a novel inflammation regulator; however, there are no studies on the role of TIPE2 in human labor. We report that in myometrium, there is decreased TIPE2 mRNA expression during late gestation which was further decreased in labor. In fetal membranes, TIPE2 mRNA expression was decreased with both term and preterm labor compared to no labor samples. Knockdown of TIPE2 by siRNA in primary myometrium and amnion cells was associated with an augmentation of IL1B and TNF-induced expression of pro-inflammatory cytokines and chemokines; expression of contraction-associated proteins and secretion of the uterotonic prostaglandin PGF2α and expression of extracellular matrix degrading enzymes. In TIPE2-deficient myometrial cells treated with inhibitors of NF-κB or ERK1/2, the secretion of pro-labor mediators was reduced back to control levels. In conclusion, these in vitro experiments indicate that loss of TIPE2 exacerbates the inflammatory response.

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.

TNFAIP8 family gene expressions in the mouse tail intervertebral disc injury model

INTRODUCTION

The TNF-α-induced protein-8 (TNFAIP8, also known as TIPE) family of molecules comprises four members: TNFAIP8 and TIPEs1-3. Since the first description of these proteins, their roles in fine-tuning inflammation and in directing leukocyte migration have been described in several organ systems. However, their relationship with intervertebral disc (IVD) is unknown.

MATERIALS AND METHODS

Here, we describe the expression of TNFAIP8 family genes in the nucleus pulposus (NP) and annulus fibrosus (AF) of the normal adult murine IVD. We further describe the expression of these genes in the injured male and female murine IVD.

RESULTS

Tnfaip8 gene expression was decreased, and Tipe1 gene expression was essentially unchanged, in response to injury. Tipe2 and Tipe3 gene expression was markedly elevated in response to IVD injury, along with those encoding known inflammatory markers (ie, Tnfa, Il6, Cxcl1, and Adam8). Additionally, sex-related differences were also observed for some of these genes in intact and injured mouse IVDs. Future studies include examining tissue distribution of TNFAIP8 family proteins and identifying cells that produce them. In addition, examining mice that are deficient in TNFAIP8 molecules, in relation to gene expression, tissue morphology and mouse behavior, may further delineate the roles of these molecules in IVD inflammation and degeneration.

Down-regulation of anti-inflammatory TIPE2 may aggravate adenoidal hypertrophy in children

Adenoidal hypertrophy (AH) is a common disorder in the pediatric population, with common symptoms including mouth breathing, nasal congestion, hyponasal speech, snoring and obstructive sleep apnea. Although the pathogenesis of AH has not been fully elucidated, recent studies have indicated that immune responses may play an important role in AH. Tumor necrosis factor‐alpha (TNF‐α)‐induced protein‐8 like‐2 (TIPE2) is a newly identified protein that negatively regulates the activation of inflammatory pathways. Here, we investigated the effect of TIPE2 in AH in children. We observed that the levels of TNF‐α and interleukin‐6 were greater in the adenoid tissue of AH children than in healthy control subjects (P < 0.01), and this increase was positively correlated with the severity of AH. The level of TIPE2 expression was decreased compared with control and was negatively correlated with AH. TIPE2 overexpression in primary human monocytes (isolated from adenoid tissue of children with AH) inhibited the activation of nuclear factor‐κB and the expression of TNF‐α and interleukin‐6. These results suggest that overexpression of TIPE2 may attenuate AH through inactivation of the nuclear factor‐κB signaling pathway.

TNFAIP8 regulates autophagy, cell steatosis, and promotes hepatocellular carcinoma cell proliferation

Tumor necrosis factor-α-induced protein 8 (TNFAIP8) expression has been linked to tumor progression in various cancer types, but the detailed mechanisms of TNFAIP8 are not fully elucidated. Here we define the role of TNFAIP8 in early events associated with development of hepatocellular carcinoma (HCC). Increased TNFAIP8 levels in HCC cells enhanced cell survival by blocking apoptosis, rendering HCC cells more resistant to the anticancer drugs, sorafenib and regorafenib. TNFAIP8 also induced autophagy and steatosis in liver cancer cells. Consistent with these observations, TNFAIP8 blocked AKT/mTOR signaling and showed direct interaction with ATG3-ATG7 proteins. TNFAIP8 also exhibited binding with fatty acids and modulated expression of lipid/fatty-acid metabolizing enzymes. Chronic feeding of mice with alcohol increased hepatic levels of TNFAIP8, autophagy, and steatosis but not in high-fat-fed obese mice. Similarly, higher TNFAIP8 expression was associated with steatotic livers of human patients with a history of alcohol use but not in steatotic patients with no history of alcohol use. Our data indicate a novel role of TNFAIP8 in modulation of drug resistance, autophagy, and hepatic steatosis, all key early events in HCC progression.

