Serine proteases mediate leukocyte recruitment and hepatic microvascular injury in the acute phase following extended hepatectomy.

OBJECTIVE: Post-hepatectomy liver failure (PHLF) is the main limitation of extended liver resection. The molecular mechanism and the role of leukocytes in the development of PHLF remain to be unveiled. We aimed to address the impact of serine proteases (SPs) on the acute phase after liver resection by intravitally analyzing leukocyte recruitment and changes in hemodynamics and microcirculation of the liver. METHODS: C57BL/6 mice undergoing 60% partial hepatectomy were treated with aprotinin (broad-spectrum SP inhibitor), tranexamic acid (plasmin inhibitor), or vehicle. Sham-operated animals served as controls. In vivo fluorescence microscopy was used to quantify leukocyte-endothelial interactions immediately after, as well as 120 min after partial hepatectomy in postsinusoidal venules, along with measurement of sinusoidal perfusion rate and postsinusoidal shear rate. Recruitment of leukocytes, neutrophils, T cells, and parameters of liver injury were assessed in tissue/blood samples. RESULTS: Leukocyte recruitment, sinusoidal perfusion failure rate, and shear rate were significantly increased in mice after 60% partial hepatectomy compared to sham-operated animals. The inhibition of SPs or plasmin significantly attenuated leukocyte recruitment and improved the perfusion rate in the remnant liver. ICAM-1 expression and neutrophil recruitment significantly increased after 60% partial hepatectomy and were strongly reduced by plasmin inhibition. CONCLUSIONS: Endothelial activation and leukocyte recruitment in the liver in response to the increment of sinusoidal shear rate were hallmarks in the acute phase after liver resection. SPs mediated leukocyte recruitment and contributed to the impairment of sinusoidal perfusion in an ICAM-1-dependent manner in the acute phase after liver resection.

Blockage of CX3CL1 Attenuates Platelet and Leukocyte Recruitment in Murine Hepatic I/R.

INTRODUCTION: The chemokine fractalkine (CX3CL1) is critically involved in the pathophysiology of different inflammatory diseases and myocardial ischemia-reperfusion (I/R). This study aimed to analyze the role of CX3CL1 in the activation of platelets and leukocytes during hepatic I/R. METHODS: Under inhalation anesthesia, C57BL6 mice were subjected to warm hepatic I/R (90 min/240 min). The animals were pretreated either with a function-blocking anti-mouse CX3CL1 antibody or IgG control administered systemically before ischemia. Sham-operated animals served as controls (n = 7 each group). The inflammatory response and sinusoidal perfusion failure were evaluated by intravital microscopy. Hepatic transaminases plasma levels and histopathological tissue damage were determined as markers of hepatocellular injury. RESULTS: Sinusoidal perfusion failure, leukocyte recruitment to the liver, and transaminase activities were sharply increased upon I/R compared to sham-operated mice. Firm adhesion of platelets and concordantly leukocytes to endothelial cells is reduced significantly by a function-blocking anti-CX3CL1 antibody. We demonstrate that inhibition of CX3CL1 signaling attenuates leukocyte adhesion in the postischemic liver but does not significantly ameliorate overall perfusion failure and hepatocellular injury. DISCUSSION/CONCLUSION: Our in vivo data demonstrate a mild attenuating effect of CX3CL1 blockade on platelet and leukocyte, but not CD4+ T cell accumulation and activation in hepatic I/R injury. We report a significant effect of blocking chemokine CX3CL1 on sinusoidal perfusion failure without considerably improving overall hepatocellular injury during early reperfusion.

Indocyanine green fluorescence imaging during partial adrenalectomy.

BACKGROUND: Indocyanine green (ICG) fluorescence imaging represents an emerging technology that facilitates the assessment of tissue vascularity, tissue distinction, and tumor localization during surgery. The aim of this study was to investigate the potential role of ICG imaging during laparoscopic partial adrenalectomy. METHODS: Indocyanine fluorescence imaging was carried out during laparoscopic partial adrenalectomy for bilateral pheochromocytoma and bilateral Cushing's syndrome. A first bolus of 5 mg ICG was applied intravenously upon exposure of the retroperitoneal plane to identify the adrenal borders. The fluorescence was visualized using a Storz® NIR/ICG endoscopic system. As the camera of this system detects NIR light as a blue signal, the well-vascularized adrenal tissue was expected to show a strong fluorescence in the blue color channel in contrast to the surrounding adipose tissue. Following partial adrenalectomy, a second bolus of 5 mg ICG was applied intravenously to evaluate the vascularity of the remaining adrenal tissue. RESULTS: We investigated six adrenal glands from three patients undergoing bilateral partial adrenalectomy. The indication for surgery was pheochromocytoma in two patients and Cushing's syndrome with bilateral adenomas in one patient. Regarding left adrenalectomies, ICG imaging was helpful in visualizing the adrenal borders and the adrenal vein. Further, it facilitated the identification of the hypofluorescent pheochromocytoma and to resect the entire tumor. On the right side, due to the more apparent anatomy, ICG imaging did not contribute to the conduct of the operation. Four adrenal remnants showed a strong vascularization and two remnants were only reasonably vascularized. CONCLUSION: ICG fluorescence may be helpful in guiding partial adrenalectomy and assessing the vascularity of remaining adrenal tissue.

