PREVENTION OF ISCHEMIA REPERFUSION INJURY BY POSITIVE PULMONARY VENOUS PRESSURE IN ISOLATED RAT LUNG

Dose variation of hepatocyte growth factor and its effects on an animal model of TPN-induced liver injury

BACKGROUND

Total parenteral nutrition (TPN) induced liver failure is the leading indication for transplantation in children. Our previous research demonstrated the benefit of a specific intravenous dose of hepatocyte growth factor (HGF) in the amelioration of TPN-induced liver injury. This study was designed to ascertain the optimum concentration of HGF in an animal model of TPN-induced liver injury.

MATERIALS AND METHODS

Twenty adult female Sprague-Dawley rats underwent 70% small bowel resection and placement of venous catheters connected to subcutaneous osmotic minipumps. Four groups (n=5 each) based on the contents of the osmotic pump were utilized as follows: group 1 (control): saline; group 2: HGF 75 mcg/kg/d; group 3: HGF 150 mcg/kg/d; and group 4: HGF 250 mcg/kg/d. Each rat received 14 d of TPN without enteral nutrition. After sacrifice, the liver was harvested. Hepatic inflammation was evaluated using antibodies for TNF-α and IL-6. Apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) technique.

RESULTS

All concentrations induced statistically significantly less IL-6 and TNF- α expression compared to the control animals. Increased efficacy was demonstrated with increasing dose concentration up to 150 mcg/kg/d but not 250 mcg/kg/d. Apoptotic activity was decreased statistically significantly for all dose concentrations compared with the controls, as well as to increases in dose concentration.

CONCLUSIONS

Increasing concentrations of HGF were directly correlated with increased modulation of inflammatory response and apoptotic index in this animal model for TPN-induced liver injury, up to 150 mcg/kg/d. Further increases were significant with respect to apoptotic index only. Further investigations are warranted to determine if HGF may be useful to minimize TPN-induced liver injury in children.

Lung-lung interaction in isolated perfused unilateral hyperventilated rat lungs

The technique of conducting high tidal volume (TV) ventilation-induced lung inflammation including remote organs is still open to discussion, and our aim is to investigate this issue in isolated ventilated rat lungs perfused with salt solution. Selective right lung (RL) hyperventilation (TV of 15 mL/kg with air containing 5% CO(2) on zero or 2.5 cm H(2)0 end expiratory pressure [ZEEP or PEEP] in addition to left lung (LL) on 2.5 cm H(2)0 continuous positive airway pressure (CPAP) for 60 min, was realized after 30 min both lungs ventilation by occluding the left main bronchus, and it was allocated to the following 5 groups: groups 1 and 2 underwent hyperventilation under ZEEP, groups 3 and 4 underwent hyper ventilation under PEEP with recirculation or nonrecirculation (R-ZEEP or NR-ZEEP and R-PEEP or NR-PEEP), and group 5 served as the control group. Recirculation means the same perfusate recirculates the system throughout the procedure. The wet/dry ratio and protein content of bronchoalveolar lavage fluid (Prot-BALF), cytokine messenger RNAs (mRNAs), localization of tumor necrosis factor-alpha (TNF-alpha) by immunofluorescence double staining, and TNF-alpha concentration in the perfusate and BALF in each lung were measured and compared between groups by Kruskal-Wallis test. Lung injury (increased wet/dry ratio, Prot-BALF, and TNF-alpha on endothelial and epithelial cells) was shown in the hyperventilated RLs with ZEEP compared with their corresponding CPAP LLs. PEEP prevented these injuries. Lung injury was also demonstrated in the recirculated LL compared with the nonrecirculated LL (Prot-BALF, TNF-alpha and interleukin-1beta [IL-1beta] mRNAs: the LL of the R-ZEEP is greater than the LL of NR-ZEEP by P < 0.01). Unilateral hyperventilated lungs with ZEEP induced TNF-alpha, increased permeability, and injured the control lung via perfusion.

