Hepatic platelet and leukocyte adherence during endotoxemia

The Interplay between Liver Sinusoidal Endothelial Cells, Platelets, and Neutrophil Extracellular Traps in the Development and Progression of Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) represents a societal burden due to the lack of effective treatment and incomplete pathophysiology understanding. This review explores the intricate connections among liver sinusoidal endothelial cells (LSECs), platelets, neutrophil extracellular traps (NETs), and coagulation disruptions in MASLD pathogenesis. In MASLD's early stages, LSECs undergo capillarization and dysfunction due to excessive dietary macronutrients and gut-derived products. Capillarization leads to ischemic changes in hepatocytes, triggering pro-inflammatory responses in Kupffer cells (KCs) and activating hepatic stellate cells (HSCs). Capillarized LSECs show a pro-inflammatory phenotype through adhesion molecule overexpression, autophagy loss, and increased cytokines production. Platelet interaction favors leucocyte recruitment, NETs formation, and liver inflammatory foci. Liver fibrosis is facilitated by reduced nitric oxide, HSC activation, profibrogenic mediators, and increased angiogenesis. Moreover, platelet attachment, activation, α-granule cargo release, and NETs formation contribute to MASLD progression. Platelets foster fibrosis and microthrombosis, leading to parenchymal extinction and fibrotic healing. Additionally, platelets promote tumor growth, epithelial-mesenchymal transition, and tumor cell metastasis. MASLD's prothrombotic features are exacerbated by insulin resistance, diabetes, and obesity, manifesting as increased von Willebrand factor, platelet hyperaggregability, hypo-fibrinolysis, and a prothrombotic fibrin clot structure. Improving LSEC health and using antiplatelet treatment appear promising for preventing MASLD development and progression.

Megakaryocytes respond during sepsis and display innate immune cell behaviors

Megakaryocytes (MKs) are precursors to platelets, the second most abundant cells in the peripheral circulation. However, while platelets are known to participate in immune responses and play significant functions during infections, the role of MKs within the immune system remains largely unexplored. Histological studies of sepsis patients identified increased nucleated CD61+ cells (MKs) in the lungs, and CD61+ staining (likely platelets within microthrombi) in the kidneys, which correlated with the development of organ dysfunction. Detailed imaging cytometry of peripheral blood from patients with sepsis found significantly higher MK counts, which we predict would likely be misclassified by automated hematology analyzers as leukocytes. Utilizing in vitro techniques, we show that both stem cell derived MKs (SC MKs) and cells from the human megakaryoblastic leukemia cell line, Meg-01, undergo chemotaxis, interact with bacteria, and are capable of releasing chromatin webs in response to various pathogenic stimuli. Together, our observations suggest that MK cells display some basic innate immune cell behaviors and may actively respond and play functional roles in the pathophysiology of sepsis.

Antiplatelet drugs and liver fibrosis

Liver fibrosis results from an imbalance between extracellular matrix formation and degradation. The background of liver fibrosis is chronic inflammation and subsequent microcirculation disturbance including microthrombosis. Platelets actively participate in liver fibrosis not only as a part of the clotting system but also by releasing granules containing important mediators. In fact, platelets may play a dual role in the pathophysiology of liver fibrosis as they are able to stimulate regeneration as well as aggravate the destruction of the liver. Recent studies revealed that antiplatelet therapy correlates with inhibition of liver fibrosis. However, liver impairment is associated with extensive coagulation disorders thus the safety of antiplatelet therapy is an area for detailed exploration. In this review, the role of platelets in liver fibrosis and accompanying hemostatic disorders are discussed. Additionally, results of animal and human studies on antiplatelet drugs in liver disorders and their potential therapeutic utility are presented.

Inhibition of Matrix Metalloproteinase-8 Protects Against Sepsis Serum Mediated Leukocyte Adhesion

Purpose

Leukocyte adhesion to vascular and matrix Metalloproteinase-8 (MMP8) expression is increased in sepsis and associated with poor prognosis in sepsis patients. This study aimed to investigate the role of MMP8 in sepsis serum mediated leukocyte adhesion.

Methods

Bioinformatics analysis of GSE64457 and GSE65682 was performed to evaluate the role of MMP8 in the progression of sepsis. Expression of MMP8 in blood samples from patients with sepsis was detected by qRT-PCR and ELISA. Human umbilical vein endothelial cells (HUVECs) were treated with sepsis serum, control serum, and MMP8 inhibitor. Expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) were detected by qRT-PCR and ELISA, respectively. The protein expression of total p38, phosphorylated-p38, ERK1/2, and p-ERK1/2 was detected by Western blotting. Peripheral blood mononuclear cells (PBMCs) and polymorphonuclear neutrophils (PMNs) were incubated with the treated HUVECs to calculate leukocyte adhesion.

Results

Four hundred and twenty-nine differentially expressed genes (DEGs) and seven hub genes between sepsis patients and healthy controls were identified. GO function analysis of DEGs and hub genes indicated that the DEGs and hub genes were mainly enriched in neutrophil activation. MMP8 was selected as a key gene with an unfavorable prognosis in sepsis patients. The mRNA and protein expression of MMP8 in blood from sepsis patients were significantly higher than controls. Leukocyte adhesion and mRNA and protein expression of VCAM-1 and ICAM-1 were significantly increased in the sepsis serum group compared to that in the control group, as was the protein expression of p-p38 and p-ERK1/2. However, the MMP8 inhibitor suppressed the leukocyte adhesion promoted by sepsis serum by decreasing the expression of VCAM-1, ICAM-1, p-p38, and p-ERK1/2.

Conclusion

Our study indicated that MMP8 acts as a key gene in the development of sepsis, and sepsis serum promotes leukocyte adhesion to HUVECs via MMP8, which suggest that MMP8 might be a potential therapeutic target for sepsis.

Hepatic mosaic enhancement pattern correlates with increased inflammatory activity and adverse therapeutic outcomes in patients with Crohn's disease

PURPOSE

This study aimed to evaluate the role of hepatic mosaic enhancement pattern (HMEP) on computed tomography images in the disease activity and therapeutic outcome of Crohn's Disease (CD).

METHODS

Twenty-five CD patients with HMEP comprised the HMEP group, and 25 CD patients without HMEP, who had a similar onset age, sex, and disease course with those in the HMEP group, comprised the non-HMEP group. No underlying liver/biliary disease was observed in any of the patients. Clinical characteristics, laboratory test results, Lémann index, and CD endoscopic index of severity (CDEIS) were compared between the groups using the Student t-, Mann-Whitney U, Chi square, or Fisher's exact tests. Patients received top-down, step-up, or traditional treatment during the follow-up period. After the 1-year follow-up, therapeutic outcomes (active inflammation [CDEIS > 3.5 if the endoscopic data were available, or C-reactive protein level > 5 mg/L if the endoscopic data were unavailable] or remission) were evaluated.