Plasminogen Activator Inhibitor-1 Promotes Neutrophil Infiltration and Tissue Injury on Ischemia-Reperfusion.

OBJECTIVE: Ischemia-reperfusion (I/R) injury significantly contributes to organ dysfunction and failure after myocardial infarction, stroke, and transplantation. In addition to its established role in the fibrinolytic system, plasminogen activator inhibitor-1 has recently been implicated in the pathogenesis of I/R injury. The underlying mechanisms remain largely obscure. APPROACH AND RESULTS: Using different in vivo microscopy techniques as well as ex vivo analyses and in vitro assays, we identified that plasminogen activator inhibitor-1 rapidly accumulates on microvascular endothelial cells on I/R enabling this protease inhibitor to exhibit previously unrecognized functional properties by inducing an increase in the affinity of ß2 integrins in intravascularly rolling neutrophils. These events are mediated through low-density lipoprotein receptor-related protein-1 and mitogen-activated protein kinase-dependent signaling pathways that initiate intravascular adherence of these immune cells to the microvascular endothelium. Subsequent to this process, extravasating neutrophils disrupt endothelial junctions and promote the postischemic microvascular leakage. Conversely, deficiency of plasminogen activator inhibitor-1 effectively reversed leukocyte infiltration, microvascular dysfunction, and tissue injury on experimental I/R without exhibiting side effects on microvascular hemostasis. CONCLUSIONS: Our experimental data provide novel insights into the nonfibrinolytic properties of the fibrinolytic system and emphasize plasminogen activator inhibitor-1 as a promising target for the prevention and treatment of I/R injury.

Parathyroid Autofluorescence-How Does It Affect Parathyroid and Thyroid Surgery? A 5 Year Experience.

Injury to parathyroid glands during thyroid and parathyroid surgery is common and postoperative hypoparathyroidism represents a serious complication. Parathyroid glands possess a unique autofluorescence in the near-infrared spectrum which could be used for their identification and protection at an early stage of the operation. In the present study parathyroid autofluorescence was visualized intraoperatively using a standard Storz laparoscopic near-infrared/indocyanine green (NIR/ICG) imaging system with minor modifications to the xenon light source (filtered to emit 690 nm to 790 nm light, less than 1% in the red and green above 470 nm and no blue light). During exposure to NIR light parathyroid tissue was expected to show autofluorescence at 820 nm, captured in the blue channel of the camera. Over a period of 5 years, we investigated 205 parathyroid glands from 117 patients. 179 (87.3%) glands were correctly identified by their autofluorescence. Surrounding structures such as thyroid, lymph nodes, muscle, or adipose tissue did not reveal substantial autofluorescence. We conclude that parathyroid glands can be identified by their unique autofluorescence at an early stage of the operation. This may help to preserve these fragile structures and their vascularization and lower the rate of postoperative hypocalcemia.

In situ targeting of dendritic cells sets tolerogenic environment and ameliorates CD4+ T-cell response in the postischemic liver.

CD4+ T cells recruited to the liver play a key role in the pathogenesis of ischemia/reperfusion (I/R) injury. The mechanism of their activation during alloantigen-independent I/R is not completely understood. We hypothesized that liver-resident dendritic cells (DCs) interact with CD4+ T cells in the postischemic liver and that modulation of DCs or T-cell-DC interactions attenuates liver inflammation. In mice, warm hepatic I/R (90/120-240 min) was induced. Tolerogenic DCs were generated in situ by pretreatment of animals with the vitamin D analog paricalcitol. A mAb-CD44 was used for blockade of CD4+ T-cell-DC interactions. As shown by 2-photon in vivo microscopy as well as confocal microscopy, CD4+ T cells were closely colocalized with DCs in the postischemic liver. Pretreatment with paricalcitol attenuated I/R-induced maturation of DCs (flow cytometry), CD4+ T-cell recruitment into the liver (intravital microscopy), and hepatocellular/microvascular damage (intravital microscopy, alanine aminotransferase/aspartate aminotransferase, histology). However, interruption of T-cell-DC interaction increased proinflammatory DC maturation and even enhanced tissue damage. Simultaneous treatment with an anti-CD44mAb completely abolished the beneficial effect of paricalcitol on T-cell migration and tissue injury. Our study demonstrates for the first time that hepatic DCs interact with CD4+ T cells in the postischemic liver in vivo; modulation of DCs and/or generation of tolerogenic DCs attenuates intrahepatic CD4+ T-cell recruitment and reduces I/R injury; and interruption of CD44-dependent CD4+ T-cell-DC interactions enhances tissue injury by preventing the modulatory effect of hepatic DCs on T cells, especially type 1 T helper effector cells. Thus, hepatic DCs are strongly involved in the promotion of CD4+ T-cell-dependent postischemic liver inflammation.-Funken, D., Ishikawa-Ankerhold, H., Uhl, B., Lerchenberger, M., Rentsch, M., Mayr, D., Massberg, S., Werner, J., Khandoga, A. In situ targeting of dendritic cells sets tolerogenic environment and ameliorates CD4+ T-cell response in the postischemic liver.