Effects of the long and short isoforms of TIPE3 on the growth and metastasis of gastric cancer

Tumor necrosis factor alpha-induced protein 8-like 3 (TIPE3, also known as TNFAIP8L3) plays a vital role in tumorigenesis and development. However, it is unclear whether the two transcript variants of TIPE3 (long TIPE3 and short TIPE3) have an effect on the proliferation and metastasis of gastric cancer (GC). In this study, we demonstrated that the expression of TIPE3 decreased in GC, but patient prognosis worsened as TIPE3 expression increased. Then, overexpression models were constructed to study the role of long TIPE3 and short TIPE3. Upregulation of long TIPE3 and short TIPE3 promoted GC cell proliferation and metastasis both in vitro and in vivo, and the effect of short TIPE3 was more obvious. Further studies demonstrated that long TIPE3 and short TIPE3 promoted proliferation and metastasis of GC cells vis PI3K/Akt pathway. In conclusion, the two TIPE3 isoforms play an important role in the tumorigenesis of GC and depend on the activation of the PI3K/Akt pathway.

TIPE regulates VEGFR2 expression and promotes angiogenesis in colorectal cancer

Background: Metastasis is the leading cause of death in colorectal cancer (CRC) patients. It is regulated mainly by tumor cell angiogenesis, and angiogenesis is caused by the binding of vascular endothelial growth factor (VEGF) to vascular endothelial growth factor receptor 2 (VEGFR2). Tumor necrosis factor-α-induced protein 8 (TNFAIP8, hereto after TIPE) plays an important role in tumorigenesis, development, and prognosis. However, the relationship between TIPE and VEGFR2 in CRC angiogenesis and the mechanism of action remain unknown.

Method: In this study, we used quantitative real-time PCR, Western blotting and immunohistochemistry to detect TIPE and VEGFR2 expression in 55 specimens from CRC patients. We also used HCT116 CRC cells and human umbilical vein endothelial cells (HUVECs) for in vitro experiments by stably transducing shTIPE and shRNA control lentivirus into HCT116 cells, detecting VEGFR2 expression after TIPE knockdown and repurposing the culture supernatant as conditioned medium to stimulate angiogenesis of HUVECs. In vivo experiments with chicken chorioallantoic membranes (CAMs) and a nude mouse matrix subcutaneous tumor model were performed to validate the effects of TIPE on angiogenesis. Additionally, we analyzed the expression and phosphorylation levels of PDK1 and blocked PDK1 expression using inhibitors to determine whether TIPE-induced changes in VEGFR2-mediated angiogenesis acted via the PI3K-Akt pathway.

Results: We found that TIPE and VEGFR2 are highly expressed in CRC and act as oncogenes. TIPE knockdown also downregulated VEGFR2 expression, which resulted in simultaneous inhibition of cell proliferation, cell migration and angiogenesis. Then, in vivo experiments further demonstrated that TIPE promotes angiogenesis in CRC. Finally, we found that TIPE promotes VEGFR2-mediated angiogenesis by upregulating PDK1 expression and phosphorylation and that blocking PDK1 expression can inhibit this process.

Conclusion: TIPE promotes angiogenesis in CRC by regulating the expression of VEGFR2, which may be a target for antiangiogenic cancer therapy.

TIPE2 ameliorates lipopolysaccharide-induced apoptosis and inflammation in acute lung injury

Objective

Tumour necrosis factor-α-induced protein 8-like 2 (TIPE2) has strong anti-inflammatory properties. However, it is unknown whether increased TIPE2 is protective against lipopolysaccharide (LPS)-induced ALI. In the current study, we aimed to investigate whether increased TIPE2 can exert protective effects in a mouse model of ALI induced by LPS.

