Constitutive Expression of Functionally Active Protease-Activated Receptors 1 and 2 in Human Conjunctival Epithelial Cells

Protease-activated receptors (PARs) are G-protein-coupled receptors which initiate inflammatory responses when activated by specific serine proteases. This study was conducted to examine whether human conjunctival epithelial cells (HCECs) express functionally active PAR1 and PAR2 using Chang conjunctival epithelial cells as in vitro model. We performed RT-PCR and immunofluorescence analyses to determine the expression of PAR1 and PAR2, and monitored the production of IL-6 after activating HCECs with PAR1 activating agents (thrombin or TFLLRN) or PAR2 activating agents (tryptase, trypsin, or SLIGKV). The results show that HCECs constitutively express PAR1 and PAR2 mRNA and proteins, and produce significant amounts of IL-6 when incubated with specific PAR-activating enzymes or agonist peptides. Thrombin- and tryptase-induced HCEC activation was blocked by PAR1 and PAR2 neutralizing antibodies, respectively, and by specific enzyme inhibitors. The constitutive expression of PAR1 and PAR2, and their activation by thrombin and tryptase, respectively, may have important implications in ocular inflammation

K63-Linked Polyubiquitination on TRAF6 Regulates LPS-Mediated MAPK Activation, Cytokine Production, and Bacterial Clearance in Toll-Like Receptor 7/8 Primed Murine Macrophages

Post viral infection bacterial pneumonia is a major cause of morbidity and mortality associated with both seasonal and pandemic influenza virus illness. Despite much efforts put into the discovery of mechanisms of post viral–bacterial infections and their complications in recent years, the molecular mechanisms underlying the increased susceptibility to bacterial infection remain poorly understood. In this study, we focused on the pathways regulating immune responses in murine macrophages and modeled post viral–bacterial infections through pretreatment of bone marrow-derived macrophages (BMDMs) with a toll-like receptor (TLR) 7/8 ligand (R848) and subsequent challenge with TLR2/4 agonists to mimic bacterial infection. We found R848-primed BMDMs upon subsequent exposure to TLR2/4 ligands respond with enhanced inflammatory cytokine production, especially IL-6 and TNF-α. The enhanced cytokine production in R848-primed BMDMs in response to TLR2/4 was due to increased TGF-β-activated kinase (TAK) 1 phosphorylation with subsequent activation of ERK and p38 MAPKs. Furthermore, we identified that R848 priming leads to increased K63-linked polyubiquitination on TRAF6. K63-linked polyubiquitination on TRAF6 is a signal leading to enhanced activation of downstream pathways including TAK1. Importantly, R848-primed BMDMs infected with live bacteria exhibited decreased bacterial clearance. Small-molecule enhancer of rapamycin 3, an ubiquitin ligase inhibitor reversed the K63-linked polyubiquitination on TRAF6 in R848-primed BMDMs and subsequently decreased TAK1 and MAPK phosphorylation, and cytokine production as well as reversed the decreased bacterial clearance capacity of BMDMs. Our study may provide a novel molecular target to alleviate post viral–bacterial infections

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<p>Post viral infection bacterial pneumonia is a major cause of morbidity and mortality associated with both seasonal and pandemic influenza virus illness. Despite much efforts put into the discovery of mechanisms of post viral–bacterial infections and their complications in recent years, the molecular mechanisms underlying the increased susceptibility to bacterial infection remain poorly understood. In this study, we focused on the pathways regulating immune responses in murine macrophages and modeled post viral–bacterial infections through pretreatment of bone marrow-derived macrophages (BMDMs) with a toll-like receptor (TLR) 7/8 ligand (R848) and subsequent challenge with TLR2/4 agonists to mimic bacterial infection. We found R848-primed BMDMs upon subsequent exposure to TLR2/4 ligands respond with enhanced inflammatory cytokine production, especially IL-6 and TNF-α. The enhanced cytokine production in R848-primed BMDMs in response to TLR2/4 was due to increased TGF-β-activated kinase (TAK) 1 phosphorylation with subsequent activation of ERK and p38 MAPKs. Furthermore, we identified that R848 priming leads to increased K63-linked polyubiquitination on TRAF6. K63-linked polyubiquitination on TRAF6 is a signal leading to enhanced activation of downstream pathways including TAK1. Importantly, R848-primed BMDMs infected with live bacteria exhibited decreased bacterial clearance. Small-molecule enhancer of rapamycin 3, an ubiquitin ligase inhibitor reversed the K63-linked polyubiquitination on TRAF6 in R848-primed BMDMs and subsequently decreased TAK1 and MAPK phosphorylation, and cytokine production as well as reversed the decreased bacterial clearance capacity of BMDMs. Our study may provide a novel molecular target to alleviate post viral–bacterial infections.</p

Outcomes in Treatment-Naïve Patients With Metastatic Extremity Osteosarcoma Treated With OGS-12, a Novel Non–High-Dose Methotrexate–Based, Dose-Dense Combination Chemotherapy, in a Tertiary Care Cancer Center

Purpose: Metastatic osteosarcoma is largely treated with high-dose methotrexate (HDMTX)–based therapy, especially in the pediatric population. This mandates complex pharmacokinetic monitoring in a costly inpatient setting to mitigate unpredictable serious toxicities. Hence, a non-HDMTX–based regimen is worth exploring, especially in India and low- and middle-income countries. Materials and Methods: All consecutive treatment-naïve patients with metastatic osteosarcoma were prospectively treated on the novel OGS-12 protocol consisting of sequential doublets of doxorubicin, cisplatin, and ifosfamide. Four cycles were administered as neoadjuvant therapy followed by planned curative intent surgery and metastasectomy when feasible, followed by four cycles of adjuvant chemotherapy. Baseline characteristics, histologic response, event-free survival (EFS), overall survival (OS), and toxicity data were prospectively collected. Results: Three hundred seventeen patients were enrolled onto the OGS-12 protocol from 2011 to 2014, of whom 80 (25%) had metastatic disease; median age was 17 years. The majority of patients were nutritionally challenged with high-risk features. At presentation, 83% of patients (66 patients) had lung metastases. After neoadjuvant chemotherapy, 57% of patients were histologically good responders. Four-year EFS and OS rates were 24% and 27%, respectively, in the intent-to-treat population and 27% and 29%, respectively, in the per-protocol analysis. Significant grade 3 or 4 toxicities were febrile neutropenia (51%), thrombocytopenia (36%), and anemia (54%). Histologic response was an independent predictor for EFS and OS in patients who underwent surgery. Surgical intervention was found to be significant for survival in univariable analysis. Conclusion: The novel, low-cost, non-HDMTX–based, dose-dense OGS-12 regimen has shown comparable outcomes to international standards in metastatic osteosarcomas and is worthy of wider clinical application. An aggressive multimodality approach may result in long-term survival in a select group of patients and, hence, is worth considering