Akira Iwabuchi

Association of 72-kDa heat shock protein expression with adaptation to aspirin in rat gastric mucosa

It is well documented that gastric mucosa canincrease its resistance to mucosal damage caused byaspirin during repeated long-term administration ofaspirin. However, the underlying mechanism of thisadaptation is not well established. In the present study,we investigated the effect of long-term (chronic)administration of aspirin on expression of heat shockproteins (HSPs), which are known as endogenouscytoprotectants, in rat gastric mucosa. Rats were administeredaspirin (100 mg/kg) daily for up to 20 days. Aftervarious periods of aspirin administration, a high doseof aspirin (250 mg/kg) was administered, and the mucosal damage was assessed. Expression of heat shockproteins (HSPs) in gastric mucosa was evaluated byWestern blot. Intracellular localization of each HSP wasstudied immunohistochemically. ProstaglandinE2 (PGE2) and leukotriene B4(LTB4) levels were also investigated.Long-term aspirin administration resulted in developmentof resistance to aspirin-induced mucosal damage, and theincrease of HSP72 expression correlated with mucosal resistance to aspirin.No significant increase was observed in HSP60 and HSP90levels. Immunohistochemical study showed an increase ofHSP72 in the cytoplasm of mucosal surface cells. The PGE2 level was suppressed and nochange in the level of LTB4 was observed. Itis possible that HSP72 could play important roles ingastric mucosal adaptation when the PGE2level is suppressed by NSAIDs.

Differential Induction of HSP60 and HSP72 by Different Stress Situations in Rats (Correlation with Cerulein-Induced Pancreatitis)

We previously reported that water-immersionstress specifically induced the synthesis of a 60-kDaheat-shock protein (HSP60, chaperonin homolog) inpancreatic cells and preinduction of HSP60 completely prevented development of cerulein-inducedpancreatitis in the rat in an HSP60 quantitativelydependent manner. In order to study the cytoprotectivefunction of a 72-kDa heat-shock protein (HSP72,stress-inducible hsp70), the effect of specific preinduction ofHSP72 by hyperthermia on cerulein-induced pancreatitiswas investigated and compared with the effect ofpreinduction of HSP60 in this study. Expression of HSP60 and HSP72 in the pancreas wasinvestigated by immunoblot before and after waterimmersion or hyperthermia. Following pretreatment withwater-immersion stress or hyperthermia, the rats wereinjected with cerulein (40 μg/kg, intraperitoneally).The pancreas wet weight and serum amylase concentrationwere measured before and after cerulein injection.Hyperthermia (42.5°C, 20 min) specifically induced HSP72 in the pancreas. The synthesis of HSP60was specifically induced by water-immersion stress inthe pancreas. Cerulein-induced pancreatitis was clearlyprevented by specific preinduction of HSP60 by water-immersion stress. However, preinductionof HSP72 by hyperthermia had no preventive effect oncerulein-induced pancreatitis. Our findings suggest thatHSP60 and HSP72 have distinct functions in the pancreas, and their induction mechanisms arealso different in vivo. These results could be importantfor understanding the mechanism of “adaptivecytoprotection” in the pancreas mediated byheat-shock proteins.

Effect of preinduction of heat shock proteins on acetic acid-induced colitis in rats

In order to study the cytoprotective function ofheat shock proteins (HSPs) in vivo, the effect ofpreinduction of HSPs by hyperthermia on aceticacid-induced colitis was investigated. Expression of60-kDa, 72-kDa, and 90-kDa heat shock proteins (HSP60,HSP72, and HSP90, respectively) in rat colonic mucosawas investigated by Western blot analysis andimmunohistochemical study before and after hyperthermia. Following pretreatment with or withouthyperthermia, the rats received intrarectal infusion ofvarious doses of acetic acid. The colonic mucosal damagewas evaluated by macroscopic and microscopic assessments 24 hr after the intrarectal infusion of aceticacid. Expression of HSPs was significantly increased byhyperthermia in rat colonic mucosa. Immunohistochemicalstudy also showed the increments of HSPs in the colonic mucosal cells after hyperthermia.Acetic acid-induced colitis was dramatically preventedby pretreatment with hyperthermia when HSP72 and HSP90were preinduced. On the other hand, induction of HSP60 did not correlate with mucosalprotection. Our findings suggest that HSP72 and HSP90may have cytoprotective function against aceticacid-induced mucosal damage. These results may beimportant for understanding the mechanism of“adaptive cytoprotection” mediated byHSPs.

