Anwar Farhood

Intercellular adhesion molecule 1 (ICAM-1) expression and its role in neutrophil-induced ischemia-reperfusion injury in rat liver.

The potential role of intercellular adhesion molecule‐1 (ICAM‐1) in the pathogenesis of reperfusion injury was investigated in male Fischer rats subjected to 45 min of hepatic ischemia and 24 h of reperfusion. ICAM‐1 mRNA levels increased during ischemia in the ischemic liver lobes; however, during reperfusion mRNA levels increased in both the ischemic and nonischemic lobes. Immunohistochemical evaluation indicated ICAM‐1 expression only on sinusoidal lining cells in controls; ischemia‐reperfusion enhanced ICAM‐1 expression in the sinusoids and induced some expression on hepatocytes. The monoclonal anti–ICAM‐1 antibody 1A29, but not an immunoglobulin G control antibody, administered at 1 h and 8 h of reperfusion (2 mg/kg) significantly attenuated liver injury as indicated by 51% lower plasma alanine aminotransferase activities and 32–36% less hepatic necrosis at 24 h without affecting reactive oxygen formation by Kupffer cells and hepatic neutrophils. Although 1A29 reduced neutrophil extravasation in a glycogen peritonitis by 60%, the antibody had no significant effect on hepatic neutrophil infiltration during reperfusion. These data suggest that ICAM‐1 plays a significant role during the neutrophil‐dependent injury phase after hepatic ischemia and reperfusion and therefore blocking this adhesion molecule may have therapeutic potential against postischemic acute liver failure. J. Leukoc. Biol. 57: 368–374; 1995.

Activation of Kupffer cells and neutrophils for reactive oxygen formation is responsible for endotoxin-enhanced liver injury after hepatic ischemia.

The potential role of reactive oxygen species generated by Kupffer cells and neutrophils was investigated in a model of endotoxin-enhanced liver injury after hepatic ischemia. Male Fischer rats were subjected to 20 min ischemia and reperfusion of up to 24 h; .5 mg/kg Salmonella enteritidis endotoxin was injected at 30 min of reperfusion. The animals developed severe liver injury resulting in 50% hepatocellular necrosis at 24 h. Isolated Kupffer cells and neutrophils from the postischemic liver generated 10-fold more superoxide than cells from control livers. Treatment with gadolinium chloride (GdCl3) selectively reduced the capacity of Kupffer cells to generate superoxide by 65% and attenuated liver injury by 73% at 4 h and 58–69% at 24 h. Monoclonal antibodies against neutrophil adhesion molecules (CD11/CD18) had no effect on the early injury but reduced hepatocellular necrosis by 90–95% at 24 h. The antioxidant Trolox and the iron-chelator deferoxamine attenuated liver injury by 71 and 80%, respectively. It is concluded that Kupffer cells are mainly responsible for the initial injury, and neutrophils are the dominant cytotoxic cell type during the later phase. Reactive oxygen generated by both cell types is critical for this pathogenesis.

Sequestration Of Neutrophils In The Hepatic Vasculature During Endotoxemia Is Independent Of β2 Integrins And Intercellular Adhesion Molecule-1

