TIRAP, TRAM, and Toll-Like Receptors: The Untold Story.

Toll-like receptors (TLRs) are the most studied receptors among the pattern recognition receptors (PRRs). They act as microbial sensors, playing major roles in the regulation of the innate immune system. TLRs mediate their cellular functions through the activation of MyD88-dependent or MyD88-independent signaling pathways. Myd88, or myeloid differentiation primary response 88, is a cytosolic adaptor protein essential for the induction of proinflammatory cytokines by all TLRs except TLR3. While the crucial role of Myd88 is well described, the contribution of other adaptors in mediating TLR signaling and function has been underestimated. In this review, we highlight important results demonstrating that TIRAP and TRAM adaptors are also required for full signaling activity and responses induced by most TLRs.

Phosphatases in toll-like receptors signaling: the unfairly-forgotten.

Over the past 2 decades, pattern recognition receptors (PRRs) have been shown to be on the front line of many illnesses such as autoimmune, inflammatory, and neurodegenerative diseases as well as allergies and cancer. Among PRRs, toll-like receptors (TLRs) are the most studied family. Dissecting TLRs signaling turned out to be advantageous to elaborate efficient treatments to cure autoimmune and chronic inflammatory disorders. However, a broad understanding of TLR effectors is required to propose a better range of cures. In addition to kinases and E3 ubiquitin ligases, phosphatases emerge as important regulators of TLRs signaling mediated by NF-κB, type I interferons (IFN I) and Mitogen-Activated Protein Kinases signaling pathways. Here, we review recent knowledge on TLRs signaling modulation by different classes and subclasses of phosphatases. Thus, it becomes more and more evident that phosphatases could represent novel therapeutic targets to control pathogenic TLRs signaling. Video Abstract.

UNC93B1 interacts with the calcium sensor STIM1 for efficient antigen cross-presentation in dendritic cells.

Dendritic cells (DC) have the unique ability to present exogenous antigens via the major histocompatibility complex class I pathway to stimulate naive CD8+ T cells. In DCs with a non-functional mutation in Unc93b1 (3d mutation), endosomal acidification, phagosomal maturation, antigen degradation, antigen export to the cytosol and the function of the store-operated-Ca2+-entry regulator STIM1 are impaired. These defects result in compromised antigen cross-presentation and anti-tumor responses in 3d-mutated mice. Here, we show that UNC93B1 interacts with the calcium sensor STIM1 in the endoplasmic reticulum, a critical step for STIM1 oligomerization and activation. Expression of a constitutively active STIM1 mutant, which no longer binds UNC93B1, restores antigen degradation and cross-presentation in 3d-mutated DCs. Furthermore, ablation of STIM1 in mouse and human cells leads to a decrease in cross-presentation. Our data indicate that the UNC93B1 and STIM1 cooperation is important for calcium flux and antigen cross-presentation in DCs.

Impact of Intraoperative Pancreatoscopy with Intraductal Biopsies on Surgical Management of Intraductal Papillary Mucinous Neoplasm of the Pancreas.

BACKGROUND: Because of its known malignant potential, precise histologic diagnosis of intraductal papillary mucinous neoplasm of the pancreas (IPMN) during intraoperative pancreatoscopy (IOP) is essential for complete surgical resection. The impact of IOP on perioperative IPMN patient management was reviewed over 20 years of practice at Cliniques universitaires Saint-Luc, Brussels, Belgium. STUDY DESIGN: Among 86 IPMN patients treated by pancreatectomy between 1991 and 2013, 21 patients had a dilated main pancreatic duct enabling IOP and were retrospectively reviewed. The IOP was performed using an ultrathin flexible endoscope and biopsy forceps, and specimens of all suspicious lesions underwent frozen section examination. RESULTS: Complete IOP with intraductal biopsies was easily and safely performed in 21 patients, revealing 8 occult IPMN lesions. In 5 cases (23.8%), initially planned surgical resection was modified secondary to IOP: 3 for carcinoma in situ and 2 for invasive carcinoma. The postoperative morbidity rate at 3 months was 25.0% (5 of 20); 1 patient died from septic shock postoperatively and was excluded. Median follow-up was 93 months (range 13 to 248 months). Nineteen of 21 patients were still alive and free of disease at last follow-up (90.5%); there was 1 patient with invasive carcinoma at initial pathology (pT3 N1) who died of pulmonary recurrence 21 months after surgery. CONCLUSIONS: Intraoperative pancreatoscopy of the main pancreatic duct combined with intraductal biopsies plays a significant role in the surgical management of IPMN patients and should be used in all patients presenting a sufficiently dilated main pancreatic duct.

Does the site of platelet sequestration predict the response to splenectomy in adult patients with immune thrombocytopenic purpura?