Induction of a 72-kDa Heat Shock Protein and Cytoprotection Against Thioacetamide-Induced Liver Injury in Rats

Heat shock proteins are ubiquitous intracellularproteins induced by various physiological stress-relatedevents. A 72-kDa heat shock protein (HSP72) has beenreported to be an endogenous cytoprotectant in variety of cells in vitro . In order tostudy the cytoprotective function of HSP72 in the liver,the effect of preinduction of HSP72 in rat liver bysystemic hyperthermia on thioacetamide-induced hepatic injury was investigated in this study.Expression of HSP72 in the liver was investigated byimmunoblot and densitometric analysis. Rats wereinjected with thioacetamide (100 mg/kg, subcutaneously)with or without preinduction of HSP72 byhyperthermia. Serum AST and ALT concentrations weremeasured before and after thioacetamide injection inboth group. Histologic alteration of the liver wasevaluated also. Systemic hyperthermia (42.5°C, 20min) significantly induced HSP72 in the liver.Thioacetamide-induced hepatic injury was clearlyprevented by preinduction of HSP72 by hyperthermia.Prevention of hepatocyte damage was more clear in the areaaround central veins where HSP72 induction was apparent.Our findings might suggest that HSP72 has an importantfunction in the liver with respect to cytoprotection. These results might be important forunderstanding the mechanism of “adaptivecytoprotection” in the liver mediated by thefunction of heat shock proteins as “molecularchaperons” as reported in vitro.

Disseminated intra-abdominal cystic lymphangiomatosis with severe intestinal bleeding. A case report.

We describe cystic lymphangiomatosis with intestinal bleeding developing multiple lymphangiomas in the small intestine, mesentery, mesocolon, omentum, retroperitoneum, and spleen. Small intestinal fluorography showed multiple polypoid lesions, mainly in the jejunum. Ultrasonography, computed tomography, and magnetic resonance imaging showed diffuse cystic tumors in the mesentery and spleen. Cystic lymphangiomatosis was proved by histologic findings of the biopsied specimen at laparotomy.

Effect of pre-induction of heat shock proteins on indomethacin-induced small-intestinal lesion in rats

Systemic hyperthermia induces the synthesis of heat shock proteins (HSPs) in several organs. However, the mechanism of induction and the functions of HSPs in the small-intestinal mucosa have not been established. We examined the expression of HSPs in the small-intestinal mucosa after systemic hyperthermia, and evaluated the cytoprotective function of preinduced HSPs on experimentally induced mucosal damage. HSP expression was investigated by Western blot and densitometric analysis before and after hyperthermia (42.5°C; 20min). Expression of a 72-kDa heat shock protein (HSP72) and a 73-kDa heat shock protein (HSP73), both of which are endogenous cytoprotectants in vitro significantly increased, peaking 6–9h after hyperthermia, without any pathologic alterations, whereas the expression of a 60-kDa heat shock protein (HSP60) did not increase. To investigate the influence of pre-induction of HSPs on small-intestinal damage, rats received indomethacin (10mg/kg; orally) with or without pre-treatment with hyperthermia. Small-intestinal damage caused by indomethacin was not influenced by pre-induction of HSP72 and HSP73. We demonstrated that systemic hyperthermia induced HSP72 and HSP73, although pre-induction of these proteins did not have a cytoprotective function in the smallintestinal damage caused by indomethacin.

