Effect of isotretinoin on CYP2D6 and CYP3A activity in patients with severe acne.

AIMS: Previously, retinoids have decreased CYP2D6 mRNA expression in vitro and induced CYP3A4 in vitro and in vivo. This study aimed to determine whether isotretinoin administration changes CYP2D6 and CYP3A activities in patients with severe acne. METHODS: Thirty-three patients (22 females and 11 males, 23.5 ± 6.0 years old) expected to receive isotretinoin treatment completed the study. All participants were genotyped for CYP2D6 and CYP3A5. Participants received dextromethorphan (DM) 30 mg orally as a dual-probe substrate of CYP2D6 and CYP3A activity at two study timepoints: pre-isotretinoin treatment and with isotretinoin for at least 1 week. The concentrations of isotretinoin, DM and their metabolites were measured in 2-h postdose plasma samples and in cumulative 0-4-h urine collections using liquid chromatography-mass spectrometry. RESULTS: In CYP2D6 extensive metabolizers, the urinary dextrorphan (DX)/DM metabolic ratio (MR) (CYP2D6 activity marker) was numerically, but not significantly, lower with isotretinoin administration compared to pre-isotretinoin (geometric mean ratio [GMR] [90% confidence interval (CI)] 0.78 [0.55, 1.11]). The urinary 3-hydroxymorphinan (3HM)/DX MR (CYP3A activity marker) was increased (GMR 1.18 [1.03, 1.35]) and the urinary DX-O-glucuronide/DX MR (proposed UGT2B marker) was increased (GMR 1.22 [1.06, 1.39]) with isotretinoin administration compared to pre-isotretinoin. CONCLUSIONS: Administration of isotretinoin did not significantly reduce CYP2D6 activity in extensive metabolizers, suggesting that the predicted downregulation of CYP2D6 based on in vitro data does not translate into humans. We observed a modest increase in CYP3A activity (predominantly CYP3A4) with isotretinoin treatment. The data also suggest that DX glucuronidation is increased following isotretinoin administration.

Selected Disorders of Skin Appendages--Acne, Alopecia, Hyperhidrosis.

This article reviewed some of the more common diseases of the skin appendages that are encountered in medicine: hyperhidrosis, acne, AA, FPHL, AGA, and TE. The pathophysiology behind the conditions and their treatments were discussed so that the clinician can make logical therapeutic choices for their affected patients.

Granulomatous scleromyxedema: case report and literature review.

Scleromyxedema is a rare and frequently disabling disease characterized by generalized waxy papules, skin induration, and cardinal histological features of dermal fibroblastic proliferation, thickened collagen, and mucin deposition. A monoclonal gammopathy is almost always present with rare progression to multiple myeloma. We describe the case of a 54-year-old man who presented with a rash in the setting of a new medication and histological features suggesting a granulomatous drug reaction. Despite discontinuation of the medication, the rash persisted and a second biopsy confirmed an interstitial granulomatous pattern. Serum protein electrophoresis identified the presence of a biclonal gammopathy leading to a diagnosis of granulomatous scleromyxedema. Review of the medical literature reveals only a handful of well-documented similar cases of this rare variant. It is important for pathologists and clinicians to be familiar with this condition to facilitate timely diagnosis and optimal clinical management of these patients.

Common dermatologic conditions.

When assessing a patient with a new dermatologic condition, developing a differential diagnosis is essential to ensure the condition is not elusive as a workup and potential therapy are considered. Subsequent narrowing of that differential based on history and physical examination can allow a more targeted approach to diagnostic testing and triage, and hasten an effective treatment and resolution. The authors hope to have provided useful historical and clinical clues to aid in the rapid differentiation of the more common diagnoses for alopecias and rashes of the face, intertriginous areas, and legs.

Human TOLLIP regulates TLR2 and TLR4 signaling and its polymorphisms are associated with susceptibility to tuberculosis.

