Demonstration of β-glucan receptors in the skin of aquatic mammals—a preliminary report

Abstract

Using immunohistochemistry, the study clearly demonstrates three important β-glucan receptors (Ficolin/ P35, MBL, Dectin-1; members of the lectin-complement pathway of innate immunity) in the integument of six marine and freshwater aquatic mammals (Northern fur seal, Common seal, Walrus, Coypu, Capybara, Otter), but only weakly in two dolphin species. Most of the non-dolphin mammals exhibited strong reactions, especially with regard to the skin glands (tubular apocrine glands, sebaceous glands), for L-Ficolin/P35 and MBL. Distinct reaction staining could also be observed in the epidermis and the outer epithelial sheath of primary hair follicles.Positive Dectin-1 staining was limited to secretory cells of the apocrine tubular glands, and to peripheral and central cells of sebaceous glands of the seals. The Capybara was the only animal to show a clear Dectin reaction in the epidermis (stratum granulosum).The findings are discussed with regard to the constant and high microbial challenge of the skin in the aquatic medium, and variations in hair density of the animals.

Basic structural and functional characteristics of the epidermal barrier in wild mammals living in different habitats and climates

“…Moreover, the demonstration of defense-related material (e.g. ß-glucan receptors) present in the intercellular spaces, as shown for an endangerd epidermis like in the capybara (Meyer et al 2008), confirms again the view of a complex barrier biology (Elias 2007). Last but not least, the skin surface temperature may activate or block epidermal barrier homeostasis by temperature sensors (members of the transient receptor potential family), in particular, when the outer temperatures distinctly increase (Denda et al 2007) or decrease (Denda et al 2010).…”

“…Meyer 1986;Meyer et al 2005). On the contrary, considering the greatly varying measurement results for the capybara, for example, it has to be admitted that this animal has a very low hair coat density so that injuries and attacks of ectoparasites are not unusual (Meyer et al 2008). Such burden includes that the production of glycolipids (and substances of innate immunity) has to be intensified very rapidly if required.…”

“…However, the missing correlation for the semiaquatic species living in artic, temperate or tropical climates was mainly due to the partly extremely high hair densities in the beaver and the otter. Hair density and thickness of the vital epidermis (all measurements after embedding in water soluble and shinkage free plastic resin) according to Meyer et al (1981), Uhr (1984), Meyer (1986Meyer ( , 2010, Meyer (1996Meyer ( -2008, Bollhorn (1999), Kuhn (2009); the juvenile hippopotamus was not measured Independent of these measurements, histological analysis of the plastic sections, in particular, corroborated the view that even comparatively thin epidermis variations could be stained for specific lipid histochemical purposes (HEDAF) and analysed by LSM.…”

Demonstration of substances of innate immunity in the integument of the Malayan pangolin (Manis javanica)

“…On the effector side of innate immunity, the more or less directly attacking cationic antimicrobial peptides (CAPs) and proteins like lysozyme are involved, which can be supported by effects of free sugars. Most of the substances in question can be transported onto the epidermal surface for effective extracorporal use (e.g., Meyer et al 2000Meyer et al , 2001Meyer et al , 2003Meyer et al , 2008Meyer and Seegers 2004;Meyer 2007;Yasui et al 2007;Hornickel 2009). The keratinocyte, in particular, is major source for the different innate immunityrelated humoral compounds, including also complement factors, and complement regulatory proteins (e.g., Schroeder 1999;Bos et al 2001;Debenedictis et al 2001;Harder et al 2001;Yang et al 2001).…”

Prevalence of Epidermal Conditions in California Coastal Bottlenose Dolphins (Tursiops truncatus) in Monterey Bay

“…The pathogens involved are varied and generally include viruses, bacteria, fungi and, occasionally, ciliated protozoans, many naturally occurring in the marine environment (Van Bressem et al 2007). Infections are caused by a breakdown of the host's defense mechanisms such as the shear-resistant gel at the surface of dolphin skin (Meyer et al 2008), or the enzymes and peptide groups found in cetacean epidermis (Meyer and Seegers 2004). Pre-existing lesions or infections may provide routes of entry for a variety of pathogens (Schulman and Lipscomb 1999;Van Bressem et al 2007).…”