Effects of moderate hypothermia on proinflammatory cytokine production in a rat model of caerulein-induced pancreatitis

The effects of profound hypothermia on pancreas ischemic injury: a new experimental model

OBJECTIVE

Pancreatic ischemia-reperfusion (IR) has a key role in pancreas surgery and transplantation. Most experimental models evaluate the normothermic phase of the IR. We proposed a hypothermic model of pancreas IR to evaluate the benefic effects of the cold ischemic phase.

METHODS

We performed a reproducible model of hypothermic pancreatic IR. The ischemia was induced in the pancreatic tail portion (1-hour ischemia, 4-hour reperfusion) in 36 Wistar rats. They are divided in 3 groups as follows: group 1 (control), sham; group 2, normothermic IR; and group 3, hypothermic IR. In group 3, the temperature was maintained as close to 4.5°C. After reperfusion, serum amylase and lipase levels, inflammatory mediators (tumor necrosis factor α, interleukin 6), and pancreas histology were evaluated.

RESULTS

In pancreatic IR groups, amylase, cytokines, and histological damage were significantly increased when compared with group 1. In the group 3, we observed a significant decrease in tumor necrosis factor α (P = 0.004) and interleukin 6 (P = 0.001) when compared with group 2. We did not observe significant difference in amylase (P = 0.867), lipase (P = 0.993), and histology (P = 0.201).

CONCLUSIONS

In our experimental model, we reproduced the cold phase of pancreas IR, and the pancreas hypothermia reduced the inflammatory mediators after reperfusion.

Hypothermia slows sequential and parallel steps initiated during caerulein pancreatitis

BACKGROUND AND OBJECTIVES

Multiple deleterious signaling cascades are simultaneously activated in acute pancreatitis (AP), which may limit the success of pharmacologic approaches targeting a single step. We explored whether cooling acinar cells slows distinct steps initiated from a stimulus causing pancreatitis simultaneously, and the temperature range over which inhibition of such deleterious signaling occurs.

METHODS

Caerulein (100 nM) induced trypsinogen activation (TGA), CXCL1, CXCL2 mRNA levels, cell injury were studied at 37 °C, 34 °C, 31 °C, 29 °C and 25 °C in acinar cells. Trypsin, cathepsin B activities and cathepsin B mediated TGA were studied at 37 °C, 23 °C and 4 °C.

RESULTS

There was >80% reduction in TGA, CXCL1 and CXCL2 mRNA levels at 29 °C, and in cell injury at 34 °C, compared to those at 37 °C. Trypsin activity, cathepsin B activity and cathepsin B mediated TGA at 23 °C were respectively, 53%, 64% and 26% of that at 37 °C. Acinar cooling to 31 °C reduced LDH leakage even when cooling was initiated an hour after caerulein stimulation at 37 °C.

CONCLUSIONS

Hypothermia synergistically and simultaneously slows parallel and distinct signaling steps initiated by caerulein, thereby reducing TGA, upregulation of inflammatory mediators and acinar injury.

Hypothermia induced by adenosine 5'-monophosphate attenuates injury in an L-arginine-induced acute pancreatitis rat model

BACKGROUND AND AIM

This study sought to investigate the effects of hypothermia induced by adenosine 5'-monophosphate (5'-AMP) on L-arginine (L-Arg)-induced acute pancreatitis in rats.

METHODS

The rats were divided into four groups: the control group, the acute pancreatitis group, the 5'-AMP pretreatment group, and the 5'-AMP posttreatment group. Rats in all groups, except for the control group, received two injections of 2.5 g/kg body weight (intraperitoneally) L-Arg, with an interval of 1 h between the injections. Subsequently, the rats were observed to assess whether hypothermia induced by 5'-AMP could effectively inhibit inflammation associated with L-Arg-induced acute pancreatitis in rats.

RESULTS

Hypothermia induced by 5'-AMP produced protective effects in our acute pancreatitis model. These effects exhibited the following manifestations: (i) a significant reduction in rat mortality rates; (ii) a significant decrease in the occurrence of pancreatic edema; (iii) significant reductions in serum amylase (P < 0.001), interleukin-6 (P < 0.001), interleukin-1β (P < 0.001) and tumor necrosis factor-α (P < 0.001); (iv) the significant inhibition of nuclear factor-κB (NF-κB) activation in rats that were pre- and posttreated with 5'-AMP compared with rats that were only injected with L-Arg; and (v) significant decreases in the occurrence of pancreatic interstitial edema, inflammatory cell infiltration, hemorrhage, and acinar cell necrosis.

