TIPE2-Regulated ER-Phagy in Dendritic Cell Function Following Hemorrhagic Shock.

Hemorrhagic shock induces immune dysfunction via mesenteric lymph return, leading to systemic inflammatory response and multiple organ dysfunction. Dendritic cells (DCs) play a pivotal role in immune response following hemorrhagic shock. Therefore, identifying regulatory targets within DCs is essential for understanding hemorrhagic shock-induced immune dysfunction. Endoplasmic reticulum (ER) autophagy (ER-phagy), a selective form of autophagy, is critical for DC function. Here, we investigated the role of tumor necrosis factor-α-induced protein-8-like 2 (TIPE2), a protein known to regulate autophagy, in modulating DC ER-phagy after hemorrhagic shock. We analyzed the function and ER-phagy in splenic DCs from wild-type (WT) mice following hemorrhagic shock in vivo and DCs stimulated with posthemorrhagic shock mesenteric lymph (PHSML) in vitro . Our results showed an increased number of autophagosomes containing ER structures, with significantly enhanced colocalization between ER and autophagosomes in DCs during hemorrhagic shock. The proliferation of CD4 + T cells co-cultured with DCs was weakened, and the expression of surface molecules on the DCs was significantly increased after stimulation with PHSML. Subsequently, WT, TIPE2 -/- , and TIPE2 +/+ mice were used to further analyze the correlation between TIPE2 and ER-phagy in the context of hemorrhagic shock. The results demonstrated that under hemorrhagic shock conditions, TIPE2 -/- mice exhibited a significantly reduced microtubule-associated protein 1 light chain 3 (LC3)-II/I ratio and elevated SEC61 translocon subunit β (SEC61B) expression in the spleen tissue compared with WT mice, suggesting a diminished level of ER-phagy. Conversely, TIPE2 +/+ mice showed the opposite changes. Following stimulation with PHSML, the findings revealed a marked increase in the colocalization between ER and autophagosomes and a significant inhibition of DC function compared to the control group. Additionally, the deletion of TIPE2 weakened ER-phagy and decreased the inhibitory effect on DC function. In contrast, the overexpression of TIPE2 further enhanced ER-phagy and intensified the inhibition of DC function. In addition, TIPE2 is involved in the regulation of the nonclassical ER-phagy receptor tripartite motif 13 expression. These results suggest that ER-phagy is enhanced in DCs after hemorrhagic shock and that TIPE2 may regulate ER-phagy and DC function via tripartite motif 13. This research provides a theoretical basis for future clinical therapeutic strategies targeting the regulation of ER-phagy to improve the function of DCs.