Hyperthermia ameliorates 2,4,6-trinitrobenzene sulphonic acid-induced colitis in rats: the role of heat shock proteins.

PURPOSE: Hyperthermia is known to protect against cellular injury through the expression of heat shock proteins. In this study, the therapeutic effects of hyperthermia on experimental colitis in the rat were evaluated. MATERIALS AND METHODS: Male Wistar rats were given a single intracolonic injection of 2,4,6-trinitrobenzene sulphonic acid (TNBS). Hyperthermia was induced in anesthetized rats by placing them in a temperature-controlled water bath. We started the hyperthermic treatment on the day after the enema. The severity of colitis was evaluated pathologically, and the activities of tissue myeloperoxidase were measured 6 days after the induction of colitis. Furthermore, cytokines, and hyperthermia-induced heat shock proteins in colonic mucosa were detected by enzyme-linked immunosorbent assay and Western blotting. We also investigated the effects of geranylgeranylacetone and zinc protoporphyrin IX on the therapeutic effect of hyperthermia. RESULTS: Hyperthermia significantly improved the macroscopic scores of colitis. The TNBS-induced increases in the activities of myeloperoxidase in the colonic tissue were blunted significantly in hyperthermia-treated animals. Furthermore, hyperthermia attenuated increases in cytokine-induced neutrophil chemoattractants-1 and tumor necrosis factor-alpha in the colon. Furthermore, hyperthermia induced the production of heat shock proteins in rat colonic mucosa, and the combination of geranylgeranylacetone with hyperthermia further induced the heat shock protein HSP70, which resulted in further improvement of TNBS-induced colitis. On the other hand, the combination of zinc protoporphyrin IX with hyperthermia attenuated the therapeutic effect of hyperthermia. CONCLUSIONS: Hyperthermia ameliorates TNBS-induced colitis in rats through the expression of HSP70 and HO-1. It is postulated that hyperthermia may be useful for the treatment of inflammatory bowel diseases.

Heme oxygenase-1 (Hsp32) is involved in the protection of small intestine by whole body mild hyperthermia from ischemia/reperfusion injury in rat.

AIM: The aim of the present study was to explore whether heme oxygenase-1 (HO-1) is involved in the hyperthermia-provided protection of the small intestine from ischemia/reperfusion injury in rats. METHODS: Intestinal damage was induced in male Sprague-Dawley rats by clamping both the superior mesenteric artery and the celiac trunk for 30 min, followed by reperfusion. Whole-body hyperthermia was induced in anesthetized rats by placement in a temperature-controlled water bath. Whole-body hyperthermia to a core temperature of 42-43 degrees C for 15 min was followed by passive cooling. We started the hyperthermic treatment 6 h before the vascular clamping. The severity of the mucosal injury was evaluated by several biochemical markers and histological findings. Hyperthermia-induced heat-shock proteins were detected by Western blotting. We also investigated the effect of zinc protoporphyrin IX (an HO-1 inhibitor) on the protective effect of hyperthermia. RESULTS: The rats, which were killed after ischemia/reperfusion, had severe intestinal inflammation. Hyperthermia significantly induced the production of Hsp70 and HO-1 in intestinal mucosa and significantly reduced ischemia/reperfusion-induced mucosal injury. The combination of zinc protoporphyrin IX with hyperthermia extinguished the protective effects of hyperthermia on ischemia/reperfusion injury. CONCLUSION: Hyperthermia protects against ischemia/reperfusion injury in rat small intestine through the expression of heat-shock proteins, especially HO-1.

Efficacy of hyperthermia and polyunsaturated fatty acids on experimental carcinoma.

We investigated the efficacy of hyperthermia and gamma-linolenic acid on experimental carcinoma. This study focused on polyunsaturated fatty acids that are substrates for free radical reactions. Oleic acid, linolenic acid, alpha-linolenic acid, or gamma-linolenic acid was injected into the arteries feeding AH109A carcinoma implanted into rat hind limbs. Among these, gamma-linolenic acid had the greatest effect on tumor tissue lipid peroxidation and demonstrated an antitumor effect. Consequently, gamma-linolenic acid injection into the feeding artery of a tumor was performed immediately prior to hyperthermia. This combination therapy induced a high level of lipid peroxidation in tumor tissue and a significant antitumor effect. Hyperthermia combined with gamma-linolenic acid produces free radical reactions by increasing the radical reaction substrate and may be an effective anticancer modality.

