Biomedical subjects

Jan D Bos

Publications and source records attributed to Jan D Bos.

40 records · Page 3Linked to original sources

PubMed2002

UVB irradiation of normal human skin favors the development of type-2 T-cells in vivo and in primary dermal cell cultures.

To determine the effect of UVB exposure on the balance of type-1 or type-2 T-cells in skin, we examined the expression of key markers interferon (IFN)-gamma and interleukin (IL)-4 in cryostat sections. IFN-gamma mRNA was clearly detectable in nonirradiated control skin, and IFN-gamma protein was found in 2% of the dermal CD3pos T-cells, whereas IL-4 mRNA was hardly detectable, and no IL-4 protein was found. In contrast, IL-4 mRNA expression increased upon irradiation, and IL-4 was found in 2% of the T-cells at day 2 after UVB-exposure. Concomitantly, IFN-gamma mRNA expression decreased, and IFN-gamma protein became absent. We also analyzed T-cells present in primary dermal cell cultures, which were used as an in vitro equivalent of the in vivo situation. As compared with T-cells from control skin, T-cells in dermal cell cultures from UVB-exposed skin displayed an increased IL-4 and decreased IFN-gamma expression. No such skewing occurred when the T-cells from irradiated skin were cloned in the absence of a dermal microenvironment. Except for an occasional positive T-cell, type-1-associated cell-surface markers (CCR5, CXCR3) or type-2 markers (CCR3, CD30, CRTH2) were undetectable in situ. But these markers were expressed on cultured dermal T-cells from UVB-exposed and control skin at a comparable level, but did not correlate with the IFN-gamma and IL-4 production. Altogether, UVB-induced changes of the dermal microenvironment favor the development of type-2 T-cells.

Base Sequence↗

PubMedDate not supplied

Smallpox: what the dermatologist should know.

Despite the eradication of naturally occurring smallpox in 1977, stores of the virus have been maintained in laboratories in the United States and Russia. It is feared that certain rogue states and terrorist organizations may have illicitly acquired the virus with the intent of unleashing it as an agent of bioterrorism. The United States and other nations have begun vaccinating individuals in the military and health care workers who might become exposed. Primary care providers and dermatologists will be called upon to evaluate potential index cases and vaccination reactions. In this report, the authors review the essential clinical aspects of smallpox and potential reactions to smallpox vaccination. Special attention is given to eczema vaccinatum, which can occur in vaccinees and their family contacts with active or quiescent atopic dermatitis or a personal history of eczema.

Dermatology↗

PubMedDate not supplied

Suppression of different phases of systemic contact hypersensitivity by urocanic acid oxidation products.

On exposure to UV-B, the epidermal component trans-urocanic acid (UCA) is not only photoisomerized into cis-UCA but will also, at least in part, be photooxidized into UCA oxidation products (UOPs). We hypothesized that UOPs can mimic UV-induced systemic immunosuppression comparable to the suppressive properties already established for cis-UCA. A crude mixture of UOPs showed a significant suppression of the sensitization phase of the systemic contact hypersensitivity (CHS) response to picryl chloride (PCl). Three of the UOPs were selected for this study: imidazole-4-carboxylic acid (ImCOOH), imidazole-4-carboxaldehyde (ImCHO) and imidazole-4-acetic acid (ImAc). Effects on the sensitization, elicitation and postelicitation phases of CHS to PCl in BALB/c mice were studied and compared with the effects of cis-UCA. ImCHO was equally effective at suppressing the sensitization phase as cis-UCA. The triplet combination of the imidazoles (1:1:1) showed more pronounced suppression than that induced by cis-UCA. The most effective compounds for the suppression of the elicitation phase appeared to be ImAc and cis-UCA. Significant suppression of the postelicitation phase was only obtained with the triplet combination of ImCHO, ImCOOH and ImAc, the combination that appeared to be effective at all three tested phases. Because these three UOPs are present in UV-B-exposed human stratum corneum, these compounds may play a role in UV-B-induced immunosuppression.

Animals↗

PubMedDate not supplied

Non-steroidal topical immunomodulators provide skin-selective, self-limiting treatment in atopic dermatitis.

Topical corticosteroids are the mainstay of treatment for atopic dermatitis; however, their clinical utility is limited by potential side effects. Recently, the steroid-free topical immunomodulators tacrolimus ointment and pimecrolimus cream have become available. These agents provide effective treatment without causing skin atrophy or other steroidal side effects, and their physiochemical properties, such as relatively large molecular size and high lipophilicity, limit diffusion through skin and into the bloodstream, providing skin-selective treatment. Clinical trials with more than 1,700 paediatric and adult patients have demonstrated that treatment with either agent is associated with minimal systemic absorption of tacrolimus or pimecrolimus. Additionally, studies have shown that percutaneous absorption of tacrolimus decreases as treatment continues and clinical improvement occurs. This self-limiting facet of the treatment, together with the skin-selectivity of topical immunomodulators, is reflected in the good safety and tolerability profiles of these agents, which promise to significantly improve the long-term management of atopic dermatitis.

Administration, Topical↗