Unfolded protein response is an early, non-critical event during hepatic stellate cell activation.

Hepatic stellate cells activate upon liver injury and help at restoring damaged tissue by producing extracellular matrix proteins. A drastic increase in matrix proteins results in liver fibrosis and we hypothesize that this sudden increase leads to accumulation of proteins in the endoplasmic reticulum and its compensatory mechanism, the unfolded protein response. We indeed observe a very early, but transient induction of unfolded protein response genes during activation of primary mouse hepatic stellate cells in vitro and in vivo, prior to induction of classical stellate cell activation genes. This unfolded protein response does not seem sufficient to drive stellate cell activation on its own, as chemical induction of endoplasmic reticulum stress with tunicamycin in 3D cultured, quiescent stellate cells is not able to induce stellate cell activation. Inhibition of Jnk is important for the transduction of the unfolded protein response. Stellate cells isolated from Jnk knockout mice do not activate as much as their wild-type counterparts and do not have an induced expression of unfolded protein response genes. A timely termination of the unfolded protein response is essential to prevent endoplasmic reticulum stress-related apoptosis. A pathway known to be involved in this termination is the non-sense-mediated decay pathway. Non-sense-mediated decay inhibitors influence the unfolded protein response at early time points during stellate cell activation. Our data suggest that UPR in HSCs is differentially regulated between acute and chronic stages of the activation process. In conclusion, our data demonstrates that the unfolded protein response is a JNK1-dependent early event during hepatic stellate cell activation, which is counteracted by non-sense-mediated decay and is not sufficient to drive the stellate cell activation process. Therapeutic strategies based on UPR or NMD modulation might interfere with fibrosis, but will remain challenging because of the feedback mechanisms between the stress pathways

Optimized approach for the identification of highly efficient correctors of nonsense mutations in human diseases

About 10% of patients with a genetic disease carry a nonsense mutation causing their pathology. A strategy for correcting nonsense mutations is premature termination codon (PTC) readthrough, i.e. incorporation of an amino acid at the PTC position during translation. PTC-readthrough-activating molecules appear as promising therapeutic tools for these patients. Unfortunately, the molecules shown to induce PTC readthrough show low efficacy, probably because the mRNAs carrying a nonsense mutation are scarce, as they are also substrates of the quality control mechanism called nonsense-mediated mRNA decay (NMD). The screening systems previously developed to identify readthrough-promoting molecules used cDNA constructs encoding mRNAs immune to NMD. As the molecules identified were not selected for the ability to correct nonsense mutations on NMD-prone PTC-mRNAs, they could be unsuitable for the context of nonsense-mutation-linked human pathologies. Here, a screening system based on an NMD-prone mRNA is described. It should be suitable for identifying molecules capable of efficiently rescuing the expression of human genes harboring a nonsense mutation. This system should favor the discovery of candidate drugs for treating genetic diseases caused by nonsense mutations. One hit selected with this screening system is presented and validated on cells from three cystic fibrosis patients

How can pricing and reimbursement policies improve affordable access to medicines? Lessons learned from European countries

This article discusses pharmaceutical pricing and reimbursement policies in European countries with regard to their ability to ensure affordable access to medicines. A frequently applied pricing policy is external price referencing. While it provides some benchmark for policy-makers and has been shown to be able to generate savings, it may also contribute to delay in product launch in countries where medicine prices are low. Value-based pricing has been proposed as a policy that promotes access while rewarding useful innovation; however, implementing it has proven quite challenging. For high-priced medicines, managed-entry agreements are increasingly used. These agreements allow policy-makers to manage uncertainty and obtain lower prices. They can also facilitate earlier market access in case of limited evidence about added therapeutic value of the medicine. However, these agreements raise transparency concerns due to the confidentiality clause. Tendering as used in the hospital and offpatent outpatient sectors has been proven to reduce medicine prices but it requires a robust framework and appropriate design with clear strategic goals in order to prevent shortages. These pricing and reimbursement policies are supplemented by the widespread use of Health Technology Assessment to inform decision-making, and by strategies to improve the uptake of generics, and also biosimilars. While European countries have been implementing a set of policy options, there is a lack of thorough impact assessments of several pricing and reimbursement policies on affordable access. Increased cooperation between authorities, experience sharing and improving transparency on price information, including the disclosure of confidential discounts, are opportunities to address current challenges