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Occurrence of mental illness and mental health risks among the self-employed: a systematic review
(2021)
We aimed to systematically identify and evaluate all studies of good quality that compared the occurrence of mental disorders in the self-employed versus employees. Adhering to the Cochrane guidelines, we conducted a systematic review and searched three major medical databases (MEDLINE, Web of Science, Embase), complemented by hand search. We included 26 (three longitudinal and 23 cross-sectional) population-based studies of good quality (using a validated quality assessment tool), with data from 3,128,877 participants in total. The longest of these studies, a Swedish national register evaluation with 25 years follow-up, showed a higher incidence of mental illness among the self-employed compared to white-collar workers, but a lower incidence compared to blue-collar workers. In the second longitudinal study from Sweden the self-employed had a lower incidence of mental illness compared to both blue- and white-collar workers over 15 years, whereas the third longitudinal study (South Korea) did not find a difference regarding the incidence of depressive symptoms over 6 years. Results from the cross-sectional studies showed associations between self-employment and poor general mental health and stress, but were inconsistent regarding other mental outcomes. Most studies from South Korea found a higher prevalence of mental disorders among the self-employed compared to employees, whereas the results of cross-sectional studies from outside Asia were less consistent. In conclusion, we found evidence from population-based studies for a link between self-employment and increased risk of mental illness. Further longitudinal studies are needed examining the potential risk for the development of mental disorders in specific subtypes of the self-employed.
Design of novel IL-4 antagonists employing site-specific chemical and biosynthetic glycosylation
(2021)
The cytokines interleukin 4 (IL-4) and IL-13 are important mediators in the humoral immune response and play a crucial role in the pathogenesis of chronic inflammatory diseases, such as asthma, allergies, and atopic dermatitis. Hence, IL-4 and IL-13 are key targets for treatment of such atopic diseases.
For cell signalling IL-4 can use two transmembrane receptor assemblies, the type I receptor consisting of receptors IL-4R and γc, and type II receptor consisting of receptors IL-4R and IL-13R1. The type II receptor is also the functional receptor of IL-13, receptor sharing being the molecular basis for the partially overlapping effects of IL-4 and IL-13. Since both cytokines require the IL-4R receptor for signal transduction, this allows the dual inhibition of both IL-4 and IL-13 by specifically blocking the receptor IL-4R.
This study describes the design and synthesis of novel antagonistic variants of human IL-4. Chemical modification was used to target positions localized in IL-4 binding sites for γc and IL-13R1 but outside of the binding epitope for IL-4R. In contrast to existing studies, which used synthetic chemical compounds like polyethylene glycol for modification of IL-4, we employed glycan molecules as a natural alternative. Since glycosylation can improve important pharmacological parameters of protein therapeutics, such as immunogenicity and serum half-life, the introduced glycan molecules thus would not only confer a steric hindrance based inhibitory effect but simultaneously might improve the pharmacokinetic profile of the IL-4 antagonist.
For chemical conjugation of glycan molecules, IL-4 variants containing additional cysteine residues were produced employing prokaryotic, as well as eukaryotic expression systems. The thiol-groups of the engineered cysteines thereby allow highly specific modification. Different strategies were developed enabling site-directed coupling of amine- or thiol- functionalized monosaccharides to introduced cysteine residues in IL-4. A linker-based coupling procedure and an approach requiring phenylselenyl bromide activation of IL-4 thiol-groups were hampered by several drawbacks, limiting their feasibility. Surprisingly, a third strategy, which involved refolding of IL-4 cysteine variants in the presence of thiol- glycans, readily allowed synthesis of IL-4 glycoconjugates in form of mixed disulphides in milligram amount. This approach, therefore, has the potential for large-scale synthesis of IL-4 antagonists with highly defined glycosylation. Obtaining a homogenous glycoconjugate with exactly defined glycan pattern would allow using the attached glycan structures for fine-tuning of pharmacokinetic properties of the IL-4 antagonist, such as absorption and metabolic stability.
The IL-4 glycoconjugates generated in this work proved to be highly effective antagonists inhibiting IL-4 and/or IL-13 dependent responses in cell-based experiments and in in vitro binding studies. Glycoengineered IL-4 antagonists thus present valuable alternatives to IL-4 inhibitors used for treatment of atopic diseases such as the neutralizing anti-IL-4R antibody Dupilumab.