Collodion baby and loricrin keratoderma: a case report and mutation analysis

Exploring Pseudoainhum in Camisa syndrome

Immediate treatment of Camisa syndrome with systemic retinoids or surgery helps to prevent loss of digits. Here, we report a case of Camisa syndrome with pseudoainhum in the fifth toe leading to amputation as timely treatment was not sought.

Loricrin downregulation and epithelial-related disorders: a systematic review

Loricrin downregulation has been associated with age-related changes as well as inherited and inflammatory skin diseases. We hypothesize that changes in loricrin could be more related to altered barrier function and consequently disorders that affect epithelial cells, such as psoriasis, atopic dermatitis (AD), erythrokeratoderma, loricrin keratoderma (LK) and periodontitis. The aim of this review is to summarize what is known about the association between loricrin downregulation and epithelial-related disorders (ERDs). A search was performed on the following databases: Medline, Cochrane Library, PubMed, EMBASE, Lilacs, Scopus and Google Scholar, resulting in 16 included articles. Loricrin keratoderma was the ERD most frequently associated with loricrin mutations (730insG, 709insC and 578insG; 5/7 cases - 71.44 %). Atopic dermatitis was the ERD most frequently associated with loricrin downregulation (2/7 cases - 28.6 %). Mutilating palmoplantar keratoderma, progressive symmetrical erythrokeratoderma and a new type of erythrokeratoderma were not associated with any mutations. At the gene level, periodontitis patients showed the highest decrease (-6.89x), followed by AD (-6.5x) and psoriasis patients (-0.5x). In summary, loricrin mutation and downregulation were associated with several ERDs. The diversity in disease presentation is likely related to whether there is a total loss of loricrin, mislocalization and/or if the mutant form of loricrin causes dysfunction of other proteins and/or changes in cornification.

Hereditary Palmoplantar Keratoderma: A Practical Approach to the Diagnosis

The ridged skin of the palms and soles has several unique features: (i) presence of dermatoglyphics created by alternating ridges and grooves forming a unique pattern, (ii) presence of the highest density of eccrine sweat glands and absence of pilosebaceous units, and (iii) differential expression of keratins compared to the glabrous skin. These features explain the preferential localization of palmoplantar keratoderma (PPK) and several of its characteristic clinical features. PPK develops as a compensatory hyperproliferation of the epidermis and excessive production of stratum corneum in response to altered cornification of the palmoplantar skin due to mutations in the genes encoding several of the proteins involved in it. PPK can manifest as diffuse, focal, striate, or punctate forms per se or as a feature of several dermatological or systemic diseases. There is a wide genetic and phenotypic heterogeneity in hereditary PPK, due to which reaching an accurate diagnosis only on the basis of clinical features may be sometimes challenging for the clinicians in the absence of molecular studies. Nevertheless, recognizing the clinical patterns of keratoderma, extent of involvement, degree of mutilation, and associated appendageal and systemic involvement may help in delineating different forms. Molecular studies, despite high cost, are imperative for accurate classification, recognizing clinical patterns in resource poor settings is important for appropriate diagnosis, genetic counseling, and management. This review intends to develop a practical approach for clinical diagnosis of different types of hereditary PPK with reasonable accuracy.

Loss of epidermal AP1 transcription factor function reduces filaggrin level, alters chemokine expression and produces an ichthyosis-related phenotype

