Human hair follicle epithelium has an antimicrobial defence system that includes the inducible antimicrobial peptide psoriasin (S100A7) and RNase 7.

BACKGROUND: Hair follicle (HF) ostia represent a potential port of microbial entry into the skin. However, they rarely show clinical signs of infection. This suggests the presence of local, efficient, antimicrobial defence systems, which may include antimicrobial peptides (AMPs). OBJECTIVES: We determined the presence and distribution of the major AMPs, RNase 7 and psoriasin (S100A7), in human scalp HFs. We investigated whether HF production of these AMPs was induced by prototypic microbial products and proinflammatory cytokines, i.e. interferon (IFN)-gamma. Finally, we examined whether the classical pathways for AMP induction, such as toll-like receptor (TLR)4 and TLR5 expression, are present in human HFs and up-regulated after stimulation with bacterium-associated ligands. METHODS: Cryosections from fresh or organ-cultured full-thickness normal human scalp skin treated with lipopolysaccharide (LPS), flagellin, protein A, lipoteichoic acid (LTA) or IFN-gamma were stained for psoriasin and RNase 7 immunoreactivity (IR) as well as for TLR4 and TLR5. In addition, outer root sheath cell culture and semiquantitative analysis of mRNA expression levels of RNase 7 and psoriasin were performed. RESULTS: Specific RNase 7 IR was present throughout the entire HF outer root sheath in situ and in cell culture, whereas psoriasin IR was present only in the most distal compartment and not detectable in cultured ORS cells. Upon treatment with Gram-positive (LTA, protein A) or Gram-negative bacterial (LPS, flagellin) cell wall components, or with the cytokine IFN-gamma, the IR of both psoriasin and RNase 7 was modified. TLR4 and TLR5 IR was detected in the normal HF epithelium and were upregulated after treatment with their respective ligand. The mRNA analysis confirmed the immunohistochemistry results. CONCLUSIONS: This pilot study suggests that normal human scalp HF epithelium possesses a functional antimicrobial defence system, which includes the AMPs RNase 7 and psoriasin, and TLRs, and that these are induced by classical microbial products.

The influence of pancreas-derived stem cells on scaffold based skin regeneration.

It has been shown that Pancreatic Stem Cells (PSCs) share many features with skin stem cells. Yet, their potential role in skin regeneration remains to be elucidated. 5x10(5) PSCs from male Rattus norwegicus were seeded on Matriderm scaffold overnight. Cells survival and proliferation were then tested in vitro showing the survival of the cells and their homogenous distribution in the scaffolds. Afterwards, scaffolds were used to replace bilateral full-thickness skin wounds made on the dorsum of Nu/Nu mice. A control group of nude mice received the Matriderm scaffolds without cells. Two weeks after transplantation, wound areas were harvested and analyzed with respect to epithelialization, vascularization and wound closure. The healing area and regeneration rate were significantly increased in the group used the PSCs-seeded scaffolds (factor of 2.1). Vascularization rate showed a significant increase in the PSCs-seeded scaffolds(factor of 1.5). Morphology and immunohistochemistry showed new skin-like structures positive to epidermal markers in the healing wound bed. PSCs were detected in the regenerated tissues. This study showed that the combined use of PSCs with the Matriderm as a scaffold for dermal regeneration significantly increased the epidermalization, vascularization and healing in full-thickness wounds.

Evidence that the bulge region is a site of relative immune privilege in human hair follicles.

BACKGROUND: Recent gene profiling data suggest that, besides the anagen hair bulb, the epithelial stem cell region in the outer root sheath of hair follicles (HFs), termed the bulge, may also represent an area of relative immune privilege (IP). OBJECTIVES: To investigate whether the human HF bulge is a site of relative IP within anagen VI HFs. METHODS: Anagen VI HFs from normal human scalp skin were analysed using immunohistological staining techniques, quantitative histomorphometry and statistical analysis. For functional evidence we performed full-thickness human scalp skin organ cultures to investigate whether interferon (IFN)-gamma, a key inducer of IP collapse in hair bulbs, has a similar effect on the putative bulge IP. RESULTS: Major histocompatibility complex (MHC) class Ia, beta(2)-microglobulin and MHC class II immunoreactivity are downregulated in the human bulge. The immunosuppressants alpha-melanocyte stimulating hormone, transforming growth factor-beta2, macrophage migration inhibitory factor and indoleamine-2,3-dioxygenase (IDO) are upregulated in the CD200+, stem cell-rich bulge region. These CD200+ cells also co-express HLA-E. Furthermore, IFN-gamma induces significant ectopic MHC class Ia expression in bulge cells of organ-cultured human scalp skin. CONCLUSIONS: These data suggest that the bulge of human anagen HFs represents a hitherto unrecognized site of relative IP in human skin. Simultaneously, we present the first evidence of IDO and HLA-E protein expression in normal human HFs. Bulge IP presumably protects the HF epithelial stem cell reservoir from autoaggressive immune attack whereas a loss of bulge IP may play a central role in the pathogenesis of cicatricial alopecias.

[Difference reflectometry might permit process control for dental laser applications]. / Die Differenzrefklektometrie als mögliche Porzesssteuerung für den Lasereinsatz in der Zahnheilkunde.

Difference reflectometry is a new method for assessing material surfaces by measuring the relative amount of light reflected within a range of 300-720 nm. The in vivo and in vitro results of the present study indicate that it is possible to transfer this measuring principle to dental applications. Reflexion measurements allow the detection of hard tooth structures and their pathologic alterations with adequate exactness. With the aid of this method it is possible to differentiate between carious hard tissues and clinically healthy tissues by color and surface structure during excavation. It also allows a reliable demarcation from oral soft tissues. Due to its high measuring frequency it may be used as on-line process control. In contrast to other spectrometric methods it requires a minimum of equipment and is easy to handle.

[Vitality tests of the tooth pulp using laser Doppler flowmetry]. / Die Vitalitätsprüfung der Zahnpulpa mit der Laser-Doppler-Flussmessung.

Laser-Doppler flowmetry allows a non-invasive assessment of the microcirculation in circumscribed tissue areas. However, measurements in intact human teeth prove to be extensive, as far as instrumental equipment and time requirements are concerned. Therefore we developed an application system which allows us to transfer the principle of measurement under clinical conditions. Thus we were able to prove that the signal recorded can be regarded as a specific expression of pulpal microcirculation. A comparison between vital teeth and root-filled teeth shows that the signal to noise ratio is sufficiently high to allow a definite assessment of pulp vitality.

[A procedure for testing local anesthetics]. / Ein Verfahren zur Testung von Lokalanästhetika.

A method for testing intensity and duration of the effect of local anaesthetics is presented. The assessment of effectiveness is based on the subjective perception threshold after painful electrical tooth pulp stimuli. With respect to its practical applicability the method is tested in a clinical study using three commercial local anaesthetics. The results prove the possibility of giving reproducible and quantitative statements concerning the time course and intensity of anaesthesia. Using this method, only a restricted number of subjects is necessary for estimating the differences in the basic features of different local anaesthetics.