Alteration of basic fibroblast growth factor concentration and immunoreactivity in healing of ethanol-induced gastric mucosal damage: effect of sofalcone

"Gastric cytoprotection" is still relevant

Although Andre Robert's historic article on "gastric cytoprotection" in 1979 introduced this new name and concept, gastroprotective drugs (e.g. sofalcone, sucralfate), which prevent and/or accelerate healing of gastric ulcers without inhibiting acid secretion, were known in Japan before or around that time. But since Robert's studies were solely focused on prostaglandins (PG), they became the center of gastrointestinal research for more than 30 years. As endogenous products, PG were implicated in mediating the gastroprotective effect of other drugs such as sofalcone and sucralfate, despite that the cyclooxygenase inhibitor indomethacin diminished but never abolished gastroprotection by other drugs. Another group of endogenous substances, that is, sulfhydryls (SH), investigated in parallel with PG, also seem to play a mechanistic role in gastroprotection, especially since SH alkylators like N-ethylmaleimide counteract virtually any form of gastroprotection. In Robert's terms of "prevention of chemically induced acute mucosal lesions," so far no single mechanism could explain the beneficial effects of diverse protective agents, but I argue that these two endogenous substances (i.e. PG, SH), in addition to histamine, are the main mechanistic mediators of acute gastroprotection: PG and histamine, because as mediators of acute inflammation, they increase vascular permeability (VP), and SH scavenge free radicals. This is contrary to the search for a single mechanism of action, long focused on enhanced secretion of mucus and/or bicarbonate that may contribute but cannot explain all forms of gastroprotection. Nevertheless, based on research work of the last 30 years, in part from our lab, a new mechanistic explanation of gastroprotection may be formulated: it's a complex but orderly and evolution-based physiologic response of the gastric mucosa under pathologic conditions. Namely, one of the first physiologic defense responses of any organ is inflammation that starts with rapid vascular changes (e.g. increased VP and blood flow), followed by cellular events (e.g. infiltration by acute and chronic inflammatory cells). Thus, PG and histamine, by increasing VP create a perivascular edema that dilutes and delays toxic agents reaching the subepithelial capillaries. Otherwise, damaging chemicals may induce severe early vascular injury resulting in blood flow stasis, hypoxia, and necrosis of surrounding epithelial and mesenchymal cells. In this complex response, increased mucus and/or bicarbonate secretion seem to cause luminal dilution of gastrotoxic chemicals that is further reinforced by a perivascular, histodilutional component. This mechanistic explanation would encompass the protective actions of diverse agents as PG, small doses of histamine, motility stimulants, and dilute irritants (i.e. "adaptive cytoprotection"). Thus, although markedly increased VP is pathologic, slight increase in VP seems to be protective, that is, a key element in the complex pathophysiologic response during acute gastroprotection. Over the years, "gastroprotection" was also applied to accelerated healing of chronic gastroduodenal ulcers without reduction of acid secretion. The likely main mechanism here is the binding of angiogenic growth factors (e.g. basic fibroblast growth factor, vascular endothelial growth factor) to the heparin-like structures of sucralfate and sofalcone. Thus, despite intensive research of the last 30 years, gastroprotection is incompletely understood, and we are still far away from effectively treating Helicobacter pylori-negative ulcers and preventing nonsteroidal anti-inflammatory drugs-caused erosions and ulcers in the upper and lower gastrointestinal tract; hence "gastric cytoprotection" research is still relevant.

Expression of leptin in two-layered culture of gastric mucous cells and fibroblasts: effect of Helicobacter pylori attachment

BACKGROUND

Our recent histochemical studies have revealed an increase in myofibroblasts and in leptin and its receptor in endothelial cells, and myofibroblasts in Helicobacter pylori-infected human and Mongolian gerbil fundic mucosa.

AIM

The present study was undertaken to clarify the H. pylori-induced interaction between leptin in cultured gastric surface mucous cells and fibroblasts.

METHODS

GSM06 cells were incubated with an air- liquid interface on a collagen gel layer containing mouse fibroblast cell line L929. Medium containing H. pylori bacilli (ATCC43504) at 10-100 times higher concentration than the GSM06 cells was added from the luminal side and the localization of leptin was observed by immunohistochemistry. The transformation of L929 cells to myofibroblasts was detected by electron microscopy and PR 2D3 immunoreactivity.

RESULTS

L929 cells in the control group showed a spindle shape with scarce cytoplasm. In the H. pylori-treated group, L929 cells showed features characteristic of myofibroblasts, and most GSM06 and L929 cells showed leptin immunoreactivity. In contrast, L929 cells incubated with H. pylori alone did not undergo this differentiation.

