Microcirculation disturbance affects rats with acute severe pancreatitis following lung injury

Hemorheological and Microcirculatory Relations of Acute Pancreatitis

Acute pancreatitis still means a serious challenge in clinical practice. Its pathomechanism is complex and has yet to be fully elucidated. Rheological properties of blood play an important role in tissue perfusion and show non-specific changes in acute pancreatitis. An increase in blood and plasma viscosity, impairment of red blood cell deformability, and enhanced red blood cell aggregation caused by metabolic, inflammatory, free radical-related changes and mechanical stress contribute to the deterioration of the blood flow in the large vessels and also in the microcirculation. Revealing the significance of these changes in acute pancreatitis may better explain the pathogenesis and optimize the therapy. In this review, we give an overview of the role of impaired microcirculation by changes in hemorheological properties in acute pancreatitis.

Prognostic Value of Arterial Lactate Metabolic Clearance Rate in Moderate and Severe Acute Pancreatitis

PURPOSE

High lactate levels at hospital admission are significantly associated with poor prognosis in acute pancreatitis patients. Early high lactate clearance is a vital marker for predicting persistent organ failure and mortality in critical illness; however, its value in acute pancreatitis remains unclear.

METHOD

Data were collected from patients who were diagnosed with moderately severe acute pancreatitis and severe acute pancreatitis from January 2017 to December 2020. Initial lactate (within 2 hours after admission) and repeat lactate at 24 hours after admission were measured to determine lactate clearance. Low clearance was defined as a reduction in repeat lactate of less than 30% compared to the first measurement. High clearance was defined as a repeat lactate decrease ≥30% of the first measurement or both first and second lactate levels <2 mmol/L. Baseline data, laboratory data, mortality rate, persistent organ failure rate, and other outcomes such as the incidence of septic pancreatic necrosis and sepsis and the length of hospital stay and intensive care unit (ICU) stay were compared in the low and high lactate clearance groups. Multivariate logistic regression analyses were used to assess the value of lactate clearance for predicting death.

RESULT

Among 4425 acute pancreatitis patients, 3040 patients were diagnosed with moderate or severe acute pancreatitis, and 1028 patients had initial lactate measured. Finally, 390 patients who had initial and 24-hour repeat lactate data were included in the study. Patients who had elevated initial lactate had poor outcomes, and 51 patients in the initial elevated lactate group died. In the lactate normalization group analysis, 293 patients had 24-hour lactate normalization; compared with patients in the nonnormalization group, they had a lower rate of mortality (12.6% vs. 33%). In the lactate clearance group analysis, 70 (21.9%) patients had a low clearance after 24 hours; compared with patients in the high clearance group, they had a higher rate of developing persistent multiorgan failure (P = 0.045), and the incidence of death was higher (15% vs. 28.6%, P = 0.007). Multivariate logistic analysis showed that 24-hour lactate clearance (OR: 2.007; 95% CI:1.032-3.903, P = 0.04), elevated initial lactate (OR: 2.011; 95% CI:1.023-3.953, P = 0.043), blood urea nitrogen (OR: 2.316; 95% CI:1.061-5.056, P = 0.035), and white blood count (OR: 1.982; 95% CI:1.026-3.829, P = 0.042) were independent predictors of hospital mortality.

CONCLUSION

The 24-hour clearance of lactate is a reliable marker to predict the outcome of moderate and severe acute pancreatitis, and low lactate clearance may indicate that the patient's condition will worsen, requiring aggressive treatments to improve patient outcomes.