Methods

We administered TIPE2 adeno-associated virus (AAV-TIPE2) intratracheally into the lungs of mice. Three weeks later, ALI was induced by intratracheal injection of LPS into BALB/c mice. Twenty-four hours later, lung bronchoalveolar lavage fluid (BALF) was acquired to analyse cells and protein, arterial blood was collected for arterial blood gas analysis and the determination of pro-inflammatory factor levels, and lung issues were collected for histologic examination, transmission electron microscopy (TEM), TUNEL staining, wet/dry (W/D) weight ratio analysis, myeloperoxidase (MPO) activity analysis and blot analysis of protein expression.

Results

We found that TIPE2 overexpression markedly mitigated LPS-induced lung injury, which was evaluated by the deterioration of histopathology, histologic scores, the W/D weight ratio, and total protein expression in the BALF. Moreover, TIPE2 overexpression markedly attenuated lung inflammation, as evidenced by the downregulation of polymorphonuclear neutrophils (PMNs) in the BALF, lung MPO activity, and pro-inflammatory cytokine levels in the serum. Moreover, TIPE2 overexpression not only dramatically prevented LPS-induced pulmonary cell apoptosis in mice but also blocked LPS-activated JNK phosphorylation and NF-κB p65 nuclear translocation.

Conclusions

Our study shows that the increased expression of AAV-mediated TIPE2 in the lungs of mice inhibits acute inflammation and apoptosis and suppresses the activation of NF-κB and JNK in a murine model of ALI.

TIPE2 Suppresses Pseudomonas aeruginosa Keratitis by Inhibiting NF-κB Signaling and the Infiltration of Inflammatory Cells

Background

The role of tumor necrosis factor α (TNF-α) induced protein 8-like-2 (TIPE2) in Pseudomonas aeruginosa (PA) keratitis was explored.

Methods

Eight-week-old TIPE2 knockout (TIPE2−/−) C57BL/6 mice and their wild-type (WT) littermates were used. Corneal disease was graded at 1, 2, and 3 days postinfection, and slit lamp, clinical score, histopathology, and immunostaining were performed in the infected corneas. The corneas were harvested, and messenger ribonucleic acid (mRNA) levels of TNF-α, interleukin-1β (IL-1β), and interleukin-6 (IL-6) were tested. Enzyme-linked immunosorbent assay (ELISA) determined the protein levels, and nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB) signaling molecules were tested by Western blot. In vitro human corneal epithelial cells (HCECs) were used to determine the relationship between TIPE2 and TAK1. The HCECs were treated with TIPE2 short hairpin ribonucleic acid (shRNA) and lipopolysaccharide (LPS) to test the NF-κB signaling molecules by Western blot.

Results

Pseudomonas aeruginosa infection induced a decreased expression of TIPE2 in mouse corneas 2 days postinfection. Compared with the control group, TIPE2-deficient mice were susceptible to infection with PA and showed increased corneal inflammation. Reduced NF-κB signaling and inflammatory cell infiltration were required in the TIPE2-mediated immune modulation.

Conclusions

TIPE2 promoted host resistance to PA infection by suppressing corneal inflammation via regulating TAK1 signaling negatively and inhibiting the infiltration of inflammatory cells.

Tumour necrosis factor-α-induced protein 8-like 2 is a novel regulator of proliferation, migration, and invasion in human rectal adenocarcinoma cells

Tumour necrosis factor‐α‐induced protein 8‐like 2 (TIPE2) is a tumour suppressor in many types of cancer. However, the mechanism of action of TIPE2 on the growth of rectal adenocarcinoma is unknown. Our results showed that the expression levels of TIPE2 in human rectal adenocarcinoma tissues were higher than those in adjacent non‐tumour tissues. Overexpression of TIPE2 reduced the proliferation, migration, and invasion of human rectal adenocarcinoma cells and down‐regulation of TIPE2 showed reverse effects. TIPE2 overexpression increased apoptosis through down‐regulating the expression levels of Wnt3a, phospho (p)‐β‐Catenin, and p‐glycogen synthase kinase‐3β in rectal adenocarcinoma cells, however, TIPE2 knockdown exhibited reverse trends. TIPE2 overexpression decreased autophagy by reducing the expression levels of p‐Smad2, p‐Smad3, and transforming growth factor‐beta (TGF‐β) in rectal adenocarcinoma cells, however, TIPE2 knockdown showed opposite effects. Furthermore, TIPE2 overexpression reduced the growth of xenografted human rectal adenocarcinoma, whereas TIPE2 knockdown promoted the growth of rectal adenocarcinoma tumours by modulating angiogenesis. In conclusion, TIPE2 could regulate the proliferation, migration, and invasion of human rectal adenocarcinoma cells through Wnt/β‐Catenin and TGF‐β/Smad2/3 signalling pathways. TIPE2 is a potential therapeutic target for the treatment of rectal adenocarcinoma.