RESULTS

The occurrence rate of fistulas/abscesses was higher in the HMEP group (84%, 21/25) than in the non-HMEP group (48%, 12/25) with no statistical significance (P = 0.056). The HMEP group showed a higher C-reactive protein level (P = 0.001), erythrocyte sedimentation rate (P = 0.013), and blood platelet count (P = 0.005). There was no significant difference in therapeutic strategies between the groups (P = 0.509). The HMEP group showed a significantly lower remission ratio after anti-inflammatory treatment than the non-HMEP group (P = 0.045).

CONCLUSIONS

HMEP was correlated with increased inflammatory activity and adverse therapeutic outcomes in CD. This finding provided insights regarding novel markers of CD diagnosis and treatment.

Nonalcoholic fatty liver disease (NAFLD) severity is associated to a nonhemostatic contribution and proinflammatory phenotype of platelets

Nonalcoholic fatty liver disease (NAFLD) is the main cause of chronic liver disease and ranges from simple steatosis to nonalcoholic steatohepatitis. Recently, a platelet role in NAFLD pathogenesis and progression has been reported in mouse models and in patients. We investigated whether platelets are involved in liver and systemic inflammation processes in NAFLD. In this exploratory study we recruited 24 consecutive patients with biopsy-proven diagnosis of NAFLD and 17 healthy volunteers. We measured plasma levels of inflammatory markers by ELISA. We investigated hemostatic and inflammatory transcripts in circulating platelets and leukocytes from NAFLD patients. We analyzed platelet and neutrophil extracellular traps (NET) accumulations in liver sinusoids using CD42 and H3 citrullinated histones immunohistochemical staining on liver biopsies. NAFLD patients had increased inflammation markers and lipolysaccharides plasma levels. We found significant increase of inflammatory transcripts in circulating platelets and not in leukocytes of NAFLD subjects compared with healthy controls. We demonstrated increased intrahepatic platelet accumulation that correlated with NAFLD activity score (NAS) score and intrahepatic neutrophil extracellular traps (NET) formation in liver biopsies of NAFLD patients. NET formation was higher in livers with higher NAS and inflammation scores. The presence of low-grade systemic inflammation and proinflammatory changes of circulating platelets indicate that platelets participate on systemic inflammatory changes associated with NAFLD. Liver platelet accumulation and liver NET formation, together with low-grade endotoxemia, suggest that platelets may act to protect the liver from invading microorganisms by favoring local NET formation.

The role of platelets in sepsis

A State of the Art lecture titled "The role of platelets in sepsis" was presented at the ISTH congress in 2020. Sepsis is a life-threatening organ dysfunction caused by a dysregulated and multifaceted host response to infection. Platelets play a significant role in the coordinated immune response to infection and therefore in the inflammation and coagulation dysfunction that contributes to organ damage in sepsis. Thrombocytopenia has a high incidence in sepsis, and it is a marker of poor prognosis. The genesis of thrombocytopenia is likely multifactorial, and unraveling the involved molecular mechanisms will allow development of biomarkers of platelet function in sepsis. Such platelet biomarkers can facilitate study of antiplatelet interventions as immunomodulatory treatment in sepsis. Finally, relevant new data on this topic presented during the 2020 ISTH virtual congress are reviewed.

Platelets as Key Factors in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a primary liver cancer that usually develops in the setting of chronic inflammation and liver damage. The hepatic microenvironment plays a crucial role in the disease development, as players such as hepatic stellate cells, resident liver macrophages (Kupffer cells), endothelial cells, extracellular matrix, and a variety of immune cells interact in highly complex and intertwined signaling pathways. A key factor in these cross-talks are platelets, whose role in cancer has gained growing evidence in recent years. Platelets have been reported to promote HCC cell proliferation and invasion, but their involvement goes beyond the direct effect on tumor cells, as they are known to play a role in pro-fibrinogenic signaling and the hepatic immune response, as well as in mediating interactions between these factors in the stroma. Anti-platelet therapy has been shown to ameliorate liver injury and improve the disease outcome. However, platelets have also been shown to play a crucial role in liver regeneration after organ damage. Therefore, the timing and microenvironmental setting need to be kept in mind when assessing the potential effect and therapeutic value of platelets in the disease progression, while further studies are needed for understanding the role of platelets in patients with HCC.

Effects of different periods of gastric ischemia on liver as a remote organ1

PURPOSE

To evaluate the hepatic changes associated with gastric ischemia.

METHODS

Thirty male rabbits were studied, distributed in 3 groups (n=10). Group 1: ligature and section of the gastric vasculature and removal of the liver after three hours; Group 2: ligature and section of the gastric vasculature and removal of the liver after 6 hours; Group 3: ligature and section of the gastric vasculature and removal of the liver after 12 hours. Blood samples were collected immediately before surgery and after the determined time of ischemia in each group to evaluate the hepatic function. After the death of the rabbits, the liver was removed for macro and microscopic study.

RESULTS

An increase in aminotransferases and bilirubin occurred in groups 2 and 3. Total protein and albumin diminished in all of the animals. All of the rabbits from groups 2 and 3 presented hepatocellular necrosis.

CONCLUSION

The devascularization of the stomach for a period of above three hours is associated with hepatic morphological and functional disorders.

In vivo quantification of rolling and adhered leukocytes in human sepsis

BACKGROUND

The use of in vivo videomicroscopy at the bedside has demonstrated microcirculatory flow disturbances in sepsis. The ability of in vivo videomicroscopy to detect changes in the prevalence of rolling and adhered leukocytes that occur in sepsis is not well-described in humans. We sought to (1) develop methodology for accessing and quantifying sublingual leukocyte rolling and adherence with sidestream dark field (SDF) imaging; (2) compare the number of rolling and adhered leukocytes between patients with septic shock and non-infected controls; and (3) compare the number of rolling and adhered leukocytes between survivors and non-survivors of septic shock.

METHODS

We included adult (age > 18 years) patients in the emergency department presenting with septic shock prospectively enrolled in the ProCESS trial. We recruited comparison non-infected patients as emergency department controls. Using a SDF videomicroscope, we obtained image sequences from the sublingual mucosa, quantifying rolling and adhered leukocytes per 1 mm × 1 mm visual field in a standardized 3-s clip. We report data as median and interquartile range and depicted as box plots. We compared groups using the Mann-Whitney U test, considering a p value < 0.05 significant.

RESULTS

We included a total of 64 patients with septic shock and 32 non-infected controls. The median number of adhered leukocytes per field in the sepsis group was 1.0 (IQR 0-3.5) compared to 0 (0-0) in the non-infected group (p < 0.001). The median number of rolling leukocytes was 26 (10.3-42) in the sepsis group and 9.8 (4.8-17.3) in the non-infected group (p < 0.001) per field. Among the patients with sepsis (n = 64), there was an increased number of adhered leukocytes in non-survivors compared to survivors (3.0 (1-5.5) vs. 1.0 (0-3.0)) (p < 0.05); however, there was no difference in rolling leukocytes (35 (20-48) vs. 26 (10-41)) (p = 0.31).