The Mechanism of Lung and Intestinal Injury in Acute Pancreatitis: A Review

Acute pancreatitis (AP), as a common cause of clinical acute abdomen, often leads to multi-organ damage. In the process of severe AP, the lungs and intestines are the most easily affected organs aside the pancreas. These organ damages occur in succession. Notably, lung and intestinal injuries are closely linked. Damage to ML, which transports immune cells, intestinal fluid, chyle, and toxic components (including toxins, trypsin, and activated cytokines to the systemic circulation in AP) may be connected to AP. This process can lead to the pathological changes of hyperosmotic edema of the lung, an increase in alveolar fluid level, destruction of the intestinal mucosal structure, and impairment of intestinal mucosal permeability. The underlying mechanisms of the correlation between lung and intestinal injuries are inflammatory response, oxidative stress, and endocrine hormone secretion disorders. The main signaling pathways of lung and intestinal injuries are TNF-α, HMGB1-mediated inflammation amplification effect of NF-κB signal pathway, Nrf2/ARE oxidative stress response signaling pathway, and IL-6-mediated JAK2/STAT3 signaling pathway. These pathways exert anti-inflammatory response and anti-oxidative stress, inhibit cell proliferation, and promote apoptosis. The interaction is consistent with the traditional Chinese medicine theory of the lung being connected with the large intestine (fei yu da chang xiang biao li in Chinese). This review sought to explore intersecting mechanisms of lung and intestinal injuries in AP to develop new treatment strategies.

Intestinal barrier damage, systemic inflammatory response syndrome, and acute lung injury: A troublesome trio for acute pancreatitis

Severe acute pancreatitis (SAP), a serious inflammatory disease of the pancreas, can easily lead to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndromes (MODS). Acute lung injury (ALI) is one of the most serious complications of SAP. However, the specific pathogenesis of SAP-associated ALI is not fully understood. Crosstalk and multi-mechanisms involving pancreatic necrosis, bacteremia, intestinal barrier failure, activation of inflammatory cascades and diffuse alveolar damage is the main reason for the unclear pathological mechanism of SAP-associated ALI. According to previous research on SAP-associated ALI in our laboratory and theories put forward by other scholars, we propose that the complex pattern of SAP-associated ALI is based on the "pancreas-intestine-inflammation/endotoxin-lung (P-I-I/E-L) pathway". In this review, we mainly concentrated on the specific details of the "P-I-I/E-L pathway" and the potential treatments or preventive measures for SAP-associated ALI.

Neuroprotection of Intermedin Against Cerebral Ischemia/Reperfusion Injury Through Cerebral Microcirculation Improvement and Apoptosis Inhibition

Ischemic stroke is the primary cause of disability and mortality worldwide. Ischemia/reperfusion (I/R)-induced microcirculatory dysfunction and organ injury generally occur after ischemic stroke. Several studies have shown that intermedin (IMD) has a regulating function on cerebral microcirculation and blood-brain barrier via relaxing cerebral vessels and improving the local blood supply after cerebral ischemia. However, a unified conclusion has not been reached, and the underlying mechanism remains unclear. To observe and analyze the changes of cerebral microcirculation perfusion of cerebral IRI by IMD post-treatment in the rats and further explore the mechanism underlying the beneficial effect of IMD on cerebral IRI. Thirty-nine rats were divided into three groups: sham, I/R, and I/R + IMD groups. After IMD ischemia post-treatment, the rat cerebral infarction rate and the degree of neurological deficit were evaluated by TTC staining and neurological function score; the changes in the amount of cerebral microcirculation implantation on the injured side of the rats were observed by laser Doppler; the pathological changes and cell ultrastructure of rat cortex and hippocampus were observed by HE staining and transmission electron microscopy; the neuron apoptosis in the rat cortex and hippocampus was detected by TUNEL staining and immunohistochemical staining. Impaired neurological function, abnormal cortical/hippocampal neuron morphology, and the proportion of cerebral infarction were significantly improved in the IMD group compared with the I/R group, which suggested a possible neuroprotective role of IMD. IMD treatment also increased the average perfusion of cerebral surface microcirculation in rats by astonished 42.7 times. Finally, IMD administration decreased the caspase-3- and Bax-positive cell numbers and apoptotic cell ratio. IMD has a significant protective effect on neuronal damage caused by cerebral I/R in rats by improving cerebral microcirculation and inhibiting apoptosis.

Continuous blood purification ameliorates endothelial hyperpermeability in SAP patients with MODS by regulating tight junction proteins via ROCK

BACKGROUND

Excessive activation of inflammatory mediator cascade during severe acute pancreatitis (SAP) is a major cause of multiple organ dysfunction and is associated with a high mortality. Recently, more and more studies have shown that continuous blood purification (CBP) could improve the prognosis of patients with multiple organ dysfunction syndrome (MODS), but the exact mechanism is still unclear. Many researchers have found that the disruption of tight junction barrier was an important factor for endothelial hyperpermeability, which played a key role in the pathogenesis of MODS. Previously, we found CBP could attenuate endothelial hyperpermeability in SAP patients with lung injury through regulating cytoskeleton reorganization mediated by RhoA/ROCK. However, the effect of CBP on the change of tight junction proteins in SAP patients with MODS was still unknown. This study aimed to investigate the role of tight junctions in endothelial hyperpermeability in SAP patients with MODS using an in vitro model, and the effect of CBP on tight junction barrier.