Effect of Preinduction of Heat-Shock Proteins on Acetic Acid-Induced Small Intestinal Lesions in Rats

Bowel dysfunction such as irritable bowelsyndrome caused by stress is well described. Previousreports suggest that stress is known to cause therelease of endogenous substances such as catecholamine, beta-endorphine, 5-hydroxytryptamine,corticotropin-releasing factor, andthyrotropin-releasing hormone (TRH). However, the roleplayed by these neurohormonal mediators in boweldysfunction under stress conditions is not well known. We investigatedthe influence of water-immersion stress or TRHadministration on the expression of 60-kDa, 72-kDa, and90-kDa heat-shock proteins (HSP60, HSP72, and HSP90, respectively) in rat small intestinal mucosa byWestern blot and immunohistochemical analyses. Thecytoprotective function of preinduced HSPs onexperimentally induced mucosal damage also was studied.In order to investigate the influence ofpreinduction of HSP60 on small intestinal damage, thesmall intestinal lumen was perfused with 1.5% aceticacid 1 ml/min for 15 min with or without pretreatmentwith water-immersion stress or TRH administration.Expression of HSP60 was significantly increased bywater-immersion stress or TRH administration in thesmall intestinal mucosa, whereas HSP72 and HSP90 did not increase. Interestingly, expression of thisprotein showed the biphasic peak pattern afterwater-immersion stress or TRH administration. Each peakwas observed 3-6 hr and 21-24 hr after the initiation of water-immersion stress or TRHadministration. Immunohistochemical study also showed asignificant increment of HSP60 in both the cytoplasm andnuclei of the small intestinal mucosal cells. Nohistopathologic alteration was observed in rat small intestinalmucosa after each treatment. Small intestinal damagecaused by 1.5% acetic acid perfusion was not influencedby preinduction of HSP60. We demonstrated that waterimmersion stress or TRH administrationspecifically induced HSP60, although preinduction ofthis protein did not show a cytoprotective function inthe small intestinal mucosa.

Specific preinduction of 60-kDa heat shock protein (chaperonin homolog) by TRH does not protect colonic mucosa against acetic acid-induced lesion in rats

In order to study the cytoprotective function of colonic heat shock proteins (HSPs) in vivo, the effect of specific preinduction of HSP60 by thyrotropin-releasing hormone (TRH) administration on the development of acetic acid-induced colonic mucosal lesion was investigated. Expression of 60-kDa, 72-kDa, and 90-kDa heat shock proteins (HSP60, HSP72, and HSP90, respectively) in rat colonic mucosa was investigated by western blot and immunohistochemical analyses before and after TRH administration. Following pretreatment with or without TRH administration, the rats received intrarectal infusion of 5% acetic acid. The colonic mucosal damage was macroscopically evaluated 24 hr after the intrarectal infusion of acetic acid. Expression of HSP60 was significantly increased by TRH administration in the colonic mucosa, whereas HSP72 and HSP90 did not increase. Immunohistochemical study also showed a significant increase in HSP60 in colonic mucosal cells, especially at the surface of the colonic mucosa after TRH administration. No histopathologic alteration was observed in the colonic mucosa after TRH administration. The colonic mucosal damage caused by intrarectal infusion of 5% acetic acid was not prevented by preinduction of HSP60. We demonstrated that specific preinduction of HSP60 by TRH administration did not show cytoprotective function in the colonic mucosa, although this protein plays a crucial role for cytoprotection in the pancreatic acinar cells. Our results indicate that the role of HSP60 may be different in each organ with respect to cytoprotection.

Inhibition of CN (protein phosphatase‐2B) suppresses Ca2+‐mediated acid secretion in rats

It has been suggested that CN (calcineurin, protein phosphatase‐2B) regulates signal transduction, particularly in various secretory cells. In this study, we examined whether CN plays a role in stimulus‐secretion coupling of gastric parietal cells.

Effects of cyclosporin A on water-immersion stress-induced gastric lesion and gastric secretion in rats.

Abstract: Cyclosporin A is an immunosuppressive agent which is well known as a specific inhibitor of calcineurin (protein phosphatase 2B). In this study, we investigated the effects of cyclosporin A on water-immersion stress-induced gastric ulcer formation and gastric acid secretion in rats. We also examined the localization of calcineurin immunohistochemically. Calcineurin was specifically expressed in gastric parietal cells and chief cells of the gastric mucosa. The intraperitoneal administration of cyclosporin A dose-dependently suppressed the development of gastric mucosal lesions induced by water-immersion stress and inhibited gastric acid secretion, as assessed by pylorus ligation. These results indicated that calcineurin may play an important role in gastric acid secretion.