Effects of vitamin A-deficiency and inflammation on the conducting airway epithelium of Syrian golden hamsters

Are We Sentenced to Pharmacotherapy? Promising Role of Lycopene and Vitamin A in Benign Urologic Conditions

Benign prostatic hyperplasia, urolithiasis, recurrent urinary tract infections, and chronic prostatitis are diseases that are commonly diagnosed worldwide. Carotenoids, including lycopene, are widely available in fruits and vegetables, and it is postulated that they can be used in the prevention and treatment of benign urological conditions. The aim of this review is to familiarize doctors and their patients with the current knowledge on carotenoids and their conversion products in selected urological diseases. Most of the experimental and clinical trials show a moderate effect of lycopene and vitamin A on studied parameters. Lycopene was shown to improve the IPSS score in BPH patients, and alleviate symptoms in those with chronic prostatitis. Intake of Vitamin A was associated with decrease of urinary tract reinfection rates. In studied rat models retinol also decreased urolithiasis formation. Although the results of the cited studies are generally promising, it is evident that more detailed and extensive research must be done in this field of medicine.

Impact of Micronutrients on the Immune Response of Animals

Vitamins and minerals (micronutrients) play an important role in regulating and shaping an immune response. Deficiencies generally result in inadequate or dysregulated cellular activity and cytokine expression, thereby affecting the immune response. Decreased levels of natural killer, granulocyte, and phagocytic cell activity and T and B cell proliferation and trafficking are associated with inadequate levels of micronutrients, as well as increased susceptibility to various adverse health conditions, including inflammatory disorders, infection, and altered vaccine efficacy. In addition, most studies of micronutrient modulation of immune responses have been done in rodents and humans, thus limiting application to the health and well-being of livestock and companion animals. This exploratory review elucidates the role of vitamins and minerals on immune function and inflammatory responses in animals (pigs, dogs, cats, horses, goats, sheep, and cattle), with reference to rodents and humans.

beta-Carotene promotes the development of NNK-induced small airway-derived lung adenocarcinoma

AIM

beta-Carotene has shown cancer-preventive effects in preclinical studies while increasing lung cancer mortality in clinical trials. We have shown that beta-carotene stimulates cAMP signalling in vitro. Here, we have tested the hypothesis that beta-carotene promotes the development of pulmonary adenocarcinoma (PAC) in vivo via cAMP signalling.

METHODS

PAC was induced in hamsters with the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), followed by beta-carotene for 1.5 years. Incidence, multiplicity and size of lung tumours were recorded, and phosphorylated CREB and ERK1/2 in tumour cells were determined by Western blots. Cyclic AMP in blood cells was analysed by immunoassays, retinoids in serum and lungs by HPLC.

RESULTS

beta-Carotene increased lung tumour multiplicity, lung tumour size, blood cell cAMP, serum and lung levels of retinoids and induced p-CREB and p-ERK1/2 in lung tumours.

CONCLUSIONS

Our data suggest that beta-carotene promotes the development of PAC via increased cAMP signalling.

Adjuvant effect of vitamin A on recurrent lower urinary tract infections

BACKGROUND

The purpose of the present paper was to investigate the effects of vitamin A supplementation on recurrent lower urinary tract infections (RUTI).

METHODS

Twenty-four patients with non-complicated RUTI were included in a placebo-controlled, double-blinded study. Twelve patients received a single dose of 200,000 IU vitamin A in addition to antimicrobial therapy. Patient and control groups (each containing 12 patients) were followed for up to 1 year and were evaluated for eradication and frequency of lower urinary tract infections (UTI). Serum levels of vitamin A and beta-carotene were determined periodically.

RESULTS

During the first 6 months follow-up period the infection rate of the vitamin A-supplemented group reduced from 3.58 to 0.75 per 6 months, and in the subsequent 6 months the infection rate was 1.75 per 6 months. These values were calculated as 2.75, 2.83 and 2.66, respectively, in the placebo group.