Platelets mediate acute hepatic microcirculatory injury in a protease-activated-receptor-4-dependent manner after extended liver resection.

BACKGROUND: Small-for-size syndrome (SFSS) is a major complication following extended liver resection. The role of platelets in the early development of SFSS remains to be cleared. We aimed to investigate the impact of platelets and PAR-4, a receptor for platelet activation, on the acute phase microcirculatory injury after liver resection by in vivo microscopy analyzing the changes in leukocyte recruitment, platelet-neutrophil interaction, and microthrombosis-induced perfusion failure. METHODS: Sixty-percent partial hepatectomy (PH) models using C57BL/6 mice receiving platelet depletion with anti-GPIbα, PAR-4 blockade with tcY-NH2, or vehicle treatment with saline were used. Sham-operated animals served as controls. Epifluorescence microscopic analysis was performed 2 h after PH to quantify the leukocyte recruitment and microcirculatory changes. Sinusoidal neutrophil recruitment, platelet-neutrophil interaction, and microthrombosis were evaluated using two-photon microscopy. ICAM-1 expression and liver liver injury were assessed in tissue/blood samples. RESULTS: The increments of leukocyte recruitment in post-sinusoidal venules and sinusoidal perfusion failure, the upregulation of ICAM-1 expression, and the deterioration of liver function 2 h after 60% PH were alleviated in the absence of platelets or by PAR-4 blockade. Intensified platelet-neutrophil interaction and microthrombosis in sinusoids were observed 2 h after 60% PH, which significantly attenuated after PAR-4 blockade. CONCLUSION: Platelets play a critical role in acute liver injury after extended liver resection within 2 h. The deactivation of platelets via PAR-4 blockade ameliorated liver function deterioration by suppressing early leukocyte recruitment, platelet-neutrophil interaction, and microthrombosis in hepatic sinusoids.

Predictive Value of Prognostic Nutritional Index for Early Postoperative Mobility in Elderly Patients with Pertrochanteric Fracture Treated with Intramedullary Nail Osteosynthesis.

BACKGROUND: Early postoperative mobilization is essential for orthogeriatric patients. The prognostic nutritional index (PNI) is widely used to evaluate nutritional status. This study sought to investigate the predictive value of PNI for early postoperative mobility in patients with pertrochanteric femur fractures. MATERIALS AND METHODS: This study included 156 geriatric patients with pertrochanteric femur fractures treated with TFN-Advance™ (DePuy Synthes, Raynham, MA, USA). Mobility was evaluated on the third postoperative day and by discharge. Stepwise logistic regression analyses were performed to evaluate the association significance of PNI with postoperative mobility together with comorbidities. The optimal PNI cut-off value for mobility was analyzed using the receiver operating characteristic (ROC) curve. RESULTS: Three days postoperatively, PNI was an independent predictor of mobility (OR: 1.14, 95% CI: 1.07-1.23, p < 0.01). By discharge, it was found that PNI (OR: 1.18, 95% CI: 1.08-1.30, p < 0.01) and dementia (OR: 0.17, 95% CI: 0.07-0.40, p < 0.001) were significant predictors. PNI correlated weakly with age (r = -0.27, p < 0.001). The PNI cut-off value for mobility on the third postoperative day was 38.1 (specificity = 78.5%, sensitivity = 63.6%). CONCLUSIONS: Our findings indicate that PNI is an independent predictor of early postoperative mobility in geriatric patients with pertrochanteric femur fractures treated with TFNA™.

Gluteal Muscle Fatty Atrophy: An Independent Risk Factor for Surgical Treatment in Elderly Patients Diagnosed with Type-III Fragility Fractures of the Pelvis.

BACKGROUND: Gluteal muscle fatty atrophy (gMFA) might impair pelvic stability and negatively influence remobilization in patients with fragility fractures of the pelvis (FFP). This study aimed to investigate the association between gMFA and surgical indication in patients with FFP. METHODS AND MATERIALS: A retrospective analysis of 429 patients (age ≥80) diagnosed with FFP was performed. gMFA of the gluteus maximus, medius, and minimus was evaluated using a standard scoring system based on computer tomography images. RESULTS: No significant difference was found in gMFA between genders or among FFP types. The severity of gMFA did not correlate with age. The severity of gMFA in the gluteus medius was significantly greater than in the gluteus maximus, whereas the most profound gMFA was found in the gluteus minimus. gMFA was significantly more severe in patients who underwent an operation than in conservatively treated patients with type-III FFP, and an independent correlation to surgical indication was found using logistic regression. CONCLUSION: Our findings imply that gMFA is an independent factor for surgical treatment in patients with type-III FFP. Besides focusing on the fracture pattern, the further evaluation of gMFA could be a feasible parameter for decision making toward either conservative or surgical treatment of type-III FFP.