Dendritic cells and the assessment in vitro of skin sensitizing potential

It is now well established that dendritic cells (DC) play pivotal roles in the initiation and orchestration of adaptive immune responses, including cutaneous immune responses to chemical allergens that drive the acquisition of skin sensitization. It is not unexpected, therefore, that a large number, and wide variety, of proposed approaches for the identification of skin sensitizing chemicals in vitro are based upon the use of cultured DC or DC-like cells. The use of DC in this context is legitimate. However, with our rapidly increasing understanding of the diversity of cutaneous DC with respect to both phenotype and function, it is timely now to review briefly the potential limitations and interpretive difficulties that are associated with the use of DC-based assays. Among the important considerations are the fact that chemical-induced changes in the characteristics and function of cultured DC will not necessarily reflect accurately the events that that support the development of skin sensitization in vivo. In addition, most DC-based assays are predicated on a view that cutaneous DC have as their primary function the initiation of adaptive immune responses. However, it is now appreciated that cutaneous DC, and in particular epidermal Langerhans cells (LC), may also play important immunoregulatory roles that serve to limit and contain skin immune responses. Notwithstanding these considerations there is reason to believe that at least some in vitro DC-based assays are of value, and indeed some are currently the subject of a formal validation process. However, it is appropriate that such assays are configured and interpreted carefully, and with an appreciation of the complexity of DC biology.     

Dose metrics in the acquisition of skin sensitization: thresholds and importance of dose per unit area

Allergic contact dermatitis is a common occupational and environmental health problem and many hundreds of chemicals have been implicated as skin sensitizers. Sensitization is acquired following topical exposure to a contact allergen and induction of a cutaneous immune response of an appropriate magnitude. For effective assessment and management of human health risks there is a need to appreciate the dose metrics that drive the induction of skin sensitization. The available evidence suggests that under most normal conditions of exposure it is the dose per unit area of chemical that has over-riding impact on the effectiveness of sensitization. The exception to this rule is when the area of the application site drops below a certain critical level. Here we review in detail the evidence which supports dose per unit area as being the critical exposure metric in the induction of skin sensitization, and the mechanistic bases for this relationship.     

Sunlight, immunosuppression and skin cancer: role of histamine and mast cells

1. The development into tumours of skin cells transformed by ultraviolet (UV) B radiation of wavelengths 290-320 nm is enhanced by the ability of UVB to suppress an immune response that would otherwise destroy them. Ultraviolet B-induced immunomodulation may be by multiple mechanisms, but generally manifests in an antigen-presenting cell defect and an altered cytokine environment in the draining lymph nodes. 2. Immune responses to microbial or self-antigens may be dysfunctional by similar mechanisms following UVB exposure. 3. Earliest-acting intermediates in the initiation of UVB-induced immunosuppression are the UVB absorbers (photoreceptors) of the skin, notably DNA resulting in immunoregulatory cytokine production, and trans-urocanic acid (UCA), which, upon isomerization to its cis isomer, signals downstream immunosuppressive events. 4. In mice, dermal mast cells are critical to UVB-induced systemic immunomodulation. In mice, there is a functional link as well as a linear relationship between the prevalence of histamine-staining dermal mast cells and the log of the dose of UVB required for 50% immunosuppression. Studies with histamine receptor antagonists support histamine as the main' product of mast cells involved. Histamine acts in large part via a prostanoid-dependent pathway. 5. Approximately 50% of humans and greater than 90% of patients with non-melanoma skin cancer are UVB susceptible for suppression of a contact hypersensitivity response. Neither cytokine polymorphisms nor UVB-induced levels of cis-UCA in irradiated skin have been linked to UVB susceptibility. Patients with basal cell carcinomas (BCC) have an increased dermal mast cell prevalence in non-sun-exposed buttock skin. We propose that mast cells function in humans, as in mice, by initiating immunosuppression and, thereby, allowing a permissive environment for BCC development.     

