Background: Programmed death-ligand 1 (PD-L1) contributes to the immune escape of tumor cells and is a critical target for antitumor immunotherapy. However, the molecular mechanisms regulating PD-L1 expression remain unclear, hindering the development of effective therapies. Here we investigate the role and molecular mechanism of the core clock gene Period2 (PER2) in regulating PD-L1 expression and its role in the combination therapy of oral squamous cell carcinoma (OSCC). Methods: Quantitative real-time PCR, western blotting or immunohistochemistry to detect expression of PER2 and PD-L1 in OSCC tissues and cells. Overexpression and knockdown of PER2 detects the function of PER2. Bioinformatics, immunoprecipitation, GST pull-down, CHX chase assay and western blot and strip to detect the mechanism of PER2 regulation for PD-L1. A humanized immune reconstitution subcutaneous xenograft mouse model was established to investigate the combination therapy efficacy. Results: In OSCC tissues and cells, PER2 expression was reduced and PD-L1 expression was increased, the expression of PER2 was significantly negatively correlated with PD-L1. In vitro and in vivo experiments demonstrated that PER2 inhibited PD-L1 expression and enhanced T-cell-mediated OSCC cell killing by suppressing the IKK/NF-κB pathway. Mechanistically, PER2 binds to heat shock protein 90 (HSP90) through the PAS1 domain and reduces the interaction of HSP90 with inhibitors of kappa B kinase (IKKs), promoting the ubiquitination of IKKα/β and p65 nuclear translocation to inhibit IKK/NF-κB pathway, thereby suppressing PD-L1 expression. In humanized immune reconstitution subcutaneous xenograft mouse model, it was demonstrated that PER2 targeting combined with anti-PD-L1 treatment improved the inhibition of OSCC growth by promoting CD8⁺ T-cell infiltration into the tumor. Conclusions: Our findings reveal the role and mechanism of PD-L1 regulation by PER2 and support the potential clinical application of PER2 targeting in combination with anti-PD-L1 in OSCC immunotherapy.

Purpose. Previous studies have demonstrated that immune and inflammatory factors play an important role in recurrent seizures. The PD‐1‐PD‐L pathway plays a central and peripheral immunosuppressive role by regulating multiple signaling pathways during the inflammatory and immunologic processes. This study is aimed at assessing PD‐1 levels in cerebrospinal fluid (CSF) and serum samples from patients with intractable epilepsy. Methods. PD‐1 levels were assessed in CSF and serum samples from 67 patients with intractable epilepsy (41 and 26 individuals with partial seizure and intractable status epilepticus, respectively) and 25 healthy controls, using flow cytometric analysis and sandwich enzyme‐linked immunosorbent assays (ELISA). Results. Serum‐PD‐1+CD4⁺CD25^high Treg levels in the experimental groups and the control group were 10.26 ± 2.53 (PS group), 35.95 ± 27.51 (ISE group), and 4.69 ± 2.44 (control group). In addition, CSF‐PD‐1 level in patients with epilepsy was higher than that in the control group (50.45 ± 29.56 versus 19.37 ± 4.51), indicating a statistically significant difference (P < 0.05). Interestingly, serum‐ and CSF‐PD‐1 levels in individuals with epilepsy were not affected by antiepileptic drug and treatment course, but by epilepsy onset level. Of note, the increase of CSF‐ and serum‐PD‐1 levels was more pronounced in subjects with intractable status epilepticus than those with partial seizure. Conclusion. Serum‐ and CSF‐PD‐1 levels constitute a potential clinical diagnostic biomarker for intractable epilepsy and could also be used for differential diagnosis.