CONCLUSIONS

Hypothermia induced by 5'-AMP could inhibit the acute inflammatory reaction and NF-κB activation associated with acute pancreatitis.

Early induction of moderate hypothermia suppresses systemic inflammatory cytokines and intracellular adhesion molecule-1 in rats with caerulein-induced pancreatitis and endotoxemia

OBJECTIVES

To evaluate the systemic effects of moderate hypothermia (MH) and the timing of induction on acute pancreatitis (AP) and endotoxemia in rats.

METHODS

The effects of MH were compared in 4 groups, that is, sham group (38 degrees C), control group (38 degrees C), early MH group (32 degrees C on administration of lipopolysaccharide [LPS]), and delayed MH group (32 degrees C 1 hour after LPS). AP and endotoxemia were induced by intramuscular injection of caerulein and intraperitoneal injection of LPS.

RESULTS

Serum interleukin 6 (IL-6) in both MH groups was significantly lower than that in the control group at 3 hours. Serum interleukin 10 (IL-10) in the early MH group was significantly higher than those in the other 3 groups at 1 hour. IL-10/IL-6 ratios in both MH groups were significantly higher than that in the control group at 3 hours. Serum soluble intercellular adhesion molecule (sICAM-1) in both MH groups was significantly lower than that in the control group at 3 hours. Serum sICAM-1 in the early MH group was significantly lower than that in the delayed MH group. The tendency of pancreatic ICAM-1 was similar to that of serum sICAM-1.

CONCLUSIONS

Early induction of MH might be protective against pancreatic injury and systemic inflammation in AP and endotoxemia.

Oxidative stress is enhanced by hypothermia imposed on cerulein-induced pancreatitis in rats

BACKGROUND

Hypothermia is a frequent event in severe acute pancreatitis (AP) and its real effects on the normal pancreas have not been well demonstrated. Moreover, neither have its effects on the outcome of acute pancreatitis been fully investigated. One hypothesis is that oxidative stress may be implicated in lesions caused or treated by hypothermia.

AIM OF THE STUDY

To investigate the effect of hypothermia in cerulein-induced acute pancreatitis (CIAP) in rats and the role played by oxidative stress in this process.

METHODS

Male Wistar rats were divided into hypothermic and normothermic groups. Hypothermia was induced with a cold mattress and rectal temperature was kept at 30 masculineC for one hour. Acute pancreatitis was induced with 2 doses of cerulein (20 ìg/kg) administered at a one-hour interval. Serum amylase, pancreas vascular permeability by Evan's blue method, pancreas wet-to-dry weight ratio and histopathology were analyzed in each group.

RESULTS

When compared with normothermic rats, hypothermic animals, with cerulein-induced acute pancreatitis, showed higher levels of pancreatic vascular permeability (p < 0.05), pancreas wet-to-dry weight ratio (p = 0.03), and histologically verified edema (p < 0.05), but similar serum amylase levels. The hypothermic group showed a higher oxidized-reduced glutathione ratio than the normothermic group.

CONCLUSION

Moderate hypothermia produced a greater inflammatory response in established acute pancreatitis induced by cerulein in rats. Moreover, this study suggests that oxidative stress may be one of the mechanisms responsible for the worse outcome in hypothermic rats with cerulein-induced acute pancreatitis.

Effect of hyperthermia on experimental acute pancreatitis

BACKGROUND

[corrected] Recent studies indicate that hyperthermia can change inflammatory mechanisms and protect experimental animals from deleterious effects of secretagogue-induced acute pancreatitis

AIM

To evaluate the effects of hyperthermia post-treatment on cerulein-induced acute pancreatitis in rats

METHODS

Twenty animals were divided in two groups: group I (n = 10), rats with cerulein-induced acute pancreatitis undergone hyperthermia, and group II (n = 10), animals with cerulein-induced acute pancreatitis that were kept normothermic. In all groups, amylase serum levels, histologic damage, vascular permeability and pancreatic water content were assessed. Acute pancreatitis was induced by administration of two cerulein injections (20 mcg/kg). A single dose of Evans' blue dye was administered along with the second dose of cerulein. All animals also received a subcutaneous injection of saline solution. After this process, animals undergone hyperthermia were heated in a cage with two 100 W lamps. Body temperature was increased to 39.5 degrees C and maintained at that level for 45 minutes. Normothermia rats were kept at room temperature in a second cage

RESULTS

Control animals had typical edema, serum amylase activity and morphologic changes of this acute pancreatitis model. Hyperthermia post-treatment ameliorated the pancreatic edema, whereas the histologic damage and the serum amylase level remained unchanged

CONCLUSIONS

The findings suggest a beneficial effect of the thermal stress on inflammatory edema in experimental acute pancreatitis.

