Megakaryocyte interaction with subendothelial extracellular matrix is associated with adhesion, platelet-like shape change, and thromboxane A2 production

We have examined the morphological and secretory behavior of rat and guinea pig megakaryocytes exposed for up to 24 hours to extracellular matrix produced by cultured bovine endothelial cells. By phase-contrast microscopy of living cells and in more detail by scanning electron microscopy, the megakaryocytes showed a nonreversible adherence, an extensive formation of filopodia around the periphery like the rays of the sun, and a tendency toward flattening. These filopodia were generally linear with attenuated tips and were larger than, but resembled the filopodia of, rat or guinea pig platelets exposed to this extracellular matrix. In contrast, isolated megakaryocytes on glass or on uncoated plastic surfaces did not show these responses; adherence, in the face of gentle agitation before fixation, was minimal, with rare filopodia and no flattening. Megakaryocytes that interacted with the extracellular matrix produced significant amounts of thromboxane A2, but this did not occur on uncoated surfaces and could not be attributed to other contaminating cells in the megakaryocyte suspensions. The appearance in megakaryocytes of these typical platelet responses indicates that megakaryocytes acquire the functional capabilities of platelets by the synthesis and assembly of platelet substances and organelles. Thromboxane production by megakaryocytes stimulated by the extracellular matrix is a readily quantifiable measure of this capacity.     

Interferon-alpha2b with protease inhibitor-based antiretroviral therapy in patients with AIDS-associated Kaposi sarcoma: an AIDS malignancy consortium phase I trial

We evaluated the safety and maximum tolerated dose of interferon (IFN)-alpha2b in combination with protease inhibitor-based highly active antiretroviral therapy (HAART) in a phase 1 study in 14 patients with AIDS-associated Kaposi sarcoma (KS). Planned IFN dose levels were 0, 1, 5, 10, and 15 million IU administered by daily subcutaneous injection. Dose-limiting toxicities were neutropenia and malaise. The maximum tolerated IFN dose was 5 million IU/d. The median CD4 count increased from 260 cells/muL at baseline to a maximum on-study value of 359 cells/muL. In 6 patients with paired baseline and on-study values, the median HIV RNA level decreased from 20,179 copies/mL to a minimum on-study value of 309 copies/mL. Of 13 patients whose KS response could be evaluated, 5 showed objective tumor regression. Responses occurred in HAART-experienced and HAART-naive subjects. Five patients, including 2 responders, 2 with stable KS, and 1 with progression, had serial measurements of Kaposi sarcoma herpesvirus (KSHV) load. None of these patients, irrespective of treatment arm or KS response, showed durable clearance of KSHV from plasma or peripheral blood mononuclear cells. This study establishes a safe dose of IFN that can be used with HAART and, potentially, with other inhibitors of KS in future clinical trials.     

Safety and Preliminary Efficacy of Vorinostat With R-EPOCH in High-risk HIV-associated Non-Hodgkin's Lymphoma (AMC-075)

Introduction

Vorinostat (VOR), a histone deacetylase inhibitor, enhances the anti-tumor effects of rituximab (R) and cytotoxic chemotherapy, induces viral lytic expression and cell killing in Epstein-Barr virus-positive (EBV⁺) or human herpesvirus-8-positive (HHV-8⁺) tumors, and reactivates latent human immunodeficiency virus (HIV) for possible eradication by combination antiretroviral therapy (cART).