支气管扩张症中神经内分泌免疫网络及肥大细胞的变化

目的：探讨支气管扩张症中神经内分泌免疫网络的异常和肥大细胞（MC）在该病发病中的作用及关系。方法：应用组织化学、免疫组化、组织化学与免疫组化结合的方法和形态计量学方法进行观测。结果：支气管扩张症中，支气管上皮蛙皮素（Bombesin）阳性细胞、固有膜S-100蛋白和神经特异性烯醇化酶（NSE）阳性神经纤维、IgE阳性细胞、MC和IgE阳性MC均显著增多，且在支气管相关淋巴组织（BALT）增生的区域上述肺内分泌细胞、神经纤维和IgE阳性细胞增多尤为显著，S-100蛋白和NSE阳性神经纤维分布于弥散淋巴组织和BALT中，MC与S-100蛋白阳性神经纤维紧密接触．MC表面有IgE阳性环状带，MC和IgE阳性细胞出现在支气管上皮间和肺泡壁。结论：支气管扩张症的发病与局部神经内分泌免疫网络异常有关；MC可能作为感受器、分泌细胞或靶细胞参与神经内分泌免疫网络，在支气管扩张症的发病中起重要作用。     

Contact hypersensitivity to stainless steel cages (chromium metal) in hairless descendants of mexican hairless dogs

Canine allergic contact hypersensitivity is an uncommon skin disease as compared with human beings because hair coat is a good natural barrier to environmental contactants. In our colony of hairless dogs housed in stainless steel cages, we have encountered spontaneously occurring contact hypersensitivity. The author has attempted to study the toxicological effects of environmental sensitizing substances on the canine skin. The purpose of this study is to elucidate dermatological characteristics in canine species with contact hypersensitivity. This skin lesion was investigated by patch tests, macroscopic observations, and histopathological examinations. Patch tests exhibited positive reactions to potassium dichromate. Macroscopically, early lesions were macules and/or papules and they gradually progressed to severe inflammatory dermatitis over the dorsum. In the chronic phase, lichenification, kyperkeratosis, hyperpigmentation, dryness, scaliness, and fissuring were observed in the skin. Avoidance of contact with the stainless steel cages resulted in clinical improvement. Histopathologically, the epidermis apparently showed hyperkeratosis, thickening, hyperplasia, and rete ridge formation. Lichenified lesions had clumps of melanin granules in the stratum basale and spinosum. In the dermis, there was marked edema and dense mononuclear cell infiltration. Vasodilation, hemorrhage, and hyperplasia of sebaceous glands were also found. Both dermal mast cells and epidermal Langerhans cells significantly increased in the skin lesions, as compared with nonlesional sites. The present results revealed that constant contact with stainless steel cages (chromium metal) caused contact hypersensitivity in hairless dogs with very sparse hairs.     

Quantification of quantum dot murine skin penetration with UVR barrier impairment

Abstract

Ultraviolet radiation (UVR) skin exposure is a common exogenous insult that can alter skin barrier and immune functions. With the growing presence of nanoparticles (NPs) in consumer goods and technological applications the potential for NPs to contact UVR-exposed skin is increasing. Therefore it is important to understand the effect of UVR on NP skin penetration and the potential for systemic translocation. Previous studies qualitatively showed that UVR skin exposure can increase the penetration of NPs below the stratum corneum. In this work, an in vivo mouse model was used to quantitatively examine the skin penetration of carboxylated (CdSe/ZnS, core/shell) quantum dots (QDs) through intact and UVR barrier-disrupted murine skin by organ Cd mass analysis. Transepidermal water loss was used to measure the magnitude of the skin barrier defect as a function of UVR dose and time post-UVR exposure. QDs were applied to mice 3–4 days post-UVR exposure at the peak of the skin barrier disruption. Our results reveal unexpected trends that suggest these negative-charged QDs can penetrate barrier intact skin and that penetration and systemic transport depends on the QD application time post-UVR exposure. The effect of UVR on skin-resident dendritic cells and their role in the systemic translocation of these QDs are described. Our results suggest that NP skin penetration and translocation may depend on the specific barrier insult and the inflammatory status of the skin.     

Differential effects of cyclosporine A after acute antigen challenge in sensitized cats in vivo and ex vivo

1. We determined the effect of cyclosporine A (CsA) treatment on mast cell degranulation and lung resistance (R_L) in vivo, and tracheal smooth muscle (TSM) contraction ex vivo after antigen challenge in sensitized cats. We also determined the direct effects of addition of CsA to the tissue bath on antigen-induced responses of TSM in vitro.
2. Cats (n=10) were sensitized by i.m. injection of Ascaris suum antigen (AA); 5 cats (CsA+) received CsA twice daily for 2 weeks before acute antigen challenge in doses sufficient to suppress interleukin-2 secretion from feline peripheral blood mononuclear cells ex vivo.
3. Lung resistance increased comparably within 10 min of exposure to AA (P<0.03). Histamine content in bronchoalveolar lavage fluid from both groups increased comparably within 30 min of antigen challenge, from undetectable levels to 542±74 pg ml⁻¹ post AA for CsA+ and from 74±19 pg ml⁻¹ at baseline, to 970±180 pg ml⁻¹ post AA CsA− (P<0.05; P=NS vs CsA+).
4. In excised TSM, active tension elicited by exposure to AA in vitro was 107±38% KCl in the CsA+ group vs 144±56% KCl in the CsA− group (P=NS). However, contraction of TSM (n=4) harvested from both groups was abolished or greatly diminished after AA challenge when tissues were pre-incubated with 1 μM CsA in vitro (8±8% KCl, P<0.05 vs CsA+ and CsA−). This was associated with inhibited release of 5-hydroxytryptamine into the organ bath fluid of tissues treated with CsA in vitro only.
5. We demonstrated that CsA treatment in vivo does not inhibit the early phase asthmatic response or mast cell degranulation following antigen challenge in sensitized cats. Additionally, the effects of CsA on mast cell function ex vivo do not reflect lack of effects of CsA on mast cell function in vivo in this animal model of atopic asthma.