Splenectomy is the only potentially curative treatment for chronic immune thrombocytopenic purpura (ITP) in adults. However, one-third of the patients relapse without predictive factors identified. We evaluate the predictive value of the site of platelet sequestration on the response to splenectomy in patients with ITP. Eighty-two consecutive patients with ITP treated by splenectomy between 1992 and 2013 were retrospectively reviewed. Platelet sequestration site was studied by (111)Indium-oxinate-labeled platelets in 93% of patients. Response to splenectomy was defined at last follow-up as: complete response (CR) for platelet count (PC) ≥100 × 10(9)/L, response (R) for PC≥30 × 10(9)/L and <100 × 10(9)/L with absence of bleeding, no response (NR) for PC<30 × 10(3)/L or significant bleeding. Laparoscopic splenectomy was performed in 81 patients (conversion rate of 16%), and open approach in one patient. Median follow-up was 57 months (range, 1-235). Platelet sequestration study was performed in 93% of patients: 50 patients (61%) exhibited splenic sequestration, 9 (11%) hepatic sequestration and 14 patients (17%) mixed sequestration. CR was obtained in 72% of patients, R in 25% and NR in 4% (two with splenic sequestration, one with hepatic sequestration). Preoperative PC, age at diagnosis, hepatic sequestration and male gender were significant for predicting CR in univariate analysis, but only age (HR = 1.025 by one-year increase, 95% CI [1.004-1.047], p = 0.020) and pre-operative PC (HR = 0.112 for > 100 versus <=100, 95% CI [0.025-0.493], p = 0.004) were significant predictors of recurrence-free survival in multivariate analysis. Response to splenectomy was independent of the site of platelet sequestration in patients with ITP. Pre-operative platelet sequestration study in these patients cannot be recommended.

Hepatocellular cancer and liver transplantation: a Western experience.

Orthotopic liver transplantation is the preferred treatment option in patients with hepatocellular carcinoma developing in chronic liver disease. Unfortunately, based on classical transplantation criteria (Milan criteria), only a minority of patients with hepatocellular carcinoma are candidate to orthotopic liver transplantation. Major improvements in treatment strategy and surgical technique including the use of neoadjuvant locoregional therapies and progresses of post-transplant immunosuppressive treatment have contributed to safely expand transplantation criteria preserving acceptable surgical morbidity-mortality and good oncologic outcome. Further extension of transplantation criteria may have advantages including an increase in the number of transplant candidates and improvement of the prognosis of the disease and also disadvantages including an increase of surgical morbidity and deterioration of global oncologic outcome of orthotopic liver transplantation in hepatocellular carcinoma. In the future, identification of imaging or molecular prognostic markers could help to better define transplantation criteria.

Salirasib inhibits the growth of hepatocarcinoma cell lines in vitro and tumor growth in vivo through ras and mTOR inhibition.

BACKGROUND: Dysregulation of epidermal growth factor and insulin-like growth factor signaling play important roles in human hepatocellular carcinoma (HCC), leading to frequent activation of their downstream targets, the ras/raf/extracellular signal-regulated kinase (ERK) and the phosphoinositide 3-kinase (PI3K)/Akt/mammalian Target of Rapamycin (mTOR) pathways. Salirasib is an S-prenyl-cysteine analog that has been shown to block ras and/or mTOR activation in several non hepatic tumor cell lines. We investigated in vitro the effect of salirasib on cell growth as well as its mechanism of action in human hepatoma cell lines (HepG2, Huh7, and Hep3B) and its in vivo effect in a subcutaneous xenograft model with HepG2 cells. RESULTS: Salirasib induced a time and dose dependent growth inhibition in hepatocarcinoma cells through inhibition of proliferation and partially through induction of apoptosis. A 50 percent reduction in cell growth was obtained in all three cell lines at a dose of 150 µM when they were cultured with serum. By contrast, salirasib was more potent at reducing cell growth after stimulation with EGF or IGF2 under serum-free conditions, with an IC50 ranging from 60 µM to 85 µM. The drug-induced anti-proliferative effect was associated with downregulation of cyclin A and to a lesser extent of cyclin D1, and upregulation of p21 and p27. Apoptosis induction was related to a global pro-apoptotic balance with caspase 3 activation, cytochrome c release, death receptor upregulation, and a reduced mRNA expression of the apoptosis inhibitors cFLIP and survivin. These effects were associated with ras downregulation and mTOR inhibition, without reduction of ERK and Akt activation. In vivo, salirasib reduced tumour growth from day 5 onwards. After 12 days of treatment, mean tumor weight was diminished by 56 percent in the treated animals. CONCLUSIONS: Our results show for the first time that salirasib inhibits the growth of human hepatoma cell lines through inhibition of proliferation and induction of apoptosis, which is associated with ras and mTOR inhibition. The therapeutic potential of salirasib in human HCC was further confirmed in a subcutaneous xenograft model.