Growth factor modulation of hepatic inflammation: a novel approach to the management of total parenteral nutrition-associated liver disease

PURPOSE

Dependence on total parenteral nutrition in intestinal failure or short bowel syndrome patients can lead to many complications. The most significant complication is progressive liver injury leading to liver failure. This study assesses the potential of hepatocyte growth factor (HGF) in modulating the hepatic response in a rat cholestatic liver injury model.

METHODS

Female Sprague-Dawley rats were divided into 3 groups: control (n = 5), chronic liver injury (alpha-naphtylisocyocyanate [ANIT] every 3.5 days at 75 mg/kg; n = 5), and chronic liver injury plus HGF (ANIT + HGF at 250 microg kg(-1) d(-1); n = 5). The rats initially underwent massive (80%) small bowel resections. Seven days later, they were given intraperitoneal injections of saline (control) or ANIT and implantation of an osmotic minipump for continuous intravenous saline or HGF. Intraperitoneal saline or ANIT injections were subsequently administered every 3.5 days to create a chronic cholestatic model. After 14 days, the animals were euthanized, and liver biopsies were obtained. The liver biopsies were evaluated by histology, immunofluorescence staining for interleukin-6 and tumor necrosis factor alpha, and assessment of apoptosis by terminal dUTP-transferase-mediated nick end labeling (TUNEL) technique.

RESULTS

In this chronic liver injury model, HGF did not effect the grade of inflammation. However, HGF did induce retention of the ductal structures and avoided ductal proliferation, damage, and evidence of primary sclerosing cholangitis (P < .05). Hepatocyte growth factor induced less interleukin-6 (P < .011) and tumor necrosis factor alpha (P < .01) expression. Apoptotic activity was also significantly less in the HGF group (P < .01).

CONCLUSION

Hepatocyte growth factor preserved the hepatic ductal system, modulated the hepatic inflammatory response, and reduced the apoptotic index in this chronic cholestatic liver injury model. It may diminish or prevent liver damage in patients with total parenteral nutrition-induced liver injury.

Modulation of the inflammatory response and apoptosis using epidermal growth factor and hepatocyte growth factor in a liver injury model: a potential approach to the management and treatment of cholestatic liver disease

BACKGROUND/PURPOSE

The major side effect of total parenteral nutrition is liver injury leading to liver failure. This study was designed to assess specific growth factors in modulating the hepatic response in an ANIT-induced liver-injury model.

METHODS

Sprague-Dawley rats were divided into four groups: control (n = 5), liver-injury control (alpha-naphthylisothiocyanate [ANIT], 100 mg/kg, n = 8), ANIT + epidermal growth factor (EGF, 150 mug/kg per day, n = 10), and ANIT + hepatocyte growth factor (HGF, 250 mug/kg per day, n = 9). Rats were given intraperitoneal injections of saline (control) or ANIT and implantation of an osmotic mini-pump for 7 days of continuous intravenous saline (liver injury control), EGF, or HGF. Seven and 14 days later, liver biopsies were obtained and evaluated for interleukin (IL)-6 and tumor necrosis factor alpha expression by immunofluorescent staining, and for apoptosis, by the terminal transferase dUTP nick end labeling (TUNEL) technique. All animals were euthanized at 14 days.

RESULTS

Epidermal growth factor (P < .025) and HGF (P < .001) groups induced less IL-6 expression at day 14 compared to liver-injury controls. In addition, the interval decrease in IL-6 expression between days 7 and 14 was greater in EGF (P < .001) and HGF (P < .001) groups compared to liver-injury controls. At day 14, HGF also demonstrated decreased tumor necrosis factor alpha expression (P < .005). Apoptotic activity was significantly less for the EGF (P < .011) and HGF (P < .0012) groups.

CONCLUSION

Epidermal growth factor and HGF modulated the hepatic inflammatory response and apoptotic index in this established liver-injury model and may diminish or prevent liver damage in patients with total parenteral nutrition-induced liver injury.

