Response of the Endothelium to the Epicutaneous Application of Leukotriene B4.

BACKGROUND: Vascular changes, both endothelial and functional, are crucial events in inflammatory responses. OBJECTIVES: To investigate the dynamics of endothelial cell (EC) and functional changes during acute inflammation in an in vivo model of the skin using leukotriene B4. METHODS: EC proliferation, vascular network size, vessel diameter (VD), and hypoxia-inducible factor (HIF)-1α were studied by immunohistochemical CD31/Ki67 double staining and single staining of HIF-1α. Cutaneous perfusion (CP) was assessed using the Twente Optical Perfusion Camera. RESULTS: The initial phase illustrated an increase in VD, Ki67+ EC, and HIF-1α expression and late-phase vascular expansion. The HIF-1α and Ki67+ EC expression was limited. CP and VD were augmented after 24 h. CONCLUSION: The early phase of inflammation is characterized by EC proliferation and HIF-1α expression. Vascular expansion continues over time. CP and VD are seen in both phases of inflammation. Angiogenesis, vascular network formation, and perfusion are time-dependent processes which are mutually related during inflammation.

Perfusion Intensity Correlates with Expression Levels of Psoriasis-Related Genes and Proteins.

BACKGROUND: Previous research revealed heterogeneity in the perfusion intensity within clinically homogenous-appearing plaques, without differences in erythema. In addition, an increased perfusion was found within the perilesional skin. This raises the question whether the heterogeneity in perfusion found both inside and outside a lesion influences the expression levels of genes and proteins involved in the pathogenesis of psoriasis. OBJECTIVES: To correlate the perfusion intensity to mRNA and protein expression of genes associated with the pathogenesis of psoriasis and to visualize the dynamics of the perfusion intensity over time using laser Doppler perfusion imaging. METHODS: Fourteen patients with plaque psoriasis were included. The superficial microcirculation and clinical local scores (single usability metric, SUM, scores) were analysed in one representative lesion every 2 weeks. After 8 weeks 4 biopsies were taken, one from a highly perfused area (hotspot) and one from a low perfusion area (coldspot) of the lesional skin, one biopsy from the highly perfused perilesional skin and one from the distant uninvolved skin. RESULTS: Statistically significant differences in mRNA and protein expression, including IL-17 and TBX21/T-Bet, were found between hotspots and coldspots, and between the highly perfused perilesional and the uninvolved skin. Hotspots tend to remain on the same location during 8 weeks of follow-up. CONCLUSIONS: Within homogenous-appearing psoriatic plaques, there are remarkable differences in mRNA and protein levels, which are correlated with the perfusion intensity and can be detected by using laser Doppler perfusion imaging. In addition, differences in mRNA and protein expression between the highly perfused perilesional skin and the uninvolved skin were found, indicating that several biological changes occur well before clinical changes become manifest.

Balance of Treg versus T-effector cells during systemic treatment with adalimumab and topical treatment with calcipotriol-betamethasone dipropionate ointment.

Diminished suppressive capacity of regulatory T cells (Treg) has been demonstrated in blood and in lesional skin of psoriatic patients. Treatment with anti-TNFα restored the number and function of circulating Treg in psoriasis. We aimed to study Treg in the skin of psoriatic patients undergoing topical treatment with calcipotriol-betamethasone dipropionate (CBD) ointment (n = 12) or systemic treatment with anti-TNFα agent adalimumab (n = 10). Skin biopsies were collected from patients with chronic plaque psoriasis who responded to the above-mentioned treatments with a SUM-score improvement of at least 50% (at the end of treatment). Biopsies were processed for immunohistochemistry. As Treg function is associated with a numerical balance between Treg and effector T cells, Foxp3/CD4 ratios were calculated. It appeared that both treatments cause a significant decrease in the presence of Foxp3+ cells. However, in patients that were treated with CBD ointment, we observed lower Foxp3/CD4 ratios after 8 weeks of treatment compared to baseline (t = 0: 0.41 ± 0.08; t = 8: 0.22 ± 0.04, P = 0.033), whereas in patients who were treated with adalimumab we observed an increase of the Foxp3/CD4 ratios after 1.5 and 16 weeks of treatment compared to baseline (t = 0: 0.25 ± 0.04; t = 1.5: 0.32 ± 0.06; t = 16: 0.49 ± 0.10, P = 0.15). Based on Foxp3/CD4 ratios, we can conclude that adalimumab treated skin differs from CBD treated skin with regard to the anti-inflammatory/inflammatory balance. We suggest that, in contrast to CBD ointment, adalimumab favours local Treg function in the skin.

Are newly discovered drivers of immune-mediated skin disorders expressed in normal skin regenerating from standardized surface injury?