TNFAIP8: Inflammation, Immunity and Human Diseases

Tumor necrosis factor (TNF)-alpha-induced protein 8 (TNFAIP8 /TIPE) family proteins are known to be involved in maintaining immune homeostasis. The TIPE family contains four members: tumor necrosis factor-α-induced protein 8 (TNFAIP8), TNFAIP8 like 1 (TIPE1), TNFAIP8 like 2 (TIPE2), and TNFAIP8 like 3 (TIPE3). Here we review the latest roles and associations of a founding member of TIPE family protein - TNFAIP8 in cellular function/signaling, inflammation, and immunity related human diseases.

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.

TIPE2 acts as a biomarker for tumor aggressiveness and suppresses cell invasiveness in papillary thyroid cancer (PTC)

Background

Tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a newly described negative immune regulator and is closely associated with various tumors. However, the expression and roles of TIPE2 in PTC is unknown.

Results

In the present study, TIPE2 upregulation in PTC tissues was found to be negatively associated with tumor size, capsule infiltration, peripheral infiltration and tumor T stage, which could be used to predict tumor invasiveness. TIPE2 overexpression significantly suppressed the viability, proliferation, migration and invasion of PTC cells. Moreover, TIPE2 suppressed tumor invasiveness by inhibiting Rac1, leading to decreased expression of uPA and MMP9.

Conclusions

These results indicate that TIPE2 is a potential biomarker for predicting tumor aggressiveness and suppresses tumor invasiveness in a Rac1-dependent manner.

Electronic supplementary material

The online version of this article (10.1186/s13578-018-0247-x) contains supplementary material, which is available to authorized users.

Expression Pattern of Tumor Necrosis Factor-α-Induced Protein 8-Like 2 in Acute Rejection of Cardiac Allograft

BACKGROUND

Tumor necrosis factor-α-induced protein-8 like-2 (TIPE2) is a negative regulator of innate immunity and cellular immunity, yet the expression pattern of TIPE2 in acute rejection of cardiac allograft remain enigmatic.

METHODS

We developed cardiac transplantation models and divided into 3 groups: a naive group, a syngeneic group, and an allogeneic group. Then, we detected the messenger RNA and protein of TIPE2 in cardiac allografts. Real-time polymerase chain reaction showed expression of CD4 and CD8 in the donor heart, and immunofluorescence assay revealed the association between T cells and TIPE2.

RESULTS

In our study, we first found that the expression of TIPE2 in cardiac allografts is upregulated compared with the syngeneic control, and increases in a time-dependent manner. The immunocytochemistry of heart grafts revealed a strong expression of TIPE2 in the inflammatory cells, but not in the cardiomyocytes. Finally, we proved that CD4⁺ and CD8⁺ T cells infiltrated cardiac allografts abundantly, which express ample TIPE2.

CONCLUSIONS

The upregulated expression of TIPE2 in cardiac allografts, mainly came from T cells, which infiltrated the donor heart. This finding indicates that there may be an association between TIPE2 and acute cardiac allograft rejection.

TNFAIP8 promotes prostate cancer cell survival by inducing autophagy

Tumor necrosis factor-α-inducible protein 8 (TNFAIP8) is a TNF-α inducible anti-apoptotic protein with multiple roles in tumor growth and survival. Mechanisms of cell survival by TNFAIP8 remain elusive. We investigated the role of TNFAIP8 in the regulation of the cell cycle, autophagy, cell survival and neuroendocrine differentiation in prostate cancer cells. We showed that TNFAIP8 dysregulates cell-cycle-related proteins, in PC3 cells. Oncogenic cell survival, drug resistance and dysregulation of cell cycle-related proteins are often associated with autophagy. We demonstrated that TNFAIP8 induces autophagy by increasing expression of autophagy effectors such as LC3β I/II, Beclin1, 4EBP1, p62, and SIRT1. We also demonstrated that TNFAIP8 interacts with autophagy-related protein 3 (ATG3). TNFα treatment increased the expression of TNFAIP8, which was associated with increased autophagy and decreased apoptosis. We also observed an increase in expression of neuroendocrine differentiation markers, synaptophysin and chromogranin A, and drug resistance to anticancer drugs, docetaxel and doxorubicin, in cells transfected with TNFAIP8. Collectively, our findings reveal that by the creation of cellular autophagy events, TNFAIP8 promotes cell survival and drug resistance in prostate cancer cells.

