Focused panel sequencing points to genetic predisposition in non-cirrhotic intrahepatic portal hypertension patients in India.

OBJECTIVE: Non-cirrhotic intrahepatic portal hypertension (NCIPH), a portal microangiopathy affecting small portal vein radicles, is a disease of Indian sub-continent. NCIPH appears to be a complex disease with interactions between inherited and acquired factors, though the exact pathophysiological mechanism is unknown. We aimed at investigating the genetic variants that might contribute to susceptibility to NCIPH. METHODS: In this case-control study, we analyzed genes associated with microangiopathy-VWF-ADAMTS13 (von Willebrand factor and its cleavase enzyme - a disintegrin and matrix metalloprotease with thrombospondin type-1 motifs member 13) and alternative complement system vitamin B12 metabolism and with familial NCIPH. RESULT: Eighty-four Indian patients with liver biopsy-proven NCIPH (cases) and 103 healthy controls (matched for residential region of India) were included in the study. Targeted next-generation sequencing (NGS) panel, comprising 11 genes of interest, was done on 54 cases. Genotyping of selected variants was performed in 84 cases and 103 healthy controls. We identified variants in MBL2, CD46 and VWF genes either associated or predisposing to NCIPH. We also identified a single case with a novel compound heterozygous mutation in MBL2 gene, possibly contributing to development of NCIPH. CONCLUSION: In this first of a kind comprehensive gene panel study, multiple variants of significance have been noted, especially in ADAMTS13-VWF and complement pathways in NCIPH patients in India. Functional significance of these variants needs to be further studied.

Rodenticidal hepatotoxicity: Raised plasma Von Willebrand factor levels predict in-hospital survival and preliminary report of the outcome of Von Willebrand factor reducing management protocol.

BACKGROUND: High Von Willebrand factor (VWF) levels may predispose to multi-organ failure in acute liver failure (ALF). In rodenticide-induced hepatotoxicity patients, we analyzed if plasma VWF levels predicted survival and also the outcome of VWF lowering by N-acetyl cysteine (NAC), fresh frozen plasma (FFP) infusions, and plasma exchange (PLEX). METHODS: We retrospectively analyzed prospectively collected data. Hepatotoxicity was classified as uncomplicated acute hepatitis (UAH), acute liver injury (ALI), and ALF. ALF patients, if not opting for liver transplantation, had PLEX and NAC; ALI patients received NAC ± FFP (PLEX, if worsening); UAH patients had NAC. Plasma VWF antigen was measured (normal, 50% to 150%). In-hospital survival was analyzed as discharged alive or died/discharged in a terminal condition (poor outcome). RESULTS: Twenty-four consecutive rodenticide-induced hepatotoxicity patients (UAH in 1, ALI in 20, ALF in 3) from December 2017 to January 2019 were studied. Baseline VWF levels were 153%, 423 (146-890)% median (range), and 448 (414-555)% in UAH, ALI, ALF patients; model for end-stage liver disease (MELD) scores were 11, 24 (12-38), 36 (32-37) and in-hospital survival rates were 100%, 85%, 67%, respectively. VWF levels were higher in patients with poor outcome (555 [512-890]%) than in those discharged alive (414 [146-617]%) (p-value = 0.04). The area under the receiver operating curve of the VWF level, MELD score, and sequential organ failure assessment score to predict survival was 0.92, 0.84, and 0.66, respectively. Of 4 patients meeting criteria for liver transplantation (none had transplantation), 3 (75%) survived. CONCLUSIONS: High VWF levels predict poor outcome in rodenticide-induced hepatotoxicity. VWF reduction may be useful in such patients.

ADAMTS13 missense variants associated with defective activity and secretion of ADAMTS13 in a patient with non-cirrhotic portal hypertension.