Antibodies against cellular adhesion molecules protect against neutrophil-induced hepatic injury during ischemia-reperfusion and endotoxemia. To test if p2 integrins on neutrophils and intercellular adhesion molecule-1 (ICAM-1) on endothelial cells are involved in neutrophil sequestration in the hepatic vasculature, neutrophil accumulation in the liver was characterized during the early phase of endotoxemia. Intravenous injection of Salmonella enteritidis endotoxin induced a dose-dependent activation of complement, tumor necrosis factor-α (TNF-α) formation, and an increase of hepatic neutrophils with maximal numbers at 5 mg/kg (90 min: 339 ± 14 cells/50 high power fields; controls: 18 ± 2). Administration of 15 μg/kg TNF-α and intravascular complement activation with cobra venom factor (75 αg/kg) had additive effects on hepatic neutrophil accumulation compared with each mediator alone. Monoclonal antibodies (2 mg/kg) to ICAM-1 and the a-chain (CD11a, CD11 b) or the β-chain (CD18) of β2 integrins had no significant effect on hepatic neutrophil count after endotoxin. In contrast, these antibodies inhibited peritoneal neutrophil infiltration in response to glycogen administration by 28% (CD11b), 60% (CD11a, ICAM-1), and 92% (CD18). Our data suggest that TNF-α and complement factors contribute to hepatic neutrophil sequestration during the early phase of endotoxemia. Despite the fact that these inflammatory mediators can up-regulate integrins and ICAM-1, these adhesion molecules are not necessary for neutrophil accumulation in hepatic sinusoids. The protective effect of these antibodies against neutrophil-induced liver injury appears to be due to inhibition of transendothelial migration and adherence to parenchymal cells.

Expression of the human hematopoietic progenitor cell antigen CD34 in vascular and spindle cell tumors.

The human hematopoietic progenitor cell antigen is known as CD34. This antigen is present on normal bone marrow progenitor cells and vaseular endothelial cells. We used the monoclonal antibody auti‐CD34 and immunoperoxidase staining techniques to evaluate the expression of CD34 in benign and malignant vascular and spindle cell tumors. All of the 42 vascular lesions, except two of three lesions of intravascular papillary endothelial hyperplasia, demonstrated diffuse membraneous staining of moderate lo strong intensity of their endothelial cells. Also, normal placentas (five) showed similar staining. All neurofibromas (12), three of five neuromas, and one of four neurilemmomas revealed moderate to strong, diffuse, membraneous staining. Five of eight piloleiomyomas, two of seven angiolciomyomas, and one of five uterine leiomyomas showed focal to dilluse, and weak to moderate, membraneous staining in the smooth muscle component. Six dermatofibrosarcoma protuberans were studied: generalized, strongly positive membraneous staining was present in four. All specimens showed staining of the normal endothelial cells and the cells surrounding the hair follicles (bulge area), sebaceous glands, and eccrine glands. No staining was demonstrated in any of the following fibrohistiocytic tumors: atypical fibroxanthomas (two), fibrous dermatofibromas (23), giant cell tumor of tendon sheath (one), and hemosiderotic dermatofibromas (18). Melanocytic tumors (Spitz nevi (three) and spindle cell superficial spreading malignant melanoma (one)], Merkel cell carcinomas (six), and spindle cell squamous cell carcinomas (two) did not stain with anti‐CD34. Glomus tumors (two) and a hemangiopericytoma were also negative except for their vascular channels. This study demonstates that reactivity with anti‐CD34 is not limited to normal vascular endothelial cells and their neoplasms.

Mitochondrial Bax Translocation Accelerates DNA Fragmentation and Cell Necrosis in a Murine Model of Acetaminophen Hepatotoxicity

Mitochondria generate reactive oxygen and peroxynitrite and release endonucleases during acetaminophen (APAP) hepatotoxicity. Because mitochondrial translocation of Bax can initiate these events, we investigated the potential role of Bax in the pathophysiology of hepatic necrosis after 300 mg/kg APAP in fasted C57BL/6 mice. APAP overdose induced Bax translocation from the cytosol to the mitochondria as early as 1 h after APAP injection. At 6 h, there was extensive centrilobular nitrotyrosine staining (indicator for peroxynitrite formation) and nuclear DNA fragmentation. In addition, mitochondrial intermembrane proteins were released into the cytosol. Plasma alanine aminotransferase (ALT) activities of 5610 ± 600 U/l indicated extensive necrotic cell death. Conversely, Bax gene knockout (Bax–/–) mice had 80% lower ALT activities, less DNA fragmentation, and less intermembrane protein release at 6 h. However, immunohistochemical staining for nitrotyrosine or APAP protein adducts did not show differences between wild-type and Bax–/– mice. In contrast to the early hepatoprotection in Bax–/– mice, plasma ALT activities (7605 ± 480 U/l) and area of necrosis (53 ± 6% hepatocytes) in wild-type animals was similar to values in Bax–/– mice at 12 h. In addition, there was no difference in DNA fragmentation or nitrotyrosine immunostaining. We concluded that the rapid mitochondrial Bax translocation after APAP overdose has no effect on peroxynitrite formation but that it contributes to the mitochondrial release of proteins, which cause nuclear DNA fragmentation. However, the persistent oxidant stress and peroxynitrite formation in mitochondria may eventually trigger the permeability transition pore opening and release intermembrane proteins independently of Bax.