     

Immunological outcomes in infants with ROP after dexamethasone and aminophylline

This research aims to improve anaesthesia services given to preterm infants by the use of dexamethasone and aminophylline administrated under sevoflurane, and to analyze its effect on the cell-mediated immunity (CD4+CD25+Foxp3+(T-reg) and CD4+CD25highFoxp3+CD127low). We have examined 74 premature babies with retinopathy of prematurity (ROP) at the 3–5 stages during the 25–32 week gestation period (1–6 months after birth). Both immunomodulators had no significant effect on clinical parameters after one dose (P > .05). Aminophylline (2.4% solution, 0.1 mL/kg or 0.132 mL per infant on average) and dexamethasone (0.4% solution, 0.1 mg/kg or 0.132 mL per infant on average) were intravenously injected 15 minutes before the end of the surgery. Required anaesthesia depth was maintained with inhalation anaesthetic (1.5–2.0 IAC), and the minimum fresh gas flow was not less than 2 L. Blood samples were taken from the vein (anaesthesia induction stage) into the tubes containing EDTA (the anticoagulant), stored at 20–25°C, and then, processed and stained within 24 hours after sampling. Both immunomodulators had no significant effect on clinical parameters after one dose (P > .05). Short-term shift in regulatory T-cell level affected by dexamethasone has a negative effect combined with further withdrawal effect that this hormonal drug has. Aminophylline has such clinical effects as improving pulmonary ventilation, decrease in apnoea frequency, and improving blood gas indices. Aminophylline has less expressed but more prolonged positive effect during the day when used for several days. It may lead to a persistent positive effect with progressive treatment outcomes.     

Bradykinin B2 receptor antagonism attenuates inflammation, mast cell infiltration and fibrosis in remote myocardium after infarction in rats

Bradykinin may interfere with myocardial remodelling by promoting inflammation and mast cell activation or, alternatively, by counteracting angiotensin II-dependent collagen accumulation. The aim of the present study was to investigate the role of bradykinin B2 receptor antagonism in inflammatory and mast cell infiltration, fibroplasia and fibrosis accumulation following myocardial infarction (MI). Myocardial infarction was produced by the ligature of the left coronary artery in male Wistar rats that were 10 weeks of age. Immediately after MI, rats received the B2 receptor antagonist Hoe140 (0.5 microg/kg per min, s.c.) or saline over a period of 3 days, 1 week or 4 weeks, constituting three separate groups and their respective controls. Coronal myocardial tissue sections underwent haematoxylin and eosin, Giemsa and picrosirius red staining, as well as immunohistochemistry for alpha-smooth muscle actin (SMA). Morphometric studies were undertaken in three different myocardial regions: MI, remote non-infarcted subendocardium (non-MI SE) and remote non-infarcted interventricular septum (non-MI IVS). The MI size was comparable between Hoe140-treated groups and their respective controls (day 3: 42 +/- 4%, n = 8, vs 43 +/- 3%, n = 6; week 1: 37 +/- 5%, n = 5, vs 39 +/- 2%, n = 5; week 4: 35 +/- 3%, n = 9, vs 36 +/- 3%, n = 7). At day 3, Hoe140 treatment reduced inflammatory cell reaction within the MI (585 +/- 59 vs 995 +/- 170 cells/mm2; P = 0.02), non-MI SE (77 +/- 12 vs 214 +/- 57 cells/mm2; P = 0.02) and non-MI IVS (93 +/- 16 vs 135 +/- 14 cells/mm2; P = 0.03) regions. Mast cells were reduced within the non-MI IVS region (0.8 +/- 0.1 vs 2.5 +/- 0.4 cells/mm2; P = 0.006), but not within the MI region. In non-MI SE, mast cells were rarely found. At week 1, Hoe140 treatment reduced alpha-SMA-positive myofibroblast infiltration within the MI (2535 +/- 383 vs 5636 +/- 968 cells/mm2; P = 0.01) and non-MI SE (222 +/- 33 vs 597 +/- 162 cells/mm2; P = 0.03) regions. In the non-MI IVS region, alpha-SMA-positive myofibroblasts were rarely found. At week 4, Hoe140 treatment reduced collagen volume fraction within the MI (37 +/- 4 vs 53 +/- 4%; P = 0.03), non-MI SE (1.3 +/- 0.2 vs 2.6 +/- 0.3%; P = 0.001) and non-MI IVS (1.1 +/- 0.2 vs 1.8 +/- 0.2%; P = 0.01) regions. Bradykinin promotes inflammation, fibroplasia and fibrosis after MI. Mast cells may have a role in fibrosis deposition through a bradykinin-related mechanism.     