CONCLUSIONS

Attachment of H. pylori to surface epithelial cells caused conversion of fibroblasts to myofibroblasts. We suggest that leptin plays a role in this transformation.

Interaction of leptin with gastric myofibroblast transdifferentiation in Helicobacter pylori-infected Mongolian gerbils: the effect of rebamipide

BACKGROUND

Our recent histochemical studies have revealed the marked increase of myofibroblasts in the Helicobacter pylori-infected Mongolian gerbil fundic mucosa, while the mediators, which facilitate the conversion of fibroblasts to the myofibroblasts have remained unknown.

AIM

The present study was undertaken to clarify the alteration of leptin in the control and H. pylori-infected Mongolian gerbil stomach. The effector sites of rebamipide were also investigated in relation to leptin.

METHODS

The localization of leptin was investigated by the indirect immunofluorescence. Plasma leptin levels were determined by ELISA method. The localization of 3H-rebamipide binding sites was investigated by autoradiography.

RESULTS

Serum leptin content in H. pylori-infected Mongolian gerbils was significantly increased. The presence of leptin immunoreactivity was recognized in the endothelial cells of the microcirculatory network and very weakly in the glandular cells in the control group, while in the H. pylori-infected group leptin was markedly recognized in the mesenchymal cells. Rebamipide bound to the fibroblasts and surface mucous cells and decreased the leptin immunoreactivity in the gastric mucosa.

CONCLUSIONS

Leptin was mostly found in the mesenchymal cells. Rebamipide administration brought about the decrease of leptin in the gastric mucosaof the H. pylori-infected gerbils.

Rebamipide binds to iNOS-positive cells in acetic acid-treated but not in ethanol-treated rat gastric mucosa

BACKGROUND

Rebamipide is a gastroprotective agent to stimulate prostaglandin generation in gastric mucosa and attenuate the activity of neutrophils, but direct evidence for the effector sites of this agent has remained to be clarified.

AIM

The present study was undertaken to show the effector sites of rebamipide in control and ulcer-provoked rats.

METHODS

The rats were divided into control, acetic acid- and ethanol-treated rats. In the acetic acid-treated group, 100% acetic acid was attached to the serosal surface of the stomach for 30 s, 7 days before the experiments. In the ethanol-treated group, a dose of 0.5 mL/100 g body weight of 50% ethanol was administered through orogastric intubation 2 h before the experiments. Using the unfixed cryostat sections, aqueous solution of 3H-rebamipide was applied and the localization of the binding sites of rebamipide was investigated by autoradiography.

RESULTS

In the control rats, rebamipide was found to bind to the surface epithelial cells. In the ethanol-treated group, few binding sites were observed in the damaged gastric mucosa. In the acetic acid-treated group, the marked accumulation of the binding sites of 3H-rebamipide was observed in the mesenchymal cells in the lamina propria mucosae between the regenerated gastric epithelial cells. Combination of autoradiography and immunohistochemistry has revealed that iNOS-immunoreactive cells had the strong binding of rebamipide in the acetic acid-treated group. Some of these cells were CD68-positive macrophages, while others were CD68-negative, corresponding to polymorphonuclear leucocytes. In the ethanol-treated acute gastric mucosal injury group, few binding sites were observed in the damaged gastric mucosa.

CONCLUSIONS

Autoradiography has made it clear that rebamipide binds to iNOS-positive cells in the gastric mucosa 7 days after acetic acid-treatment.

Persistent increase in myofibroblasts in Helicobacter heilmannii-infected mice but not in Helicobacter pylori-infected Mongolian gerbils: colocalization of COX-2 and bFGF immunoreactivity

BACKGROUND

The clinical significance of Helicobacter heilmannii infection remains uncertain, owing to the lack of a specific detection method. Recently, we reported a marked increase in myofibroblasts in the early stage of Helicobacter pylori infection in Monglian gerbils.

AIM

The present study was designed to clarify changes in myofibroblasts, and in the immunoeactivities of basic fibroblast growth factor, cyclooxygenase-2 and inducible nitric oxide synthase after H. pylori infection in Monglian gerbils and H. heilmannii infection in mice.

METHODS

After oral inoculation, changes in the location of bacteria and the immunoreactivity of myofibroblasts, basic fibroblast growth factor, cyclooxygenase-2 and inducible nitric oxide synthase were stained with the indirect immunofluorescent method and observed by confocal laser microscopy.

RESULTS

In H. heilmannii-infected mice, the increases in myofibroblasts and in immunoreactivities of these three markers were sustained 12 months after infection. In H. pylori-infected Monglian gerbils, however, these increases were significant at 3 months but had returned to control levels at 12 months.

