Trappc1 intrinsically prevents ferroptosis of naive T cells to avoid spontaneous autoinflammatory disease in mice.

T lymphocytes are pivotal in adaptive immunity. The role of the trafficking protein particle complex (TRAPPC) in regulating T-cell development and homeostasis is unknown. Using CD4cre -Trappc1flox/flox (Trappc1 cKO) mice, we found that Trappc1 deficiency in T cells significantly decreased cell number of naive T cells in the periphery, whereas thymic T-cell development in Trappc1 cKO mice was identical as WT mice. In the culture assays and mouse models with adoptive transfer of the sorted WT (CD45.1+ CD45.2+ ) and Trappc1 cKO naive T cells (CD45.2+ ) to CD45.1+ syngeneic mice, Trappc1-deficient naive T cells showed significantly reduced survival ability compared with WT cells. RNA-seq and molecular studies showed that Trappc1 deficiency in naive T cells reduced protein transport from the endoplasmic reticulum to the Golgi apparatus, enhanced unfolded protein responses, increased P53 transcription, intracellular Ca2+ , Atf4-CHOP, oxidative phosphorylation, and lipid peroxide accumulation, and subsequently led to ferroptosis. Trappc1 deficiency in naive T cells increased ferroptosis-related damage-associated molecular pattern molecules like high mobility group box 1 or lipid oxidation products like prostaglandin E2, leukotriene B4, leukotriene C4, and leukotriene D4. Functionally, the culture supernatant of Trappc1 cKO naive T cells significantly promoted neutrophils to express inflammatory cytokines like TNFα and IL-6, which was rescued by lipid peroxidation inhibitor Acetylcysteine. Importantly, Trappc1 cKO mice spontaneously developed severe autoinflammatory disease 4 weeks after birth. Thus, intrinsic expression of Trappc1 in naive T cells plays an integral role in maintaining T-cell homeostasis to avoid proinflammatory naive T-cell death-caused autoinflammatory syndrome in mice. This study highlights the importance of the TRAPPC in T-cell biology.

Absence of TSC1 Accelerates CD8+ T cell-mediated Acute Cardiac Allograft Rejection.

Tuberous sclerosis complex (TSC) is an autosomal dominant disease caused by inactivating mutations in TSC1 or TSC2.Patients with TSC often require organ transplantation after organ failure. TSC1 serves as an important control node in immune cell development and responses; however, its effect on T cells in transplant immunity has not yet been explored. Here, we characterized the effect of TSC1 deficiency in T cells on acute allograft rejection using a mouse cardiac transplantation model. We observed compromised allograft survival in mice with TSC1-deficient T cells. Notably, the allografts in mice transferred with TSC1-deficient CD8+T cells showed accelerated acute allograft rejection. TSC1 deficiency triggered the increased accumulation of CD8+ T cells in allografts due to augmented infiltration caused by increased CXCR3 expression levels and elevated in-situ proliferation of TSC1-deficient CD8+ T cells. Compared to CD8+ T cells from wild-type (WT) mice, TSC1-deficient CD8+ T cells exhibited enhanced cell proliferation and increased expression levels of interferon-γ and granzyme B after alloantigen stimulation. Rapamycin, an inhibitor of mammalian target of rapamycin (mTOR), is used to treat patients with TSC and prevent rejection after solid-organ transplantation. Although rapamycin induced most cardiac allografts to survive beyond 100 d in WT mice, rapamycin-treated cardiac allografts in TSC1-deficient mice were rejected within 60 d. These results suggest that TSC1-deficient recipients may be more resistant to rapamycin-mediated immunosuppression during organ transplantation. Collectively, TSC1 significantly accelerates acute allograft rejection by enhancing the alloreactivity of CD8+ T cells, making them more resistant to mTOR inhibitor-mediated immunosuppression.

Skin and heart allograft rejection solely by long-lived alloreactive TRM cells in skin of severe combined immunodeficient mice.

Whether induced tissue-resident memory T (TRM) cells in nonlymphoid organs alone can mediate allograft rejection is unknown. By grafting alloskin or heart into severe combined immunodeficient or Rag2KO mice in which a piece of induced CD4+ and/or CD8+ TRM cell-containing MHC-matched or syngeneic skin was transplanted in advance, we addressed this issue. The induced CD4+ TRM cells in the skin alone acutely rejected alloskin or heart grafts. RNA-seq analysis showed that induced CD4+ TRM cells in skin favorably differentiated into TH17-like polarization during the secondary immune response. Inhibition of the key TH17 signaling molecule RORγt attenuated TRM cell-mediated graft rejection. Thus, we offer a unique mouse model to specifically study TRM cell-mediated allograft rejection without the involvement of lymphocytes in lymphoid organs and tissues. Our study provides strong evidence supporting the hypothesis that long-lived alloreactive TRM cells resident in other organs/tissues substantially contribute to organ allograft rejection.

Skills to Perform Vessel Eversion in Mouse Cervical Cardiac Transplantation with Cuff Technique.

INTRODUCTION: The mouse heterotopic cardiac transplant model has been extensively used to explore transplant immunity. Although the cuff technique facilitates the operation, the procedure remains difficult, and vessel eversion is the most difficult step. Cuff movement and everted vessel wall slippage are the main adverse factors in vessel eversion. Traditional strategies to prevent these factors focus on cuff fixation, while more steps or surgical instruments would be required. METHODS: According to the reported protocols and our experience, the vessel eversion skills were modified and used for transplantation. Cardiac grafts from C57BL/6(H-2b) or BALB/c(H-2d) mice were transplanted into C57BL/6(H-2b) mice. The operating times of recent 90 operations, which were divided into 9 groups according to their sequence, were summarized and analyzed. RESULTS: The mouse cervical cardiac transplantation was successfully performed by using the modified vessel eversion skills. The cuff movement, which is the most important adverse factor to prevent vessel eversion, was effectively prevented. In the recent 90 operations, the total operating time was 47.3±7.9 min and the success rate was 98%. CONCLUSIONS: The modified surgical skills simplify the vessel eversion in mouse cervical cardiac transplantation with cuff technique, characterized by less cuff movement, fewer steps, and surgical instruments. Using these surgical skills, the transplant can be performed in a short time.

The biological function and the regulatory roles of wild-type p53-induced phosphatase 1 in immune system.

Wild-type p53-induced phosphatase 1 (WIP1) belongs to the protein phosphatase 2C (PP2C) family and is a mammalian serine/threonine specific protein phosphatase to dephosphorylate numerous signaling molecules. Mammalian WIP1 regulates a wide array of targeting molecules and plays key regulatory roles in many cell processes such as DNA damage and repair, cell proliferation, differentiation, apoptosis, and senescence. WIP1 promotes the formation and development of tumors as an oncogene and a negative regulator of p53. It is also involved in the regulation of aging, neurological diseases and immune diseases. Recent studies demonstrated the critical roles of WIP1 in the differentiation and function of immune cells including T cells, neutrophils and macrophages. In the present manuscript, we briefly summarized the expression patterns, biological function and the target molecules and signal pathways of WIP1 and mainly discussed the latest advances on the regulatory effects of WIP1 in the immune system. WIP1 may be a potential target molecule to treat cancers and immune diseases such as allergic asthma.