Electrocardiographic changes after ethanol and methanol administration in albino rats

As an acute effect, both ethanol and methanol prolong P-R, Q-T and ST intervals in rat electrocardiogram. The R wave amplitude showed a marked increase with methanol. Other ECG abnormalities like S-T segment changes, appearance of Iso-electric S-T segment, inverted 'T' wave, ventricular ectopic and wandering pace maker were more common in methanol treated animals.     

肾组织肥大细胞表型特点分析研究

目的 阐明各种肾病患者肾组织肥大细胞的表型特点.方法 选取包括糖尿病肾病、IgA肾病、急性间质性肾炎、慢性间质性肾炎、过敏性紫癜性肾炎、膜性肾病和狼疮性肾炎在内的肾病患者369例,正常供肾16例,以免疫组化方法检测肾活检标本中肥大细胞类胰蛋白酶和糜蛋白酶表达情况,对其进行分型分析.结果 双连续切片分析发现,绝大多数肥大细胞表现为类胰蛋白酶和糜蛋白酶染色双阳性,仅有少数表现为类胰蛋白酶或糜蛋白酶单阳性;“双夹心”连续切片分析法显示,所谓的类胰蛋白酶或糜蛋白酶单阳性肥大细胞实际上是类胰蛋白酶和糜蛋白酶双阳性;以类胰蛋白酶为标记分子和以糜蛋白酶为标记分子检测肾组织肥大细胞的结果比较没有显著区别.结论 类胰蛋白酶糜蛋白酶亚型(MCTC亚型)是正常个体和肾病患者肾组织肥大细胞的基本亚型.     

Acute changes in 5-HT metabolism after S-adenosyl-L-methionine administration

1. This study investigates S-adenosyl-L-methionine (SAM) (10 mg/kg, i.p.)acute effects upon 5-HT metabolism in rat brain areas. 2. One hour after SAM injection 5-HT biosynthesis was increased in the corpus striatum (55%), the hippocampus (3-fold) (82% 2 hr after SAM injection) and decreased in the olfactory bulbs (34%). 3. 5-HT levels were: (a) increased in the corpus striatum (39%), the hippocampus (44%) and the frontal cortex (27%), and oppositely reduced in the olfactory bulbs (47%) 1 hr after SAM injection; (b) increased in the hippocampus (39%) and reduced in the olfactory bulbs (35%) 1.5 hr after SAM injection; (c) increased in the hippocampus (25%) 2 hr after SAM injection. 4. 5-HIAA levels were reduced in the olfactory bulbs 27% or 21% after 1 hr or 1.5 hr from SAM injection respectively. 5. These area-related changes in 5-HT biosynthesis and metabolism might suggest a possible neurochemical substrate for the antidepressant properties of SAM.     

Brain neurosteroid changes after paroxetine administration in mice.

Although it is known that selective serotonin reuptake inhibitors (SSRIs), as other antidepressants, elevate mood only after 3-4 weeks of treatment, the mechanism responsible for this delay is not understood. SSRIs have been demonstrated to alter the levels of neurosteroids such as allopregnanolone (THP) which possess anxiolytic and mood-elevating properties. We compared the effect of 9 and 21 days i.p. administration of paroxetine, a potent SSRI, on the synthesis of THP and its precursor, 5alpha-dihydroprogesterone (DHP), in the mouse cortex, hypothalamus and olfactory bulb. Cortex, olfactory bulb and hypothalamus synthesized levels of DHP were significantly raised after 9 days of paroxetine administration, whereas a significant rise in the THP synthesized level was observed only after 21 days of treatment. Peripheral synthesis of DHP, measured by the level in serum, significantly increased after 9 days, but reverted to normal values after 21 days. No increase was detected in serum THP levels either after 9 or 21 days treatment. Differences in peripheral and brain synthesis indicates independence in brain synthesis. The data indicate that paroxetine administration differentially increases [3H]DHP and [3H]THP content, depending on the duration of the treatment. Our results suggest that brain THP may be involved in the antidepressive and anxiolytic activity of paroxetine.     