METHODS

Before CBP and after CBP, blood samples were collected to observe hepatic and renal function, and arterial blood gas, while the APACHE II score was calculated to evaluate the severity of patients. To test whether RhoA/ROCK signaling pathway was involved, human umbilical vein endothelial cells (HUVECs) were exposed to serum samples taken from patients at specific time points during CBP, or preincubated with ROCK inhibitor, Y-27632, followed by treatment with serum. Then, the changes in endothelial cell permeability and the expression and distribution of tight junction proteins occludin and claudin-1 were observed. 


RESULTS

Compared with before CBP, the APACHE II score, serum creatinine and alanine aminotransferase decreased significantly, while PaO2/FiO2 increased significantly after CBP. Meanwhile, endothelial permeability induced by serum from patients significantly increased, while the expression of tight junction proteins occludin and claudin-1 significantly decreased, and severe disruption of occludin and claudin-1 was found in these cells. However, pretreated with Rho-kinase inhibitor, Y-27632 could lessen all of these abnormalities, and in a dose-dependent way. Endothelial hyperpermeability, the abnormal expression and distribution of occludin and claudin-1 were attenuated in HUVECs treated with serum from patients after CBP treatment. 


CONCLUSIONS

The abnormality of tight junctions mediated by ROCK was an important mechanism for endothelial hyperpermeability induced by serum from SAP patients with MODS. CBP could ameliorate the disorganization and redistribution of tight junction proteins, hence improve the endothelial permeability.

Protective effects of Ligustrazine, Kakonein and Panax Notoginsenoside on the small intestine and immune organs of rats with severe acute pancreatitis

BACKGROUND

Severe acute pancreatitis (SAP) is characterized by fatal pathogenic conditions and a high mortality. It is important to study SAP complicated with multiple organ injury. In this study we compared the protective effects of three traditional Chinese medicines (Ligustrazine, Kakonein and Panax Notoginsenoside) on the small intestine and immune organs (thymus, spleen and lymph nodes) of rats with SAP and explored their mechanism of action.

METHODS

One hundred forty-four rats with SAP were randomly divided into model control, Ligustrazine-treated, Kakonein-treated, and Panax Notoginsenoside-treated groups (n=36 per group). Another 36 normal rats comprised the sham-operated group. According to the different time points after operation, the experimental rats in each group were subdivided into 3-, 6- and 12-hour subgroups (n=12). At various time points after operation, the mortality rate of rats and pathological changes in the small intestine and immune organs were recorded and the serum amylase levels were measured.

RESULTS

Compared to the model control groups, the mortality rates in all treated groups declined and the pathological changes in the small intestine and immune tissues were relieved to different degrees. The serum amylase levels in the three treated groups were significantly lower than those in the model control group at 12 hours. The pathological severity scores for the small intestinal mucosa, thymus and spleen (at 3 and 12 hours) in the Ligustrazine-treated group, for the thymus (at 3 and 12 hours) and spleen (at 3 and 6 hours) in the Kakonein-treated group, and for the thymus (at 3 hours) and spleen (at 3 hours) in the Panax Notoginsenoside-treated group were significantly lower than those in the model control group. The pathological severity scores of the small intestinal mucosa (at 6 and 12 hours) and thymus (at 6 hours) in the Ligustrazine-treated group were significantly lower than those in the Kakonein- and Panax Notoginsenoside-treated groups.

CONCLUSIONS

All the three traditional Chinese drugs significantly alleviated the pathological changes in the small intestine and immune organs of SAP rats. Ligustrazine was the most effective one among them.

