Inhibition of CXCR1/2 reduces the emperipolesis between neutrophils and megakaryocytes in the Gata1low model of myelofibrosis.

Emperipolesis between neutrophils and megakaryocytes was first identified by transmission electron microscopy. Although rare under steady-state conditions, its frequency greatly increases in myelofibrosis, the most severe of myeloproliferative neoplasms, in which it is believed to contribute to increasing the transforming growth factor (TGF)-ß microenvironmental bioavailability responsible for fibrosis. To date, the challenge of performing studies by transmission electron microscopy has hampered the study of factors that drive the pathological emperipolesis observed in myelofibrosis. We established a user-friendly confocal microscopy method that detects emperipolesis by staining with CD42b, specifically expressed on megakaryocytes, coupled with antibodies that recognize the neutrophils (Ly6b or neutrophil elastase antibody). With such an approach, we first confirmed that the bone marrow from patients with myelofibrosis and from Gata1low mice, a model of myelofibrosis, contains great numbers of neutrophils and megakaryocytes in emperipolesis. Both in patients and Gata1low mice, the emperipolesed megakaryocytes were surrounded by high numbers of neutrophils, suggesting that neutrophil chemotaxis precedes the actual emperipolesis event. Because neutrophil chemotaxis is driven by CXCL1, the murine equivalent of human interleukin 8 that is expressed at high levels by malignant megakaryocytes, we tested the hypothesis that neutrophil/megakaryocyte emperipolesis could be reduced by reparixin, an inhibitor of CXCR1/CXCR2. Indeed, the treatment greatly reduced both neutrophil chemotaxis and their emperipolesis with the megakaryocytes in treated mice. Because treatment with reparixin was previously reported to reduce both TGF-ß content and marrow fibrosis, these results identify neutrophil/megakaryocyte emperipolesis as the cellular interaction that links interleukin 8 to TGF-ß abnormalities in the pathobiology of marrow fibrosis.

Acrolein-induced oxidative stress and genotoxicity in rats: protective effects of whey protein and conjugated linoleic acid.

Acrolein (AC), a highly reactive hazardous pollutant, poses serious threats to human health. Whey protein (WP) and conjugated linoleic acid (CLA) have beneficial health implications. We investigated the protective effects of WP and CLA against AC-induced toxicity in rats. The animals were orally gavaged with CLA (200 mg/kg/day), WP (200 mg/kg/day), AC (5 mg/kg/day), CLA + AC (200 + 5 mg/kg/day), and WP + AC (200 + 5 mg/kg/day) six days per week for 30 days. The oral administration of AC significantly induced oxidative stress by increasing thiobarbituric acid reactive substances (TBARS) and protein carbonyls (PCOs) levels and decreasing glutathione (GSH) level in the spleen, thymus, and polymorphonuclear leukocytes (PMNs). It also increased the frequencies of micronucleus (MN) and megakaryocytic emperipolesis (ME) and decreased the ratio of polychromatic erythrocytes (PCEs) in bone marrow. Slight alterations in urinary 8-hydroxydeoxyguanosine (8-OHdG) levels were not significant. Co-treatment with CLA + AC or WP + AC ameliorated the values of oxidative stress, MN, PCE, and ME. These data suggest that CLA and WP can improve the antioxidant defenses and preclude the formation of genetic damage and ME.

Argan oil reduces oxidative stress, genetic damage and emperipolesis in rats treated with acrylamide.

Acrylamide (AA), a well-known toxicant, is present in high-temperature-processed foods in heated foods. Argan oil (AO), a natural vegetable oil, is receiving increasing attention due to its powerful biological properties. However, limited information is available about its effects in lymphoid organs and bone marrow. The aim of this study is to investigate the effects of AO on hematological parameters, 8-hydroxydeoxyguanosine (8-OHdG), thiobarbituric acid reactive substances (TBARs), protein carbonyl (PCO), glutathione (GSH), myeloperoxidase (MPO) levels, the formation of micronucleus (MN) and megakaryocytic emperipolesis (ME) against AA-induced toxicity in rats. The animals were treated with AA (50mg/kg/day), AO (6ml/kg/day per day) and AA+AO (50mg+6ml/kg/day) for 30days. Treatment of rats with AA significantly decreased the hematological parameters, GSH and MPO activity and PCEs ratio while it increased TBARs, PCOs and 8-OHdG levels and formation of MN and ME. No significant differences were observed in the animals received the AO alone. Co-treatment with AA+AO ameliorated almost all of the alterations caused by AA and exhibited protective effect in rats. Based on the obtained results, we suggest that integration of AO in diet or using its supplements may be a good strategy for improving tissue injury in many diseases.

The effects of acrylamide on the frequency of megakaryocytic emperipolesis and the mitotic activity of rat bone marrow cells.

BACKGROUND: Although the pathophysiological importance of emperipolesis is not known exactly, it has been reported to increase significantly in cases of various cancer types, different tumours and thrombosis disorders. In this study the effects of acrylamide on the frequency of megakaryocytic emperipolesis and the mitotic activity in rat bone marrow cells were determined. For this purpose, two separate experiments were performed with Sprague-Dawley rats gavaged with 0, 30, 45 and 60 mg acrylamide kg⁻¹ body weight (BW) for five consecutive days. In the second experiment, 3 mg colchicine kg⁻¹ BW was injected intraperitoneally 2 h before cervical dislocation. Bone marrow samples were taken 24 h after the last application in both experiments. RESULTS: It was found that only the highest dose of acrylamide significantly decreased the incidence of megakaryocytic emperipolesis and that the types of bone marrow cells engulfed by megakaryocytes were mostly neutrophil granulocytes. Neither megakaryocytes nor engulfed cells showed any morphological degeneration. In the mitotic activity experiment, doses of 45 and 60 mg acrylamide kg⁻¹ BW decreased the mitotic activity of bone marrow cells in comparison with the control group. CONCLUSION: It was concluded that the decrease in megakaryocytic emperipolesis frequency might be a consequence of the decrease in mitotic activity in bone marrow cells.