Modulatory effects of VIP and related peptides from the gastrointestinal tract on cell mediated cytotoxicity against tumour cells in vitro

Triple therapy with octreotide, galanin, and serotonin reduces the size and blood vessel density and increases apoptosis of a rat colon carcinoma

A rat colonic adenocarcinoma was implanted subcutaneously in female nude (C57BL/6JBom-nu) mice. After 7 days, the animals were divided into different groups. One group received triple therapy with octreotide, galanin, and serotonin, 10 microg/kg body weight of each, twice daily. The second group served as controls and received only saline solution. Three groups received 10 microg/kg body weight twice daily of octreotide, galanin, or serotonin. The last group consisted of controls that received only saline solution. The treatment lasted for 5 days. The tumour volume, wet weight, and relative volume density of blood vessels were significantly decreased after the triple treatment, as compared to controls. Apoptotic index was significantly increased, but the proliferation index was not affected in the group of mice that received triple therapy. There was no significant difference between controls and mice treated with octreotide, galanin, or serotonin regarding tumour volume or weight. The relative volume density of blood vessels was decreased in tumours treated with galanin, but not with octreotide or serotonin. There was no statistical difference in the proliferation index between controls and animals treated with octreotide, galanin, or serotonin, as compared with controls. Tumour necrosis and increased apoptosis may be responsible for the reduction in the volume and weight of the tumour after triple therapy. Tumour necrosis may be caused by the induction of tumour ischemia due to a reduction in tumour blood flow, which is caused by decreased incidence of tumour-feeding blood vessels, and by constriction of tumour-feeding arterioles. These results are promising and may offer treatment for colon cancer.

Oncology in neuroimmunomodulation. What progress has been made?

In 1987 in Dubrovnik, Yugoslavia, N.H. Spector named a new discipline: Neuroimmunomodulation. R. Ader called this new discipline psychoneuroimmunomodulation when the major emphysis was on its behavioral aspects. Neuroimmunomodulation (NIM) is devoted to the study of the interactions at different morphologic and functional levels among the immune, nervous, and endocrine systems. In fact, this science is the modern manifestation of an old science: in the words of B.D. Jankovic (1987), "Neuroimmunomodulation is a modern reflection in neurosciences and immunosciences of the ideas and experience of philosophers and ingenious observers of ancient Egypt, Greece, China, India, and other civilizations that the mind is involved in the defense against diseases." Twelve years ago NIM was regarded by many conventional scientists almost as a form of witchcraft. Today it may be the fastest growing area of biomedical science research in the world. Important clinical applications will not be far behind. NIM research has also progressed in the field of oncology research. Topics such as treatment of hormone-dependent cancer with analogues of hypothalamic hormones, the role of opioids and T cells in cancer, stress-cancer-immune connections, the anticancer role of melatonin and cytokines, immunotherapy of cancer, and the role of psychotherapy in cancer patients represent some lines of research that have been or are being investigated by scientists. Some areas remain to be thoroughly investigated such as the influence of physical exercise (sports), music (classical or modern), and/or relaxation techniques (e.g. yoga) on the development of human cancer. This paper reviews the role of NIM in oncology and provides some perspectives for further research and development of clinical applications.

Vasoactive intestinal polypeptide (VIP) innervation of rat spleen, thymus, and lymph nodes

In the thymus, VIP-positive (+) fibers were found in the capsular/septal system, cortex, and medulla. In the spleen, VIP+ nerves coursed along large arteries and central arterioles, and in the white pulp, venous/trabecular system, and red pulp. Splenic VIP innervation was more robust in Long-Evans hooded rats than in Fischer 344 rats. VIP+ nerves in mesenteric lymph nodes were found in the cortex, and along the cortical vasculature and medullary cords. No VIP innervation was observed in popliteal lymph nodes. Immunocytes also were VIP+, suggesting that both neural and cellular synthesis of VIP contributes to VIP concentration in lymphoid organs. Surgical sympathectomy did not alter splenic or thymic VIP content, respectively, and VIP innervation of these organs was not altered, suggesting an origin for VIP+ nerves other than the sympathetic nervous system.

