HSP90 is secreted by cancer cells into the extracellular milieu, where it exerts protumoral activities by activating extracellular substrate proteins and triggering autocrine signals through cancer cell surface receptors. Emerging evidence indicates that HSP90 co-chaperones are also secreted and may direct HSP90 extracellular activities. In this study, we found that the HSP90 co-chaperone Morgana is released by cancer cells and, in association with HSP90, induces cancer cell migration through TLR2, TLR4, and LRP1. In syngeneic cancer mouse models, a mAb targeting Morgana extracellular activity reduced primary tumor growth via macrophage-dependent recruitment of CD8+ T lymphocytes, blocked cancer cell migration, and inhibited metastatic spreading. Overall, these data define Morgana as a new player in the HSP90 extracellular interactome and suggest that Morgana may regulate HSP90 activity to promote cancer cell migration and suppress antitumor immunity.Significance: This work suggests the potential therapeutic value of targeting the extracellular HSP90 co-chaperone Morgana to inhibit metastasis formation and enhance the CD8+ T-cell–mediated antitumor immune response.

Damage-associated molecular patterns (DAMPs) are endogenous molecules activating the immune system upon release from injured cells. Here we show that the IFI16 protein, once freely released in the extracellular milieu of chronically inflamed tissues, can function as a DAMP either alone or upon binding to lipopolysaccharide (LPS). Specifically, using pull-down and saturation binding experiments, we show that IFI16 binds with high affinity to the lipid A moiety of LPS. Remarkably, IFI16 DAMP activity is potentiated upon binding to subtoxic concentrations of strong TLR4-activating LPS variants, as judged by TLR4-MD2/TIRAP/MyD88-dependent IL-6, IL-8 and TNF-α transcriptional activation and release in stimulated monocytes and renal cells. Consistently, using co-immunoprecipitation (co-IP) and surface plasmon resonance (SPR) approaches, we show that IFI16 is a specific TLR4-ligand and that IFI16/LPS complexes display a faster stimulation turnover on TLR4 than LPS alone. Altogether, our findings point to a novel pathomechanism of inflammation involving the formation of multiple complexes between extracellular IFI16 and subtoxic doses of LPS variants, which then signal through TLR4. IFI16 is a nuclear protein involved in a variety of physiological processes, including cell cycle regulation, tumor suppression, and virus sensing. Emerging evidence indicates that IFI16 is released in the extracellular milieu under injury or stress conditions. Here we show that extracellular IFI16 acts as a damage-associated molecular pattern (DAMP), triggering inflammation through Toll-like receptor 4 (TLR4) activation. Furthermore, we demonstrate that IFI16 activity is potentiated upon binding to subtoxic concentrations of strong TLR4-activating lipopolysaccharide (LPS) variants, which are known to be present in various pathological settings other than gram-negative infections. Our study provides new insights into the role of extracellular IFI16 during low-grade endotoxemia.

Human cytomegalovirus (HCMV) is an opportunistic pathogen causing severe diseases in immunosuppressed individuals. To replicate its double-stranded DNA genome, HCMV induces profound changes in cellular homeostasis that may resemble senescence. However, it remains to be determined whether HCMV-induced senescence contributes to organ-specific pathogenesis. Here, we show a direct cytopathic effect of HCMV on primary renal proximal tubular epithelial cells (RPTECs), a natural setting of HCMV disease. We find that RPTECs are fully permissive for HCMV replication, which endows them with an inflammatory gene signature resembling the senescence-associated secretory phenotype (SASP), as confirmed by the presence of the recently established SenMayo gene set, which is not observed in retina-derived epithelial (ARPE-19) cells. Although HCMV-induced senescence is not cell-type specific, as it can be observed in both RPTECs and human fibroblasts (HFFs), only infected RPTECs show downregulation of LAMINB1 and KI67 mRNAs, and enhanced secretion of IL-6 and IL-8, which are well-established hallmarks of senescence. Finally, HCMV-infected RPTECs have the ability to trigger a senescence/inflammatory loop in an IL-6-dependent manner, leading to the development of a similar senescence/inflammatory phenotype in neighboring uninfected cells. Overall, our findings raise the intriguing possibility that this unique inflammatory loop contributes to HCMV-related pathogenesis in the kidney.