BACKGROUND: Non-cirrhotic intrahepatic portal hypertension (NCIPH) is characterized by thrombotic microangiopathy of the portal venous system, low ADAMTS13 (a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs-13), and high vWF (von Willebrand factor) levels. This study aimed to screen for ADAMTS13 mutations, focusing on the CUB domain, in these patients. METHODS: Prospectively recruited NCIPH patients and healthy volunteers underwent tests for plasma vWF-ADAMTS13 balance. Sanger sequencing of the CUB domain of ADAMTS13 was done in a subset of the NCIPH patients, and the detected mutation was screened for in all the study participants. Next-generation sequencing of clinically relevant exome and liver immunostaining for ADAMTS13 was done in patients with detected ADAMTS13 mutation. RESULTS: Plasma vWF-ADAMTS13 balance was significantly altered in 24 NCIPH patients (Child's class A:23, B:1) as compared to 22 controls. On initial sequencing of the CUB domain (17 cases and 3 controls), one NCIPH patient showed a rare missense variant (SNV) at position c.3829C >T resulting in p.R1277W (rs14045669). Subsequent RFLP analysis targeted to the R1277W variant did not detect this in any other NCIPH patient, nor in any of the 22 controls. The NCIPH patient with the R1277W variant had severe ADAMTS13 deficiency, consistently high vWF, other missense SNVs in ADAMTS13, vWF, and complement genes. Immunostaining of his liver biopsy revealed globules of ADAMTS13 within stellate cells. CONCLUSIONS: We report missense variants in ADAMTS13, vWF, and complement genes in a patient with NCIPH who had decreased secretion and activity of ADAMTS13 protein. Further studies are needed in NCIPH patients in this regard.

Arsenicosis, possibly from contaminated groundwater, associated with noncirrhotic intrahepatic portal hypertension.

BACKGROUND AND AIMS: Idiopathic noncirrhotic intrahepatic portal hypertension (NCIPH), a chronic microangiopathy of the liver caused by arsenicosis from use of contaminated groundwater, was reported from Asia. This study aimed to see, if in the twenty-first century, arsenicosis was present in NCIPH patients at our hospital and, if present, to look for groundwater contamination by arsenic in their residential locality. METHODS: Twenty-seven liver biopsy proven NCIPH patients, 25 portal hypertensive controls with hepatitis B or C related cirrhosis and 25 healthy controls, matched for residential locality, were studied. Eighty-four percent to 96 % of study subjects belonged to middle or lower socioeconomic category. Arsenicosis was looked for by estimation of arsenic levels in finger/toe nails and by skin examination. Arsenic levels in nails and in ground water (in NCIPH patients with arsenicosis) was estimated by mass spectrometry. RESULTS: Nail arsenic levels were raised in five (10 %) portal hypertensive study subjects [two NCIPH patients (both had skin arsenicosis) and three portal hypertensive controls]. All of these five patients were residents of West Bengal or Bangladesh. Skin arsenicosis was noted in three NCIPH patients (11 %) compared to none of disease/healthy controls. Ground water from residential locality of one NCIPH patient with arsenicosis (from Bangladesh) showed extremely high level of arsenic (79.5 µg/L). CONCLUSIONS: Arsenicosis and microangiopathy of liver, possibly caused by environmental contamination continues in parts of Asia. Further studies are needed to understand the mechanisms of such 'poverty-linked thrombophilia'.

Investigation into celiac disease in Indian patients with portal hypertension.

BACKGROUND: There is limited data on celiac disease in patients with cryptogenic cirrhosis or idiopathic noncirrhotic intrahepatic portal hypertension (NCIPH). Our objective was to evaluate for celiac disease in patients with portal hypertension in India. METHODS: Consecutive patients with portal hypertension having cryptogenic chronic liver disease (cases) and hepatitis B- or C-related cirrhosis (controls) were prospectively enrolled. We studied tissue transglutaminase (tTG) antibody and duodenal histology in study patients. RESULT: Sixty-one cases (including 14 NCIPH patients) and 59 controls were enrolled. Celiac disease was noted in six cases (including two NCIPH patients) as compared to none in controls. In a significant proportion of the remaining study subjects, duodenal biopsy showed villous atrophy, crypt hyperplasia, and lamina propria inflammation, not accompanied by raised intraepithelial lymphocytes (IELs); this was seen more commonly in cases as compared to controls. An unexpectedly high rate of tTG antibody positivity was seen in study subjects (66 %) of cases as compared to 29 % in controls (p-value < 0.001), which could indicate false-positive test result. CONCLUSION: In this study, 10 % of patients with unexplained portal hypertension (cryptogenic chronic liver disease) had associated celiac disease. In addition, an unexplained enteropathy was seen in a significant proportion of study patients, more so in patients with cryptogenic chronic liver disease. This finding warrants further investigation.