A dose-finding study of liposomal daunorubicin with CVP (COP-X) in advanced NHL

Background:Standard therapy for lymphoma consists of acyclophosphamide (C), doxorubicin, vincristine (V), and prednisone (P) (CHOP)combination regimen. Liposomal daunorubicin (DaunoXome®) is an alternativeto doxorubicin for patients with lymphoma because of its more favorable safetyprofile and potentially more selective uptake in lymphoma. The objectives ofthis study were to determine the maximum tolerated dose (MTD) of liposomaldaunorubucin with CVP (COP-X) and the tolerability of the regimen in patientswith indolent lymphoma. Patients and methods:Patients with low-grade andintermediate-grade lymphoma having adequate cardiac, hepatic, and renalfunction were enrolled. Patients received C 750 mg/m², V 1.4mg/m² (maximum 2.0 mg), and liposomal daunorubicin 50–100mg/m² i.v. on day 1 and P 100 mg p.o. on days 1–5. MTD wasthe liposomal daunorubicin dose associated with 20% dose-limitingtoxicity (ANC <500/mm³ for >5 days or febrile neutropenia). Results:Twenty patients, median age 59 years, were treated. Theliposomal daunorubicin MTD combined with CVP was 70–80 mg/m²,depending on patient population. No significant non-hematologic toxicityoccurred. Response rate was 44% (2 complete and 5 partial responses). Conclusions:A liposomal daunorubicin dose of 80 mg/m²in the COP-X regimen was well tolerated with little non-hematologic toxicity.     

Kaposi sarcoma-associated herpesvirus serum DNA and antibodies not associated with subsequent non-Hodgkin lymphoma risk

Our objective was to analyze, in formula-fed infants, correlates of HIV mother-to-child transmission, including cytomegalovirus (CMV) infection. HIV-infected infants were matched with HIV uninfected by maternal HIV RNA in a case-control design. Infant CMV infection was determined by CMV IgG at 18 months and timed by earlier CMV IgM or CMV DNA. Correlations were assessed using logistic regression. In utero HIV infection was independently associated with congenital CMV infection (P = 0.01), intrapartum HIV infection with congenital-plus-intrapartum/neonatal CMV infection (P = 0.01), and overall HIV with overall CMV infection (P = 0.001), and prematurity (P = 0.004). Congenital and acquired CMV infections are strong independent correlates of mother-to-child HIV transmission.     

Effects of P-MAPA Immunomodulator on Toll-Like Receptors and p53: Potential Therapeutic Strategies for Infectious Diseases and Cancer

Background

Compounds that can act as agonists for toll-like receptors (TLRs) may be promising candidates for the development of drugs against infectious diseases and cancer. The present study aimed to characterize the immunomodulatory effects of P-MAPA on TLRs in vitro and in vivo, as well as to investigate its potential as adjuvant therapy in infectious diseases and cancer.

Methods

For these purposes, the activity of P-MAPA on TLRs was assayed in vitro through NF-??B activation in HEK293 cells expressing a given TLR, and using an in vivo animal model for bladder cancer (BC). The antimicrobial activity of P-MAPA was tested against Mycobacterium tuberculosis (TB) in vitro in an MIC assay, and in vivo using an aerosol infection model of murine tuberculosis. Antitumor effects of P-MAPA were tested in an animal model with experimentally induced BC. Moxifloxacin (MXF) and Bacillus Calmette-Guerin (BCG) were used as positive controls in the animal models.

Results

The results showed that P-MAPA, administered alone or in combination with MXF, induced significant responses in vivo against TB. In contrast, the compound did not show antimicrobial activity in vitro. P-MAPA showed a significant stimulatory effect on human TLR2 and TLR4 in vitro. In BC, TLR2, TLR4 and p53 protein levels were significantly higher in the P-MAPA group than in the BCG group. The most common histopathological changes in each group were papillary carcinoma in BC group, low-grade intraepithelial neoplasia in BCG group and simple hyperplasia in P-MAPA group. Concerning the toxicological analysis performed during BC treatment, P-MAPA did not show evidence for hepatotoxicity and nephrotoxicity.

Conclusions

In conclusion, P-MAPA acted as TLR ligand in vitro and improved the immunological status in BC, increasing TLR2 and TLR4 protein levels. P-MAPA immunotherapy was more effective in restoring p53 and TLRs reactivities and showed significantly greater antitumor activity than BCG. The activation of TLRs and p53 may provide a hypothetical mechanism for the therapeutic effects in both cancer and infectious diseases. Taken together data obtained will encourage the further investigation of P-MAPA as a potential candidate for the treatment of cancer and infectious diseases.