Heat shock proteins 47 and 70 expression in rodent skin model as a function of contact cooling temperature: Are we overcooling our target?

BACKGROUND AND OBJECTIVES

The degree of protective cooling required during laser therapy to achieve an optimal result is unknown. The expression of heat shock proteins, Hsp47 and Hsp70, were examined in the epidermis and dermis as biomarkers to quantify the degree and depth of tissue affected by non-ablative laser treatment using variable protective cooling parameters.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-one male Sprague-Dawley rats were treated with a 1,319 nm Nd:YAG laser using a sapphire cooling plate attached to the hand piece. A 4 cmx4 cm area on each side of the rat was treated with the same energy and pulse settings, with variable contact cooling. Protective cooling parameters, for each degree increment, ranging from 0 to 25 degrees C were studied. Immunohistochemistry (IHC), Western blot and PCR were performed to evaluate the effects of superficial cooling on Hsp47, and Hsp70 expressions.

RESULTS

Our data showed the extent of topical cooling needed to produce a thermal effect at different depths in the dermis, quantified by the expression of Hsp47 and Hsp70. Significant Hsp expression was observed with cooling of 13 degrees C and warmer; no identifiable cellular reaction was observed when cooling below 5 degrees C. There was no evidence of epidermal injury when treating the skin with any protective cooling ranging from 0 to 25 degrees C.

CONCLUSION

Our data would suggest contact cooling temperatures 5 degrees C and below completely protects through the entire dermis. There was no evidence of epidermal injury with protective cooling at any temperature between 0 and 25 degrees C. Warmer temperatures are safe and adequately protect the epidermis in this model.

The Receptor for Advanced Glycation End Products Is Highly Expressed in the Skin and Upregulated by Advanced Glycation End Products and Tumor Necrosis Factor-Alpha

Advanced glycation end products (AGEs) form non-enzymatically from reactions of proteins with reducing sugars. In the skin, AGEs were reported to accumulate in dermal elastin and collagens and to interact nonspecifically with the cell membrane of dermal fibroblasts. Therefore, AGEs may influence the process of skin aging. We investigated the presence of the AGE receptor RAGE in skin and the influence of AGEs on receptor expression and the formation of extracellular matrix (ECM). Sections of sun-protected and sun-exposed skin were analyzed with monoclonal antibodies against (RAGE), heat-shock protein 47, factor XIIIa, CD31, and CD45. RAGE was mainly expressed in fibroblasts, dendrocytes, and keratinocytes and to a minor extent in endothelial and mononuclear cells. Human foreskin fibroblasts (HFFs) highly expressed RAGE on the protein and mRNA level when analyzed by quantitative Western blotting and real-time PCR. Incubation of HFFs with the specific RAGE ligand Nepsilon-(carboxymethyl)lysine-modified BSA (CML-BSA) and tumor necrosis factor-alpha resulted in significant upregulation of RAGE expression. CML-BSA induced a mildly profibrogenic pattern, increasing connective tissue growth factor, transforming growth factor-beta (TGF-beta) 1, and procollagen-alpha1(I) mRNA, whereas expression of matrix metalloproteinase (MMP)-1, -2, -3, and -12 was unaffected. We conclude that in HFFs, AGE-RAGE interactions may influence the process of skin aging through mild stimulation of ECM gene expression.

Exogenous nitric oxide enhances the synthesis of type I collagen and heat shock protein 47 by normal human dermal fibroblasts

BACKGROUND

It is well established that the alterations of dermal matrix contributes to skin aging characterized by wrinkles. On the other hand, physiological NO is useful to maintain skin homeostasis such as a vasodilatation. However, a role of NO on production of dermal matrix has been clarified.

OBJECTIVE

In this study, we have attempted to analyze the role of NO on type I collagen synthesis of normal human dermal fibroblasts including expression of procollagen alphaI S(1) mRNA/protein and heat shock protein 47 (HSP47).

METHODS

The effects of NO which was generated by two types of NO donors, sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP), on type I collagen and HSP47 and their related mRNA expression were examined with ELISA and RT-PCR.

RESULTS

NO was significantly accelerated the production of type I collagen by fibroblasts corresponding with up-regulation of procollagen alphaI (1) mRNA. Furthermore, NO increased both levels of HSP47 protein and mRNA in fibroblasts in a dose-dependent manner.

CONCLUSIONS

These results suggest that NO has dual effects on collagen synthesis by fibroblasts as follows; one is the direct stimulation of collagen synthesis due to the up-regulation of procollagen alphaI(1) mRNA, and the other is an indirect effect through the increase of HSP47 mRNA expression. This is the first report that exogenous NO stimulates HSP47 production by dermal fibroblasts.