CONCLUSION

Vitamin A supplementation may have an adjuvant effect on the treatment of RUTI.

Elastase causes secretory discharge in bronchi of hamsters with elastase-induced secretory cell metaplasia

A single intratracheal instillation of human neutrophil elastase (HNE) into hamsters causes granule discharge from bronchial secretory cells followed by marked accumulation of granules, visible by light microscopy at 21 days and persisting through 18 months. To determine whether persistence of this secretory cell metaplasia (SCM) is due to inability of the metaplastic secretory cells to secrete their granules, hamsters having HNE-induced SCM were challenged with the potent secretagogue HNE. Four groups of 10 hamsters each received 300 micrograms HNE intratracheally. Twenty-one days later, hamsters were intratracheally treated with HNE or saline; the groups were designated HNE-HNE and HNE-SAL, respectively. Hamsters were killed 2 h or 21 days following the second treatment. Using light microscopy, nucleated epithelial cells were counted in plastic sections of the left main intrapulmonary bronchus. Cells were classified as ciliated (C), basal (B), indeterminate (IN), or secretory. Secretory cells were subcategorized as S0 (0 granules), S1 (1-4 granules), S2 (> or = 5 granules with intervening cytoplasm), and S3 (abundant granules completely filling the cytoplasm). At 2 h, S3 cell frequency in the HNE-HNE group was 13.0 +/- 2.2 (% mean +/- SE), significantly lower than in the 2 h HNE-SAL group (31.1 +/- 4.5). Concomitantly, higher cell frequencies were seen in the other secretory categories of the HNE-HNE group compared to the HNE-SAL group; S2 17.1 +/- 1.9 compared to 9.4 +/- 1.9, S1 2.4 +/- 0.4 compared to 1.1 +/- 0.5, and S0 2.4 +/- 0.5 compared to 1.1 +/- 0.5, respectively. The S3 cell frequency of the 21-day HNE-HNE group was 25.4 +/- 4.7, increased significantly compared to the 2 h HNE-HNE group; this change was concomitant with significant decrease in the frequency of the S0 secretory cells. Cell frequencies of C, B, and IN were not affected by treatment or time. It is concluded that metaplastic secretory cells discharge their granules in response to HNE; SCM returns to its original state after HNE rechallenge; persistent SCM is not due to the inability of metaplastic secretory cells to discharge their granules.

Squamous cell metaplasia in the human lung: molecular characteristics of epithelial stratification

Squamous cell metaplasia (SCM) is a frequent epithelial alteration of the human tracheobronchial mucosa. This review pays particular attention to the fact that SCM can mimic esophageal, and in some instances even skin-type differentiation, showing striking similarities not only in morphology but also in terms of gene expression. Therefore, characterization of this dynamic process lends insight into the process of stratification, squamous cell formation, and "keratinization" in a pathologically relevant in vivo situation in man. First, the concept of metaplasia is presented with certain historical viewpoints on histogenesis. Then, the morphological characteristics of normal bronchial epithelium are compared with the altered phenotype of cells in SCM. These changes are described as a disturbance of the finely tuned balance of differentiation and proliferation through the action of a variety of extrinsic and intrinsic factors. Molecular aspects of altered cell/cell and cell/extracellular matrix interactions in stratified compared with single-layered epithelia are discussed with reference to SCM in the lung. Intracellular organizational and compositional changes are then summarized with special emphasis on the differential distribution of the cytokeratin (CK) polypeptides. Finally, the still unresolved problems of the histogenetic relationships between normal bronchial mucosa, SCM, and pulmonary neoplasms are addressed. As these questions remain open, examples for detection of well defined "markers" are provided that may be employed as objective criteria for determining clinically important cellular differentiation features.

