HYDROXYETHYL STARCH NORMALIZES PLATELET AND LEUKOCYTE ADHESION WITHIN PULMONARY MICROCIRCULATION DURING LPS-INDUCED ENDOTOXEMIA

Comparison of Treatment Effects of Different Iron Chelators in Experimental Models of Sepsis

Growing evidence indicates that dysregulated iron metabolism with altered and excess iron availability in some body compartments plays a significant role in the course of infection and sepsis in humans. Given that all bacterial pathogens require iron for growth, that iron withdrawal is a normal component of innate host defenses and that bacterial pathogens have acquired increasing levels of antibiotic resistance, targeting infection and sepsis through use of appropriate iron chelators has potential to provide new therapeutics. We have directly compared the effects of three Food and Drug Administration (FDA)-approved chelators (deferoxamine—DFO; deferiprone—DFP; and deferasirox—DFX), as were developed for treating hematological iron overload conditions, to DIBI, a novel purpose-designed, anti-infective and anti-inflammatory water-soluble hydroxypyridinone containing iron-selective copolymers. Two murine sepsis models, endotoxemia and polymicrobial abdominal sepsis, were utilized to help differentiate anti-inflammatory versus anti-infective activities of the chelators. Leukocyte adhesion, as measured by intravital microscopy, was observed in both models, with DIBI providing the most effective reduction and DFX the poorest. Inflammation in the abdominal sepsis model, assessed by cytokine measurements, indicated exacerbation by DFX and DFO for plasma Interleukin (IL)-6 and reductions to near-control levels for DIBI and DFP. Peritoneal infection burden was reduced 10-fold by DIBI while DFX and DFP provided no reductions. Overall, the results, together with those from other studies, revealed serious limitations for each of the three hematological chelators, i.e., as potentially repurposed for treating infection/sepsis. In contrast, DIBI provided therapeutic benefits, consistent with various in vitro and in vivo results from other studies, supporting the potential for its use in treating sepsis.

Hyperthermic intrathoracic chemotherapy after extended pleurectomy and decortication for malignant pleura mesothelioma: an observational study on outcome and microcirculatory changes

Background

In the treatment of malignant pleural mesothelioma the Hyperthermic Intra THOracic Chemotherapy (HITHOC) can improve the efficacy of pleurectomy and decortication with a local cytotoxic effect. However its biological impact in patient's hemodynamic and microcirculatory changes were rarely investigated. Aim of this study is to describe our experience with HITHOC after pleurectomy and decortication evaluating the role of sublingual video-microscopy in assessing the microcirculatory changes in the perioperative period.

Methods

This is a prospective and observational study concerning 10 consecutive patients undergoing extended P/D followed by HITHOC. These patients underwent sublingual microcirculatory monitoring, which was adopted as a routine procedure since 2012. Haemodynamic parameters were collected at eight consecutive times: the day before surgery (T1), induction of anaesthesia (T2), surgical phase before HITHOC beginning (T3), 5 and 30 minutes after HITHOC start (T4 and T5, respectively), 5 minutes from HITHOC end (T6), after the admission in ICU (T7), at discharge from the ICU (T8). Cardiac output (CO) was calculated with MostCare. Systemic vascular resistance (SVR), oxygen delivery (DO₂), and oxygen extraction rate (O₂ER) were calculated using standard formulas. Arterial blood pressure and central venous pressure (CVP) were obtained with standard arterial and venous catheters. At the same times we assessed the sublingual microcirculation with Sidestream Dark Field technique.

Results

Hemodynamic and microcirculatory data were collected in 10 patients, 8 male and 2 females (mean age 68.6±9.0, and body surface area of 1.9±0.1 m²). All patients had arterial hypertension, and one patient had diabetes. The mean arterial pressure significantly decreased at T2, with respect to T1 (P=0.05). CO, CVP, DO₂, O₂ER, and ScvO₂, did not change significantly over the time. All patients needed infusion of noradrenalin from T4 to T6. TVD significantly decreased from T1 to T3, T5, and T8. Similarly, PVD significantly decreased from T1 to T3 and T8, and MFI from T1 to T6 and T8. PPV and HI did not change over the study period. No correlation was found between hemodynamic parameters (MAP, CO, CVP, DO₂, O₂ER, ScvO₂) and microcirculatory data (TVD, PVD, PPV, MFI, HI), at any time of the study.

Conclusions

In patients who receive HITHOC the fluid load can reduce the microvascular impairment restoring the normal tissue perfusion. This process takes days but is most evident in the first 72 h. The use of colloid and blood transfusion is much more effective in restoring microcirculation and reducing tissue damaging.