CONCLUSIONS

Our results demonstrated a higher number of rolling and adhered leukocytes in patients with septic shock when compared to non-infected controls, and an increased number of adhered leukocytes in non-survivors.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT00793442 ; Registered on 19 November 2008 PG0GM076659 (US NIH Grant/Contract). First submitted 18 July 2007. First posted 2 August 2007.

Review article: the role of the microcirculation in liver cirrhosis

BACKGROUND

Intrahepatic microvascular derangements and microcirculatory dysfunction are key in the development of liver cirrhosis and its associated complications. While much has been documented relating to cirrhosis and the dysfunction of the microcirculation in the liver parenchyma, far less is known about the state of the extrahepatic microcirculation and the role this may have in the pathogenesis of multiple organ failure in end stage liver cirrhosis.

AIM

To provide an update on the role of the microcirculation in the pathophysiology of cirrhosis and its associated complications and briefly discuss some of the imaging techniques which may be used to directly investigate the microcirculation.

METHODS

A Medline literature search was conducted using the following search terms: 'cirrhosis', 'microcirculation', 'circulation', 'systemic', 'inflammation', 'peripheral', 'hepatorenal' and 'hepatopulmonary'.

RESULTS

Significant heterogeneous microvascular alterations exist in patients with cirrhosis. Data suggest that the systemic inflammation, associated with advanced cirrhosis, induces microcirculatory dysregulation and contributes to haemodynamic derangement. The resultant vasoconstriction and hypoperfusion in the systemic extrahepatic microvasculature, is likely to be instrumental in the pathophysiology of organ failure in decompensated cirrhosis, however the mechanistic action of vasoactive agents used to correct the circulatory disturbance of advanced cirrhosis is poorly understood.

CONCLUSIONS

Further research into the role of the microcirculation in patients with liver cirrhosis, will improve physicians understanding of the pathophysiology of cirrhosis, and may provide a platform for real time evaluation of an individual's microcirculatory response to vasoactive mediators, thus guiding their therapy.

Hemodynamic coherence in sepsis

Microvascular alterations are a hallmark of sepsis and play a crucial role in its pathophysiology. Such alterations are the result of overwhelming inflammation, which negatively affects all the components of the microcirculation. As the severity of microvascular alterations is associated with organ dysfunction and mortality, several strategies have been tested for improving microcirculation. Nevertheless, they are mainly based on the conventional manipulation of systemic hemodynamics to increase the total flow to the organs and tissues. Other therapeutic interventions are still being investigated. In this review, we discuss the pathophysiology of septic microcirculatory dysfunction and its implications for possible treatments.

Platelets: No longer bystanders in liver disease

Growing lines of evidence recognize that platelets play a central role in liver homeostasis and pathobiology. Platelets have important roles at every stage during the continuum of liver injury and healing. These cells contribute to the initiation of liver inflammation by promoting leukocyte recruitment through sinusoidal endothelium. They can activate effector cells, thus amplifying liver damage, and by modifying the hepatic cellular and cytokine milieu drive both hepatoprotective and hepatotoxic processes.

CONCLUSION

In this review we summarize how platelets drive such pleiotropic actions and attempt to reconcile the paradox of platelets being both deleterious and beneficial to liver function; with increasingly novel methods of manipulating platelet function at our disposal, we highlight avenues for future therapeutic intervention in liver disease. (Hepatology 2016;64:1774-1784).

Microcirculatory dysfunction in sepsis: pathophysiology, clinical monitoring, and potential therapies

Abnormal microvascular perfusion, including decreased functional capillary density and increased blood flow heterogeneity, is observed in early stages of the systemic inflammatory response to infection and appears to have prognostic significance in human sepsis. It is known that improvements in systemic hemodynamics are weakly correlated with the correction of microcirculatory parameters, despite an appropriate treatment of macrohemodynamic abnormalities. Furthermore, conventional hemodynamic monitoring systems available in clinical practice fail to detect microcirculatory parameter changes and responses to treatments, as they do not evaluate intrinsic events that occur in the microcirculation. Fortunately, some bedside diagnostic methods and therapeutic options are specifically directed to the assessment and treatment of microcirculatory changes. In the present review we discuss fundamental aspects of septic microcirculatory abnormalities, including pathophysiology, clinical monitoring, and potential therapies.

The profile of platelet α-granule released molecules affects postoperative liver regeneration

Platelets promote liver regeneration through site-specific serotonin release from dense granules, triggering proliferative signaling in hepatocytes. However, the effects of factors derived from platelet α-granules on liver regeneration are unclear, because α-granules contain bioactive molecules with opposing functions. Because α-granule molecules are stored in separate compartments, it has been suggested that platelets selectively release their α-granule content dependent on the environmental stimulus. Therefore, we investigated the pattern of circulating α-granule molecules during liver regeneration in 157 patients undergoing partial hepatectomy. We measured plasma levels of α-granule-derived factors in the liver vein at the end of liver resection, as well as on the first postoperative day. We observed a rapid accumulation of platelets within the liver after induction of liver regeneration. Platelet count and P-selectin (a ubiquitous cargo of α-granules) were not associated with postoperative liver dysfunction. However, low plasma levels of vascular endothelial growth factor (VEGF), but high levels of thrombospondin 1 (TSP-1), predicted liver dysfunction after resection. Patients with an unfavorable postoperative α-granule release profile (high TSP-1/low VEGF) showed substantially worse postoperative clinical outcomes. The unfavorable postoperative α-granule release profile was associated with increased postoperative portal venous pressure and von Willebrand factor antigen levels as a marker for intrahepatic endothelial dysfunction.

CONCLUSION

The postoperative profile of circulating platelet-derived factors correlates with the ability of the remnant liver to regenerate. Portal venous pressure and intrahepatic endothelial dysfunction might account for the selective granule release profile. Selective modulation of platelet α-granule release in patients may represent an attractive target for therapeutic interventions to improve liver regeneration and clinical outcomes after partial hepatectomy.

Microcirculatory alterations in shock states

Functional components of the microcirculation provide oxygen and nutrients and remove waste products from the tissue beds of the body's organs. Shock states overwhelmingly stress functional capacity of the microcirculation, resulting in microcirculatory failure. In septic shock, inflammatory mediators contribute to hemodynamic instability. In nonseptic shock states, the microcirculation is better able to compensate for alterations in vascular resistance, cardiac output, and blood pressure. Therefore, global hemodynamic and oxygen delivery parameters are appropriate for assessing, monitoring, and guiding therapy in hypovolemic and cardiogenic shock but, alone, are inadequate for septic shock.