Effects of Salvia miltiorrhiza on intercellular adhesion molecule 1 protein expression in the lungs of rats with severe acute pancreatitis or obstructive jaundice

OBJECTIVE

The objective of the study was to observe the effects of Salvia miltiorrhiza on intercellular adhesion molecule 1 (ICAM-1) protein expression in the lungs of rats with severe acute pancreatitis (SAP) or obstructive jaundice (OJ).

METHODS

A total of 288 rats were used for SAP- and OJ-associated experiments. The rats were randomly divided into sham-operated, model control, and treated group. According to the difference of time points after operation, the SAP rats of each group were subdivided into 3-, 6-, and 12-hour groups, whereas the OJ rats were divided into 7-, 14-, 21-, and 28-day groups. The contents of interleukin (IL) 6, IL-18, nitric oxide, malondialdehyde, and superoxide dismutase in serum were determined, and pathological changes and ICAM-1 protein expression in the lungs were observed.

RESULTS

Compared with the respective model control groups, in treated groups of SAP and OJ rats, the numbers of dead rats declined; serum superoxide dismutase content significantly increased, and serum IL-18, IL-6, and malondialdehyde contents were significantly decreased; the positive staining intensity of ICAM-1 protein in the lungs decreased significantly (P < 0.05, P < 0.01, or P < 0.001); and pathological changes in the lungs were relieved.

CONCLUSIONS

Salvia miltiorrhiza plays a positive role in the protection of the lungs of SAP and OJ rats.

Pathophysiological role of platelets and platelet system in acute pancreatitis

The most successful approach for restoring normal long-term glucose homeostasis in type I diabetes mellitus is whole-organ pancreas transplantation. Graft pancreatitis is observed in up to 20% of patients and may lead to loss of the transplanted organ. Several pathophysiological events have been implicated in this form of pancreatitis. The most important cause of early graft pancreatitis is ischemia/reperfusion (I/R)-related disturbance of microvascular perfusion with subsequent hypoxic tissue damage. Recently, considerable evidence accumulated that, among a variety of other pathophysiological events, the activation of platelets can contribute to I/R injury in the course of acute pancreatitis experimentally and clinically. This review summarizes the events affecting platelet function and, therefore, pancreatic microcirculation leading to acute pancreatitis. Therapeutic approaches and own results are presented.

Role of cytokine-induced neutrophil chemoattractant in acute lung injury during acute pancreatitis

AIM: To investigate the role of cytokine-induced neutrophil chemoattractant (CINC) in the pathogenesis of acute lung injury (ALI) during acute pancreatitis (AP).

METHODS: AP model was induced by intraperitoneal injection of cerulein or retrograde infusion of 50 g/L sodium taurocholate into the bili-pancreatic duct in Sprague Dawley rats. A total of 84 rats were randomly divided into 4 groups: cerulein group, saline control group, sodium taurocholate group and operational control group. The level of serum amylase, the pulmonary dry/wet weight ratio and histological changes were measured at different time points in each group. The expression of pulmonary CINC protein and mRNA were detected by immunohistochemistry and semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR), respectively.

RESULTS: No significant difference was found between cerulein group and saline control group at different time points (P > 0.05). In comparison with those in operational control group, the level of serum amylase and pulmonary dry/wet weight ratio were significantly higher in sodium taurocholate group 1 h after operation (P < 0.01), and the expression of pulmonary CINC mRNA started to increase at the 1st h after operation (1 h: 0.23 ± 0.07 vs 0.07 ± 0.04, P < 0.05; 3 h: 0.36 ± 0.07 vs 0.06 ± 0.04, P < 0.05; 6 h: 0.56 ± 0.07 vs 0.09 ± 0.05, P < 0.01; 12 h: 0.49 ± 0.09 vs 0.11 ± 0.03, P < 0.01). The expression of pulmonary CINC protein was detected at 3rd h after operation, and then up-regulated gradually. Moreover, the expression of CINC was correlated with pulmonary histological changes.

CONCLUSION: CINC plays an important role in the pathogenesis of ALI during AP.

Effect of early continuous high-volume hemofiltration on histopathological changes of pancreas and extrapancreatic organs in pigs with severe acute pancreatitis

AIM: To observe the effect of early continuous high-volume hemofiltration on the histopatho-logical changes of pancreas and extrapancreatic organs in pigs with severe acute pancreatitis (SAP).