Surgical stress-induced alterations in retinoid metabolism in the small intestine: role of oxygen free radicals.

Oxidative stress in the small intestine can result in altered cell proliferation, migration, and differentiation of villus-crypt cells. Retinoid metabolism is recognized as an important mediator of cellular differentiation in the intestine. This study examined the effect of oxidative stress in retinoid metabolism in a surgical stress model. Surgical stress was performed by handling the intestine as done during laparotomy. Villus-crypt cells were isolated at different time periods and various retinoid concentrations in the cell homogenate and the retinoic acid forming enzymes were quantitated using HPLC. Surgical stress resulted in altered retinoid levels in various cell populations in the small intestine at 1 and 12h. The activity of alkaline phosphatase and retinal oxidase was also altered at these time points and all these changes were prevented by inhibiting superoxide generation using xanthine oxidase inhibitor, allopurinol. These studies suggest that alterations seen in enterocytes during surgical stress may be mediated by changes in retinoid metabolism.

Surgical manipulation of the intestine and distant organ damage-protection by oral glutamine supplementation.

BACKGROUND: The intestine is increasingly recognized as a primary effector of distant organ damage, such as the lung, after any abdominal surgery. Earlier studies have shown that surgical manipulation of the intestine induces generation of reactive oxygen species in the intestine, resulting in mucosal and lung damage. Because glutamine is preferentially used by the small intestine as an energy source, this study examined the effect of glutamine and glutamic acid on intestinal and lung damage after surgical manipulation. METHODS: Controls and rats were pretreated for 7 days with 2% glutamine or glutamic acid, or the isonitrogenous amino acids glycine or alanine in the diet and subjected to surgical manipulation of the intestine. The intestine and lung were assessed for damage, and protection offered by various amino acids was studied. RESULTS: Surgical manipulation resulted in oxidative stress in the intestine as evidenced by increased xanthine oxidase activity and decreased antioxidant status. Enterocyte mitochondria were also functionally impaired with altered calcium flux, decreased respiratory control ratio, and increased swelling. Gut manipulation also resulted in neutrophil infiltration and oxidative stress in the lung as assessed by an increase in myeloperoxidase activity, lipid peroxidation, and antioxidant status. Glutamine or glutamic acid supplementation for 7 days before surgical manipulation showed a protective effect against the intestinal and lung damage. CONCLUSIONS: This study suggests that preoperative enteral glutamine or glutamic acid supplementation attenuates intestinal and lung damage in rats during surgical manipulation and that this effect might offer protection from postsurgical complications.

Altered glycosylation of surfactant and brush border membrane of the small intestine in response to surgical manipulation.

BACKGROUND: Surgical stress can lead to bacterial translocation from the intestine into systemic circulation. Adherence of bacteria onto the glycoconjugates of the brush border membrane (BBM) and surfactant coat (SLP) of the mucosal cells is the first step in the translocation of luminal bacteria. Our earlier study showed that surgical manipulation of the intestine results in oxidative stress leading to structural and functional alterations in the mucosa. This study looks at the effect of surgical manipulation on the glycoconjugate alterations of SLP and BBM. MATERIALS AND METHODS: SLP and BBM were isolated from control and after surgical manipulation and the sugar composition was analyzed. Bacterial adherence using E. coli isolated from cecum was compared after coating microtiter plates with SLP or BBM isolated from control and after surgical manipulation. RESULTS: An increase in various sugars was seen after surgical manipulation both in SLP and BBM and this increase was maximum at 12 h after surgery. These alterations increased bacterial adherence onto SLP and BBM. Inhibiting superoxide generation by allopurinol treatment prior to surgical manipulation prevented glycosylation alteration and bacterial adherence. CONCLUSION: Surgical manipulation results in altered glycoconjugates of SLP and BBM which leads to increased bacterial adherence. These alterations are probably brought about by oxygen-free radicals. This is clinically significant because postsurgical complications such as sepsis may be brought about by altered glycosylation.