Tuberculosis, one of the leading causes of death worldwide, stimulates inflammatory responses with beneficial and pathologic consequences. The regulation and nature of an optimal inflammatory response to Mycobacterium tuberculosis remains poorly understood in humans. Insight into mechanisms of negative regulation of the TLR-mediated innate immune response to M. tuberculosis could provide significant breakthroughs in the design of new vaccines and drugs. We hypothesized that TOLLIP and its common variants negatively regulate TLR signaling in human monocytes and are associated with susceptibility to tuberculosis. Using short hairpin RNA knockdown of TOLLIP in peripheral blood human monocytes, we found that TOLLIP suppresses TNF and IL-6 production after stimulation with TLR2 and TLR4 ligands. In contrast, secretion of the anti-inflammatory cytokine IL-10 was induced by TOLLIP. We also discovered two common polymorphisms that are associated with either decreased levels of mRNA expression (rs3750920) or increased IL-6 production (rs5743899) in a sample of 56 healthy volunteers. Furthermore, in a case-population study in Vietnam with 760 cord blood samples and 671 TB case patients, we found that SNPs rs3750920 and rs5743899 were associated with susceptibility to tuberculosis (p = 7.03 × 10(-16) and 6.97 × 10(-7), respectively). These data demonstrate that TOLLIP has an anti-inflammatory effect on TLR signaling in humans and that TOLLIP deficiency is associated with an increased risk of tuberculosis. To our knowledge, these data also show the first associations of TOLLIP polymorphisms with any infectious disease. These data also implicate an unexpected mechanism of negative regulation of TLR signaling in human tuberculosis pathogenesis.

Host genotype-specific therapies can optimize the inflammatory response to mycobacterial infections.

Susceptibility to tuberculosis is historically ascribed to an inadequate immune response that fails to control infecting mycobacteria. In zebrafish, we find that susceptibility to Mycobacterium marinum can result from either inadequate or excessive acute inflammation. Modulation of the leukotriene A(4) hydrolase (LTA4H) locus, which controls the balance of pro- and anti-inflammatory eicosanoids, reveals two distinct molecular routes to mycobacterial susceptibility converging on dysregulated TNF levels: inadequate inflammation caused by excess lipoxins and hyperinflammation driven by excess leukotriene B(4). We identify therapies that specifically target each of these extremes. In humans, we identify a single nucleotide polymorphism in the LTA4H promoter that regulates its transcriptional activity. In tuberculous meningitis, the polymorphism is associated with inflammatory cell recruitment, patient survival and response to adjunctive anti-inflammatory therapy. Together, our findings suggest that host-directed therapies tailored to patient LTA4H genotypes may counter detrimental effects of either extreme of inflammation.

The lta4h locus modulates susceptibility to mycobacterial infection in zebrafish and humans.

Exposure to Mycobacterium tuberculosis produces varied early outcomes, ranging from resistance to infection to progressive disease. Here we report results from a forward genetic screen in zebrafish larvae that identify multiple mutant classes with distinct patterns of innate susceptibility to Mycobacterium marinum. A hypersusceptible mutant maps to the lta4h locus encoding leukotriene A(4) hydrolase, which catalyzes the final step in the synthesis of leukotriene B(4) (LTB(4)), a potent chemoattractant and proinflammatory eicosanoid. lta4h mutations confer hypersusceptibility independent of LTB(4) reduction, by redirecting eicosanoid substrates to anti-inflammatory lipoxins. The resultant anti-inflammatory state permits increased mycobacterial proliferation by limiting production of tumor necrosis factor. In humans, we find that protection from both tuberculosis and multibacillary leprosy is associated with heterozygosity for LTA4H polymorphisms that have previously been correlated with differential LTB(4) production. Our results suggest conserved roles for balanced eicosanoid production in vertebrate resistance to mycobacterial infection.

Unusual granulomatous variant of scleromyxedema.

Scleromyxedema is notable for significant morbidity and mortality. A generalized eruption of waxy papules in the absence of thyroid disease with histologic findings of mucin deposition, increased fibroblast proliferation, and fibrosis are the characteristic features of scleromyxedema. We report a case of scleromyxedema that, on histology, was associated with interstitial granuloma annulare-like features. Based on our literature review, this is a rare presentation of this disease. Familiarity with the histologic aspects of scleromyxedema, as described in this report, can help to improve the accuracy of this diagnosis, particularly in atypical presentations.