The significance of vasoactive intestinal polypeptide (VIP) in immunomodulation

Evidence for VIP influences on immune function comes from studies demonstrating VIP-ir nerves in lymphoid organs in intimate anatomical association with elements of the immune system, the presence of high-affinity receptors for VIP, and functional studies where VIP influences a variety of immune responses. Anatomical studies that examine the relationship between VIP-containing nerves and subpopulations of immune effector cells provide evidence for potential target cells. Additionally, the presence of VIP in cells of the immune system that also possess VIP receptors implies an autocrine function for VIP. The functional significance of VIP effects on the immune system lies in its ability to help coordinate a complex array of cellular and subcellular events, including events that occur in lymphoid compartments, and in musculature and intramural blood circulation. Clearly, from the work described in this chapter, the modulatory role of VIP in immune regulation is not well understood. The pathways through which VIP can exert an immunoregulatory role are complex and highly sensitive to physiological conditions, emphasizing the importance of in vivo studies. Intracellular events following activation of VIP receptors also are not well elucidated. There is additional evidence to suggest that some of the effects of VIP on cells of the immune system are not mediated through binding of VIP to its receptor. Despite our lack of knowledge regarding VIP immune regulation, the evidence is overwhelming that VIP can interact directly with lymphocytes and accessory cells, resulting in most cases, but not always in cAMP generation within these cells, and a subsequent cascade of intracellular events that alter effector cell function. VIP appears to modulate maturation of specific populations of effector cells, T cell recognition, antibody production, and homing capabilities. These effects of VIP are tissue-specific and are probably dependent on the resident cell populations within the lymphoid tissue and the surrounding microenvironment. Different microenvironments within the same lymphoid tissue may influence the modulatory role of VIP also. Effects of VIP on immune function may result from indirect effects on secretory cells, endothelial cells, and smooth muscle cells in blood vessels, ducts, and respiratory airways. Influences of VIP on immune function also may vary depending on the presence of other signal molecules, such that VIP alone will have no effect on a target cell by itself, but may greatly potentiate or inhibit the effects of other hormones, transmitters, or cytokines. The activational state of target cells may influence VIP receptor expression in these cells, and therefore, may determine whether VIP can influence target cell activity. Several reports described in this chapter also indicate that VIP contained in neural compartments is involved in the pathophysiology of several disease states in the gut and lung. Release of inflammatory mediators by cells of the immune system may destroy VIP-containing nerves in inflammatory bowel disease and in asthma. Loss of VIPergic nerves in these disease states appears to further exacerbate the inflammatory response. These studies indicate that altered VIP concentration can have significant consequences in terms of health and disease. In addition, the protective effects of VIP from tissue damage associated with inflammatory processes described in the lung also may be applicable to other pathological conditions such as rheumatoid arthritis, anaphylaxis, and the swelling and edema seen in the brain following head trauma. While VIP degrades rapidly, synthetic VIP-like drugs may be developed that interact with VIP receptors and have similar protective effects. Synthetic VIP-like agents also may be useful in treating neuroendocrine disorders associated with dysregulation of the hypothalamic-pituitary-adrenal axis, and pituitary release of prolactin.

Neuroenteric peptides affect natural killer activity by intestinal lamina propria mononuclear cells

The effect of the neuropeptides bombesin and vasoactive intestinal peptide, as well as neurotensin, on natural killer activity by lamina propria mononuclear cells isolated from histologically normal mucosa was assessed. Bombesin and vasoactive intestinal peptide were found to dose-dependently stimulate natural killer activity against Caco-2 colon carcinoma target cells, especially in a short incubation assay, whereas no alterations of cytotoxicity were found against K-562 target cells. Neurotensin, on the contrary, was not found to affect this type of cellular cytotoxicity. Differences in the modulatory effects of these gastrointestinal peptides on natural killer activity by lamina propria mononuclear cells may be related to the distinct localization differences of these peptides within the bowel. The present findings illustrate the existence of neuro-immune interactions at the intestinal mucosa level.

Normal inflammatory bowel disease mucosa conceals alterations in natural killer cell activity

Non-major histocompatibility complex-restricted cytotoxicity or natural killer (NK) activity could be detected in all intestinal lamina propria mononuclear cell preparations of histologically normal mucosa from 57 patients with gastrointestinal disease. Similar levels of NK activity were detected among the different disease groups. Within the inflammatory bowel disease patient group, however, Crohn's disease patients showed a threefold higher level of NK activity than detected in ulcerative colitis patients. Cytotoxicity levels in Crohn's disease patients were also higher than in the control carcinoma patients, whereas ulcerative colitis patients had considerably lower cytotoxicity levels than the carcinoma patients. Thus, unaffected normal inflammatory bowel disease mucosa conceals alterations in NK activity which might occur before the inflammation. The colon adenocarcinoma cell line Caco-2 was found to be a representative target for detecting individual differences in NK activity of lamina propria mononuclear cells compared with standard K-562 targets. The latter can be of relevance when studying mucosal immunoregulatory mechanisms in intestinal disease.

Natural killer cell activity in patients with neuroendocrine tumours of the gastrointestinal tract; relation with circulating gastrointestinal hormones

We have evaluated the peripheral blood natural killer (NK) cell activity and the in vitro effect of recombinant gamma-interferon (r gamma-IFN) on NK cell activity in 23 patients with a neuroendocrine tumour of the pancreas, small intestine or liver, and 23 healthy controls. Patients with a gastrinoma showed a NK cell activity which was not different from that of the control group, whereas patients with another type of neuroendocrine tumour had a decreased NK cell activity compared to the controls (p less than 0.05) and the gastrinoma patients (p less than 0.02). The impaired NK cell activity in these patients was as such not related to the presence of liver metastasis or performance status of the patients. r gamma-IFN significantly stimulated the NK cell activity in patients and controls. However, the cytotoxic response of the patients with a hormone production other than gastrin remained lower than in the two other groups. Follow-up studies in 8 patients showed NK cell activities not to vary with stable disease, to decrease with progressive disease, and to increase with regression of disease. In conclusion, NK cell activity is suppressed in patients with neuroendocrine tumours that produce hormones other than gastrin. This impairment is not related to the presence of metastasis but seems to be related to the course of the disease.