Whole-body moderate hypothermia confers protection from wood smoke-induced acute lung injury in rats: The therapeutic window*

OBJECTIVE

Toxic smoke inhalation causes acute lung injury. We studied the efficacy and therapeutic window of whole-body hypothermia in rats with wood smoke-induced acute lung injury.

DESIGN

Randomized, controlled study.

SETTING

Research laboratory.

SUBJECTS

Anesthetized, paralyzed, and artificially ventilated rats (n = 100) were used.

INTERVENTIONS

Air or wood smoke (30 breaths) was delivered into the lung using a respirator. Immediately after challenge, the rat's colonic temperature was kept a) 37 degrees C (normothermia, NT) for 1 (NT-1-Air and NT-1-Smoke), 2.5 (NT-2.5-Air and NT-2.5-Smoke), or 5 hrs (NT-5-Air and NT-5-Smoke) in six groups; b) 30 degrees C (hypothermia, HT) for 2.5 (HT-2.5-Smoke) or 5 hrs (HT-5-Air and HT-5-Smoke) in three groups; c) 30 degrees C for the first 2.5 hrs followed by 37 degrees C for another 2.5 hrs (HT-NT-5-Smoke) in one group; or d) 37 degrees C for the first 2.5 hrs followed by 30 degrees C for another 2.5 hrs (NT-HT-5-Smoke) in on group.

MEASUREMENTS AND MAIN RESULTS

Various acute lung injury indexes were assessed at 1, 2.5, or 5 hrs after challenge. In the air group, whole-body hypothermia did not affect the level of lung lipid peroxidation and the amount of proteins, total and differential cell counts, and concentrations of tumor necrosis factor-alpha and interleukin-1beta in bronchoalveolar lavage fluid. In the smoke groups, these acute lung injury indexes were increased showing that NT-5-Smoke > NT-2.5-Smoke > NT-1-Smoke. Whole-body hypothermia prevented increases in these acute lung injury indexes in the HT-2.5-Smoke and HT-5-Smoke groups. The efficacy of whole-body hypothermia in the HT-NT-5-Smoke group was superior to that in the NT-HT-5-Smoke group and similar to that in the HT-5-Smoke group. Whole-body hypothermia also alleviated smoke-induced poor gas exchange, pulmonary edema, and pathohistologic injurious signs.

CONCLUSIONS

Whole-body hypothermia confers protection from wood smoke-induced acute lung injury in rats by suppressing oxidant bronchoalveolar damage and pulmonary inflammation. Early and short-period (2 hrs) application of whole-body hypothermia provides favorable therapeutic effects.

Mild hypothermia protects against sodium taurocholate (NaTc)-induced acute pancreatitis in rats with adverse effects on serum cytokines

OBJECTIVES

To test the effect of mild hypothermia in reducing pancreatic damage and improving the survival of acute hemorrhagic and necrotic pancreatitis (AHNP) in rats.

METHODS

Thirty-six male Sprague-Dawley rats were studied. Sham animals (n = 12) received laparotomy and normothermia; for AHNP with normothermia (n = 12), the core temperature was maintained at 37 degrees C to 37.5 degrees C after AHNP for 2 to 5 hours; for AHNP with hypothermia (n = 12), the core temperature was maintained at 32 degrees C to 33 degrees C afterward. Serum amylase and lipase, interleukin (IL)-1beta, and tumor necrosis factor (TNF-alpha) were measured. The pancreas was examined histologically. In a separate experiment, the core temperature was kept either in normothermia (n = 20) or mild hypothermia (n = 20) for 12 hours after the induction of AHNP; the animals were then returned to their cage. The survival rate was monitored up to 72 hours.

RESULTS

Mild hypothermia significantly decreased the release of serum amylase and lipase compared with AHNP normothermia at 2 and 5 hours. Histology examination revealed significantly less tissue damage in AHNP hypothermia. There was a further increase in TNF-alpha and IL-1beta in AHNP in animals with hypothermia compared with normothermia animals. The application of mild hypothermia significantly improved the survival in animals induced with AHNP.

CONCLUSIONS

Mild hypothermia decreases amylase and lipase release and improves a survival of AHNP in rats.