CONCLUSIONS

Two types of Helicobacter infection showed different patterns of myofibroblast proliferation, coinciding with the extent of inflammation. These findings suggest that this difference may be related to the consequences of the infection.

Acute ethanol increases angiogenic growth factor gene expression in rat skeletal muscle

Moderate ethanol consumption demonstrates a protective effect against cardiovascular disease and improves insulin sensitivity, possibly through angiogenesis. We investigated whether 1) ethanol would increase skeletal muscle growth factor gene expression and 2) the effects of ethanol on skeletal muscle growth factor gene expression were independent of exercise-induced growth factor gene expression. Female Wistar rats were used. Four groups (saline + rest; saline + exercise; 17 mmol/kg ethanol + rest; and 17 mmol/kg ethanol + exercise) were used to measure the growth factor response to acute exercise and ethanol administration. Vascular endothelial growth factor (VEGF), transforming growth factor-beta(1) (TGF-beta(1)), basic fibroblast growth factor (bFGF), Flt-1, and Flk-1 mRNA were analyzed from the left gastrocnemius by quantitative Northern blot. Ethanol increased VEGF, TGF-beta(1), bFGF, and Flt-1 mRNA at rest and after acute exercise. Ethanol increased resting Flk-1 mRNA. Ethanol increased bFGF mRNA independently of exercise. These findings suggest that 1) ethanol can increase skeletal muscle angiogenic growth factor gene expression and 2) the mechanisms responsible for the ethanol-induced increases in VEGF, TGF-beta(1), and Flt-1 mRNA appear to be different from those responsible for exercise-induced regulation. Therefore, these results provide evidence in adult rat tissue that the protective cardiovascular effects of moderate ethanol consumption may result in part through the increase of angiogenic growth factors.

The effect of sofalcone on indomethacin-induced gastric ulcers in a Helicobacter pylori-infected gnotobiotic murine model

BACKGROUND

Sofalcone has been reported to exert anti-ulcer and gastroprotective actions, but its exact mechanism of action remains unknown. In our laboratory, we found that indomethacin-induced gastric ulcers become worse when associated with Helicobacter pylori infection.

METHODS

We employed the H. pylori-infected gnotobiotic murine model to examine the effect of sofalcone on indomethacin-induced gastric ulcers in the presence of H. pylori infection. In vitro experiments were also done to evaluate the effects of sofalcone on H. pylori growth, adherence of H. pylori to the MKN45 cells (a human gastric epithelial cell line), and these cells' IL-8 production in the presence of H. pylori.

RESULTS

We found that sofalcone produced a significant improvement in ulcer size as well as a substantial reduction in the number of H. pylori colonies in H. pylori-infected gnotobiotic mice. In vitro sofalcone has a significant bacteriocidal effect against H. pylori and can also significantly prevent adherence of this bacterium to MKN45 cells, thus remarkably reducing IL-8 production of these cells in response to stimulation by H. pylori.

CONCLUSION

Our results suggest that sofalcone can improve ulcer healing by the mechanisms mentioned above.

Autonomic nervous regeneration in acetic acid-induced ulcer from the viewpoint of synapse formation--effect of basic fibroblast growth factor and sofalcone in the rat

BACKGROUND

Monoclonal antibodies against GAP43 and synaptophysin, markers of regenerated nerves, have recently become available.

AIM

To investigate the regeneration of the autonomic nerves after acetic acid treatment, as well as the effect of recombinant basic fibroblast growth factor (bFGF-CS23) and sofalcone on reinnervation.

METHODS

Ulcers were induced by the direct application of 100% acetic acid to the serosal surface of the rat fundic stomach. Some rats were treated with bFGF-CS23 or sofalcone every 12 h after the acetic acid treatment. The immunohistochemical location of GAP43 and synaptophysin was observed by confocal laser microscopy, and the uptake sites of 14C-sofalcone were observed by autoradiography.

RESULTS

Both GAP43 and synaptophysin immunoreactivities surrounding microvessels were weak in the control group, whereas in the acetic acid-treated group, these immunoreactivities were increased. Treatment with bFGF-CS23 and sofalcone increased these immunoreactivities. The binding sites of sofalcone coincided with the location of regenerated nerves and surface mucous cells. The progenitors of the autonomic nerves were more abundant than expected.

CONCLUSION

Both bFGF and sofalcone seem to stimulate nerve regeneration.

Effect of basic fibroblast growth factor on gastric ulcer healing and its own mRNA expression

BACKGROUND

The application of an acid-stable mutein of basic fibroblast growth factor (bFGF) called CS23 results in acceleration of ulcer healing. The modes by which this cytokine exerts these effects are not yet completely understood.