Sirtuin 2 Regulates Microvascular Inflammation during Sepsis

Objective. Sepsis and septic shock, the leading causes of death in noncoronary intensive care units, kill more than 200,000/year in the US alone. Circulating cell-endothelial cell interactions are the rate determining factor in sepsis inflammation. Sirtuin, a seven-member family of proteins (SIRT1-7), epigenetically controls inflammation. We have studied the roles of SIRTs 1, 3, and 6 in sepsis previously. In this project, we studied the role of SIRT2 on sepsis-related inflammation. Methods. Sepsis was induced in C57Bl/6 (WT), SIRT2 knockout (SIRT2KO), and SIRT2 overexpressing (SIRT2KI) mice by cecal ligation and puncture (CLP). We studied leukocyte/platelet adhesion using intravital microscopy and E-selectin/ICAM-1 adhesion molecule expression in the small intestine with immunohistochemistry (IHC) six hours post-CLP/sham surgery. We also studied 7-day survival rates in WT, SIRT2KO, and SIRT2KI sepsis mice. Results. Compared to WT mice, SIRT2KO mice show exaggeration while SIRT2KI mice show attenuation of cellular adhesion with sepsis in the small intestine. We also show that the small intestinal E-selectin and ICAM-1 expressions increased in SIRT2KO and decreased in SIRT2KI mice versus those in WT sepsis mice. We show that the 7-day survival rate is decreased in SIRT2KO and increased in SIRT2KI sepsis mice. Conclusion. SIRT2 modulates microvascular inflammation in sepsis and affects survival.

The impact of fluid therapy on microcirculation and tissue oxygenation in hypovolemic patients: a review

PURPOSE

An optimal volume replacement strategy aims to restore systemic hemodynamics with the ultimate goals of improving organ perfusion and microcirculation for sustaining adequate tissue oxygenation. This review presents the (patho)physiological basis of hypovolemia, microcirculation, and tissue oxygenation and presents a literature review on the effects of plasma substitutes on microperfusion and oxygenation in the clinical setting.

METHODS

Literature review of the effects of fluid therapy on microcirculation and tissue oxygenation using PubMed search including original papers in English from 1988 to 2009.

RESULTS

We identified a total of 14 articles dealing with the effects of different crystalloids and colloids on organ perfusion, microcirculation, and tissue oxygenation in patients. The results are divergent, but there is a general trend that colloids are superior to crystalloids in improving organ perfusion, microcirculation, and tissue oxygenation. Due to the limited number of studies and different study conditions, a meta-analysis on the effects of the volume replacement strategies on microcirculation is not possible.

CONCLUSIONS

Improving the microcirculation by volume replacement appears to be a promising issue when treating the critically ill. The growing insights from animal experiments have to be translated into the clinical setting to identify the optimal fluid regimen for correcting hypovolemia. New techniques for monitoring microcirculation at the bedside might provide such endpoints, although these have to be validated also in the clinical setting. Whether improved microperfusion and tissue oxygenation by fluid therapy will also improve patient outcomes will have to be proven by future studies.

In vivo tumor cell adhesion in the pulmonary microvasculature is exclusively mediated by tumor cell--endothelial cell interaction

BACKGROUND

Metastasis formation is the leading cause of death among colon cancer patients. We established a new in-situ model of in vivo microscopy of the lung to analyse initiating events of metastatic tumor cell adhesion within this typical metastatic target of colon cancer.

METHODS

Anaesthetized CD rats were mechanically ventilated and 106 human HT-29LMM and T84 colon cancer cells were injected intracardially as single cell suspensions. Quantitative in vivo microscopy of the lung was performed in 10 minute intervals for a total of 40 minutes beginning with the time of injection.

RESULTS

After vehicle treatment of HT-29LMM controls 15.2 +/- 5.3; 14.2 +/- 7.5; 11.4 +/- 5.5; and 15.4 +/- 6.5 cells/20 microscopic fields were found adherent within the pulmonary microvasculature in each 10 minute interval. Similar numbers were found after injection of the lung metastasis derived T84 cell line and after treatment of HT-29LMM with unspecific mouse control-IgG. Subsequently, HT-29LMM cells were treated with function blocking antibodies against beta1-, beta4-, and alphav-integrins wich also did not impair tumor cell adhesion in the lung. In contrast, after hydrolization of sialylated glycoproteins on the cells' surface by neuraminidase, we observed impairment of tumor cell adhesion by more than 50% (p < 0.05). The same degree of impairment was achieved by inhibition of P- and L-selectins via animal treatment with fucoidan (p < 0.05) and also by inhibition of the Thomson-Friedenreich (TF)-antigen (p < 0.05).

CONCLUSIONS

These results demonstrate that the initial colon cancer cell adhesion in the capillaries of the lung is predominantly mediated by tumor cell - endothelial cell interactions, possibly supported by platelets. In contrast to reports of earlier studies that metastatic tumor cell adhesion occurs through integrin mediated binding of extracellular matrix proteins in liver, in the lung, the continuously lined endothelium appears to be specifically targeted by circulating tumor cells.

Update on treatments for endotoxemia

Endotoxemia is a major cause of morbidity and mortality in horses affected by colic. This article briefly reviews the pathogenesis of endotoxemia in horses with colic, reviews current established treatments, and describes new advances in the treatment of endotoxemia.