Testicular changes in rats after administration of organotin complex

Intratesticular administration of di-n-butyltin (o-hydroxyacetophenone S-methyldithiocarbazate) has been shown to induce marked degenerative changes in the testes of adult rats. The possible mechanism of its action is discussed. In particular, an atrophy of seminiferous tubules with complete arrest of spermatogenesis has been noted.     

Plasma and tissue iron changes in the rat after acute administration of ethionine

1. Ethionine administered acutely to the adult female rat markedly elevates and then lowers plasma iron concentration over several days. Liver iron undergoes a reverse cycle. 2. Ethionine does not cause changes in the blood parameters, including total plasma iron-binding capacity and plasma iron clearance. Erythrocytes of rats injected with ethionine show altered responses to hypertonicity. 3. Increased reticulo-endothelial activity of the spleen, indicated by increased uptake of 59Fe-labelled erythrocytes by liver and spleen, apparently contributes to plasma iron elevation. Also the liver releases iron which further raises plasma iron.     

肥大细胞与IgA肾病患者肾间质病变关系的研究

目的研究肥大细胞与IgA肾病患者肾间质病变之间的关系。方法收集49例IgA肾病患者的临床资料和肾活检标本,采用免疫组织化学技术检测肥大细胞在IgA肾病患者肾组织中的表达,并分析其意义。结果正常肾组织中偶见或无肥大细胞的存在,而在IgA肾病患者肾组织中肥大细胞表达明显增强（肥大细胞检出阳性率为42.86%）,并且随着肥大细胞的表达增多IgA肾病肾间质纤维化程度逐渐加重（χ2=9.1189,P〈0.05）;肥大细胞与临床指标的相关性：肥大细胞数量与血肌酐呈显著正相关（r=0.65,P〈0.05）,与尿蛋白定量无明显相关性（r=0.18,P〉0.05）。结论肥大细胞可能是IgA肾病肾间质纤维化的重要参与者,与IgA肾病肾间质病变的发生发展可能具有一定的关系。     

Pimecrolimus: skin disposition after topical administration in minipigs in vivo and in human skin in vitro.

The dermal disposition of pimecrolimus, a non-steroid, anti-inflammatory calcineurin inhibitor used for the treatment of atopic dermatitis, was evaluated in minipigs in vivo and in human skin in vitro using tritium-radiolabeled compound, and in dermal toxicokinetic investigations in minipigs using unlabeled compound. Following topical application of pimecrolimus 1% market form (MF) cream to minipig skin, approximately 2% of the dose penetrated into the stratum corneum and part of it into deeper skin layers. The remainder of the dose was recovered non-absorbed on the skin surface. The total systemic absorption was or=94% of dose remained non-absorbed, 3.1% was found in the epidermis (including stratum corneum) and 2.9% in the dermis. There was no indication of metabolism of pimecrolimus in human skin in vitro or minipig skin in vivo. No drug accumulation was observed in minipig skin after up to 13 weeks of once daily topical application of 0.1% or 0.3% pimecrolimus cream.     

儿童朗格汉斯细胞组织细胞增生症的诊治新进展

朗格汉斯细胞组织细胞增生症(Langerhans cell histiocytosis,LCH)是一组以CD1a+、CD207+树突状细胞异常增生为特点的组织细胞增生性疾病,临床表现复杂多样,可侵犯单器官、多器官及多系统,以骨骼、皮肤及垂体损伤常见,分为单系统LCH、高危多系统LCH、低危多系统LCH及特定部位LCH四类;目前主要有炎症性增生学说与肿瘤性增生假说,现多认为与丝裂原活化蛋白激酶(MAPK)通路异常活化密切相关。病理仍是诊断的金标准,而液体活检将可能成为新的无创性确诊手段,根据侵犯的部位、范围及程度制定个体化的治疗方案。近年来,靶向治疗已成为研究的热点,并有望取代传统的治疗方案,但在儿童中的使用仍处于临床研究阶段。现就儿童LCH临床特点及诊治新进展进行综述,以期提高临床诊疗水平。