Contribution of the platelet activating factor signaling pathway to cerebral microcirculatory dysfunction during experimental sepsis by ExoU producing Pseudomonas aeruginosa

Intravital microscopy was used to assess the involvement of ExoU, a Pseudomonas aeruginosa cytotoxin with phospholipase A2 activity, in dysfunction of cerebral microcirculation during experimental pneumosepsis. Cortical vessels from mice intratracheally infected with low density of the ExoU-producing PA103 P. aeruginosa strain exhibited increased leukocyte rolling and adhesion to venule endothelium, decreased capillar density and impaired arteriolar response to vasoactive acetylcholine. These phenomena were mediated by the platelet activating factor receptor (PAFR) pathway because they were reversed in mice treated with a PAFR antagonist prior to infection. Brains from PA103-infected animals exhibited a perivascular inflammatory infiltration that was not detected in animals infected with an exoU deficient mutant or in mice treated with the PAFR antagonist and infected with the wild type bacteria. No effect on brain capillary density was detected in mice infected with the PAO1 P. aeruginosa strain, which do not produce ExoU. Finally, after PA103 infection, mice with a targeted deletion of the PAFR gene exhibited higher brain capillary density and lower leukocyte adhesion to venule endothelium, as well as lower increase of systemic inflammatory cytokines, when compared to wild-type mice. Altogether, our results establish a role for PAFR in mediating ExoU-induced cerebral microvascular failure in a murine model of sepsis.

New directions for sepsis and septic shock research

BACKGROUND

Septic shock is a frequent complication in intensive care unit that can result in multiple organ failure and death. In addition, recent data suggested that severe sepsis and septic shock represent an economic burden. Therefore, septic shock is an important public health problem.

METHOD

In this review, we will focus on the recent evidences concerning the stages of septic shock, the complex macrocirculation and microcirculation relationship, and the importance of those evidences for future resuscitation goals and therapeutic strategies during late septic shock.

RESULT

Recently, two stages of septic shock are suggested. In early stage, hypovolemia is the main contributing factor. During this stage, macrocirculatory and microcirculatory changes run parallel, and fluid resuscitation seems to be effective in restoring the hemodynamic parameters. Late stage of septic shock is characterized by complex microcirculation and macrocirculation relationship.

CONCLUSIONS

Although early goal-directed therapy is a stepwise approach in the treatment of septic shock, tissue perfusion remains an important factor that contributes to septic shock outcome. Because appropriate monitoring of tissue perfusion is a matter of debt, the ideal therapeutic strategy remains a controversial issue that needs further investigations.

Comparative suitability of CFDA-SE and rhodamine 6G for in vivo assessment of leukocyte-endothelium interactions

Intravital fluorescence microscopy (IVM) is a predestined tool for investigating the fate of leukocytes during the process of leukocyte recruitment. In the present study, the commonly used dye for this purpose, rhodamine 6G, and carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) were compared for leukocytes labelling with respect to suitability for IVM studies. Their potential in labelling different leukocytes subpopulations as well as their fluorescence intensities were assessed by flow cytometry revealing distinct differences between both dyes. These differences had a profound impact on their application for in vivo imaging of leukocyte-endothelium interactions. In summary, CFDA-SE revealed superior in labelling leukocytes for in vivo microscopy with respect to image quality. In addition, we could show the efficiency of CFDA-SE also under disease condition in an animal model of sepsis.

Signal transduction of platelet-induced liver regeneration and decrease of liver fibrosis

Platelets contain three types of granules: alpha granules, dense granules, and lysosomal granules. Each granule contains various growth factors, cytokines, and other physiological substances. Platelets trigger many kinds of biological responses, such as hemostasis, wound healing, and tissue regeneration. This review presents experimental evidence of platelets in accelerating liver regeneration and improving liver fibrosis. The regenerative effect of liver by platelets consists of three mechanisms; i.e., the direct effect on hepatocytes, the cooperative effect with liver sinusoidal endothelial cells, and the collaborative effect with Kupffer cells. Many signal transduction pathways are involved in hepatocyte proliferation. One is activation of Akt and extracellular signal-regulated kinase (ERK)1/2, which are derived from direct stimulation from growth factors in platelets. The other is signal transducer and activator of transcription-3 (STAT3) activation by interleukin (IL)-6 derived from liver sinusoidal endothelial cells and Kupffer cells, which are stimulated by contact with platelets during liver regeneration. Platelets also improve liver fibrosis in rodent models by inactivating hepatic stellate cells to decrease collagen production. The level of intracellular cyclic adenosine monophosphate (cyclic AMP) is increased by adenosine through its receptors on hepatic stellate cells, resulting in inactivation of these cells. Adenosine is produced by the degradation of adenine nucleotides such as adenosine diphosphate (ADP) and adenosine tri-phosphate (ATP), which are stored in abundance within the dense granules of platelets.

Septic liver: clinical relevance of early inhomogeneous enhancement of the liver in patients with acute pyelonephritis

BACKGROUND

CT scans of patients with febrile illness occasionally show hepatobiliary changes, although infection does not originate in the hepatobiliary system. These findings may cause radiologists and clinicians to misrecognize hepatobiliary diseases and initiate an inappropriate treatment. Thus, it is important to recognize hepatobiliary CT findings in cases of extrahepatobiliary infectious disease.

PURPOSE

To evaluate extrarenal CT manifestations in patients with acute pyelonephritis and to determine the correlation between these extrarenal CT findings and septic liver based on laboratory parameters of sepsis.

MATERIAL AND METHODS

This study included 157 retrospectively identified patients with confirmed acute pyelonephritis based on CT imaging and urine test, and who had also undergone multi-phase dynamic contrast-enhanced CT scan. Two radiologists reviewed CT findings including early inhomogeneous enhancement of the liver, periportal low density and gallbladder edema, which were correlated with laboratory data including liver function enzymes, albumin, C-reactive protein, white blood cell count, and results of a blood culture by using the Fisher's exact test and Mann-Whitney U test.

RESULTS

Forty-six patients (29.3%) showed early inhomogeneous enhancement of the liver, which was associated with increased C-reactive protein (P < 0.001), a positive blood culture (P < 0.005), and decreased albumin level (P < 0.002). The periportal low density and gallbladder wall edema were noted in 15 patients (9.6%) and six patients (3.8%), respectively. These two CT findings were significantly associated with only decreased albumin level (P < 0.001 and P < 0.040).

CONCLUSION

Early inhomogeneous enhancement of the liver in patients with acute pyelonephritis was significantly associated with increased CRP level, a positive blood culture and decreased albumin level, reflecting sepsis and sepsis-associated liver dysfunction, requiring rapid and appropriate intensive treatment.

