Cell proliferation and apoptosis in the pathogenesis of oesophagogastric lesions in pigs

Caracterização histomorfológica do sistema tegumentar auricular de cateto - Pecari tajacu Linnaeus, 1758)

RESUMO A criopreservação de tecido somático derivado da pele de catetos consiste numa alternativa para a conservação da biodiversidade por meio da associação com a transferência nuclear. Nesse contexto, a manipulação de tecidos da pele é uma etapa crucial para o sucesso dessa biotécnica. Portanto, o objetivo do presente estudo, foi caracterizar o sistema tegumentar auricular periférico de catetos, visando aprimorar a conservação tecidual. Para tanto, fragmentos auriculares de oito animais foram avaliados quanto às camadas teciduais, aos componentes, à atividade proliferativa e à viabilidade metabólica, usando-se as colorações hematoxilina-eosina e tricrômico de Gomori, quantificação de AgNORs e microscopia eletrônica de transmissão. Assim, tamanhos de 104,2µm e 222,6µm foram observados para epiderme e derme, com uma proporção volumétrica de 36,6% e 58,7%, respectivamente. Além disso, na epiderme, foram evidenciadas as camadas basal (22,5µm), intermediárias (53,5µm) e córnea (28,2µm), com valores médios de 65,3 células epidermais, 43,4 melanócitos e 14,8 halos perinucleares. Já a derme apresentou 127 fibroblastos, com 2,5 AgNORs/nucléolo. Adicionalmente, a atividade metabólica foi de 0,243. Em conclusão, o sistema tegumentar auricular periférico de catetos possui algumas marcantes variações em relação a outros mamíferos, quanto ao número de camadas e espessura da epiderme, quantidade de células epidermais, melanócitos e parâmetros proliferativos.

Cell proliferation in pathogenesis of esophagogastric lesions in pigs

Esophagogastric ulcer is an independent disease in swine that is characterized by ulcerous autodigestion of the cutaneous mucosa, which does not exhibit a tendency to recover, but, on the contrary, a tendency toward severe hemorrhaging, with a predominantly lethal outcome. Since it develops in the part of the stomach that is morphologically and functionally different from other glandular mucosa, it was questioned earlier whether it could be a peptic ulcer based on its nature. Spontaneous ulcers, usually of the stomach, commonly occur in many domestic animals. Some of these lesions are chronic and they may occur in either the glandular or squamous-lined regions of the stomach. As with the human disease, the pathogenesis in domestic animals is multifactorial, poorly understood, and variable between and within species. Environmental stress and dietary factors are very important in the ulcer disease in swine. It has been shown that the Helicobacter spp. is strongly associated with naturally occurring ulcer and preulcer lesions of the pars esophagea in swine, which raises the possibility that Helicobacter spp. is an important factor in the pathogenesis of these lesions. The dynamics of the development of esophagogastric ulcers imply hyperplastic lesions (parakeratosis and hyperkeratosis), keratolysis, erosions, peptic necrosis, and the development of ulcers with all the characteristics of peptic ulcerations in other localities. In addition, K6 is expressed in association with the mucosal changes. The pattern of the intermediate filaments of keratin suggests that epithelial proliferation, which leads to visible hyperkeratosis, constitutes the essence of gastric ulcers in swine.

Detection of helicobacter candidatus suis by PCR in oesophagogastric ulcers of swine in Italy

The aim of this study was to evaluate by PCR the presence of Helicobacter spp. in gastric mucus from the fundic region of the stomach and to investigate its role in oesophagogastric ulcers in swine bred and regularly slaughtered in Piedmont (Northern Italy). Stomachs from 595 regularly slaughtered swine were subjected to gross pathological examination in order to evaluate the presence of gastric ulcers (revealed in 75 cases, 12.6%). Histopathological examination was performed to better characterise erosions and ulcers. DNA extracted from gastric mucus collected from all the ulcer-affected and from 25 normal stomachs was submitted to PCR using Helicobacter spp. 16S rRNA gene target primers. Sixty-three percent (47/75) of the affected stomachs was positive as well as 24% (6/25) of the non-affected ones. Sequence analysis from 5 positive samples showed 99% homology with Helicobacter candidatus suis 16S ribosomal RNA gene.