Role of caspase-1 and interleukin-1β in acetaminophen-induced hepatic inflammation and liver injury

Acetaminophen (APAP) overdose can result in serious liver injury and potentially death. Toxicity is dependent on metabolism of APAP to a reactive metabolite initiating a cascade of intracellular events resulting in hepatocellular necrosis. This early injury triggers a sterile inflammatory response with formation of cytokines and innate immune cell infiltration in the liver. Recently, IL-1beta signaling has been implicated in the potentiation of APAP-induced liver injury. To test if IL-1beta formation through caspase-1 is critical for the pathophysiology, C57Bl/6 mice were treated with the pan-caspase inhibitor Z-VD-fmk to block the inflammasome-mediated maturation of IL-1beta during APAP overdose (300 mg/kg APAP). This intervention did not affect IL-1beta gene transcription but prevented the increase in IL-1beta plasma levels. However, APAP-induced liver injury and neutrophil infiltration were not affected. Similarly, liver injury and the hepatic neutrophilic inflammation were not attenuated in IL-1-receptor-1 deficient mice compared to wild-type animals. To evaluate the potential of IL-1beta to increase injury, mice were given pharmacological doses of IL-1beta after APAP overdose. Despite increased systemic activation of neutrophils and recruitment into the liver, there was no alteration in injury. We conclude that endogenous IL-1beta formation after APAP overdose is insufficient to activate and recruit neutrophils into the liver or cause liver injury. Even high pharmacological doses of IL-1beta, which induce hepatic neutrophil accumulation and activation, do not enhance APAP-induced liver injury. Thus, IL-1 signaling is irrelevant for APAP hepatotoxicity. The inflammatory cascade is a less important therapeutic target than intracellular signaling pathways to attenuate APAP-induced liver injury.

Increased P‐selectin gene expression in the liver vasculature and its role in the pathophysiology of neutrophil‐induced liver injury in murine endotoxin shock

We studied the role of P‐selectin, an adhesion molecule known to be important for neutrophil localization to sites of inflammation, in a model of inflammatory liver injury. Male C3Heb/ FeJ (ET‐sensitive) mice treated with 700 mg/kg galactosamine and 100 μg/kg Salmonella abortus equi endotoxin (Gal/ET), murine tumor necrosis factor α (TNF‐α,15 μg/kg), or interleukin‐1 (IL‐1, 13–23 μg/kg), showed increased P‐selectin mRNA levels in the liver. In contrast, C3H/HeJ (ET‐resistant) mice responded only to cytokines with P‐selectin mRNA formation. Whereas no P‐selectin expression was detectable in control livers, there was temporary staining of endothelium in large blood vessels but not in sinusoids between 3 and 5 h after ET, TNF‐α, or IL‐1 treatment. Severe liver injury induced by Gal/ET at 7 h was not inhibited by an anti‐P‐selectin antibody in C3Heb/FeJ mice or in P‐selectin‐deficient animals. Sequestration of neutrophils in sinusoids, i.e. those neutrophils that have been identified as critical for the injury, was not affected by the antibody or in P‐selectin‐deficient mice. However, the temporary margination in portal and postsinusoidal venules was reduced by 75% in anti‐P‐selectin antibody‐treated animals and by 51% in P‐selectin‐deficient mice. We conclude that hepatic P‐selectin gene transcription in vivo involves cytokines. However, blocking P‐selectin neither attenuated sinusoidal neutrophil sequestration nor prevented neutrophil‐induced liver injury during endotoxin shock but attenuated neutrophil margination in larger vessels. Thus, our data demonstrate similarities and fundamental differences in the requirement for adhesion molecules to localize neutrophils in the liver vasculature compared to other organs during an inflammatory response. J. Leukoc. Biol. 63: 288–296; 1998.