AP1 transcription factors are important controllers of epidermal differentiation. Multiple family members are expressed in the epidermis in a differentiation-dependent manner, where they function to regulate gene expression. To study the role of AP1 factor signaling, TAM67 (dominant-negative c-jun) was inducibly expressed in the suprabasal epidermis. The TAM67-positive epidermis displays keratinocyte hyperproliferation, hyperkeratosis and parakeratosis, delayed differentiation, extensive subdermal vasodilation, nuclear loricrin localization, tail and digit pseudoainhum and reduced filaggrin level. These changes are associated with increased levels of IFNγ, CCL3, CCL5, CXCL9, CXCL10, and CXCL11 (Th1-associated chemokines), and CCL1, CCL2, CCL5 and CCL11 (Th2-associated chemokines) in the epidermis and serum. S100A8 and S100A9 protein levels are also markedly elevated. These changes in epidermal chemokine level are associated with increased levels of the corresponding chemokine mRNA. The largest increases were observed for CXCL9, CXCL10, CXCL11, and S100A8 and S100A9. To assess the role of CXCL9, CXCL10, CXCL11, which bind to CXCR3, on phenotype development, we expressed TAM67 in CXCR3 knockout mice. Using a similar strategy, we examine the role of S100A8 and S100A9. Surprisingly, loss of CXCR3 or S100A8/A9 did not attenuate phenotype development. These studies suggest that interfering with epidermal AP1 factor signaling initiates a loss of barrier function leading to enhanced epidermal chemokine production, but that CXCR3 and S100A8/A9 do not mediate the phenotypic response.

Embryonic AP1 Transcription Factor Deficiency Causes a Collodion Baby-Like Phenotype

AP1 transcription factors are important controllers of gene expression in the epidermis, and altered AP1 factor function can perturb keratinocyte proliferation and differentiation. However, our understanding of how AP1 signaling changes may underlie or exacerbate skin disease is limited. We have shown that inhibiting AP1 factor function in suprabasal adult epidermis leads to reduced filaggrin levels and to a phenotype that resembles the genetic disorder ichthyosis vulgaris. We now show that inhibiting AP1 factor function during development in embryonic epidermis produces marked phenotypic changes including reduced filaggrin mRNA and protein levels, compromised barrier function, marked ultrastructural change, and enhanced dehydration susceptibility that resembles the phenotype observed in the flaky tail mouse, a model for ichthyosis vulgaris. In addition, the AP1 factor-deficient newborn mice display a collodion membrane phenotype that is not observed in flaky tail mice or in newborn individuals with ichthyosis vulgaris but is present in other forms of ichthyosis. This mixed phenotype suggests the need for a better understanding of the possible role of filaggrin loss and AP1 transcription factor deficiency in ichthyoses and collodion membrane formation.

Pathologic and Environmental Studies Provide New Pathogenetic Insights Into Ringtail of Laboratory Mice

Ringtail is a pathologic condition of laboratory rodents characterized by annular constrictions of the tail. Traditionally, it is classified as an environmental disorder caused by low relative humidity, but other factors (temperature, dietary deficiencies, genetic susceptibility, and caging type) have also been proposed. Twenty litters of mice with ringtail lesions occurred from September 2010 to August 2013 in a facility located in the northern Italy. Mice were maintained under controlled environmental conditions and fed a standard diet. Retrospective analysis of environmental data (relative humidity, temperature) was carried out. Gross, histopathologic, scanning, and transmission electron microscopy examination of tails and limbs was performed. The incidence of ringtail was 0.075% (20/26 800) of all weaned litters over the 3-year period of examination. Temperature and relative humidity remained within accepted limits in all cases except one. We observed annular constrictions in tail, digits of pes, crus, and antebrachium in 116 (100.0%), 47 (40.5%), 11 (9.5%), and 2 (1.7%) of 116 affected mice, respectively. Histologic and ultrastructural examination revealed abnormal keratin desquamation and presence of a keratin ring encircling the tail, causing progressive strangulation of the growing tail with subsequent compression and ulceration of underlying soft tissues, resulting in circulatory changes (edema, hyperemia, thrombosis, hemorrhages), ischemic necrosis, and eventually auto-amputation distal to the constriction. On the basis of our findings, we suggest a disorder of cornification as the primary lesion of ringtail in mice. The cause of these cases, however, remained undetermined, even though traditional etiologic factors (relative humidity, temperature, diet, caging type) were reasonably excluded.