Anti-tumor effects of hyperthermia plus granulocyte colony-stimulating factor.

The role of neutrophils in the anti-tumor effects of hyperthermia was investigated in an experimental rat model, and the efficacy of hyperthermia combined with recombinant human granulocyte colony-stimulating factor (G-CSF) was similarly investigated. AH109A carcinoma cells were transplanted into the hind legs of Donryu rats, then heated by a radio-frequency dielectric heater. In this study, because the myeloperoxidase (MPO) activity of neutrophils was not affected by heating or G-CSF, MPO activity was measured as an index of neutrophil migration into tumor tissue. After hyperthermia, MPO activity in tumor tissue increased significantly, suggesting migration of neutrophils into tumor tissue. Depletion of circulating neutrophils by the intraperitoneal injection of anti-rat neutrophil antibody decreased the anti-tumor effects of hyperthermia. Subsequently, we used hyperthermia plus intraarterial G-CSF to enhance the anti-tumor effect. Hyperthermia was induced 1 h after injection of G-CSF, a time when MPO activity in tumor tissue was maximal. A satisfactory thermal effect was noted even in cases where tissue could not be heated sufficiently. In conclusion, neutrophils have an important role in the anti-tumor effects of hyperthermia, and administration of G-CSF enhances these effects.

The role of active oxygen species and lipid peroxidation in the antitumor effect of hyperthermia.

The role of active oxygen species and lipid peroxidation in the antitumor effect of hyperthermia was studied in an experimental rabbit model. VX2 tumors were transplanted into rabbit hind legs, and the effect of hyperthermia on tumor growth was measured at 7 and 14 days after heating. As an index of lipid peroxidation, thiobarbituric acid-reactive substances in the tumor tissue were measured prior to hyperthermia and 3, 6, 12, and 24 h after hyperthermia. Tumor growth in rabbits treated with hyperthermia was significantly reduced, and thiobarbituric acid-reactive substances in the tumor tissue treated with hyperthermia were significantly increased until 6 h after hyperthermia. In addition, alpha-tocopherol in the tumor tissue was significantly decreased after hyperthermia. The antitumor effect of hyperthermia and the increase of thiobarbituric acid-reactive substances in the tumor tissue treated with hyperthermia were significantly inhibited by the administration of superoxide dismutase and catalase or dimethyl sulfoxide. These results suggest that lipid peroxidation mediated by active oxygen species plays an important role in the antitumor effect of hyperthermia.

[Role of polymorphonuclear leukocytes (PMN) and active oxygen species in hyperthermia--antitumor effect of hyperthermia combined with rhG-CSF].

We have reported that polymorphonuclear leukocytes (PMN) and active oxygen species from PMN may play an important role in the mechanism of the antitumor effect of hyperthermia. At this time, we focused our experimental studies on rat AH109A carcinoma treated with hyperthermia combined with arterial injection of rhG-CSF. Rats with transplantable AH109A carcinoma at the hind leg received hyperthermia. These tumors showed mild suppression of further development only by hyperthermia. However, when arterial injection of rhG-CSF was applied together with hyperthermia, marked suppression of tumor development was observed. Our data suggest that hyperthermia combined with rhG-CSF is closely related to the generation of free radical-mediated tumor cell killing, and it can be an effective treatment for cancer.

[Role of polymorphonuclear leukocytes (PMN) and active oxygen species in hyperthermia--enhancing effect of G-CSF on superoxide generation from PMN].

We examined in vitro the effect of G-CSF and temperature on superoxide (O2-) generation by Cypridina luciferin analog (CLA) dependent chemiluminescence. PMN significantly generated O2- at the concentration of G-CSF 25 ng/ml or more at 37 degrees C within the range of 0.1 from 1,000 ng/ml. O2- generation from PMN was remarkably enhanced, stimulated by opsonized zymosan (OZ) and phorbol myristate acetate (PMA), at 41 degrees C as compared with 37 degrees C. O2- generation was enhanced with the addition of 25 ng/ml of G-CSF at 41 degrees C as compared to without it at 41 degrees C. A significant enhancement of O2- generation from PMN was observed at 25 ng/ml G-CSF and 41 degrees C.