Pathophysiology of microcirculatory dysfunction and the pathogenesis of septic shock

Multiple experimental and human trials have shown that microcirculatory alterations are frequent in sepsis. In this review, we discuss the various mechanisms that are potentially involved in their development and the implications of these alterations. Endothelial dysfunction, impaired inter-cell communication, altered glycocalyx, adhesion and rolling of white blood cells and platelets, and altered red blood cell deformability are the main mechanisms involved in the development of these alterations. Microcirculatory alterations increase the diffusion distance for oxygen and, due to the heterogeneity of microcirculatory perfusion in sepsis, may promote development of areas of tissue hypoxia in close vicinity to well-oxygenated zones. The severity of microvascular alterations is associated with organ dysfunction and mortality. At this stage, therapies to specifically target the microcirculation are still being investigated.

The association of near infrared spectroscopy-derived StO2 measurements and biomarkers of endothelial activation in sepsis

Near infrared spectroscopy (NIRS) may be utilized in conjunction with a vascular occlusion test to quantify a tissue bed's ability to re-oxygenate by measuring continuous tissue oxygen saturation recovery rate. We hypothesize that NIRS recovery slope will be associated with expression of endothelial biomarkers, thus, making it a feasible bedside surrogate for assessing endothelial activation/dysfunction in patients with sepsis. A secondary analysis of a prospective, multicenter, observational study was done on a convenience sample of adult patients at four university emergency departments consisting of patients with septic shock, sepsis without shock and patients without infection. At enrollment we measured the NIRS-derived measurements and collected plasma to assay biomarkers of endothelial activation. 186 patients were enrolled in the study. The mean age was 63 (± 16) years with 60 % male gender. Univariate analysis assessing the linear relationship between the recovery slope with endothelial biomarkers, found a weak but statistical significant association between NIRS recovery slope and soluble fms-like tyrosine kinase-1 (sFLT-1) and tPAI-1 (r = -0.08, p < 0.0001 and r = -0.06, p = 0.002). When adjusting for diabetes, age and sequential organ failure assessment score at enrollment, only sFLT-1 persisted having a statistically significant association (r = -0.04, p = 0.01). We found a weak, but statistically significant relationship between NIRS-derived measurements and biomarkers of endothelial activation/dysfunction in patients with sepsis. This study fails to support the use of NIRS-derived measurements as a clinical or research tool to identify patients with endothelial cell activation/dysfunction and informs researchers that this is not a robust option for identifying this lesion at the bedside.

Tissue-specific neutrophil recruitment into the lung, liver, and kidney

The recruitment of immune cells is crucial for the development of inflammatory processes. The classical recruitment cascade of neutrophils into inflamed tissues is well understood and consists of capturing, rolling, slow rolling, arrest, postadhesion strengthening, crawling, and transmigration. While this commonly agreed paradigm might be applicable to most peripheral tissues, recruitment mechanisms may substantially vary in different organs such as the lung, liver, and kidney. These organs are highly specialized tissues with unique cell populations and structural organization, which enables them to fulfill their individual functions. The published research over the last decade has shed some light on organ-specific mechanisms of neutrophil recruitment and helped to generate a deeper understanding of the specific recruitment mechanisms involved in this process. The aim of this review is to highlight current concepts of tissue-specific differences and similarities of neutrophil recruitment into the lung, liver, and kidney.

Novel therapy for liver regeneration by increasing the number of platelets

Platelets are the smallest blood constitutes which contain three types of granules; alpha granules, dense granules, and lysosomal granules. Each granule contains various biophysiological substances such as growth factors, cytokines, etc. Platelets have been conventionally viewed as a trigger of inflammatory responses and injury in the liver. Some studies revealed that platelets have strong effects on promoting liver regeneration. This review presents experimental evidence of platelets in accelerating liver regeneration and describes three different mechanisms involved; (1) the direct effect on hepatocytes, where platelets translocate to the space of Disse and release growth factors through direct contact with hepatocytes, (2) the cooperative effect with liver sinusoidal endothelial cells, where the dense concentration of sphingosine-1-phosphate in platelets induces excretion of interleukin-6 from liver sinusoidal endothelial cells, and (3) the collaborative effect with Kupffer cells, where the functions of Kupffer cells are enhanced by platelets.

Alterations of the Erythrocyte Membrane during Sepsis

Erythrocytes have been long considered as “dead” cells with transport of oxygen (O₂) as their only function. However, the ability of red blood cells (RBCs) to modulate the microcirculation is now recognized as an important additional function. This capacity is regulated by a key element in the rheologic process: the RBC membrane. This membrane is a complex unit with multiple interactions between the extracellular and intracellular compartments: blood stream, endothelium, and other blood cells on the one hand, and the intracytoplasmic compartment with possible rapid adaptation of erythrocyte metabolism on the other. In this paper, we review the alterations in the erythrocyte membrane observed in critically ill patients and the influence of these alterations on the microcirculatory abnormalities observed in such patients. An understanding of the mechanisms of RBC rheologic alterations in sepsis and their effects on blood flow and on oxygen transport may be important to help reduce morbidity and mortality from severe sepsis.

Interaction between Kupffer cells and platelets in the early period of hepatic ischemia-reperfusion injury--an in vivo study

BACKGROUND

Hepatic ischemia-reperfusion (I/R) leads to activation of Kupffer cells (KCs). The activated KCs cause platelet and leukocyte adhesion to the sinusoidal endothelium. Previously, we reported that platelet-endothelium interactions occur earlier than leukocyte responses. The aim of this study was to evaluate the interaction between platelets and KCs in the hepatic microcirculation after I/R.

MATERIALS AND METHODS

Sprague-Dawley rats were divided into three groups: the no-ischemia group (control group; n = 6); the 20-min ischemia group (I/R group; n = 6); and the 20-min ischemia + anti-rat platelet serum group (APS group; n = 6). KCs were labeled using the liposome entrapment method. The number of adherent platelets was observed for up to 120 min after reperfusion by intravital microscopy. To investigate the effects of platelets on I/R injury, rats were injected intravenously with rabbit APS for platelet depletion.

RESULTS

In the I/R group, the number of adherent platelets increased significantly after I/R. More than 50% of the adherent platelets adhered to KCs. Electron microscopy indicated that the platelets attached to the KCs after hepatic ischemia. The histologic findings indicated liver damage and apoptosis of hepatocytes in zone 1. In the I/R group, but not in the control and APS groups, serum ALT increased immediately after reperfusion.

CONCLUSIONS

We succeeded in visualizing the dynamics of both KCs and platelets in the hepatic sinusoids. Liver ischemia induced the adhesion of platelets to KCs in the early period, which could play a key role in reperfusion injury of the liver.