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.

TIPE2 Inhibits the Expression of Asthma-Related Inflammatory Factors in Hyperstretched Bronchial Epithelial Cells Through the Wnt/β-Catenin Pathway

Childhood asthma, an airway inflammatory disease, is a serious threat to the child's quality of life. Recently, TIPE2 expression was reported to be decreased in children with asthma. Therefore, additional studies focusing on TIPE2 might provide an approach for treating childhood asthma. In this study, we found that TIPE2 was poorly expressed in hyperstretched human bronchial epithelial cells (BEAS-2B). TIPE2 overexpression also significantly suppressed the stretch-induced secretion of asthma-related inflammatory factors (TNF-α, TSLP, MMP-9, and VEGF). In contrast, TIPE2 inhibition significantly promoted the secretion of TNF-α, TSLP, MMP-9, and VEGF. Furthermore, overexpression of TIPE2 remarkably inhibited the activation of Wnt/β-catenin in hyperstretched BEAS-2B cells, while siTIPE2 activated Wnt/β-catenin in hyperstretched BEAS-2B cells. Further analysis showed that the Wnt/β-catenin signal inhibitor Dkk-1 could further enhance the TIPE2-induced suppression of Wnt/β-catenin signaling, which also suppressed the siTIPE2-induced secretion of TNF-α, TSLP, MMP-9, and VEGF in hyperstretched BEAS-2B cells. Dkk-1 reversed the effects of siRNA-TIPE2 on Wnt/β-catenin signaling and inflammatory cytokines. In summary, we have exhibited that TIPE2 inhibited the expression of asthma-related inflammatory factors in hyperstretched BEAS-2B cells by suppressing the Wnt/β-catenin signaling pathway. TIPE2 may be involved in airway inflammation during asthma attack, and it may be used as a potential therapeutic target for bronchial epithelial inflammation in childhood asthma.

A novel TNFAIP8 gene mediates l-arginine metabolism in Apostichopus japonicus

Tumor necrosis factor (TNF)-α-induced protein 8 (TNFAIP8) family is a newly identified protein with vital roles in maintaining immune homeostasis. In the current study, we first cloned and characterized a TNFAIP8 gene from the invertebrate sea cucumber Apostichopus japonicus. The gene was designated as AjTNFAIP8. The full-length cDNA of AjTNFAIP8 was 1455 bp long and encoded a matured protein of 201 amino acid residues. Structural analysis indicated that AjTNFAIP8 had a death effector domain (DED)-like domain and composed of six α-helices. Multiple sequence alignment and phylogenetic analysis supported that AjTNFAIP8 is a new member of the TNFAIP8 family. Analysis of basal transcription in five tissues revealed the constitutive expression of AjTNFAIP8 in the detected tissues with highest expression in the respiratory tree and minimum expression in the tentacle. Vibrio splendidus infection and LPS stimulation could significantly downregulate the mRNA expression of AjTNFAIP8. More importantly, the transcription of pro-inflammatory molecule NOS and its production of NO content were significantly increased after AjTNFAIP8 silencing, with the suppression of agmatinase transcript and arginase activity. These results clearly indicated that AjTNFAIP8 is an essential negative regulator in innate immunity. Basic information for further exploration of the functional mechanisms of TNFAIP8 family in other marine invertebrate is provided.