METHODS: Twenty-four domestic pigs were randomly and averagely assigned into 3 groups: control group (untreated model group) as group A, low-volume hemofiltration [20 mL/(kg·h)] group as group B, and high-volume hemofiltration [100 mL/(kg·h)] group as group C. SAP model was produced by injection of sodium taurocholate (40 g/L, 1 mL/kg) and trypsin (2 U/kg) via the pancreatic duct. The pigs in group B and C received hemofiltration immediately after modeling. The parameters including survival time and histopathological scores of pancreas and extra-pancreatic organs were observed.

RESULTS: The median survival times were 41, 50 and 65 h in group A, B, and C, respectively, and there were significant differences among them (P < 0.01). The histopathological scores had no marked differences between the three groups (P > 0.05). However, the scores for hepatocellular degeneration, pulmonary hyaline membranes and microthrombi, and renal tubular damage were obviously lower than those in the other groups (P < 0.05).

CONCLUSION: Although hemofiltration can not reduce the pancreatic damage in pigs with SAP, early continuous high-volume hemofiltration can significantly ameliorate the hepatocellular degeneration, the formation of pulmonary hyaline membranes and microthrombi, and the renal tubular damage in pigs with SAP, which is useful in improving the survival time.

Mechanism of lung injury and protective effect of prostaglandin E1 in experimental acute pancreatitis

AIM: To explore the mechanism of lung injury in experimental acute pancreatitis (AP) and the protective effect of prostaglandin E₁ (PGE₁).

METHODS: Seventy-eight rats were averagely and randomly divided into sham operation, AP, and PGE₁ group. AP model was induced by creating a closed duod enal loop in rats. The rats in PGE₁ group were intravenously injected with PGE₁ (60 ng/kg). The histopathological changes of pancreatic and pulmonary tissues were examined by microscopy. The serum level of amylase, the activity of myeloperoxidase (MPO), the pulmonary level of lipid peroxidation (LPO), and lung capillary permeability (LCP) were measured. The expression of pulmonary intercellular adhesion molecule-1 (ICAM-1) was determined by immunohistochemical technique (ABC).

RESULTS: In AP group, the progressive pathological damages in the pancreas and lung tissues were clearly observed. The activity of pulmonary MPO (12 h: 5.65 ± 0.80 vs 1.22 ± 0.71 kat/g, P < 0.01; 24 h: 7.22 ± 1.05 vs 1.48 ± 0.57 kat/g, P < 0.01), the level of LPO (12 h: 1.44 ± 0.63 vs 0.38 ± 0.07 μmol/g, P < 0.01; 24 h: 3.64 ± 0.83 vs 0.44 ± 0.15 μmol/g, P < 0.01) and LCP (12 h: 145.4 ± 23.0 vs 47.3 ± 5.5 μg/g wet weight, P < 0.01), as well as pulmonary ICAM-1 expression were markedly increased as compared with those in sham operation group. In comparison with those in AP group, the activity of MPO (12 h: 2.96 ± 1.04 vs 5.65 ± 0.80 kat/g, P < 0.05; 24 h: 3.68 ± 1.15 vs 7.22 ± 1.05 kat/g, P < 0.05) and the level of LPO (12 h: 0.86 ± 0.34 vs 1.44 ± 0.63 μmol/g, P < 0.05; 24 h: 1.69 ± 0.45 vs 3.64 ± 0.83 μmol/g, P < 0.05) in the lung tissues were significantly decreased, and the level of LCP (12 h: 105.9 ± 23.9 vs 145.4 ± 23.0 μg/g wet weight, P < 0.05), as well as pulmonary ICAM-1 expression was down-regulated (12 h: P < 0.05; 24 h: P < 0.01) in PGE1 group. Pathological examination revealed that intra-alveolar hemorrhage, edema and polymorphonuclear leukocytes (PMN) infiltration in the lung tissues were attenuated after PGE₁ treatment, although pancreatic damages were not alleviated.

CONCLUSION: The over-expression of ICAM-1, PMN infiltration and the release of free oxygen radicals in lung tissues may be closely related to pancreatitis-associated lung injury. PGE₁ can ameliorate lung injury by reducing ICAM-1 expression and inhibiting PMN activation and the release of free oxygen radicals.