Smoking and the pathogenesis of gastroduodenal ulcer--recent mechanistic update

Peptic ulcer is a common disorder of gastrointestinal system and its pathogenesis is multifactorial, where smoking and nicotine have significant adverse effects. Smoking and chronic nicotine treatment stimulate basal acid output which is more pronounced in the smokers having duodenal ulcer. This increased gastric acid secretion is mediated through the stimulation of H2-receptor by histamine released after mast cell degranulation and due to the increase of the functional parietal cell volume or secretory capacity in smokers. Smoking and nicotine stimulate pepsinogen secretion also by increasing chief cell number or with an enhancement of their secretory capacity. Long-term nicotine treatment in rats also significantly decreases total mucus neck cell population and neck-cell mucus volume. Smoking also increases bile salt reflux rate and gastric bile salt concentration thereby increasing duodenogastric reflux that raises the risk of gastric ulcer in smokers. Smoking and nicotine not only induce ulceration, but they also potentiate ulceration caused by H. pylori, alcohol, nonsteroidal anti-inflammatory drugs or cold restrain stress. Polymorphonuclear neutrophils (PMN) play an important role in ulcerogenesis through oxidative damage of the mucosa by increasing the generation of reactive oxygen intermediates (ROI), which is potentiated by nicotine and smoking. Nicotine by a cAMP-protein kinase A signaling system elevates the endogenous vasopressin level, which plays an aggressive role in the development of gastroduodenal lesions. Smoking increases production of platelet activating factor (PAF) and endothelin, which are potent gastric ulcerogens. Cigarette smoking and nicotine reduce the level of circulating epidermal growth factor (EGF) and decrease the secretion of EGF from the salivary gland, which are necessary for gastric mucosal cell renewal. Nicotine also decreases prostaglandin generation in the gastric mucosa of smokers, thereby making the mucosa susceptible to ulceration. ROI generation and ROI-mediated gastric mucosal cell apoptosis are also considered to be important mechanism for aggravation of ulcer by cigarette smoke or nicotine. Both smoking and nicotine reduce angiogenesis in the gastric mucosa through inhibition of nitric oxide synthesis thereby arresting cell renewal process. Smoking or smoke extract impairs both spontaneous and drug-induced healing of ulcer. Smoke extract also inhibits gastric mucosal cell proliferation by reducing ornithine decarboxylase activity, which synthesises growth-promoting polyamines. It is concluded that gastric mucosal integrity is maintained by an interplay of some aggressive and defensive factors controlling apoptotic cell death and cell proliferation and smoking potentiates ulcer by disturbing this balance.

Heat Shock Proteins (HSPs) 27, 72 and 73 in Normal and Pre-ulcerative Mucosa of the Gastric Pars Oesophagea in Swine

Heat shock proteins (HSPs), known to play a key role in cellular homeostasis, may also play a role in the defensive mechanisms of gastric mucosa. By means of appropriate immunohistochemical and immunobiochemical techniques, the expression of HSP27, HSP72 and HSP73 within the epithelium of normal and pre-ulcerative (hyperkeratinized) mucosa of the pars oesophagea of abattoir pigs was assessed. In normal mucosa, HSP72 and HSP73 expression was mainly limited to the basal epithelial cell layer, whereas HSP27 expression was consistently detected within the superficial epithelial cell layers. In hyperkeratinized mucosa, HSP72 and HSP73 immunoreactivity appeared to be more widespread, becoming very intense within epithelial cells affected by hydropic degeneration. Hyperkeratinized mucosa also showed HSP27 immunoreactivity, which was particularly intense in epithelial areas affected by hydropic degeneration. Western blot analysis confirmed HSP27, HSP72 and HSP73 expression in normal and in pre-ulcerative mucosa of the pars oesophagea. Semi-quantitative analysis showed that for all three HSPs the immunoreactivity was more intense in pre-ulcerative mucosa than in normal mucosa. The different expression patterns observed may have functional significance; further studies are needed, however, to define the role of HSPs in swine oesophagogastric lesions, the aetiology and pathogenesis of which are largely unknown.