Chronic Pruritus and Connective Tissue Disorders: Review, Gaps, and Future Directions

Chronic itch is a common skin manifestation in many connective tissue diseases. However, the cause of chronic itch in these diseases is still not fully understood. The complex, and in some cases incomplete understanding of, pathogenesis in each condition makes it difficult to target specific mediators of chronic itch. It is important to better understand the pathophysiology of chronic itch in these conditions, as this information might provide a fuller understanding of the pathogenesis of the diseases in general and lead to the development of more specific treatments for connective tissue diseases in patients with chronic itch. We present a review of the literature on what is known about the prevalence, possible pathophysiology, and effect on quality of life of chronic itch in patients with scleroderma, Sjögren’s syndrome, dermatomyositis, systemic lupus erythematosus, cutaneous lupus erythematosus, and mixed connective tissue disease

Regulation of proline accumulation and its molecular and physiological functions in stress defence

The accumulation of proline is a conserved response of plants to abiotic stress conditions. Moreover, the activation of proline metabolism takes place during the plant response to some pathogens. Although these responses are well documented, the molecular and physiological functions of proline accumulation under stress are still a matter of debate. The biochemical pathways that lead to proline accumulation and its functions in regulating development are described in the cognate chapter “Proline Metabolism and its Functions in Development”. In this chapter, we will describe the potential roles assigned to proline accumulation, dissecting the data coming from in vitro/in silico and in vivo approaches, and those coming from bacterial or unicellular eukaryotes and plants. With this, we aim to present a clear view of the evidence related to the molecular and physiological functions of proline accumulation under stress conditions in plants. In recent years, the understanding of the regulation of proline accumulation at transcriptional level under stress conditions in plants has been increased considerably, yet little is known about the possible occurrence of post-translational regulatory mechanisms. We will integrate this knowledge with the potential roles of proline accumulation to see whether it contributes to comprehending which roles might be physiologically more relevant

Proline Metabolism and Its Functions in Development and Stress Tolerance

Proline takes an exceptional place among the proteinogenic amino acids by its specific accumulation in pollen and in response to multiple types of stress. Despite the more than 50 years of research, the biochemical pathways of proline biosynthesis and degradation still await their complete characterization in plants. Also, the molecular and physiological functions of proline metabolism in plant development and defense against stress are not yet fully understood. This chapter focuses on the current knowledge about the biochemical pathways of proline metabolism in plants, on its tissue-specific regulation and subcellular compartmentation, and on still open questions. Furthermore, we will summarize what is known about the influence of proline metabolism on plant development under optimal growth conditions and how it may support continued development despite the impact of stress. The cognate chapter “Regulation of Proline Accumulation and its molecular and physiological Functions in Stress Defense” will focus on the possible beneficial functions of proline metabolism and accumulation in the defense response against diverse stresses. With these two cohesive chapters, we aim to provide a comprehensive picture of the current knowledge and the open research questions in proline-dependent stress defense