Isolation of human small intestinal brush border membranes using polyethylene glycol and effect of exposure to various oxidants in vitro.

This study presents a method of brush border membrane (BBM) preparation from the human small intestine using polyethylene glycol (PEG) precipitation and also looks at the effect of in vitro oxidant exposure on structural and functional alterations in the membrane. Isolated BBM were relatively pure as judged by 10- to 14-fold enrichment of marker enzymes with less than 1% contamination by other subcellular organelles. These membranes showed uphill transport of glucose and lipid analysis showed a cholesterol-phospholipid (C/P) ratio of 1.19. Isolated BBM were found to be susceptible to superoxide generated by xanthine oxidase (XO), resulting in lipid and protein oxidation along with altered glucose uptake. Superoxide exposure also resulted in phospholipid alterations, especially generation of lyso phospholipids. These changes were prevented by inhibiting XO by allopurinol or scavenging superoxide by superoxide dismutase (SOD). Other oxidants studied did not have significant affect on these membranes. These studies suggest that PEG can be used for preparation of BBM from the human small intestine and these membranes undergo structural and functional alterations on exposure to superoxide.

Heat preconditioning prevents oxidative stress-induced damage in the intestine and lung following surgical manipulation.

BACKGROUND: The intestine is increasingly recognized as a primary effector of distant organ damage, such as lung, following abdominal surgery. Surgical manipulation of the intestine generates oxygen free radicals resulting in mucosal damage. Heat preconditioning has been proposed to prevent various stress-induced alterations in cells and tissues, including oxidative stress. This study examined the effect of heat preconditioning on oxidative stress-induced damage to the intestine and lung, following surgical manipulation. METHODS: Control rats and rats pretreated with heat were subjected to surgical manipulation by opening the abdominal wall and handling the intestine as done during laparotomy. Intestine and lung were assessed for damage by histology and markers of oxidative stress. RESULTS: Surgical manipulation resulted in ultrastructural changes in the intestine. Biochemical alterations in the enterocytes were evident, with increased xanthine oxidase activity resulting in production of superoxide anion and with a decrease in antioxidant status. Gut manipulation also resulted in neutrophil infiltration and oxidative stress in the lung as assessed by histology, myeloperoxidase activity, lipid peroxidation and antioxidant status. Heat conditioning before surgical manipulation had a protective effect against this intestinal and lung damage. CONCLUSION: This study suggests that mild whole-body hyperthermia before surgery might offer protection from postoperative complications.

Heat preconditioning prevents enterocyte mitochondrial damage induced by surgical manipulation.

BACKGROUND: The small intestine is susceptible to free radical-induced damage and our earlier work has shown that surgical manipulation of the intestine results in generation of oxygen free radicals, leading to mucosal damage. Heat preconditioning has been shown to offer protection against various stresses including oxidative stress and this study looked at the effect of heat preconditioning on surgical manipulation-induced intestinal mitochondrial alterations. METHODS: Control and rats pretreated with heat were subjected to surgical manipulation by opening the abdominal wall and handling the intestine as done during laparotomy. Mitochondria were prepared from isolated enterocytes and structural and functional alterations were assessed. RESULTS: Surgical manipulation of the intestine resulted in mitochondrial alterations as seen by ultrastructural changes and altered lipid composition. Mitochondria were functionally impaired as evidenced by altered calcium flux, decreased respiratory control ratio, and increased tetrazolium dye reduction and swelling. Along with this, biochemical alterations such as increased lipid and protein oxidation were seen following surgical manipulation. Mild heat preconditioning of the animal prevented these damaging effects. CONCLUSIONS: These studies suggest that stress in the small intestine due to surgery can affect enterocyte mitochondrial structure and function and these effects can be prevented by mild whole body hyperthermia prior to surgery.