Stable silencing of TIPE2 reduced the Poly I:C‑induced apoptosis in THP‑1 cells

The present study aimed to determine the underlying mechanism of toll‑like receptor (TLR) agonist polyinosinic:polycytidylic acid (Poly I:C)‑induced apoptosis in THP‑1 cells following silencing the expression of tumor necrosis factor α‑induced protein 8‑like 2 (TIPE2). THP‑1 cells were incubated with different concentrations of the TLR agonist. Following incubation, reverse transcription‑quantitative polymerase chain reaction was performed to quantify the mRNA expression of TIPE2. Lentiviral technology was used to silence the expression of TIPE2. MTT assay was performed to assess cell proliferation, Annexin V/PI double staining was used to evaluate the apoptosis and western blotting was used to determine the expression levels of caspase‑8 following TIPE2 silencing. The TLRs agonist Poly I:C increased the expression level of TIPE2. During the incubation, Poly I:C also inhibited the proliferation of THP‑1 cells and induced apoptosis. Following silencing of TIPE2 in THP‑1 cells, the Poly I:C‑induced TIPE2 expression was significantly downregulated. Additionally, the Poly I:C‑induced proliferation inhibition and apoptosis in THP‑1 cells were significantly reduced following silencing of TIPE2. The findings of the western blot analysis indicated that the active form of caspase‑8, p18, was downregulated following silencing of TIPE2. In conclusion, the expression of TIPE2 in THP‑1 cells may be upregulated by Poly I:C, which may also inhibit cell proliferation and induce apoptosis. Following the downregulation of TIPE2 the aforementioned effect of Poly I:C treatment was reversed and may be associated with the reduced activity of caspase‑8 that was observed in the TIPE2 silenced group.

Evolutionary divergence of the vertebrate TNFAIP8 gene family: Applying the spotted gar orthology bridge to understand ohnolog loss in teleosts

Comparative functional genomic studies require the proper identification of gene orthologs to properly exploit animal biomedical research models. To identify gene orthologs, comprehensive, conserved gene synteny analyses are necessary to unwind gene histories that are convoluted by two rounds of early vertebrate genome duplication, and in the case of the teleosts, a third round, the teleost genome duplication (TGD). Recently, the genome of the spotted gar, a holostean outgroup to the teleosts that did not undergo this third genome duplication, was sequenced and applied as an orthology bridge to facilitate the identification of teleost orthologs to human genes and to enhance the power of teleosts as biomedical models. In this study, we apply the spotted gar orthology bridge to help describe the gene history of the vertebrate TNFAIP8 family. Members of the TNFAIP8 gene family have been linked to regulation of immune function and homeostasis and the development of multiple cancer types. Through a conserved gene synteny analysis, we identified zebrafish orthologs to human TNFAIP8L1 and TNFAIP8L3 genes and two co-orthologs to human TNFAIP8L2, but failed to identify an ortholog to human TNFAIP8. Through the application of the orthology bridge, we determined that teleost orthologs to human TNFAIP8 genes were likely lost in a genome inversion event after their divergence from their common ancestor with spotted gar. These findings demonstrate the value of this enhanced approach to gene history analysis and support the development of teleost models to study complex questions related to an array of biomedical issues, including immunity and cancer.

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.

TIPE2 Overexpression Suppresses the Proliferation, Migration, and Invasion in Prostate Cancer Cells by Inhibiting PI3K/Akt Signaling Pathway

Tumor necrosis factor-α (TNF-α)-induced protein 8-like 2 (TNFAIP8L2, TIPE2) is involved in the invasion and metastasis of human tumors. However, the functional role of TIPE2 in prostate cancer remains unclear. In the present study, we explored the role of TIPE2 in prostate cancer and cancer progression including the molecular mechanism that drives TIPE2-mediated oncogenesis. Our results showed that TIPE2 was lowly expressed in human prostate cancer tissues and cell lines. In addition, restored TIPE2 obviously inhibits proliferation in prostate cancer cells. TIPE2 overexpression also suppresses the epithelial–mesenchymal transition (EMT) process and migration/invasion in prostate cancer cells. Mechanistically, TIPE2 overexpression obviously inhibits the phosphorylation levels of phosphatidylinositol 3-kinase (PI3K) and Akt in prostate cancer cells. In conclusion, for the first time we demonstrated that TIPE2 overexpression may suppress proliferation, migration, and invasion in prostate cancer cells by inhibiting the PI3K/Akt signaling pathway. Therefore, TIPE2 might serve as a potential therapeutic target for human prostate cancer.

Gene delivery of TIPE2 inhibits breast cancer development and metastasis via CD8+ T and NK cell-mediated antitumor responses

