Giovanna Donnarumma

Toll-like receptor 2 (TLR2) mediates intracellular signalling in human keratinocytes in response to Malassezia furfur.

Toll-like receptors (TLRs) are crucial players in the innate immune response to microbial invaders. The lipophilic yeast Malassezia furfur has been implicated in the triggering of scalp lesions in psoriasis. The aim of the present study was to assess the role of TLRs in the defence against M. furfur infection. The expression of the myeloid differentiation factor 88 (MyD88) gene, which is involved in the signalling pathway of many TLRs, was also analysed. In addition, a possible correlation of antimicrobial peptides of the β-defensin family to TLRs was tested. Human keratinocytes infected with M. furfur and a variety of M. furfur-positive psoriatic skin biopsies were analysed by RT-PCR, for TLRs, MyD88, human β-defensin 2 (HBD-2), HBD-3 and interleukin-8 (IL-8) mRNA expression. When keratinocytes were infected with M. furfur, an up-regulation for TLR2, MyD88, HBD-2, HBD-3 and IL-8 mRNA was demonstrated, compared to the untreated cells. The same results were obtained when psoriatic skin biopsies were analysed. The M. furfur-induced increase in HBD-2 and IL-8 gene expression is inhibited by anti-TLR2 neutralising antibodies, suggesting that TLR2 is involved in the M. furfur-induced expression of these molecules. These findings suggest the importance of TLRs in skin protection against fungi and the importance of keratinocytes as a component of innate immunity.

Antimicrobial human beta-defensin-2 stimulates migration, proliferation and tube formation of human umbilical vein endothelial cells

Human beta-defensin-2 (hBD-2) is an antimicrobial peptide which is released upon microbial invasion and contributes to mucosal and epithelial defense modulating both innate and adaptive immunity. We found that hBD-2 stimulates chemotaxis of human endothelial cells with an extent similar to that exerted by the vascular endothelial growth factor (VEGF). The hBD-2-dependent chemotaxis is dose-dependent, maximal effect being reached at 500 ng/ml concentration. In the absence of any growth factor, hBD-2 favors wound healing of endothelial cells, causing an about 2-fold increase in the speed of wound closure with respect to the control. Furthermore, hBD-2 promotes endothelial cell proliferation, although at a minor extent as compared to VEGF. When plated on matrigel enriched with angiogenic factors, endothelial cells form a three-dimensional network of tubes that gives rise to capillary-like structures. Similarly to VEGF, hBD-2 promotes capillary-like tube formation of human endothelial cells. Pro-angiogenic effect promoted by hBD-2 is dose-dependent, peaks at a 500 ng/ml hBD-2 concentration and is prevented by blocking anti-alphavbeta3 monoclonal antibody. However, hBD-2-induced pro-angiogenic activity is not due to endogenously produced VEGF because it is not prevented by neutralizing anti-VEGF antibodies. Overall, our findings suggest that hBD-2 could link inflammation and the host defense through its pro-angiogenic activity.

Malassezia furfur induces the expression of β-defensin-2 in human keratinocytes in a protein kinase C-dependent manner

Antimicrobial peptides of the β-defensin family are expressed in all human epithelial tissues tested to date and have recently been the subject of vigorous investigation. Their localization and characteristics support the hypothesis that these peptides play a role in mucosal and skin defense. The lipophilic yeast Malassezia furfur is a saprophyte found in normal human cutaneous flora. Malassezia furfur is not only a saprophyte, but is also associated with several diseases such as Malassezia folliculitis, seborrheic dermatitis and some forms of atopic dermatitis, psoriasis and confluent and reticulate papillomatosis. Little is known about the mechanism by which M. furfur overcomes the natural barrier of the skin. To further define the role of the β-defensins in the innate human skin immune response, we analyzed the mRNA expression of two human β-defensins HBD-1 and HBD-2 in human keratinocytes treated with M. furfur. In addition, we looked into how M. furfur of TGF-β1 and IL-10, cytokines that interfere with the development of protective cell immunity, regulate their expression. Finally, we examined the signal transduction mechanisms involved during M. furfur uptake. Cultured human keratinocytes were treated with M. furfur. The mRNA and protein expression were analyzed, respectively, by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting. Our data demonstrate that M. furfur does not modify HBD-1 expression, whereas it up-regulates, via protein kinase C (PKC), the expression of HBD-2, TGFβ-1 and IL-10 48 h after treatment. Our results suggest that β-defensins are integral components of innate host defenses. They play an essential part in the resistance of the human skin surfaces against M. furfur uptake and other microbial invasion.