Year in review 2010: Critical Care--Cardiology

We review key research papers in cardiology and intensive care published during 2010 in Critical Care and quote related studies published in other journals if appropriate. Papers were grouped into the following categories: cardiovascular therapies, biomarkers, hemodynamic monitoring, cardiovascular diseases, and microcirculation.

Microcirculatory alterations: potential mechanisms and implications for therapy

Multiple experimental and human trials have shown that microcirculatory alterations are frequent in sepsis. In this review, we discuss the characteristics of these alterations, the various mechanisms potentially involved, and the implications for therapy. Sepsis-induced microvascular alterations are characterized by a decrease in capillary density with an increased number of stopped-flow and intermittent-flow capillaries, in close vicinity to well-perfused capillaries. Accordingly, the surface available for exchange is decreased but also is highly heterogeneous. Multiple mechanisms may contribute to these alterations, including endothelial dysfunction, impaired inter-cell communication, altered glycocalyx, adhesion and rolling of white blood cells and platelets, and altered red blood cell deformability. Given the heterogeneous nature of these alterations and the mechanisms potentially involved, classical hemodynamic interventions, such as fluids, red blood cell transfusions, vasopressors, and inotropic agents, have only a limited impact, and the microcirculatory changes often persist after resuscitation. Nevertheless, fluids seem to improve the microcirculation in the early phase of sepsis and dobutamine also can improve the microcirculation, although the magnitude of this effect varies considerably among patients. Finally, maintaining a sufficient perfusion pressure seems to positively influence the microcirculation; however, which mean arterial pressure levels should be targeted remains controversial. Some trials using vasodilating agents, especially nitroglycerin, showed promising initial results but they were challenged in other trials, so it is difficult to recommend the use of these agents in current practice. Other agents can markedly improve the microcirculation, including activated protein C and antithrombin, vitamin C, or steroids. In conclusion, microcirculatory alterations may play an important role in the development of sepsis-related organ dysfunction. At this stage, therapies to target microcirculation specifically are still being investigated.

Characteristics of clinical sepsis reflected in a reliable and reproducible rodent sepsis model

BACKGROUND

Sepsis models are frequently based on induction of peritonitis, with cecal ligation and puncture reflecting the prototypical model. However, there is an ongoing discussion about the limitations of these models due to their variability in progression and outcome. Since standardization is a cornerstone of experimental models, we aimed to develop a reliable and reproducible procedure for induction of peritonitis.

MATERIALS AND METHODS

A human stool batch was processed for -80° storage. For induction of peritonitis in fluid-resuscitated rats, a defined volume of stool suspension from this batch was injected intraperitoneally. For characterization of the model, physiologic and inflammatory changes were evaluated after sepsis induction. Survival analyses with the same batch were repeated in four independent experiments over a time period of 16 mo.

RESULTS

The polymicrobial infection resulted in severe peritoneal inflammation with a systemic increase in cytokines. The mortality rate at 15 h was 29% and this was reproducible over a 16 mo time period. If antibiotic treatment was applied, a 50% survival was achieved. Laboratory markers indicated a progressive multi-organ dysfunction, while blood gas analysis showed respiratory compensation of a metabolic acidosis, and maintenance of PaO(2). Intravital microscopy of the liver revealed an impaired microcirculation. A decreased hemostatic potential was demonstrated by rotational thromboelastometry. Despite clinical recovery within 3 d, surviving animals showed laboratory and histologic signs of persisting inflammation even after 2 wk.

CONCLUSIONS

This model reflects many features of human sepsis. Application of an infectious focus that is both quantitatively and qualitatively defined assures high reproducibility. Moreover, the procedure is simple and can be easily standardized.

The relationship between endotoxemia and hepatic endocannabinoids in cirrhotic rats with portal hypertension

BACKGROUND & AIMS

Cirrhosis is characterized by endotoxemia and increased intrahepatic resistance, which is caused by hepatic fibrosis and endothelial dysfunction, as well as the activated endocannabinoids system, including cannabinoid (CB(1) and CB(2)) receptors. Besides accelerating hepatic fibrogenesis, endotoxins induce the release of circulating endocannabinoids and portal hypertension in cirrhosis. This study examines how suppression of endotoxemia by antibiotics affects intrahepatic resistance and the hepatic endocannabinoid system in bile-duct-ligated (BDL) rats.

METHODS

Measurements were performed that included: mean arterial pressure, cardiac index (CI), systemic vascular resistance, superior mesenteric arterial blood flow and resistance, PVP, plasma endotoxin and hepatic tumor necrosis factor-α (TNFα), anandamide and 2-arachidonylglycerol, hepatic expression of cannabinoid receptors, endothelial nitric oxide synthase (eNOS), phospho-eNOS, Akt, phospho-Akt and thromboxane synthase (TXS), matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-2 (TIMP-2), hepatic fibrosis, and leukocyte infiltration. Hepatic endothelial dysfunction was evaluated in BDL rats receiving vehicle (BDL-V) or 2-weeks of ciprofloxacin (BDL-cipro).

RESULTS

Plasma endotoxin and hepatic TNFα, anandamide and 2-arachidonylglycerol, expression of TXS, MMP-2, TIMP-2, hepatic fibrosis and infiltration of hepatic leukocytes, CI, PVP and intrahepatic resistance were significantly lower in BDL-cipro than in BDL-V rats. Conversely, systemic vascular resistance, eNOS and Akt phosphorylation were significantly higher in BDL-cipro than in BDL-V rats. Improvement of hepatic endothelial dysfunction was associated with lower expression of hepatic CB(1) and a higher expression of hepatic CB(2) in BDL-cipro rats.

CONCLUSIONS

In cirrhotic rats, ciprofloxacin suppressed endotoxemia and the hepatic endocannabinoid system thus ameliorating hyperdynamic circulation and decreased intrahepatic resistance by preventing hepatic fibrogenesis and endothelial dysfunction.

Critical care "normality": individualized versus protocolized care

Patients with critical illness are heterogeneous, with differing physiologic requirements over time. Goal-directed therapy in the emergency room demonstrates that protocolized care could result in improved outcomes. Subsequent studies have confirmed benefit with such a "bundle-based approach" in the emergency room and in preoperative and postoperative scenarios. However, this cannot be necessarily extrapolated to the medium-term and long-term care pathway of the critically ill patient. It is likely that the development of mitochondrial dysfunction could result in goal-directed types of approaches being detrimental. Equally, arterial pressure aims are likely to be considerably different as the patient's physiology moves toward "hibernation." The agents we utilize as sedative and pressor agents have considerable effects on immune function and the inflammatory profile, and should be considered as part of the total clinical picture. The role of gut failure in driving inflammation is considerable, and the drive to feed enterally, regardless of aspirate volume, may be detrimental in those with degrees of ileus, which is often a difficult diagnosis in the critically ill. The pathogenesis of liver dysfunction may be, at least in part, related to venous engorgement that will contribute toward portal hypertension and gut edema. This, in association with loss of the hepatosplanchnic buffer response, it is likely to contribute to venous pooling in the abdominal cavity, impaired venous return, and decreased central blood volumes. Therapies such as those used in "small-for-size syndrome" may have a role in the chronic stages of septic vascular failure.