Vitamin A deficiency and inflammation: the pivotal role of secretory cells in the development of atrophic, hyperplastic and metaplastic change in the tracheal epithelium in vivo

We showed previously that the proliferation of hamster airway secretory cells decreases during vitamin A deficiency (VAD) but later increases when submucosal inflammation develops (Virchows Arch [B] 59:231-242, 1990). This observation has important biological implications since two morphological extremes (atrophy and quiescence versus hyperplasia and hyperproliferation) are reported in the literature for VAD tracheal epithelium in vivo. In the present study, histological slides of tracheal rings from 35-day-old control and VAD hamsters (Virchows Arch [B] 45:197-219, 1984) were reviewed again. Rings from VAD hamsters were selected based on the absence or presence of a florid submucosal inflammation. Quantitative analyses were made on the cartilaginous part of rings from the anterior third of the trachea. When inflammation was absent, a mucociliary pseudostratified epithelium was, for the most part, maintained. The mitotic rate (MR, 6 h colchicine blockade) of secretory cells was markedly reduced (29-fold) but that of basal cells was not changed significantly. Moreover, cell density was not changed by VAD but ciliated cells and secretory cells were decreased and basal cells were increased, proportionally. We call this "minimal morphological change." Thinning (atrophy) of the minimally changed epithelium was associated with focal cell sloughing. Small scattered foci of epidermoid metaplasia (multiple layers of highly keratinized cells which were extremely flat, so that the epithelium was thin and attenuated) were also seen. We call this "atrophic epidermoid metaplasia." When inflammation was present, hyperplastic changes (stratification and epidermoid metaplasia) predominated and cells were in mitosis at all epithelial levels (low, middle, superficial) except in the most superficial (terminally differentiated) squames. The tracheal epithelium was thickened and hypercellular. The cells were piled up at the stratified lesions, and epithelial height, cell density and epithelial MR were significantly increased compared with the non-inflamed VAD epithelium. The effects of VAD and inflammation on cell proliferation were analyzed further by studying 7 h bromodeoxyuridine (BrdU) labelling patterns of cells in VAD tracheal epithelium, with and without submucosal inflammation. In addition, inflammation was induced in "minimally changed epithelium" by mild mechanical injury. The BrdU labelling patterns confirmed that DNA synthesis by secretory cells is reduced markedly by VAD. However, this suppression is overidden by the influx of inflammatory cells (the nature of the stimulus is unknown). The results indicate that the morphological contrasts (atrophy and hyperplasia) seen in the trachea during VAD in vivo are related to extremes in proliferation rates of tracheal secretory cells, regulated by VAD alone (minimal replication) and by inflammation (maximal replication).

Resistance of hamster bronchiolar epithelium to neutrophil elastase: investigation by cell surface lectin cytochemistry

An intratracheal instillation of human neutrophil elastase (HNE) causes accumulation of an excess number of secretory granules in the epithelial secretory cells lining the hamster bronchus. This chronic lesion, which we refer to as secretory cell metaplasia (SCM), is not seen in the trachea or bronchioles. Because luminal cell surface lectin binding is much higher in the trachea than in the bronchus, we concluded that tracheal resistance may be due to a protective glycoconjugate coat. In the present ultrastructural study, we analyzed the lectin-binding capability of bronchiolar epithelial cells to determine whether their luminal cell surface glycoconjugate layer is similar to tracheal epithelial cells. None of the six ferritin-conjugated lectins showed higher binding in bronchioles compared to the bronchus, suggesting that a high level of surface oligosaccharides is not necessary for resistance to the metaplastic effects of HNE. HNE caused a significant reduction in bronchiolar surface binding of the gold-labeled, secretory cell-specific lectin, Helix pomatia agglutinin. The principal granulated secretory cell type in bronchioles was ultrastructurally similar to a form of bronchial Clara cell that converts to a mucous cell phenotype in response to HNE. The results suggest that absence of bronchiolar SCM is not attributable to a protective layer of cell surface oligosaccharides, a lack of cellular contact by HNE, or the presence of a morphologically distinct population of epithelial cells in bronchioles.