Salvage of nonischemic control lung from injury by unilateral ischemic lung with apocynin, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, in isolated perfused rat lung

Ischemia reperfusion (I/R) injury of the lung affects the function of the nonischemic lung. Our objective is to determine how apocynin, which is a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, protects the nonischemic control right lung (RL) from injury by the unilateral ischemic left lung (LL). In isolated ventilated (by air containing 5% CO(2)) rat lungs, in which differential perfusion of the RL or LL was feasible, the LL was selectively made ischemic (60 min) and reperfused (30 min) in a nonrecirculating or recirculating manner with buffer (Krebs-Henseleit) solution, or in a recirculating manner with buffer that contained apocynin (10 mmol/L) or apocynin + TACEI (tumor necrosis factor)-alpha converting enzyme inhibitor; 10 microg/mL) (each group: n = 12) or with buffer that contained SOD (superoxide dismutase, 3000 U before ischemia and at reperfusion) or SOD + TACEI (each group: n = 5). The permeability of pulmonary endothelium/epithelium (wet/dry ratio and protein content of bronchoalveolar lavage fluid of each lung), perfusion pressure, and cytokine messenger RNA (mRNA) expression was increased not only in the LL (compared with nonischemic control RL, P < 0.01 with paired-samples T) but also in the RL in recirculating groups (compared with RL in the nonrecirculating group). Apocynin + TACEI as well as SOD + TACEI prevented those permeability increases in the RL by the ischemic LL. However, apocynin with or without TACEI as well as SOD with or without TACEI could only partially ameliorate I/R injury in the LL (P < 0.01 by 1-way analysis of variance (ANOVA)). TNF-alpha and possibly reactive oxygen species produced and released from the ischemic lung may synergistically induce control RL (remote organ) damage.

NONISCHEMIC LUNG INJURY BY MEDIATORS FROM UNILATERAL ISCHEMIC REPERFUSED LUNG

We hypothesized that the ischemic reperfused (I/R) lung expresses and liberates tumor necrosis factor-alpha (TNF-alpha) to injure the nonischemic lung, and that a TNF-alpha-converting enzyme inhibitor (TACEI) prevents injury of the nonischemic lung by blocking TNF-alpha liberation from the I/R lung. In isolated ventilated rat lungs in which differential perfusion to the right (RL) or left (LL) lung was feasible, LLs were selectively made ischemic (60 min) while maintaining perfusion to RLs, then reperfused (30 min) in a nonrecirculating manner with buffer solution (non-R; n = 18) or in a recirculating manner with buffer containing TACEI (TACEI[+]; n = 18) or without TACEI (TACEI[-]; n = 18). Ischemia reperfusion induced TNF-alpha messenger RNA expression in the ischemic LLs; the expression was highest in TACEI(+) group (P < 0.01). The expression of TNF-alpha, which was detected as immunofluorescence signals on CD34-positive endothelial cells, was observed in ischemic LLs; the highest expression being that in the TACEI(+) group. Wet/dry ratio and protein content in bronchoalveolar lavage fluid were higher in LLs than in RLs, and among the RLs, these 2 parameters were significantly increased in the TACEI(-) group (P < 0.01) in which the RLs were exposed to the TNF-alpha-rich perfusate. On the other hand, protein content in bronchoalveolar lavage fluid of the TACEI(+) group in which RLs were exposed to recirculating perfusate containing little TNF-alpha was decreased to a level close to but still higher than that in the non-R group (P < 0.05). The unilateral I/R lung affected the permeability of the nonischemic lung by liberating mainly TNF-alpha and induced TNF-alpha, interleukin (IL)-1beta, IL-6, and IL-10 messenger RNA expression in the nonischemic lung. These findings support the idea of organ-organ interaction in which an injured organ affects a remote organ by liberating humoral mediators.