Surgical manipulation of the small intestine and its effect on the lung.

BACKGROUND: Surgical manipulation of the intestine results in generation of oxygen free radicals leading to mucosal damage as evidenced by ultrastructural and biochemical changes. It is likely that the gut-derived mediators can bring about damage to distant organs such as the lung. METHODS: Surgical manipulation of the gut was performed by opening the abdominal wall and handling the intestine. Lung damage was assessed by histology, markers of oxidative stress, and protein content in bronchoalveolar lavage fluid. Protection offered by pretreatment with various compounds such as allopurinol, L-arginine, quinacrine, and indomethacin was also studied. RESULTS: Gut manipulation resulted in neutrophil infiltration, oxidative stress, and permeability changes in the lung and these changes were maximum 30 and 60 min following surgical manipulation, which recovered with time and reversed to normal by 24 h. Prior treatment with inhibitors of xanthine oxidase, phospholipase A(2), or cyclooxygenase showed a protective effect against lung damage. CONCLUSION: This study has shown that laparotomy and intestinal handling result in distant organ (lung) damage which is probably brought about by neutrophil infiltration and oxidative stress on the lung. This is likely mediated by compounds generated in the intestine and transported into the systemic circulation since inhibition of generation of chemical mediators in the intestine offers protection against lung damage.

Effect of surgical manipulation of the rat intestine on enterocyte populations.

BACKGROUND: The intestine is susceptible to operations at remote locations, and the barrier function is altered during intestinal manipulation, leading to bacterial or endotoxin translocation into the systemic circulation. One of the mainstays for the maintenance of the integrity of the barrier function is epithelial cell proliferation and migration. The present study looked at the effect of gut manipulation after laparotomy on different cell populations of the intestinal epithelium. METHODS: Surgical manipulation of the gut was performed by opening the abdominal wall and handling the intestine, as is done during laparotomy. Villus and crypt cells were isolated at different time periods after gut manipulation, and mitochondria were prepared from isolated enterocytes. The effects of surgical manipulation on enterocytes and isolated mitochondria were studied. RESULTS: Mechanical manipulation of the gut resulted in alterations in the intestinal epithelium, as shown by decreased cell viability and yield in the crypt cells. The alterations were associated with actin reorganization, as well as with altered cell proliferation and adenosine deaminase activity. At the mitochondrial level, altered mitochondrial function, such as decreased respiratory control ratio, increased 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide reduction, and induction of permeability transition in the crypt cells, was observed. These alterations were maximal 1 hour after surgical manipulation and partially recovered to normal by 24 hours. CONCLUSIONS: Mechanical manipulation of the gut that occurs during any abdominal operation induces alterations in the intestine, both at the cellular and the subcellular levels. The crypt cells bear the brunt of the damage, and the reversibility of the damage is possibly brought about by increased proliferation and movement of the cells.

Nitric oxide protects the intestine from the damage induced by laparotomy and gut manipulation.