The gut virome is a complex community that exists in equilibrium with the host. Disruptions of this balance could drive the development of inflammatory diseases, such as inflammatory bowel disease (IBD). RNA editing, particularly A‐to‐I editing by ADAR1, prevents the excessive immune response to viral double strand (ds) RNA. Failure of RNA editing may sustain inflammation and this study explore the role of ADAR1 in IBD. ADAR1 was analyzed in IBD patients and healthy controls (CTR) using western blotting and qPCR. Colonic epithelial cells (HCEC‐1CT), ex vivo organ cultures, and colonic organoids were treated poly I:C after ADAR1 silencing with an antisense oligonucleotide (AS). Inflammatory pathways and PANoptosome were measured by western blotting, flow cytometry, and ELISA. The role of ADAR1 was also studied in DSS‐colitis model. ADAR1 was significantly reduced in the inflamed epithelium of ulcerative colitis (UC) gut samples. ADAR1 silencing in HCEC‐1CT, ex vivo organ cultures or colonic organoids strongly increases the immune response to poly I:C and leads to activation of inflammatory pathways and PANoptosis. Inhibition of gut ADAR1 expression during DSS‐colitis exacerbated gut inflammation. JAK inhibition or AhR activation mitigated the immune response that follows ADAR1 silencing. These data suggest that ADAR1 could be involved in IBD inflammation.

Taurine is a semi-essential micronutrient that acts as an anti-inflammatory molecule. The oral administration of taurine to colitic mice attenuates ongoing mucosal inflammation. This study aimed to determine whether inflammatory bowel diseases (IBDs) are marked by changes in the circulating levels of taurine. We measured the serum concentrations of taurine in 92 IBD patients [46 with ulcerative colitis (UC) and 46 with Crohn’s disease (CD)] and 33 healthy controls with a commercial ELISA kit. The taurine levels were significantly decreased in both patients with UC and patients with CD compared to the controls, while there was no difference between CD and UC. Taurine levels declined with age in healthy controls but not in IBDs. IBD patients younger than 50 years had levels of taurine reduced compared to their age-matched controls. In the IBD group, taurine levels were not influenced by the body mass index of the patients and the consumption of taurine-rich nutrients, while they were significantly reduced in UC patients with clinically active disease compared to those in clinical remission. These findings indicate that IBDs are marked by serum taurine deficiency, which would seem to reflect the activity of the disease, at least in UC.

The reorganization of the cell cytoskeleton and changes in the content of cell adhesion molecules are crucial during the metastatic spread of tumor cells. Colorectal cancer (CRC) cells express high SMAD7, a protein involved in the control of CRC cell growth. In the present study, we evaluated whether SMAD7 regulates the cytoskeleton reorganization and dynamics in CRC. Knockdown of SMAD7 with a specific antisense oligonucleotide (AS) in HCT116 and DLD1, two human CRC cell lines, reduced the migration rate and the content of F-ACTIN filaments. A gene array, real-time PCR, and Western blotting of SMAD7 AS-treated cells showed a marked down-regulation of the X-linked inhibitor of apoptosis protein (XIAP), a member of the inhibitor of apoptosis family, which has been implicated in cancer cell migration. IL-6 and IL-22, two cytokines that activate STAT3, enhanced XIAP in cancer cells, and such induction was attenuated in SMAD7-deficient cells. Finally, in human CRC, SMAD7 mRNA correlated with XIAP expression. Our data show that SMAD7 positively regulates XIAP expression and migration of CRC cells, and suggest a mechanism by which SMAD7 controls the architecture components of the CRC cell cytoskeleton.