Attenuation of warm ischemia-reperfusion injury in the liver by bucillamine through decreased neutrophil activation and Bax/Bcl-2 modulation

BACKGROUND AND AIM

Liver transplantation and resection surgery involve a period of ischemia and reperfusion to the liver, which initiates an inflammatory cascade resulting in liver and remote organ injury. Bucillamine is a low molecular weight thiol antioxidant that is capable of rapidly entering cells. We hypothesized that bucillamine acts by replenishing glutathione levels, thus reducing neutrophil activation, modulating Bax/Bcl-2 expression, and subsequently, attenuating the effects of warm ischemia-reperfusion injury (IRI) in the liver.

METHODS

The effect of bucillamine was studied in a rat model of liver IRI with 45 min of partial (70%) liver ischemia and 3 h of reperfusion. Liver injury was assessed by measuring serum transaminases (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) and liver histology. Oxidative stress was quantified by measuring F(2) isoprostane and glutathione levels. Leukocyte adhesion was assessed by intravital microscopy, and inflammatory cytokine response was assessed by measuring serum cytokine-induced neutrophil chemoattractant-1 (CINC-1) levels. Bax and Bcl-2 expression was measured by reverse transcription-polymerase chain reaction.

RESULTS

The model produced significant liver injury with elevated transaminases and an acute inflammatory response. Bucillamine reduced the liver injury, as indicated by reduced AST (932 ± 200.8 vs 2072.5 ± 511.79, P < 0.05). Bucillamine reduced Bax expression, serum CINC-1 levels, and neutrophil adhesion, and upregulated Bcl-2. However, bucillamine did not affect tissue glutathione levels nor the levels of oxidative stress, as measured by plasma and hepatic F(2) isoprostane levels.

CONCLUSIONS

Bucillamine reduces warm ischemia-reperfusion in the liver by inhibiting neutrophil activation and modulating Bax/Bcl-2 expression.

Kupffer cell depletion reduces hepatic inflammation and apoptosis but decreases survival in abdominal sepsis

OBJECTIVE

During abdominal sepsis, the activation of hepatic Kupffer cells (KC) and its consequences are of central interest. This study evaluates the impact of selective KC depletion on hepatic microcirculation, cytokine release, and systemic alterations in the colon ascendens stent peritonitis (CASP), a model of polymicrobial abdominal sepsis.

METHODS

For KC depletion clodronate liposomes were injected 24 h before CASP surgery in female C57BL/6N mice. Three and 12 h after CASP, in-vivo fluorescence microscopy of the liver was performed. Analysis of hepatocellular apoptosis was conducted by immunohistochemistry. In addition, levels of tumor necrosis factor (TNF), IL-6, and IL-10 in the liver, lungs, spleen, and plasma were determined, and bacteriology and survival analysis were performed.

RESULTS

CASP led to significant sinusoidal perfusion failure, increased leukocyte recruitment, hepatocellular apoptosis and increased levels of TNF, IL-6, and IL-10 in the liver and plasma. KC depletion before CASP significantly reduced leukocyte recruitment to the liver and hepatocellular apoptosis. IL-10 secretion decreased dramatically in the liver and plasma of KC-depleted septic mice. In contrast, TNF levels were clearly elevated after clodronate treatment. In the lung and spleen, a compensatory upregulation of IL-10 could be detected after KC depletion. Clodronate treatment resulted in a significant reduction in survival.

CONCLUSION

The results indicate that KC depletion is locally protective in polymicrobial abdominal sepsis, as it reduces hepatic inflammation and apoptosis. These effects could be observed in the presence of clearly elevated TNF levels. However, the lack of IL-10 in KC-depleted mice resulted in a detrimental systemic proinflammation.

Early microvascular changes in sepsis and severe sepsis

Efforts to improve survival from sepsis are focusing increasingly on intervention during the earliest stages of this disease. The importance of derangements in microvascular flow in patients with established sepsis is well recognized. However, little data are available to describe microvascular changes in early sepsis. After research ethics committee approval, observational data were collected in healthy volunteers and within 6 h of presentation in patients with sepsis and severe sepsis. Sidestream dark-field imaging was used to obtain video images of the sublingual microcirculation. Cardiac index was measured using the noninvasive suprasternal Doppler method. Forty-eight patients and 16 healthy volunteers were recruited. Twenty-eight patients were diagnosed with sepsis and 19 with severe sepsis. Eight patients (17%) did not survive to leave hospital. For small vessels (<20 microm), microvascular flow index (P < 0.05), heterogeneity index (P < 0.05) and the proportion of perfused vessels (P < 0.05) were lower in patients with sepsis and severe sepsis compared with healthy volunteers. Perfused vessel density (P < 0.05) was lower in the severe sepsis group compared with the sepsis group. The proportion of perfused vessels (P < 0.01) and MAP (P < 0.05) were lower in nonsurvivors compared with survivors. Sepsis results in derangements of microvascular flow, which can be identified in the early stages of this disease. These abnormalities are more marked in the most severely ill patients. Further research is required to fully characterize the effects of sepsis on microvascular function.

Organ failure in sepsis

The development of organ failure determines the course and prognosis of the septic patient. Although several successful clinical trials in recent years have raised the enthusiasm of intensivists, severe sepsis and septic shock still have an increasing incidence with more or less unchanged mortality. Recent sepsis research, including progress made in definitions, epidemiology, pathophysiology, diagnosis, standard and adjunctive therapy, and experimental approaches, is encouraging. This includes genomic information for stratifying subgroups of patients, a broader field of laboratory diagnostics due to clinical studies, and basic research on the cellular mechanisms of inflammation and organ dysfunction. Furthermore, new findings in pathogenesis and therapeutic approaches to organ failure merit attention. In this review, state-of-the-art publications are presented to elucidate the possible impact of sepsis-induced organ failure on clinical routine.

Influence of hydroxyethyl starch on healing of colonic anastomosis in a rat model of peritonitis

BACKGROUND

This study was designed to evaluate the role of different intravascular volume replacement regimens of HES 130/0.4 on wound healing process in left colonic anastomoses in the presence of intra-abdominal sepsis induced by murine model of cecal ligation and puncture (CLP).

METHODS

The left colonic anastomosis was performed in 40 rats that were divided into five groups (n = 8/group): saline controls (30 ml/kg); CLP plus saline (30 ml/kg); CLP plus HES (7.5, 15, or 30 ml/kg, respectively). Saline or HES was treated before the construction of left colonic anastomosis and on a regular daily basis. Anastomotic bursting pressures were measured in vivo on day 5. Tissue samples were obtained for analyses of hydroxyproline (HP) contents, myeloperoxidase (MPO) activity, malondialdehyde (MDA), reduced glutathione (GSH) levels, and nuclear factor-kappa B (NF-kappa B) activation. The plasma levels of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 were also measured.

