Tumor Necrosis Factor-α-Induced Protein 8-like 2 Downregulation Reduces CD4⁺ T Lymphocyte Apoptosis in Mice with Thermal Injury

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.

Researches on cognitive sequelae of burn injury: Current status and advances

Burn injury is a devastating disease with high incidence of disability and mortality. The cognitive dysfunctions, such as memory defect, are the main neurological sequelae influencing the life quality of burn-injured patients. The post-burn cognitive dysfunctions are related to the primary peripheral factors and the secondary cerebral inflammation, resulting in the destruction of blood-brain barrier (BBB), as is shown on Computed Tomography (CT) and magnetic resonance imaging examinations. As part of the neurovascular unit, BBB is vital to the nutrition and homeostasis of the central nervous system (CNS) and undergoes myriad alterations after burn injury, causing post-burn cognitive defects. The diagnosis and treatment of cognitive dysfunctions as burn injury sequelae are of great importance. In this review, we address the major manifestations and interventions of post-burn cognitive defects, as well as the mechanisms involved in memory defect, including neuroinflammation, destruction of BBB, and hormone imbalance.

EGFR promotes the apoptosis of CD4+ T lymphocytes through TBK1/Glut1 induced Warburg effect in sepsis

INTRODUCTION

Sepsis-induced apoptosis leads to lymphopenia including the decrease of CD4⁺ T cells thus favoring immunosuppression.

OBJECTIVES

Although epidermal growth factor receptor (EGFR) inhibitors significantly improve the survival rate of septic mice, the effect of EGFR on the function and metabolism of CD4⁺ T cells in sepsis remained unknown.

METHODS

CD4⁺ T cells from septic mice and patients were assessed for apoptosis, activation, Warburg metabolism and glucose transporter 1 (Glut1) expression with or without the interference of EGFR activation.

RESULTS

EGFR facilitates CD4⁺ T cell activation and apoptosis through Glut1, which is a key enzyme that controls glycolysis in T cells. EGFR, TANK binding kinase 1 (TBK1) and Glut1 form a complex to facilitate Glut1 transportation from cytoplasm to cell surface. Both the levels of membrane expression of EGFR and Glut1 and the activation levels of CD4⁺ T cells were significantly higher in patients with sepsis as compared with healthy subjects.

CONCLUSION

Our data demonstrated that through its downstream TBK1/Exo84/RalA protein system, EGFR regulates Glut1 transporting to the cell surface, which is a key step for inducing the Warburg effect and the subsequent cellular activation and apoptosis of CD4⁺ T lymphocytes and may eventually affect the immune functional status, causing immune cell exhaustion in sepsis.

TLR2/TLR4-Enhanced TIPE2 Expression Is Involved in Post-Hemorrhagic Shock Mesenteric Lymph-Induced Activation of CD4+T Cells

Purpose

Post hemorrhagic shock mesenteric lymph (PHSML) return contributes to CD4+ T cell dysfunction, which leads to immune dysfunction and uncontrolled inflammatory response. Tumor necrosis factor α induced protein 8 like-2 (TIPE2) is one of the essential proteins to maintain the immune homeostasis. This study investigated the role of TIPE2 in regulation of CD4+ T lymphocyte function in interaction of PHSML and TLR2/TLR4.

Methods

The splenic CD4+ T cells were isolated from various mice (WT, TLR2-/-, TLR4-/-) by immunomagnetic beads, and stimulated with PHSML, normal lymphatic fluid (NML), respectively. Application of TIPE2-carrying interfering fragments of lentivirus were transfected to WT, TLR4-/-, and TLR2-/- CD4+ T cells, respectively. After interference of TIPE2, they were stimulated with PHSML and NML for the examinations of TIPE2, TLR2, and TLR4 mRNA expressions, proliferation, activation molecules on surface, and cytokine secretion function.

