Human monoclonal antibody MBL-HCV1 delays HCV viral rebound following liver transplantation: a randomized controlled study.

Rapid allograft infection complicates liver transplantation (LT) in patients with hepatitis C virus (HCV). Pegylated interferon-α and ribavirin therapy after LT has significant toxicity and limited efficacy. The effect of a human monoclonal antibody targeting the HCV E2 glycoprotein (MBL-HCV1) on viral clearance was examined in a randomized, double-blind, placebo-controlled pilot study in patients infected with HCV genotype 1a undergoing LT. Subjects received 11 infusions of 50 mg/kg MBL-HCV1 (n=6) or placebo (n=5) intravenously with three infusions on day of transplant, a single infusion on days 1 through 7 and one infusion on day 14 after LT. MBL-HCV1 was well-tolerated and reduced viral load for a period ranging from 7 to 28 days. Median change in viral load (log10 IU/mL) from baseline was significantly greater (p=0.02) for the antibody-treated group (range -3.07 to -3.34) compared to placebo group (range -0.331 to -1.01) on days 3 through 6 posttransplant. MBL-HCV1 treatment significantly delayed median time to viral rebound compared to placebo treatment (18.7 days vs. 2.4 days, p<0.001). As with other HCV monotherapies, antibody-treated subjects had resistance-associated variants at the time of viral rebound. A combination study of MBL-HCV1 with a direct-acting antiviral is underway.

MyD88-dependent pathways mediate resistance to Cryptosporidium parvum infection in mice.

Cryptosporidium spp. cause diarrheal disease worldwide. Innate immune responses mediating resistance to this parasite are not completely understood. To determine whether MyD88-dependent pathways play a role in resistance to Cryptosporidium parvum, we compared the course of infection in MyD88(-/-) mice to that in their wild-type (WT) littermate controls. Three- to 4-week-old mice were infected with C. parvum, and infection was monitored by quantifying fecal oocyst shedding. Twelve days postinfection, the histology of the intestines was examined to quantify intestinal parasite burden and to determine if there were any pathological changes. Fecal oocyst shedding and intestinal parasite burden were significantly greater in MyD88(-/-) mice than in littermate controls. Nonetheless, both WT and MyD88(-/-) mice cleared the infection within 3 weeks. These results indicate that MyD88-dependent pathways are involved in mediating initial resistance to C. parvum. Since gamma interferon (IFN-gamma) is known to mediate resistance to C. parvum, we also studied infection in MyD88(-/-) mice and WT controls in which this cytokine was temporarily neutralized. Fecal oocyst shedding, as well as intestinal parasite burden, intestinal inflammation, and mortality, was significantly greater in MyD88(-/-) mice in which IFN-gamma was neutralized than in IFN-gamma-neutralized WT mice or in MyD88(-/-) mice in which this cytokine was active. These results suggest that MyD88 and IFN-gamma had an additive effect in conferring protection from C. parvum infection. While this study confirms the importance of IFN-gamma in conferring resistance to infection with C. parvum, it suggests that MyD88-mediated pathways also play a role in innate immunity to this parasite.

Affinity for the insulin-like growth factor-II (IGF-II) receptor inhibits autocrine IGF-II activity in MCF-7 breast cancer cells.

We have investigated the autocrine regulation of insulin-like growth factor-II (IGF-II) signaling by the insulin-like growth factor-I receptor (IGF-IR) and the insulin-like growth factor-II/mannose 6-phosphate receptor (IGF-IIR) in MCF-7 breast cancer cells, employing retroviruses encoding both IGF-I, IGF-II, and IGF-I and II mutants with reductions in affinity for either the IGF-IR or the IGF-IIR. These studies revealed reciprocal roles for IGF-IR and IGF-IIR affinity in the regulation of autocrine IGF-II activity. IGF-IR affinity was required for serum-free proliferation but also for efficient IGF-II secretion. In contrast, cellular proliferation, receptor tyrosine kinase-dependent signaling, and extracellular IGF-II protein accumulation were all reduced in the presence of IGF-IIR affinity. Inhibition of IGF-II signaling appeared to be the sole consequence of IGF-IIR affinity, as no cellular responses attributable to selective IGF-IIR binding by a reduced IGF-IR affinity IGF-II mutant could be detected. By operating as an IGF-II antagonist, the IGF-IIR has tumor suppressor-like properties, a suggestion consistent with reports of loss of heterozygosity at the IGF-IIR locus in a variety of human malignancies.

Early alterations in ras protooncogene mRNA expression in testosterone and estradiol-17 beta induced prostatic dysplasia of noble rats.

BACKGROUND: The simultaneous treatment of intact Noble rats with testosterone and estradiol-17 beta for 16 weeks consistently induces intraductal dysplasia exclusively in the dorsolateral lobe (DLP) of the prostate. The lesion closely resembles human prostatic dysplasia and is considered to be a preneoplastic alteration, since invasive carcinoma frequently develop after long-term treatment of rats with both steroids. In our current study, we investigated steady-state ras transcript expression at the earliest recognized stages of sex steroid-induced dysplasia in the DLP. Our interest in studying ras expression in these evolving lesions stems from the pivotal role this family of genes are thought to play in the regulation of cell division and differentiation as well as in the genesis of a variety of human and animal neoplasms. EXPERIMENTAL DESIGN: Northern blotting and in situ hybridization were used to study ras protooncogene mRNA expression in the DLPs of NBL rats harboring sex steroid-induced ductal dysplasia and to compare findings with those from prostates of castrated and castrated androgen-treated animals. Since the prostate is an androgen-dependent gland, alterations in ras expression were compared with changes in the transcript levels of two androgen-responsive genes that encode for a prostatic secretory protein, seminal vesicle secretion protein II, and the androgen receptor. RESULTS: Similar to the situation for androgen receptor expression, orchiectomy initially enhanced levels of both H- and K-ras transcripts, whereas T administration to castrates was found to return the values to levels found in intact rats. Sixteen weeks of T and E2 administration to intact rats caused levels of H-ras mRNA and a 2.4 kb K-ras transcript to rise by 50 and 60%, respectively in the DLPs with dysplasia when compared with counterpart lobes from untreated control animals. In situ hybridization revealed markedly enhanced H-ras expression in some dysplastic DLP foci and no changes in histologically normal ducts and acini. CONCLUSIONS: Taken together, results from our studies suggest that the enhanced focal expression of ras protooncogenes may participate in early aberrant proliferation of prostatic ductal cells of the DLP. Early alterations of ras expression in dysplastic lesions may therefore be a key contributing event in the multistage development of prostate cancer in this animal model.

The detection of Epstein-Barr virus in hairy cell leukemia cells by in situ hybridization.

Epstein-Barr virus (EBV) has been implicated in the pathogenesis of several B-cell lymphoid proliferations. Because patients with hairy cell leukemia (HCL) have a high incidence of seropositivity for EBV antigens, we studied the cells of HCL for evidence of EBV infection using in situ hybridization techniques. EBV mRNA was detected in the tumor cells in four of six cases using a radiolabeled RNA probe. Confirmatory serologic data were available in three cases in which the viral DNA was detected and in one negative case. Our results suggest that EBV infection may have a pathogenetic role in this disorder.