Immunohistochemical analysis of clear cell carcinoma of the gynecologic tract

Clear cell carcinoma of the gynecologic tract has been defined in terms of its clinical and histologic features; however, its immunophenotypic profile has not been fully characterized. Seventeen cases of primary clear cell carcinoma from various sites within the female genital tract (11 ovary, 5 uterus, 1 vagina) were analyzed by immunohistochemistry. These tumors were assessed for the expression of cytokeratin 7 (CK7), cytokeratin 20 (CK20), low and high molecular weight cytokeratins (CAM5.2 and 34&bgr;E12, respectively), carcinoembryonic antigen (CEA), Leu-M1, vimentin, estrogen receptor (ER), progesterone receptor (PR), bcl-2, p53, HER-2/neu, and CA-125. The characteristic immunoprofile for all sites was positivity for CK7, CAM5.2, 34&bgr;E12, CEA, Leu-M1, vimentin, bcl-2, p53, and CA-125; variably positivity for ER and HER-2/neu; and negativity for CK20 and PR. For comparison, two cases of urologic clear cell carcinoma (1 bladder, 1 urethra) were also studied, and their profile was found to be similar to the gynecologic cases. Aside from minor differences, clear cell carcinoma appears to have the same immunophenotype regardless of whether it originates in the endometrium, ovary, or genitourinary tract. Much of its profile is similar to other gynecologic adenocarcinomas, but some of the markers studied may be useful in the differential diagnosis of this tumor.

Acetaminophen-induced hepatic neutrophil accumulation and inflammatory liver injury in CD18-deficient mice.

Background: Acetaminophen (APAP) hepatotoxicity is currently the most frequent cause of acute liver failure in the US and many European countries. Although intracellular signalling mechanisms are critical for hepatocellular injury, a contribution of inflammatory cells, especially neutrophils, has been suggested. However, conflicting results were obtained when using immunological intervention strategies.

Neutrophil activation during acetaminophen hepatotoxicity and repair in mice and humans.

Following acetaminophen (APAP) overdose there is an inflammatory response triggered by the release of cellular contents from necrotic hepatocytes into the systemic circulation which initiates the recruitment of neutrophils into the liver. It has been demonstrated that neutrophils do not contribute to APAP-induced liver injury, but their role and the role of NADPH oxidase in injury resolution are controversial. C57BL/6 mice were subjected to APAP overdose and neutrophil activation status was determined during liver injury and liver regeneration. Additionally, human APAP overdose patients (ALT: >800 U/L) had serial blood draws during the injury and recovery phases for the determination of neutrophil activation. Neutrophils in the peripheral blood of mice showed an increasing activation status (CD11b expression and ROS priming) during and after the peak of injury but returned to baseline levels prior to complete injury resolution. Hepatic sequestered neutrophils showed an increased and sustained CD11b expression, but no ROS priming was observed. Confirming that NADPH oxidase is not critical to injury resolution, gp91(phox)⁻/⁻ mice following APAP overdose displayed no alteration in injury resolution. Peripheral blood from APAP overdose patients also showed increased neutrophil activation status after the peak of liver injury and remained elevated until discharge from the hospital. In mice and humans, markers of activation, like ROS priming, were increased and sustained well after active liver injury had subsided. The similar findings between surviving patients and mice indicate that neutrophil activation may be a critical event for host defense or injury resolution following APAP overdose, but not a contributing factor to APAP-induced injury.