Isw1 functions in parallel with the NuA4 and Swr1 complexes in stress-induced gene repression.

The packaging of DNA into chromatin allows eukaryotic cells to organize and compact their genomes but also creates an environment that is generally repressive to nuclear processes that depend upon DNA accessibility. There are several classes of enzymes that modulate the primary structure of chromatin to regulate various DNA-dependent processes. The biochemical activities of the yeast Isw1 ATP-dependent chromatin-remodeling enzyme have been well characterized in vitro, but little is known about how these activities are utilized in vivo. In this work, we sought to discern genetic backgrounds that require Isw1 activity for normal growth. We identified a three-way genetic interaction among Isw1, the NuA4 histone acetyltransferase complex, and the Swr1 histone replacement complex. Transcription microarray analysis revealed parallel functions for these three chromatin-modifying factors in the regulation of TATA-containing genes, including the repression of a large number of stress-induced genes under normal growth conditions. In contrast to a recruitment-based model, we find that the NuA4 and Swr1 complexes act throughout the genome while only a specific subset of the genome shows alterations in transcription.

Targeted point mutagenesis of mouse Kcnq1: phenotypic analysis of mice with point mutations that cause Romano-Ward syndrome in humans.

Inherited long QT syndrome is most frequently associated with mutations in KCNQ1, which encodes the primary subunit of a potassium channel. Patients with mutations in KCNQ1 may show only the cardiac defect (Romano-Ward syndrome or RWS) or may also have severe deafness (Jervell and Lange-Nielsen syndrome or JLNS). Targeted disruption of mouse Kcnq1 models JLNS in that mice are deaf and show abnormal ECGs. However, the phenotype is broader than that seen in patients. Most dramatically, the inner ear defects result in a severe hyperactivity/circling behavior, which may influence cardiac function. To understand the etiology of the cardiac phenotype in these mice and to generate a potentially more useful model system, we generated new mouse lines by introducing point mutations associated with RWS. The A340E line phenocopies RWS: the repolarization phenotype is inherited in a dominant manner and is observed independent of any inner ear defect. The T311I line phenocopies JLNS, with deafness associated with inner hair cell malfunction.

Hairpin-bisulfite PCR: assessing epigenetic methylation patterns on complementary strands of individual DNA molecules.

Epigenetic inheritance, the transmission of gene expression states from parent to daughter cells, often involves methylation of DNA. In eukaryotes, cytosine methylation is a frequent component of epigenetic mechanisms. Failure to transmit faithfully a methylated or an unmethylated state of cytosine can lead to altered phenotypes in plants and animals. A central unresolved question in epigenetics concerns the mechanisms by which a locus maintains, or changes, its state of cytosine methylation. We developed "hairpin-bisulfite PCR" to analyze these mechanisms. This method reveals the extent of methylation symmetry between the complementary strands of individual DNA molecules. Using hairpin-bisulfite PCR, we determined the fidelity of methylation transmission in the CpG island of the FMR1 gene in human lymphocytes. For the hypermethylated CpG island of this gene, characteristic of inactive-X alleles, we estimate a maintenance methylation efficiency of approximately 0.96 per site per cell division. For de novo methylation efficiency (E(d)), remarkably different estimates were obtained for the hypermethylated CpG island (E(d) = 0.17), compared with the hypomethylated island on the active-X chromosome (E(d) < 0.01). These results clarify the mechanisms by which the alternative hypomethylated and hypermethylated states of CpG islands are stably maintained through many cell divisions. We also analyzed a region of human L1 transposable elements. These L1 data provide accurate methylation patterns for the complementary strand of each repeat sequence analyzed. Hairpin-bisulfite PCR will be a powerful tool in studying other processes for which genetic or epigenetic information differs on the two complementary strands of DNA.