BACKGROUND: The intestine is highly susceptible to free radical-induced damage, and our earlier work has shown that surgical stress induces the generation of oxygen free radicals in enterocytes, resulting in intestinal damage along with ultrastructural changes. Since nitric oxide (NO) is an important mediator of gastrointestinal function, this study looked at the effect of NO on surgical stress-induced intestinal alterations. MATERIALS AND METHODS: Control rats and rats pretreated with the NO donor l-arginine were subjected to surgical stress by opening the abdominal wall and handling the intestine as done during laparotomy. Enterocytes were isolated and homogenate prepared, and the protection offered by l-arginine against damage due to surgical stress was determined and compared with normal controls. Protection to structural as well as functional aspects of the intestine was also examined. RESULTS: Intestinal manipulation affected intestinal structure as assessed by electron microscopy. Functional impairment of the enterocyte was also evident, with increased xanthine oxidase activity resulting in production of superoxide anion. This impairment is more dramatic in the crypt cells. Increased protease activity was also seen following laparotomy and handling. Pretreatment with the NO synthase substrate l-arginine prevented these damaging effects. Arginine protection was abolished in the presence of the NO synthase inhibitor NG-nitro-l-arginine methyl ester, indicating the role of NO. CONCLUSION: Stress in the small intestine due to any surgery can affect enterocyte structure and function. These damaging effects can be prevented by NO, an important modulator of cellular function.

Nitric oxide prevents intestinal mitochondrial dysfunction induced by surgical stress.

BACKGROUND: The intestine is highly susceptible to free radical-induced damage and earlier work has shown that surgical stress induces generation of oxygen free radicals in enterocytes, resulting in intestinal damage along with changes in mitochondrial structure and function. Nitric oxide is an important mediator of gastrointestinal function and this study looked at the effect of nitric oxide on surgical stress-induced intestinal mitochondrial alterations. METHODS: Controls and rats pretreated with the nitric oxide donor L-arginine were subjected to surgical stress by opening the abdominal wall and handling the intestine. Enterocytes were isolated, mitochondria prepared and the protection offered by L-arginine against damage due to surgical stress was determined. Protection to structural as well as functional aspects of mitochondria was examined. RESULTS: Mild handling of the intestine affected the enterocyte mitochondrial structure as assessed by lipid composition and electron microscopy. Mitochondria were also functionally impaired with altered calcium flux and decreased respiratory control ratio. Pretreatment with the nitric oxide synthase substrate L-arginine prevented these damaging effects of surgical stress. Protection with arginine was abolished by the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester, indicating the role of nitric oxide. CONCLUSION: Surgical stress in the small intestine can affect enterocyte mitochondrial structure and function. These damaging effects can be prevented by nitric oxide, an important modulator of cellular function.

A novel method of preparation of small intestinal brush border membrane vesicles by polyethylene glycol precipitation.

A novel method of brush border membrane vesicle (BBMV) preparation from the small intestinal mucosa using polyethylene glycol (PEG) precipitation has been presented. This preparation is compared with calcium-precipitated BBMVs in marker enzyme enrichment, contamination by other subcellular membranes, transport of glucose, and lipid composition. PEG-precipitated BBMVs are comparable with calcium-precipitated membranes in all parameters except lipid composition and thiol content. PEG-precipitated membranes have more phosphatidylcholine and phosphatidylethanolamine and less lysophosphatidylcholine and lysophosphatidylethanolamine as compared to calcium-precipitated membranes. Diacylglycerol and triacylglycerol content are also high in PEG-precipitated membranes. Alteration in lipid composition indicate the possible activation of lipase and phospholipase by calcium during BBMV preparation, which is not seen in PEG precipitation. Thiol content is almost double in PEG-precipitated membranes as compared to calcium-precipitated membranes. These results indicate that PEG can be used for the preparation of BBMVs in native form from the intestine without any alteration in their structural components, and these membranes show comparable transport activity.

Surgical stress induces phospholipid degradation in the intestinal brush border membrane.