Increased Expression of Periplasmic Cu,Zn Superoxide Dismutase Enhances Survival of Escherichia coli Invasive Strains within Nonphagocytic Cells

ABSTRACT We have studied the influence of periplasmic Cu,Zn superoxide dismutase on the intracellular survival of Escherichia colistrains able to invade epithelial cells by the expression of theinv gene from Yersinia pseudotuberculosis but unable to multiply intracellularly. Intracellular viability assays, confirmed by electron microscopy observations, showed that invasive strains of E. coli engineered to increase Cu,Zn superoxide dismutase production are much more resistant to intracellular killing than strains containing only the chromosomalsodC copy. However, we have found only a slight difference in survival within HeLa cells between a sodC-null mutant and its isogenic wild-type strain. Such a small difference in survival correlates with the very low expression of this enzyme in the wild-type strain. We have also observed that acid- and oxidative stress-sensitiveE. coli HB101(pRI203) is more rapidly killed in epithelial cells than E. coli GC4468(pRI203). The high mortality ofE. coli HB101(pRI203), independent of the acidification of the endosome, is abolished by the overexpression of sodC. Our data suggest that oxyradicals are involved in the mechanisms of bacterial killing within epithelial cells and that high-level production of periplasmic Cu,Zn superoxide dismutase provides bacteria with an effective protection against oxidative damage. We propose that Cu,Zn superoxide dismutase could offer an important selective advantage in survival within host cells to bacteria expressing high levels of this enzyme.

Possible role of Malassezia furfur in psoriasis: modulation of TGF‐β1, integrin, and HSP70 expression in human keratinocytes and in the skin of psoriasis‐affected patients

Background:  Psoriasis is a disease characterized by an abnormal pattern of keratinocyte growth and differentiation. Malassezia furfur forms part of the normal human skin flora. It may also be involved in the pathogenesis of psoriasis. To define the role of M. furfur in the pathogenesis of psoriasis, we investigated how M. furfur regulates molecules involved in cell migration and proliferation. The experiments were performed using human keratinocytes and skin biopsies from M. furfur‐positive and ‐negative psoriasis‐affected patients. In addition, we examined the signal transduction mechanisms involved.

Polydatin, a natural precursor of resveratrol, induces β-Defensin production and reduces inflammatory response.

It is well known that human keratinocytes produce the anti-microbial peptide β-defensin 2. Its production is enhanced by pathogenic microorganisms or other environmental stressors. In this study, we evaluated the effect of resveratrol, a polyphenol found in several dietary source as grape seed, and its natural precursor, polydatin on heat-stressed human keratinocytes. By reverse transcription-polymerase chain reaction and enzyme-linked immunoadsorbent assay, we demonstrated that resveratrol used in combination with polydatin was able to modulate interleukin (IL)-6, IL-8 and tumor necrosis factor-alpha gene expression. In addition, our data show that resveratrol and polydatin increased the heat shock protein (Hsp)70B′ gene expression, a Hsp that plays an important role in the cytoprotection and repair of cells and tissues. Worthy of note, polydatin used alone or in combination with resveratrol, increased the release of human β-defensin 2. These results highlighted the ability of polydatin and resveratrol to reinforce cytoprotective response in stress conditions and suggest their use in cosmetic or pharmaceutical preparations.

Bacterial components induce cytokine and intercellular adhesion molecules-1 and activate transcription factors in dermal fibroblasts.

