👤 Mathias Francois

The pathogenesis of atopic dermatitis (AD) is complex and multifactorial. However, recent advancements in the genetics and pathophysiology of AD suggest that epidermal barrier dysfunction is paramount in the development and progression of the condition (Boguniewicz M, Leung DYM, Immunol Rev 242(1):233-246, 2011). In addition to standard therapy for AD, there are a plethora of nonprescription treatment modalities which may be employed. Over-the-counter treatments for atopic dermatitis can come in the form of topical corticosteroids, moisturizers/emollients, and oral antihistamines. Though these treatments are beneficial, prescription treatments may be quicker acting and more efficacious in patients with moderate to severe disease or during flares. OTC agents are best used for maintenance between flares and to prevent progression of mild disease. Alternative and complementary treatments lack strong efficacy evidence. However, wet wraps, bleach baths, and other treatments appear to be promising when used in conjunction with conventional treatments. With the financial burden of atopic dermatitis ranging from 364 million to 3.8 billion dollars each year in the United States, we suspect this topic will gain further research attention. Show less

Infantile hemangioma (IH) is a benign vascular tumor that undergoes an initial rapid growth phase followed by spontaneous involution. A fibrofatty residuum remains in many tumors and often necessitates resection. We recently discovered that R(+) propranolol, the non-β blocker enantiomer, inhibits blood vessel formation of IH patient-derived hemangioma stem cells (HemSC) xenografted in mice. HemSC are multipotent cells with the ability to differentiate into endothelial cells, pericytes, and adipocytes. We investigated how R(+) propranolol affects HemSC adipogenic differentiation and lipid accumulation, in vitro and in a preclinical murine model for IH. We conducted a 10-day adipogenesis assay on 4 IH patient-derived HemSCs. Oil Red O (ORO) staining was used to identify the onset and level of lipid accumulation in HemSC while quantitative real-time polymerase chain reaction was conducted to determine the temporal expression of key factors implicated in adipogenesis. 5-20µM R(+) propranolol treatment was added to HemSC induced to undergo adiogenesis for 4 and 8 days, followed by quantification of lipid-stained areas and transcript levels of key adipogenic factors. We immunostained for lipid droplet-associated protein Perilipin 1 (PLIN1) in HemSC-xenograft sections from mice treated with R(+) propranolol and quantified the area using ImageJ. We found that different patient-derived HemSC exhibit a robust and heterogenous adipogenic capacity when induced for adipogenic differentiation in vitro. Consistently across four IH patient-derived HemSC isolates, R(+) propranolol reduced ORO-stained areas and lipoprotein lipase (LPL) transcript levels in HemSC after 4 and 8 days of adipogenic induction. In contrast, R(+) propranolol had no significant inhibitory effect on transcript levels encoding adipogenic transcription factors. In a pre-clinical HemSC xenograft model, PLIN1-positive area was significantly reduced in xenograft sections from mice treated with R(+) propranolol, signifying reduced lipid accumulation. Our findings suggest a novel regulatory role for the R(+) enantiomer of propranolol in modulating lipid accumulation in HemSC. This highlights a novel role of R(+) propranolol in the involuting phase of IH and a strategy to reduce fibrofatty residua in IH. Propranolol is the mainstay treatment for infantile hemangioma (IH), the most common tumor of infancy, but its use can be associated with concerning β-blocker side effects.R(+) propranolol, the enantiomer largely devoid of β-blocker activity, was recently shown to inhibit endothelial differentiation of hemangioma-derived stem cells (HemSC) in vitro and reduce blood vessel formation in a HemSC-derived xenograft murine model of IH. R(+) propranolol inhibits lipid accumulation in HemSC in vitro.R(+) propranolol does not affect mRNA transcript levels of key adipogenic transcription factors in differentiating HemSC in vitro.R(+) propranolol reduces lipid accumulation in a pre-clinical xenograft murine model of IH. The R(+) enantiomer of propranolol could be advantageous in terms of reduction in β-adrenergic side effects and fibrofatty tissue formation in the involuting phase of IH.Less fibrofatty residua might reduce the need for surgical resection.Disfigurement and associated psychosocial impacts might be improved in this young patient cohort. Show less

In budding yeast, PKC1 plays an essential role in cell integrity and proliferation through a linear MAP (Mitogen Activated Protein) kinase phosphorylation cascade, which ends up with the activation of the Slt2-MAP kinase by dual phosphorylation on two conserved threonine and tyrosine residues. In this phosphorylated form, Slt2p kinase activates by phosphorylation at least two known downstream targets: Rlm1p, which is implicated in the expression of cell wall-related genes, and SBF, required for transcription activation of cell cycle-regulated genes at the G1 to S transition. In this paper, we demonstrate by two-hybrid, in vitro immunoprecipitation and tandem affinity purification (TAP) methods that Knr4p physically interacts with Slt2p. Moreover, we show that the absence of Knr4p alters proper signalling of Slt2p to its two known downstream targets. In a knr4 null mutant, the SLT2-dependent activation of Rlm1p is strongly reduced and the transcriptional activity of Rlm1p is decreased, although the phosphorylated form of Slt2p is more abundant than in wild-type cells. On the contrary, SBF is abnormally activated in this mutant, as shown by a more abundant phosphorylated form of Swi6p, by higher beta-galactosidase levels from a SCB-lacZ gene fusion, and by deregulation of the cyclic behaviour of several cell cycle-regulated genes. These results, taken together with our recent finding that Bck2p requires Knr4p to activate additively with Cln3-Cdc28p SBF target genes, lead to a model in which Knr4p is involved in co-ordinating the Slt2p-mediated cell wall integrity pathway with progression of the cell cycle. Show less

In budding yeast, PKC1 plays an essential role in cell wall integrity and cell proliferation through a bifurcated PKC1/mitogen-activated protein (MAP) kinase pathway. The evidence that KNR4 is a member of the PKC1 pathway and genetically interacts with BCK2, a gene involved together with Cln3-Cdc28 in the G1 to S transition phase of the cell cycle, was as follows. Both KNR4 and BCK2 were isolated as a dosage suppressor of a calcofluor white hypersensitive ( cwh43) mutant. Overexpression of either of the two genes in a wild-type strain led to increased resistance to wall-affecting drugs, while this effect was not obtained in a bck2 Delta mutant that overexpressed KNR4. Deletion of KNR4 or BCK2 was synthetically lethal with components of the linear PKC1/MAP kinase pathway. Loss of Knr4 was lethal in combination with loss of Cln3, as was shown for Bck2. A protein interaction between Knr4 and Bck2 was measured using the two-hybrid system, although a direct physical interaction could not be detected by co-immunuprecipation methods. Finally, a genome-wide analysis of cells that overexpress BCK2 or KNR4 indicated that both genes also have effects independent of each other. In particular, the microarray data showed up-regulation of SWI4, which may account for the suppression of the cell lysis of a pkc1 null mutant, due to overexpression of BCK2. Show less