Breast cancer is the second leading cause of cancer-related deaths in the female patients which was mainly caused by metastasis. Development of target gene therapy for breast cancer to suppress tumor progress and metastasis will improve the therapeutic options and be of great benefit to the patients. Tumor necrosis factor-alpha-induced protein 8-like 2 is a novel molecule for maintaining immune homeostasis and is involved in cancer development. In the present study, we overexpressed TIPE2 in breast cancer cells to investigate the role of TIPE2 in the development of breast cancer. Our results showed that overexpression of TIPE2 significantly inhibited the proliferation of 4T1 cells in vitro and in vivo. We constructed a non-viral targeted gene therapeutic system by using the minicircle plasmids expressing TIPE2. We found that the growth and metastasis of breast cancer was significantly inhibited by hydrodynamic gene delivery of TIPE2 plasmids in vivo. Mechanistically, TIPE2 increased T and NK cells, and decreased MDSCs. Gene delivery of TIPE2 up-regulated the production of IFN-γ and TNF-α by CD8⁺ T and NK cells in spleens and tumor microenvironment, and enhanced the cytotoxic activity of CD8⁺ T and NK cells. Taken together, TIPE2 inhibited breast cancer development and metastasis possibly via promoting CD8⁺ T and NK cell-mediated antitumor immune responses. Thus, the results indicate that TIPE2 may be a potential therapeutic target for breast cancer therapy.

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.

Upregulation of Tumor Necrosis Factor-α-Induced Protein 8-Like 2 mRNA Is Negatively Correlated with Serum Concentrations of Tumor Necrosis Factor-α and Interleukin 6 in Type 2 Diabetes Mellitus

BACKGROUND

Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a negative regulator of natural and adaptive immunity. The role of TIPE2 in type 2 diabetes mellitus (T2DM) remains unknown, although TIPE2 plays key roles in preserving inflammatory homeostasis.

METHODS

TIPE2 expression was measured by Western blotting and real-time polymerase chain reaction (RT-PCR) in peripheral blood mononuclear cells (PBMCs) isolated from T2DM patients and healthy controls, and tumor necrosis factor-α (TNF-α), high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6), and other related biometabolic parameters were detected using a nephelometer or by ELISA. Differentiated THP-1 cells were exposed to siTIPE2 and TIPE2 adenovirus.

RESULTS

TIPE2 was significantly increased in PBMCs from T2DM patients compared with those from healthy controls and was negatively correlated with serum TNF-α, IL-6, and hsCRP concentrations but positively correlated with HbA1c and LDL-C in T2DM patients. High glucose treatment (50 mmol/L) can upregulate the expression of TIPE2 and cytokine secretion in differentiated THP-1 cells. siTIPE2 infection exacerbated the increased TNF-α and IL-6 concentrations in differentiated THP-1 cells under high glucose conditions (50 mmol/L), while infection with TIPE2 adenovirus reversed the increased TNF-α concentration.

CONCLUSIONS

The present study indicates that TIPE2 may participate in T2DM by regulating TNF-α production.

Protective effect of Xuebijing injection on D-galactosamine- and lipopolysaccharide-induced acute liver injury in rats through the regulation of p38 MAPK, MMP-9 and HO-1 expression by increasing TIPE2 expression

Xuebijing injection (XBJ) has long been used to treat infectious diseases in China. The therapeutic effect of XBJ is probably associated with anti-inflammatory effects. However, the precise mechanisms responsible for the effects of XBJ remain unknown. The present study was conducted in order to evaluate the protective effects of XBJ in a rat model of D-galactosamine (D-Gal)- and lipopolysaccharide (LPS)-induced acute liver injury. In the present study, the rats were injected with D-Gal and LPS intraperitoneally to induce acute liver injury. Two hours prior to D-Gal and LPS administration, the treatment group was administered XBJ by intravenous infusion. The effects of XBJ on D-Gal- and LPS-induced expression of tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 (TIPE2), nuclear factor-κB (NF-κB), matrix metalloproteinase-9 (MMP-9) and heme oxygenase-1 (HO-1) as well as mitogen-activated protein kinase (MAPK) signaling was examined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blot analysis, immunofluorescence, as well as by analysing the serum levels of pro-inflammatory cytokines and the transaminases, alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Myeloperoxidase (MPO), malondialdehyde (MDA) and superoxide dismutase (SOD) levels in the rat liver tissues were also measured. For histological analysis, hematoxylin and eosin (H&E)-stained liver samples were evaluated. The results showed that XBJ upregulated TIPE2 and HO-1 expression, reduced the expression of NF-κB65 and MMP-9, inhibited the LPS-induced gene expression of c-jun N-terminal kinase (JNK) and p38 MAPK, decreased the generation of pro-inflammatory cytokines [interleukin (IL)-6, IL-13 and TNF-α], inhibited ALT and AST activity, and ameliorated D-Gal- and LPS-induced liver injury. The histological results also demonstrated that XBJ attenuated D-Gal- and LPS-induced liver inflammation. It was found that XBJ may prevent LPS-induced pro-inflammatory gene expression through inhibiting the NF-κB and MAPK signaling pathways by upregulating TIPE2 expression, thereby attenuating LPS-induced liver injury in rats. The marked protective effects of XBJ suggest that it has the potential to be used in the treatment of LPS-induced liver injury.