This study investigated the effect of various structural components of Gram-positive (lipotheichoic acid and protein A) and Gram-negative (porins and lipopolysaccharide) bacteria on human dermal fibroblasts. Fibroblasts are important effector cells which have a potential role in augmenting the inflammatory response in various diseases. In this study we present a profile of TNF-alpha, IL-6 and IL-8, the expression of intercellular adhesion molecules (ICAM-1) and the activation of transcriptional nuclear factor NF-kB and AP-1 in human dermal fibroblasts stimulated by bacterial surface components. Compared to the controls, increased ICAM-1, IL-6 and IL-8 gene expression after stimulation of LPS and porins at 2 and 4 h was more evident than that obtained following stimulation of LTA and PA. Gene expression was also associated with the production of cytokine proteins in culture supernatants. TNF-alpha gene expression remained undetectable. Moreover, LPS and porin treatments determined IkBalpha phosphorylation and degradation in human dermal fibroblasts and the subsequent activation of nuclear factors NF-kB and AP-1. These data suggest the importance of such stimuli in the first step of the inflammatory process, as well as the important role played by fibroblasts in skin inflammatory disease.

Anti-inflammatory effects of moxifloxacin and human β-defensin 2 association in human lung epithelial cell line (A549) stimulated with lipopolysaccharide

Epithelia in the human airways, from the nasal aperture to the alveoli, are covered in a protective film of fluid containing a number of antimicrobial proteins. Defensins are single-chain, strongly cationic peptides and are one of the most extensively studied classes of antimicrobial peptides. Moxifloxacin (MXF) is a fluoroquinolone that acts against both Gram positive and Gram negative bacteria. In this study, we evaluated the effects of HBD2, MXF and the association MXF/HBD2 on some cytokines and on the ICAM-1 expression in LPS-stimulated A549 cells. Our results suggest that by lowering the epithelial cell-derived IL-1beta, IL-6, IL-8 and ICAM-1 expression, the MXF/HBD2 association interferes with the multifunctional cytokine network evolving during inflammatory processes of the respiratory tract; this anti-inflammatory potential could be of great value in the treatment of inflammatory disorders.

Effect of low-nutrient seawater on morphology, chemical composition, and virulence of Salmonella typhimurium

The response of Salmonella typhimurium to low nutrient levels was determined by measuring the concentrations of lipids, carbohydrates, DNA, RNA, and proteins over a 32-day starvation period. Ultrastructural integrity was observed by transmission electron microscopy. Lipid and carbohydrate content of bacterial cells rapidly declined within the first 16 days, while DNA and proteins exhibited a more gradual decline over the 32 days of starvation. In contrast, RNA content did not decrease appreciably upon nutrient starvation. Structural damage occurred especially after 16 days of starvation. After 32 days of nutrient deprivation, we recorded degenerative cellular forms, a coccoidal cell shape, a decrease in cellular volume, and the loss of the three-layered outer membrane. The morphological and structural alterations correlated with virulence in infected animals. We observed a decrease in virulence of S. typhimurium after 9, 16, and 32 days of starvation, reaching a maximal decrease after 32 days of nutrient deprivation. The decrease in virulence correlated to surface hydrophobicity alterations, adherence to eukaryotic cells, and phagocytosis.

New Strategies in Dandruff Treatment: Growth Control of Malassezia ovalis

Background: Cutaneous infections induced by Malassezia ovalis (Pityrosporum ovale) represent a therapeutic problem due to the high rate of recurrence. Objective: We studied feasible strategies to control the growth of M. ovalis, compatible with topical use in cosmetic formulations. Studies were performed on the effects of pH, ionic strength, cinnamic acid and related compounds on mycotic growth. Methods:M. ovalis was cultivated in modified Sabouraud agar. The effects of pH, ionic strength and cinnamic acid and related compounds on mycotic growth were studied by the membrane filter method. Results: In vitro growth of M. ovalis is strongly affected by pH and ionic strength. pH 4.5 induced a growth inhibition of about 95% and 1 M NaCl, at the optimal growth pH, reduced cell growth by over 90%. Cinnamic acid showed an inhibitory effect of 50% at 0.005 g/dl; 30 min incubation with cinnamic acid 0.5 g/dl had a mycocidic effect. Conclusion: These results suggest the use of cosmetic compositions containing cinnamic acid or buffered acidic lotions and shampoos in the treatment of M. ovalis infections of the scalp, eventually in addition or alternative to antimycotic drugs or in maintenance therapy. Cosmetic formulations with high ionic strength or skin irritant derivatives such as cinnamaldehyde cannot be proposed for practical use.