Results

PHSML stimulation significantly upregulated TIPE2, TLR2, and TLR4 mRNA expressions, decreased proliferation, CD25 expression, and IFN-γ secretion, and increased the secretion ability of IL-4 in WT CD4+ T cells. TIPE2 silencing enhanced proliferative capacity, upregulated CD25 expression, and increased IFNγ secretion in CD4+ T cells. PHSML stimulated TLR2-/-CD4+ T or TLR4-/-CD4+ T cells of which TIPE2 were silenced. TLR2 or TLR4 knockout attenuated PHSML-induced CD4+ T cells dysfunction; PHSML stimulation of silent TIPE2-expressing TLR2-/-CD4+ T or TLR4-/-CD4+ T revealed that the coexistence of low TIPE2 expression with lack of TLR2 or TLR4 eliminated this beneficial effect.

Conclusion

TIPE2 improves the PHSML-mediated CD4+T cells dysfunction by regulating TLR2/TLR4 pathway, providing a new intervention target following hemorrhagic shock-induced immune dysfunction.

TNF-α-induced protein 8-like 2 negatively regulates the immune function of dendritic cells by suppressing autophagy via the TAK1/JNK pathway in septic mice

Tumor necrosis factor (TNF)-α-induced protein 8-like 2 (TIPE2) is a newly discovered negative immunoregulatory protein that is involved in various cellular immune responses to infections. However, the underlying mechanism by which TIPE2 affects the immune function of dendritic cells (DCs) is not yet understood. This study aimed to determine the correlations among DCs TIPE2 expression, autophagic activity and immune function in the context of sepsis. In addition, the signaling pathway by which TIPE2 regulates autophagy in DCs was investigated. We reported for the first time that TIPE2 overexpression (knock-in, KI) exerted an inhibitory effect on autophagy in DCs and markedly suppressed the immune function of DCs upon septic challenge both in vitro and in vivo. In addition, TIPE2 knockout (KO) in DCs significantly enhanced autophagy and improved the immune response of DCs in sepsis. Of note, we found that the transforming growth factor-β (TGF-β)-activated kinase-1 (TAK1)/c-Jun N-terminal kinase (JNK) pathway was inhibited by TIPE2 in DCs, resulting in downregulated autophagic activity. Collectively, these results suggest that TIPE2 can suppress the autophagic activity of DCs by inhibiting the TAK1/JNK signaling pathway and further negatively regulate the immune function of DCs in the development of septic complications.

TIPE2-modified human amnion-derived mesenchymal stem cells promote the efficacy of allogeneic heart transplantation through inducing immune tolerance

Background

Immune rejection of heart transplantation has been regarded as the biggest challenge encountered by a patient suffering from end-stage heart disease. The transplantation of human amnion-derived mesenchymal stem cells (hAD-MSCs) has exhibited promising application prospects in organ transplantation. However, its persistent unsatisfactory tolerance has limited the widespread application of this technology. We aim to investigate the role of tumor necrosis factor-α-induced protein-8 like-2 (TIPE2)-mediated hAD-MSCs in immune tolerance in heart transplantation and its molecular regulatory mechanisms.

Methods

This project detected the effect of TIPE2 on immune tolerance by constructing an allogeneic heart transplantation mouse model through which TIPE2-overexpressed hAD-MSCs were injected into recipients. The fluorescence distribution of TIPE2-hAD-MSCs in mice was observed by a small animal in vivo imaging system. Pathological changes of the transplanted heart were detected by hematoxylin and eosin (HE) staining. Flow cytometry was performed to detect the content of cardiac lymphocytes. The expression of immune-induced related factors was measured by quantitative real-time PCR (qRT-PCR) and western blot assays.

Results

TIPE2-hAD-MSCs protected myocardial tissue structures, reduced the spleen and thymus indexes in recipient mice, minimized the content of cardiac lymphocytes, reduced expressions of ERK, p38, and IFN-γ, and elevated expressions of both IL-10 and TGF-β, markedly improving the survival time and survival rates of recipient mice.

Conclusions

TIPE2-hAD-MSCs induce immune tolerance and improve the survival rates of allogeneic heart transplantation in mice. This study is expected to offer an ideal source and target of cells for organ transplantation.