BACKGROUND: Surgical stress can lead to translocation of bacteria from the intestine into the systemic circulation. The intestinal brush border membrane (BBM) plays an important role in defense against such invasion by luminal bacteria and endotoxin. Our earlier work has shown the development of oxidative stress in the intestine after surgical stress and since the BBM is sensitive to free radical attack, this study examined the effect of surgical stress on the structure and function of intestinal BBM. METHODS: Intestinal BBM were isolated from control and after surgical stress and compared for structural and functional alterations. Surgical stress was also carried out following pretreatment with the xanthine oxidase inhibitor allopurinol or the nitric oxide donor l-arginine, to study the protection offered by these compounds. RESULTS: Surgical stress affected intestinal BBM structure as well as function. A decrease in alkaline phosphatase activity and alpha-tocopherol content, accompanied by an increase in lipid peroxidation, was seen. Surgical stress induced phospholipid degradation with generation of arachidonic acid. Functional impairment with a decrease in glucose transport ability was also seen. These changes are prevented by inhibition of xanthine oxidase by allopurinol pretreatment but not by NO. CONCLUSION: Surgical stress in the small intestine causes structural and functional alterations in the BBM through oxidative stress. This damage could affect gut barrier integrity and generation of arachidonic acid might mediate distal organ dysfunction.

Role of xanthine oxidase in small bowel mucosal dysfunction after surgical stress.

BACKGROUND: The small intestine is highly susceptible to surgical stress even at remote locations. An earlier study using a rat model indicated that oxidative stress plays an important role in this process. The enzyme xanthine oxidase is an important source of free radicals in the small intestine. The role of this enzyme in intestinal damage after surgical stress was examined. METHODS: Rats pretreated with xanthine oxidase inhibitors were subjected to surgical stress by opening the abdomen and handling the intestine, as done during laparotomy. Enterocytes at various stages of differentiation were isolated and the protection offered by xanthine oxidase inhibitors against damage due to surgical stress was determined and compared with normal controls. Protection against ultrastructural changes to the mucosa, as well as mitochondrial function was examined. RESULTS: Surgical stress affected both the villus as well as crypt cells, causing increased superoxide generation, accompanied by increased activity of xanthine oxidase. Xanthine oxidase inhibitors ameliorated the increased superoxide generation, and protected against mitochondrial damage and ultrastructural changes in the intestine. CONCLUSION: Surgical stress affects both the villus and crypt cell populations in the small intestine. The enzyme xanthine oxidase maybe an important mediator of surgical stress in the intestine.

Protease activation during surgical stress in the rat small intestine.

BACKGROUND: Surgical stress affects intestinal permeability and our earlier study using a rat model indicated that oxidative stress plays an important role in this process. Proteases are important mediators of cellular damage and are known to be activated in oxidative stress. This study looked at protease activity in enterocytes after surgical stress. METHODS: Surgical stress was induced by opening the abdominal wall and handling the intestine as done during laparotomy, in normal and xanthine oxidase-deficient rats. Enterocytes at various stages of differentiation were isolated and protease activity and protection offered by xanthine oxidase inhibitors were determined. Mitochondria and cytosol were prepared from total isolated enterocytes at different periods after surgical stress and protease activation was studied. RESULTS: Surgical stress induced activation of proteases in both the villus and crypt cells. Protease activation is seen in both mitochondria and cytosol, and similar to the other alterations in mucosal cells, protease activation was maximum 60 min after stress, returning to normal by 24 h. Thiol compounds modulate protease activity in both mitochondria and cytosol and the activation is not seen in xanthine oxidase-deficient animals. CONCLUSIONS: Surgical stress induces activation of proteases in villus and crypt cells of the small intestine. Both mitochondrial and cytosolic proteases are activated and free radicals generated by xanthine oxidase may mediate protease activation after surgical stress in the intestine.

Surgical stress and the gastrointestinal tract.

Surgery on any part of the body results in a wide spectrum of alterations in normal body homeostasis. The gastrointestinal tract is extremely sensitive to surgical stress, even at remote locations. It is now evident that the G.I. tract also plays an important role in development of postoperative complications, such as the systemic immune response syndrome and multiple organ failure syndrome. The amount of information available on the cellular and subcellular changes occurring in the gastrointestinal tract after surgical stress is scant. These changes are important since they would act as initiators of tissue damage seen at a later stage, which in turn lead to postoperative complications. This review looks at the information available on the effect of surgical stress on the small intestine, the role of oxygen free radicals in this process, and the changes occurring at the cellular level.