RESULTS

Intra-abdominal sepsis led to significant decreases in colonic anastomotic bursting pressures, and perianastomotic tissue HP contents and GSH levels, along with increases in perianastomotic tissue MPO activity, MDA levels and NF-kappa B activation and plasma levels of TNF-alpha and IL-6. After treated with HES, these provoked perianastomotic tissue MPO activity, MDA levels, NF-kappa B activation, and plasma levels of TNF-alpha and IL-6 were suppressed and GSH levels were restored, especially in 15 ml/kg HES group. Without obvious influence on systemic nutritional condition, HES 15 ml/kg but not HES 7.5 ml/kg significantly increased anastomotic bursting pressures, and perianastomotic tissue HP contents. However, HES 30 ml/kg even led to adverse effects on anastomotic bursting pressures.

CONCLUSIONS

This study showed that moderate doses (15 ml/kg) of HES 130/0.4 administration significantly prevented this intraperitoneal sepsis-induced impaired anastomotic healing of the left colon. It also suggested the possibility of poorer anastomotic healing receiving HES at higher doses (30 ml/kg). Clearly, HES 130/0.4 now should not be recommended to use at a high doses postoperatively in sepsis.

Prognostic significance of serum platelet-activating factor in chronic severe hepatitis B

AIM: To evaluate the prognostic significance of serum platelet-activating factor (PAF) in chronic severe hepatitis B.

METHODS: Forty-nine patients with chronic severe hepatitis B were divided into two groups: improvement group (n = 26) and death group (n = 23). A control group was made up of 20 healthy individuals. All patients underwent combined therapy. The levels of PAF and endotoxin in the serum were detected before and after therapy. The case fatality of patients with chronic severe hepatitis B was calculated.

RESULTS: The incidence rate of endotoxemia in 49 patients with chronic severe hepatitis B was 85.71% (42/49). The serum endotoxin and PAF levels in the death group and improvement group were significantly higher than that in the control group (all P < 0.01). The serum endotoxin and PAF levels were significantly lower in the improvement group after therapy than before therapy (both P < 0.01). The serum PAF level in patients with endotoxemia was significantly higher than that in patients without endotoxemia (P < 0.05). Logistic regression analysis showed that total bilirubin, serum endotoxin and PAF levels were positively correlated with the prognosis of patient with chronic severe hepatitis B (all P < 0.01 or 0.05; OR = 0.799, 0.040 and 2.007, respectively), and prothrombin activity was negatively correlated with the prognosis of patient with chronic severe hepatitis B (P < 0.05, OR = 0.015). PAF is the best parameter to evaluate the prognosis of patient with chronic severe hepatitis B.

CONCLUSION: A decrease in serum PAF level is closely associated with the improvement of hepatic function. Serum PAF level can be used as a prognostic factor in chronic severe hepatitis B.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

Hydroxyethyl starch 130/0.4 augments healing of colonic anastomosis in a rat model of peritonitis

BACKGROUND

This study was designed to investigate the role of hydroxyethyl starch (HES) 130/0.4 on the wound healing process in left colonic anastomoses in the presence of intra-abdominal sepsis.

METHODS

The left colonic anastomosis was performed in 40 rats that were divided into 4 groups: (1) group SHAM, laparatomy plus cecal mobilization (n = 10); (2) group SHAM + HES, HES130/.4-treated controls (n = 10); and (3) group CLP, cecal ligation and puncture (n = 10); (4) group CLP + HES, CLP plus HES130/.4 (n = 10). HES130/.4 was administrated before the construction of colonic anastomosis, 15 mL/kg/24 hours and daily for 4 postoperative days. Anastomotic bursting pressures (ABPs) were measured in vivo on day 5. Tissue samples were obtained for analyses of hydroxyproline (HP) contents, myeloperoxidase (MPO) activity, malondialdehyde (MDA), reduced glutathione (GSH) levels, and nuclear factor-kappaB (NF-kappaB) activation. The plasma levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, d-dimer, and protein C (PC) were also measured. Anastomotic granulation tissues were fixed for transmission electron microscopic (TEM) analyses.

RESULTS

Intra-abdominal sepsis led to significant decreases in colonic anastomotic bursting pressures, perianastomotic tissue HP contents, GSH levels, and plasma levels of PC, along with increases in perianastomotic tissue MPO activity, MDA levels, NF-kappaB activation, and plasma levels of TNF-alpha, IL-6, and d-dimer. However, HES130/.4 treatment significantly inhibited all these responses. TEM analyses revealed that there was a trend toward a higher density of fibroblast distribution and a higher rate of fibroblast activation in the SHAM- and HES 130/0.4-treated animals, compared with the CLP group.

CONCLUSIONS

This study showed that moderate doses (15 mL/kg) of HES 130/0.4 administration significantly prevented this intraperitoneal sepsis-induced impaired anastomotic healing of the left colon. This beneficial effect of HES 130/0.4 can be mainly attributed to its anti-inflammatory and antioxidant properties and beneficial effects of modulating endothelial-associated coagulopathy.

Bucillamine improves hepatic microcirculation and reduces hepatocellular injury after liver warm ischaemia-reperfusion injury

BACKGROUND

Liver transplantation and resection surgery involve a period of ischaemia and reperfusion to the liver which initiates an inflammatory cascade resulting in liver and remote organ injury. Bucillamine is a low-molecular-weight thiol antioxidant that is capable of rapidly entering cells.

METHODS

The effect of bucillamine was studied in a rat model of liver ischaemia-reperfusion injury with 45 min of partial (70%) liver ischaemia and at 3 and 24 h of reperfusion. Controls included ischaemia-reperfusion (I/R) only, sham and bucillamine alone (without ischaemia reperfusion). Liver injury was assessed by serum transaminases (AST and ALT). Sinusoidal blood flow and hepatocyte apoptosis were measured using intravital microscopy (IVM).

RESULTS

The hepatocellular injury of I/R produced a markedly elevated serum AST which was reduced with bucillamine (2072.5 +/- 511.79 vs. 932 +/- 200.8, P < 0.05) at 3 h reperfusion. Bucillamine treatment with I/R also increased parenchymal blood flow [red blood cell (RBC) velocity 242.66 +/- 16.86 vs. 181.11 +/- 17.59, at the end of 3 h of reperfusion) and reduced hepatocyte necrosis/apoptosis at 3 h as well as 24 h (P > 0.001).

CONCLUSION

Bucillamine reduces the hepatocellular injury of liver ischaemia reperfusion and improves parenchymal perfusion.