Tumor Necrosis Factor-α-Induced Protein 8-Like 2 Gene Overexpression Prolongs the Survival of Rat Allogeneic Heart Allografts

BACKGROUND

The objective of the study was to examine whether overexpression of the tumor necrosis factor-α-induced protein 8-like 2 (TNFAIP8L2; TP8L2) gene might prolong the survival of a rat heart allograft and to explore the possibility of gene-induced immune tolerance and its specific mechanisms of action in rats.

METHODS

A gene vector (AdC68) was constructed of a rat's TP8L2 gene to overexpress the TP8L2 gene in the models. The Wistar-to-Dawley rat allogeneic heart allograft models were created and randomly separated into 5 groups: control, no treatment after surgery; Fk506, treated with immune inhibitor FK506 0.5 mg/kg/d after surgery; TP8L2, treated with 0.25 × 10(9) Pfu recombinant TP8L2 adenovirus after surgery; FK506+TP8L2, treated with FK506 0.25 mg/kg/d and 0.25 × 10(9) Pfu recombinant TP8L2 adenovirus after surgery; and no-TP8L2, treated with 0.25 × 10(9) Pfu recombinant adenovirus without TP8L2 gene overexpression after surgery. We also examined whether the overexpressed TP8L2 gene can prolong the donor heart's mean survival time and detect the changes of various related indicators.

RESULTS

The survival time of the donor heart in the TP8L2 and FK506+TP8L2 groups was significantly longer than that in the remaining groups; the difference was statistically significant (P < .05). The percentage of CD4(+)CD25(+) regulatory T cells in the TP8L2 and FK506+TP8L2 groups was significantly higher than that in the remaining groups; the difference was statistically significant (P < .05). The expression of interleukin (IL)-2, tumor necrosis factor-α, and interferon-γ in the FK506+TP8L2 group was significantly lower and the expression of IL-4 and IL-10 was significantly higher than those in other groups; the differences in cytokine levels were significant (P < .05).

CONCLUSIONS

TP8L2 plays an important role in the induction of immune tolerance in heart allografts.

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.

Association between the expression levels of tumor necrosis factor-α-induced protein 8 and the prognosis of patients with gastric adenocarcinoma

The present study aimed to investigate the expression levels of tumor necrosis factor-α-induced protein 8 (TNFAIP8) in gastric adenocarcinoma. TNFAIP8 expression levels in gastric adenocarcinoma tissue samples (with and without lymph node metastasis), adjacent normal tissue samples and metastatic lymph node tissue samples were detected by immunohistochemistry. The correlation between TNFAIP8 expression levels and clinicopathological data and gastric adenocarcinoma prognosis was analyzed. The results demonstrated that TNFAIP8 expression in gastric adenocarcinoma tissue samples and metastatic lymph node tissue samples markedly increased at a rate of 47.2% (50/106) and 81.7% (49/60), respectively, as compared with the adjacent normal tissue samples in which no TNGFAIP8 expression was detected (0%). This increase in TNFAIP8 expression was statistically significant. TNFAIP8 expression rates in the primary tumors (60%, 36/60) of patients with lymph node metastasis were significantly higher compared with the primary tumors of patients without lymph node metastasis (30.4%, 14/46). TNFAIP8 expression was associated with an increase in the severity of TNM stage, tumor grade, vascular invasion, lymph node metastasis and serum CA72-4 levels. The overall survival rate of patients with gastric adenocarcinoma and high TNFAIP8 expression was poorer compared with patients with low TNFAIP8 expression, and TNFAIP8 expression was negatively correlated with patient prognosis. The results also demonstrated that TNFAIP8 was an independent prognostic marker in gastric adenocarcinoma (relative risk, 1.736; P=0.029). In conclusion, the results of the present study demonstrated that TNFAIP8 expression was associated with the occurrence, development and metastasis of gastric adenocarcinoma, and negatively correlated with the prognosis of patients with gastric adenocarcinoma. TNFAIP8 may therefore serve as a prognostic factor for gastric adenocarcinoma.