O-Acyl Sugars Protect a Wild Tobacco from Both Native Fungal Pathogens and a Specialist Herbivore.

O-Acyl sugars (O-AS) are abundant trichome-specific metabolites that function as indirect defenses against herbivores of the wild tobacco Nicotiana attenuata; whether they also function as generalized direct defenses against herbivores and pathogens remains unknown. We characterized natural variation in O-AS among 26 accessions and examined their influence on two native fungal pathogens, Fusarium brachygibbosum U4 and Alternaria sp. U10, and the specialist herbivore Manduca sexta At least 15 different O-AS structures belonging to three classes were found in N. attenuata leaves. A 3-fold quantitative variation in total leaf O-AS was found among the natural accessions. Experiments with natural accessions and crosses between high- and low-O-AS accessions revealed that total O-AS levels were associated with resistance against herbivores and pathogens. Removing O-AS from the leaf surface increased M. sexta growth rate and plant fungal susceptibility. O-AS supplementation in artificial diets and germination medium reduced M. sexta growth and fungal spore germination, respectively. Finally, silencing the expression of a putative branched-chain α-ketoacid dehydrogenase E1 ß-subunit-encoding gene (NaBCKDE1B) in the trichomes reduced total leaf O-AS by 20% to 30% and increased susceptibility to Fusarium pathogens. We conclude that O-AS function as direct defenses to protect plants from attack by both native pathogenic fungi and a specialist herbivore and infer that their diversification is likely shaped by the functional interactions among these biotic stresses.

Differential expression pattern of antimicrobial peptides in nasal mucosa and secretion.

OBJECTIVE: The intact nasal barrier is a prerequisite for a functioning defense of the upper airway system, in particular the permanent threat by inhaled potentially harmful microorganisms. Antimicrobial peptides (AMP) play an important role in maintaining barrier function. There is few data about AMP in respect of nasal mucosa. This study is addressed to gain further insight into the differential AMP expression and secretion pattern according to defined anatomical regions of the vestibulum nasi and turbinates. PATIENTS AND METHODS: ELISA was applied to quantify concentrations of AMP RNase-7, psoriasin, hBD-2, hBD-3 and LL-37 in nasal secretions of 20 healthy volunteers. Immunohistochemistry was used to detect the local cellular sources of AMP in the vestibulum nasi (squamous epithelium) and compared to the mucosa of the turbinates (pseudostratified epithelium) in 10 healthy volunteers. RESULTS: Expression of RNase 7 and psoriasin was detected in all nasal secretion specimens, whereas LL-37 was detected in 16, hBD-2 in 5 and hBD-3 in 6 specimens. In the vestibulum nasi, luminal cell layers were demonstrated as local cellular sources for hBD-3 and RNase 7, whereas psoriasin was found in all layers of the stratified squamous epithelium. LL-37 was detected in 1 stroma cells sample, whereas hBD-2 was not detected at all. In turbinate biopsie,s hBD-3 and LL-37 were detectable in the epithelium, stroma cells and submucosal glands. RNase 7 was only present in submucosal glands. HBD-2 and psoriasin were not detected. CONCLUSION: These data demonstrate that the nasal epithelium contains a chemical defense shield through the expression and secretion of various AMP.

Enhanced expression and secretion of antimicrobial peptides in atopic dermatitis and after superficial skin injury.

Human skin can defend itself against potentially invading microorganisms by production of antimicrobial peptides (AMPs). The expression of AMPs in atopic dermatitis (AD) is still emerging. To gain more insight into the role of AMPs in AD, we systematically analyzed the expression of ribonuclease 7 (RNase 7), psoriasin, and human beta-defensins (hBD)-2 and -3 in AD compared with psoriatic and healthy control skin as well as after experimental barrier disruption. Immunostaining revealed enhanced expression of all AMPs in the lesional skin of untreated AD and psoriasis when compared with non-lesional skin and controls. Accordingly, induced in vivo secretion of RNase 7, psoriasin, and hBD-2 was detected using ELISA on lesional skin in AD and in even higher concentrations in psoriasis. The secretion of AMPs did not correlate with severity of AD and Staphylococcus aureus colonization. Skin barrier disruption caused enhanced immunoreactivity of hBD-2 and hBD-3 after 24 hours. Strong secretion of RNase 7 was already detected after 1 hour, whereas hBD-2 secretion was significantly enhanced after 24 hours only under occlusion. Thus, a disturbed skin barrier may trigger AMP induction in AD and psoriasis. The functional role of AMP in AD, especially with regard to the control of S. aureus colonization, needs further analysis.

Differential expression of antimicrobial peptides in margins of chronic wounds.

Skin wounds usually heal without major infections, although the loss of the mechanical epithelial barrier exposes the tissue to various bacteria. One reason may be the expression of antimicrobial peptides (AMP) of which some [human beta-defensins (hBD) and LL-37] were recently shown to support additionally certain steps of wound healing. There are no studies which have compared expression patterns of different classes of AMP in chronic wounds. The aim of our study was therefore to analyse the expression profile of hBD-2, hBD-3, LL-37, psoriasin and RNase 7 by immunohistochemistry from defined wound margins of chronic venous ulcers. We detected a strong induction of psoriasin and hBD-2 in chronic wounds in comparison with healthy skin. Except for stratum corneum, no expression of RNase 7 and LL-37 was detected in the epidermis while expression of hBD-3 was heterogeneous. Bacterial swabs identified Staphylococcus aureus and additional bacterial populations, but no association between colonization and AMP expression was found. The differential expression of AMP is noteworthy considering the high bacterial load of chronic ulcers. Clinically, supplementation of AMP with the capability to enhance wound healing besides restricting bacterial overgrowth could present a physiological support for treatment of disturbed wound healing.

Programmable cells of monocytic origin (PCMO): a source of peripheral blood stem cells that generate collagen type II-producing chondrocytes.

The focus of this study was a new adult pluripotent cell derived from human peripheral blood monocytes identified as a "programmable cell of monocytic origin" (PCMO). In contrast to bone marrow-derived stem cells, these cells can be harvested from peripheral venous blood without aspiration of the bone marrow and have multilineage potential comparable to that of mesenchymal stem cells (MSC). The aim of this study was to evaluate the potential of PCMOs to differentiate into collagen type II-producing chondrocytes using various extrinsic cues (TGFbeta-1, IGF-1, BMP-2, and BMP-7). Collagen type I and II proteins were localized using immunohistochemistry and quantified by enzyme-linked immunosorbent assays (ELISA). The shape of the differentiating PCMOs was monitored with electron microscopy. Collagen type I and II messenger RNA expression was analyzed using real-time reverse transcriptase-polymerase chain reaction (RT PCR) and regular RT PCR. Immunohistochemistry revealed a strong accumulation of collagen type II after a 6-week incubation period with BMP-2, BMP-7, TGF-beta, IGF-I, and TGF-beta, and IGF-1. Collagen type I was only mildly induced by the applied stimulants. Electron microscopy findings showed a shift from a monocyte-like structure to a chondrocyte-like structure after 2 weeks of stimulation. Stimulation of PCMOs with BMP-2, BMP-7, TGF-beta, IGF-I, and TGF-beta, and IGF-1 induced a chondrogenic differentiation with continuous expression of collagen type II mRNA and protein over several weeks time. Collagen type I and II expression in undifferentiated PCMOs or in control cells incubated without any stimulant was not detected. PCMOs have the potential to differentiate into collagen type II synthesizing chondrocytes. The ability to reprogram and differentiate PCMOs from peripheral blood into sizable quantities might enable their clinical application in cartilage repair after mechanical injury or in cases of osteoarthritis.