AIM

To describe the pattern of bFGF-mRNA expression during ulcer healing and to examine the effects of exogenously applied CS23 on gastric ulcer healing in an animal model.

METHODS

The speed of healing of gastric ulcers, expression of extracellular matrix gene mRNAs such as pro alpha(I) collagen (by non-radioactive in situ hybridization), cellular proliferation evidenced by the display of PCNA (by immunohistochemistry), angiogenesis, and the feedback of this growth factor on its own mRNA expression pattern were used to evaluate the effects of CS23 on rat gastric ulcer healing in an animal model.

RESULTS

CS23 accelerates gastric ulcer healing at 7, 14 and 21 days after ulcer induction. We found an increase in connective tissue beneath the ulcer bed in treated animals in comparison to controls. The expression of PCNA as well as pro alpha(I) collagen mRNA was markedly increased in ulcers, yet there was no distinct difference between treatment arms. In contrast, the density of microvessels was significantly increased in the submucosa of ulcers by CS23 application. bFGF-mRNA expression is up-regulated in the submucosa during early ulcer healing; this increase diminishes within days but can be restituted by the exogenous application of CS23.

CONCLUSIONS

CS23 speeds gastric ulcer healing and significantly increases the density of microvessels in the ulcerated tissue without affecting the numbers of proliferating cells or the transcription of collagen mRNA. In addition, it augments the expression of bFGF-mRNA during the later stages of healing, suggesting a positive feedback loop.

Appearance of myofibroblasts in the gastric mucosa after ingestion of ethanol and lansoprazole with reevaluation of the mucoid cap

The mucoid cap is important in the restitution of surface epithelial cells of the gastric mucosa. We conducted the present study to clarify the relationship of the mucoid cap and the myofibroblasts in the course of healing of the gastric mucosa with ethanol-induced damage. The effect of lansoprazole on ulcer healing was also evaluated. Wistar strain male rats were administered ethanol (50%) by gastric intubation. Thirty minutes later, either an aqueous solution of lansoprazole (LPZ; 10 mg/100 g of body weight), or the same amount of physiological saline was administered by gastric intubation. Localization of the myofibroblasts was evaluated at 1, 3, and 12 hr after LPZ treatment, and compared with the number and localization of cells positive for rhodamine-phalloidin. The concentration of basic fibroblast growth factor (FGF) was determined by EUSA. We observed PR 2D3-immunoreactive cells in the lamina propria mucosae of the control fundus that were weakly positive or negative for rhodamine-phalloidin. Erosive lesions reaching more than half of the whole gastric mucosal layer were induced 1 hr after ethanol ingestion. An abundance of PR 2D3 and rhodamine-phalloidin double-positive cells was present in the lamina propria mucosae just below the erosive lesion. The administration of LPZ brought about an increase in bFGF concentration, an acceleration of ulcer healing, and an increase in immunoreactivity to PR 2D3. In conclusion, LPZ strongly influenced the healing of gastric mucosal damage related to ethanol administration, possibly through an increase in the concentration of bFGF. The immunophenotype of the myofibroblasts changed to the muscle type during healing, suggesting an involvement of these cells in ulcer healing.

Effect of combined administration of lansoprazole and sofalcone on microvascular and connective tissue regeneration after ethanol-induced gastric mucosal damage

We undertook the present study to clarify the alteration of localization of basic fibroblast growth factor (bFGF), endothelial cells, and myofibroblasts in the healing of ethanol-induced gastric mucosal damage by the combined administration of lansoprazole and sofalcone. Wistar strain male rats were used. Ethanol 50% was given through orogastric intubation. Thirty minutes later, an aqueous solution of lansoprazole, sofalcone, a combination of lansoprazole and sofalcone, or physiologic saline was given orally. The stomach was removed and the localization of bFGF, myofibroblast, and endothelial cells was examined using monoclonal antibodies. Some rats were pretreated with indomethacin to rule out the effect of endogenous prostaglandin. The combined administration of lansoprazole and sofalcone brought about increased concentrations and immunoreactive areas of bFGF and a greater number of endothelial cells, compared with the ethanol-alone treatment. The number of myofibroblasts increased more significantly in the group treated with a combination of agents than in that treated with ethanol alone, ethanol plus sofalcone, or ethanol plus lansoprazole. Indomethacin pretreatment partly abolished the effects of single and combined administration of these agents. In conclusion, the mixed administration of lansoprazole and sofalcone accelerated the microvascular and connective tissue regeneration during the healing of ethanol-induced gastric mucosal damage.