BACKGROUND: In healthy skin, tape stripping induces a transient wave of histological changes resembling immune-mediated skin diseases, such as psoriasis. The response to surface trauma may harbor mechanisms which are also relevant to the development of Koebner-positive skin disorders. However, studies on newly discovered drivers of inflammation in regenerative skin are lacking. METHODS: The course of epidermal proliferation and keratinization as well as key representatives of innate and acquired immunity were studied during the first 72 h after tape stripping. RESULTS: Epidermal rupture rapidly activates various epidermal processes, which remain upregulated for 72 h. Elastase+ and IL-17+ cells dominate the acute phase and their numbers decrease rapidly thereafter. The number of T-Bet+ cells increases more gradually, reaching maximum levels several hours later when the other cell types decrease. CONCLUSIONS: This model permits investigations on the sequence of crucial inflammatory processes set off by cutaneous injury, which are presumed to play a role within the pathogenesis of immune-mediated skin diseases exhibiting the Koebner phenomenon.

In vivo induction of cutaneous inflammation results in the accumulation of extracellular trap-forming neutrophils expressing RORγt and IL-17.

Clinical trials successfully using antibodies targeting IL-17 in psoriasis support the importance of IL-17 in the pathophysiology of this disease. However, there is a debate concerning the source and dynamics of IL-17 production in inflamed skin. Here we characterized IL-17-producing immune cells over time, using two established in vivo models of human skin inflammation that share many histological features with psoriasis, i.e., leukotriene B4 application and tape-stripping. Both treatments revealed a clear influx of neutrophils and T cells. Staining for IL-17 revealed that the majority of IL-17 was expressed by neutrophils and mast cells, in both models. Neutrophils, but not mast cells, coexpressed the IL-17-associated transcription factor RORγt and were able to form extracellular traps. While the presence of mast cells remained steady during the skin inflammatory process, the presence of neutrophils was clearly dynamic in time. Therefore, it is attractive to hypothesize that IL-17+/RORγt+ neutrophils contribute to human skin inflammation in vivo and possibly to the pathogenesis of skin diseases such as psoriasis. Surprisingly, T cells represented a minority of the IL-17-expressing cell population. These observations challenge the classical opinion that IL-17 is predominantly associated with T cells in skin inflammation.

Whole field laser Doppler imaging of the microcirculation in psoriasis and clinically unaffected skin.

BACKGROUND: Angiogenesis represents a key phenomenon in psoriasis. Insights in the microcirculation within psoriatic lesions in a whole field are lacking. Recently, the Twente Optical Perfusion Camera (TOPCam) was developed, which provides the possibility of evaluating the superficial cutaneous microcirculation in a whole field. OBJECTIVES: This pilot study aims to examine whether the TOPCam can be used to visualize the microcirculation within and around psoriatic lesions, and whether it is capable of revealing vascular changes during topical treatment. METHODS: Five patients with chronic plaque psoriasis were included. The superficial microcirculation and clinical local scores (SUM score) were analyzed in two comparable lesions within one patient. At baseline and after 2, 4, 6, and 8 weeks the disease's natural course was evaluated in one plaque versus topical treatment in the other. RESULTS: The TOPCam was able to visualize an increased microcirculation within psoriatic lesions and perfusion variability due to the heartbeat. Whole field images demonstrated heterogeneity in perfusion intensity (hot and cold spots) within clinically homogeneous-looking plaques. Topical therapy induced a decrease in overall perfusion and a significant decrease in SUM score. CONCLUSION: The TOPCam is the first noninvasive technique to visualize the microcirculation of psoriatic lesions in a whole field, to correct images for the heartbeat, and to reveal heterogeneity in perfusion intensity.

Well-defined clinical presentation of Ehlers-Danlos syndrome in patients with tenascin-X deficiency: a report of four cases.

The Ehlers-Danlos syndrome (EDS) is a clinically and genetically heterogeneous group of inherited connective tissue disorders. The six major, well-defined, subtypes are classified according to diagnostic criteria, formalized in the Villefranche revised nosology. Shortly after the publication of these criteria in 1998, a further distinct type of EDS, the tenascin-X (TNX)-deficient type EDS, was reported. The phenotype of this largely unknown type of EDS resembles the phenotype of the classical type of EDS, but its inheritance is autosomal recessive and wound healing is normal; hence, no atrophic scars are present. The clinical diagnosis can be confirmed by the absence of TNX in the serum and by mutation analysis of the TNXB gene. Because the TNX-deficient type EDS is rare and not included in the current diagnostic criteria, this diagnosis is often delayed or even overlooked. Here, we describe four cases which improve the clinical recognition of this type of EDS.