1α,25-dihydroxyvitamin D3-eluting nanofibrous dressings induce endogenous antimicrobial peptide expression.

AIM: The aim of this study was to develop a nanofiber-based dressing capable of local sustained delivery of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) and augmenting human CAMP induction. MATERIALS & METHODS: Nanofibrous wound dressings containing 1,25(OH)2D3 were successfully prepared by electrospinning, which were examined in vitro, in vivo and ex vivo. RESULTS: 1,25(OH)2D3 was successfully loaded into nanofibers with encapsulation efficiency larger than 90%. 1,25(OH)2D3 showed a sustained release from nanofibers over 4 weeks. Treatment of U937 and HaCaT cells with 1,25(OH)2D3-loaded poly(ϵ-caprolactone) nanofibers significantly induced hCAP18/LL37 expression in monocytes and keratinocytes, skin wounds of humanized transgenic mice and artificial wounds of human skin explants. CONCLUSION: 1,25(OH)2D3 containing nanofibrous dressings could enhance innate immunity by inducing antimicrobial peptide production.

Photoprotective Properties of Isothiocyanate and Nitrile Glucosinolate Derivatives From Meadowfoam (Limnanthes alba) Against UVB Irradiation in Human Skin Equivalent.

Exposure to ultraviolet B (UVB) irradiation of the skin leads to numerous dermatological concerns including skin cancer and accelerated aging. Natural product glucosinolate derivatives, like sulforaphane, have been shown to exhibit chemopreventive and photoprotective properties. In this study, we examined meadowfoam (Limnanthes alba) glucosinolate derivatives, 3-methoxybenzyl isothiocyanate (MBITC) and 3-methoxyphenyl acetonitrile (MPACN), for their activity in protecting against the consequences of UV exposure. To that end, we have exposed human primary epidermal keratinocytes (HPEKs) and 3D human skin reconstructed in vitro (EpiDermTM FT-400) to UVB insult and investigated whether MBITC and MPACN treatment ameliorated the harmful effects of UVB damage. Activity was determined by the compounds' efficacy in counteracting UVB-induced DNA damage, matrix-metalloproteinase (MMP) expression, and proliferation. We found that in monolayer cultures of HPEK, MBITC and MPACN did not protect against a UVB-induced loss in proliferation and MBITC itself inhibited cell proliferation. However, in human reconstructed skin-equivalents, MBITC and MPACN decrease epidermal cyclobutane pyrimidine dimers (CPDs) and significantly reduce total phosphorylated γH2A.X levels. Both MBITC and MPACN inhibit UVB-induced MMP-1 and MMP-3 expression indicating their role to prevent photoaging. Both compounds, and MPACN in particular, showed activity against UVB-induced proliferation as indicated by fewer epidermal PCNA+ cells and prevented UVB-induced hyperplasia as determined by a reduction in reconstructed skin epidermal thickness (ET). These data demonstrate that MBITC and MPACN exhibit promising anti-photocarcinogenic and anti-photoaging properties in the skin microenvironment and could be used for therapeutic interventions.

Pathotype Identification of Xanthomonas citri pv. citri Strains Causing Citrus Canker in Vietnam.

Asiatic citrus canker caused by Xanthomonas citri pv. citri is a bacterial disease of major economic importance in tropical and subtropical citrus-producing areas. It probably originated in Asia (2). X. citri pv. citri induces erumpent, callus-like lesions with a water-soaked margin on aerial organs of the plants. Severe attacks cause premature fruit drop and twig dieback. This pathogen has consequently been subjected to international quarantine regulation and eradication efforts. Two pathogenic variants of X. citri pv. citri can be separated by their host range. X. citri pv. citri pathotype A strains cause severe infection worldwide in a wide range of citrus species; grapefruit (Citrus paradisi) is particularly susceptible. More recently, another group of strains from different areas of West Asia has been designated as X. citri pv. citri pathotype A* (4). These A* strains are genetically related to X. citri pv. citri, but their host range is primarily restricted to Mexican lime (C. aurantifolia) and they do not infect grapefruit. Strains similar in host range were later reported in Florida, Thailand, and Cambodia (2). In this study, we investigated the distribution of X. citri pv. citri pathotypes in Southeast Asia. A large survey on citrus was conducted in 14 provinces in the north (Ha Noi, Hung Yen, Nghe Han, Ha Ting, and Phu Tho) and south (Can Tho, Long An, Dong Nai, Tien Giang, Vinh Long, Ben Tre, Dong Thap, Vung Tau, and Lam Dong) of Vietnam. We collected 557 X. citri pv. citri isolates, after cultivation on KC semiselective medium (3), from citrus species, including 60 strains from Mexican lime in eight provinces. Ligation mediated (IS-LM)-PCR analysis using primers targeting three insertion sequences (1) was done on all Vietnamese strains and on additional reference strains of X. citri pv. citri-A, -A*, and X. citri pv. aurantifolii. IS-LM-PCR indicated that all Vietnamese isolates were pathotype A and did not include any with a restricted host range (X. citri pv. citri-A* and X. citri pv. aurantifolii). Amplified fragment length polymorphism (AFLP) analysis was carried out on a subset of 84 X. citri pv. citri strains, including 22 strains from Mexican lime from seven provinces. AFLP was carried out using SacI/MspI and four primer pairs (unlabeled MspI +1 [A, C, T or G] primers and 5'-labeled - SacI + C primer for the selective amplification step) (2) and the data confirmed that all Vietnamese X. citri pv. citri strains were genetically related to pathotype A strains. Mexican lime and Duncan grapefruit or pineapple sweet orange leaves were inoculated with 25 strains from lime (representative of the genetic diversity) using a detached leaf assay (3) and they produced typical canker lesions on both host species. In spite of the presence of pathotype A* strains in neighboring countries (2), no strains genetically or pathogenically related to this pathotype were identified in this collection. A survey of commercial Mexican lime orchards, especially in Vietnamese provinces bordering Cambodia, should be undertaken to detect and eradicate A* strains because these are known to strongly impact lime production in other parts of Asia (e.g., Thailand). References: (1) L. Bui Thi Ngoc et al. Appl. Environ. Microbiol. 75:1173, 2009. (2) L. Bui Thi Ngoc et al. FEMS Microbiol. Lett. 288:33, 2008. (3) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005. (4) C. Vernière et al. Eur. J. Plant Pathol. 104:477, 1998.