Bacterial pneumonia is a common serious infectious disease with high morbidity and mortality. Prokineticin 2 (PK2) has recently been identified as a novel immunomodulator in a variety of diseases; however, its role in bacterial pneumonia remains unclear. The levels of PK2 were measured and analyzed in patients with pneumonia and healthy controls. The effects of PK2 on the host response to pneumonia were evaluated by in vivo animal experiments and in vitro cell experiments. PK2 levels dramatically decreased in patients with pneumonia compared with healthy controls, and PK2 levels were lower in patients with severe pneumonia than in pneumonia. In a mouse model of bacterial pneumonia, transtracheal administration of recombinant PK2 significantly alleviated lung injury and improved the survival, which was associated with increased host's bacterial clearance capacity, as manifested by decreased pulmonary bacterial loads. PK2 enhanced the chemotaxis, phagocytosis, and killing ability of macrophages, whereas the protective efficacy of PK2 was abolished after macrophage depletion. Impaired alveolar macrophage function caused by decreased PK2 is a new endogenous cause of the occurrence and development of bacterial pneumonia. The administration of recombinant PK2 may be a potential adjuvant therapy for bacterial pneumonia.

The persistent challenge of sepsis-related mortality underscores the necessity for deeper insights. Our multicenter, cross-age cohort study identified insulin-like growth factor binding protein 6 (IGFBP6) as a critical regulator in sepsis diagnosis, prognosis, and mortality risk evaluation. Mechanistically, IGFBP6 engages in IGF-independent binding to prohibitin2 (PHB2) on epithelial cells, driving PHB2 tyrosine phosphorylation during sepsis. This process disrupts STAT1 phosphorylation, nuclear translocation, and its recruitment to the CCL2 promoter, ultimately impairing CCL2 transcription and macrophage chemotaxis. Crucially, PHB2 silencing via siPHB2 and STAT1 activation using 2-NP restored CCL2 expression in vitro and in vivo, improving bacterial clearance and survival in septic mice. Concurrently, IGFBP6 compromised macrophage bactericidal activity by inhibiting Akt phosphorylation, reducing ROS/IL-1β production and phagocytic capacity — defects reversible by Akt agonist SC79. Collectively, IGFBP6 emerges as an endogenous driver of sepsis pathogenesis, positioning it as a dual diagnostic biomarker and therapeutic target. Intervention strategies targeting IGFBP6-mediated signaling may offer transformative approaches for sepsis management.

The immune checkpoint pathway PD-1/PD-L, known for its role in immunosuppression via regulatory T cells (Tregs) and inflammatory signaling, is implicated in the neuroinflammation of drug-refractory epilepsy (DRE). Given the emerging importance of immune dysregulation in epilepsy, identifying immune-related biomarkers may improve diagnosis and guide treatment strategies. This study aimed to evaluate the potential of PD-1 as a diagnostic biomarker in the cerebrospinal fluid (CSF) and plasma and to investigate whether the therapeutic effect of valproic acid (VPA) in intractable status epilepticus (ISE) is mediated through immunomodulation. A cohort of 74 patients with DRE (46 with partial seizures (PS) and 28 with ISE) and 25 healthy controls was enrolled. PD-1 levels in CSF and plasma were quantified by flow cytometry and ELISA. In a VPA-treatment sub-study of 25 ISE patients, serial samples were analyzed for PD-1⁺CD4⁺CD25^high Tregs and cytokine (IL-10/IL-6) levels at baseline (d0) and after 48 h (d3). VPA concentrations were determined by LC-MS/MS. Significantly elevated PD-1 levels were observed in both plasma and CSF of epilepsy patients compared to controls, with the highest levels in the ISE subgroup. IL-10 and IL-6 levels were also elevated in intractable epilepsy (IE) patients compared to controls. Critically, clinical improvement was associated with a reduction in PD-1⁺ Tregs at d3, whereas VPA concentrations did not correlate with treatment response. These findings reveal a compartmentalized immune response, with peripheral immunosuppression and localized CNS immune activation in IE. These findings identify PD-1 as a promising immune-inflammatory biomarker for DRE and its severe forms. Moreover, they suggest that the efficacy of VPA in ISE is mediated through the modulation of the PD-1 pathway and related cytokines, rather than a direct concentration-dependent pharmacological effect.