Overexpression of GILZ in macrophages limits systemic inflammation while increasing bacterial clearance in sepsis in mice

Studies support the beneficial effects of glucocorticoids (GCs) during septic shock, steering research toward the potential role of GC-induced proteins in controlling excessive inflammatory responses. GILZ is a glucocorticoid-induced protein involved in the anti-inflammatory effects of GCs. We investigated whether the overexpression of GILZ specifically limited to monocytes and macrophages (M/M) alone could control inflammation, thus improving the outcome of septic shock in animal models. We also monitored the expression of GILZ in M/M from septic mice and septic-shock patients. M/M from patients and septic mice displayed significantly lower expression of GILZ than those isolated from controls. Furthermore, transgenic mice (Tg-mice) experiencing sepsis, with increased expression of GILZ restricted to M/M, showed lower frequencies of inflammatory monocytes than their littermates and lower plasma levels of inflammatory cytokines. Tg-mice also had lower blood bacterial counts. We further established that the upregulation of GILZ in M/M enhanced their phagocytic capacity in in vivo assays. The increase of GILZ in M/M was also sufficient to improve the survival rates of septic mice. These results provide evidence for a central role of both GILZ and M/M in the pathophysiology of septic shock and a possible clue for the modulation of inflammation in this disease.

Polymorphic UHRF1BP1 drives superior anti-tumor immunity in ovarian cancer

Despite the emergence of immunotherapy for the treatment of cancer, many of the fundamental mechanisms which characterize tumors that are amenable to immunotherapy and/or drive superior endogenous anti-tumor immune responses likely remain uncharacterized. We have identified a single-nucleotide polymorphism, rs13205210, in the gene encoding UHRF1BP1 (UBP). This polymorphism is associated with a dramatic survival benefit in ovarian cancer patients. The function of the protein encoded by this gene remains elusive, however we demonstrate UBP-ablated ovarian tumor cells display global modulation of methylated cytosine, suggesting it has a role as an epigenetic integrator. Interestingly, this polymorphism is also associated with systemic lupus erythematosus, an immune-driven pathology. Accordingly, we demonstrate that human ovarian tumors with polymorphic UBP display increased frequency of activated CD8+ T cells, as well as a type I IFN signature. In vivo, inducible autochthonous murine ovarian tumors driven by oncogenic Kras and ablation of p53, in which UBP was conditionally deleted, demonstrated a significantly enhanced overall survival with a concomitant type I IFN and CXCR3-chemokine signature, as well as an enhanced T cell infiltrate compared to controls. RNA-seq analyses of UBP-deficient ovarian tumors revealed an elevation of inflammatory cytokines and the activation of canonical inflammatory pathways. Furthermore, ectopic expression of polymorphic human UBP in ovarian tumor cells drove elevated NF-kB signaling under inflammatory conditions. Overall our work suggests that UBP functions as a regulator of inflammation, which is unleashed in the polymorphic variant leading to enhanced anti-tumor immunity.

Frontline Science: Microbiota reconstitution restores intestinal integrity after cisplatin therapy

Due to their cytotoxic activities, many anticancer drugs cause extensive damage to the intestinal mucosa and have antibiotic activities. Here, we show that cisplatin induces significant changes in the repertoire of intestinal commensal bacteria that exacerbate mucosal damage. Restoration of the microbiota through fecal-pellet gavage drives healing of cisplatin-induced intestinal damage. Bacterial translocation to the blood stream is correspondingly abrogated, resulting in a significant reduction in systemic inflammation, as evidenced by decreased serum IL-6 and reduced mobilization of granulocytes. Mechanistically, reversal of dysbiosis in response to fecal gavage results in the production of protective mucins and mobilization of CD11b+ myeloid cells to the intestinal mucosa, which promotes angiogenesis. Administration of Ruminococcus gnavus, a bacterial strain selectively depleted by cisplatin treatment, could only partially restore the integrity of the intestinal mucosa and reduce systemic inflammation, without measurable increases in the accumulation of mucin proteins. Together, our results indicate that reconstitution of the full repertoire of intestinal bacteria altered by cisplatin treatment accelerates healing of the intestinal epithelium and ameliorates systemic inflammation. Therefore, fecal microbiota transplant could paradoxically prevent life-threatening bacteremia in cancer patients treated with chemotherapy.

Glucocorticoid-Induced Leucine Zipper Protein Controls Macropinocytosis in Dendritic Cells

Ag sampling is a key process in dendritic cell (DC) biology. DCs use constitutive macropinocytosis, receptor-mediated endocytosis, and phagocytosis to capture exogenous Ags for presentation to T cells. We investigated the mechanisms that regulate Ag uptake by DCs in the steady-state and after a short-term LPS exposure in vitro and in vivo. We show that the glucocorticoid-induced leucine zipper protein (GILZ), already known to regulate effector versus regulatory T cell activation by DCs, selectively limits macropinocytosis, but not receptor-mediated phagocytosis, in immature and recently activated DCs. In vivo, the GILZ-mediated inhibition of Ag uptake is restricted to the CD8α⁺ DC subset, which expresses the highest GILZ level among splenic DC subsets. In recently activated DCs, we further establish that GILZ limits p38 MAPK phosphorylation, providing a possible mechanism for GILZ-mediated macropinocytosis control. Finally, our results demonstrate that the modulation of Ag uptake by GILZ does not result in altered Ag presentation to CD4 T cells but impacts the efficiency of cross-presentation to CD8 T cells. Altogether, our results identify GILZ as an endogenous inhibitor of macropinocytosis in DCs, the action of which contributes to the fine-tuning of Ag cross-presentation.