Cerebrospinal and peripheral human immunodeficiency virus type 1 load in a multisite, randomized, double-blind, placebo-controlled trial of D-Ala1-peptide T-amide for HIV-1-associated cognitive-motor impairment

D-Ala1-peptide T-amide (DAPTA) has shown neuroprotection in vitro against gp120-induced loss of dendritic arborization and is promulgated as a CCR5 antagonist. A multisite, randomized, double-blind clinical trial of DAPTA versus placebo prior to combination antiretroviral therapy conducted with human immunodeficiency virus (HIV)-1 seropositive participants having cognitive impairment showed no overall cognitive effect, though subgroups with greater impairment and CD4 cell counts of 201 to 500 cells/mm3 at baseline showed significant improvement. The objective of this study was to examine whether intranasal administration of DAPTA at a dose of 2 mg three times per day (tid) was associated with a reduction of cerebrospinal fluid (CSF) and peripheral (plasma and serum) viral load among a subgroup of participants completing 6 months of treatment. Baseline and 6-month CSF (n = 92) and peripheral (plasma n = 33; serum n = 24) viral load were measured by the Roche Ultrasensitive assay, version 1.5, with reflexive use of the AMPLICOR assay and preservation of the blind. A DAPTA treatment indicator variable was tested using generalized linear models on change in viral load. Peripheral load (combined plasma and serum) was significantly reduced in the DAPTA-treated group. No group differences in CSF viral load were found. This retrospective study on a limited subgroup of the original trial sample indicated that DAPTA treatment may reduce peripheral viral load without concomitant CSF effects. Future studies should be undertaken to confirm the existence of this result and the CSF-periphery dissociation observed with respect to HIV-1-associated cognitive-motor impairment.

Nasal bioavailability of peptide T in rabbits: absorption enhancement by sodium glycocholate and glycofurol

The aim of the present study was to investigate the absolute nasal bioavailability of Peptide T from aqueous formulations containing sodium glycocholate, an absorption enhancer with known effect on epithelial tight junctions, and/or glycofurol in a crossover study in rabbits. Additionally, the reversibility of the absorption enhancing effect of sodium glycocholate was studied by applying enhancer and peptide T with different time intervals and calculating Area Under the Curve of the peptide in plasma. It was shown that the bioavailability of Peptide T was significantly enhanced when glycofurol or sodium glycocholate was added to a nasal formulation. The nasal bioavailability of Peptide T in water (control formulation), 5% glycofurol, 5% glycofurol+1% sodium glycocholate and 1% sodium glycocholate was 5.9, 22, 29 and 59%, respectively. As indicated by the differences in t(max), C(max) and time-concentration profiles different patterns of Peptide T absorption were seen from the vehicles containing glycofurol and sodium glycocholate. In the reversibility study, the enhancing effect of sodium glycocholate on nasal absorption of Peptide T was found to be reversible within 4 h. It was concluded, that nasal absorption of Peptide T in rabbits was effectively enhanced by co-administration of sodium glycocholate, which also provided very fast absorption rates as well as a relatively short lasting effect of the absorption enhancing effect. Co-administration of glycofurol leads to enhanced and prolonged absorption of the peptide. Combining the two enhancers did not lead to increased peptide T absorption compared to 5% glycofurol alone.

Peptide T does not ameliorate experimental autoimmune encephalomyelitis (EAE) in Lewis rats

Peptide T has been shown to inhibit T cell activation and cytokine production and function. Moreover, it has been reported to be a safe treatment in humans. We have studied the ability of peptide T to prevent or ameliorate EAE in Lewis rats. Peptide T was administered subcutaneously at different doses and phases of the disease according to several treatment protocols, but we could not observe a consistent effect of peptide T ameliorating the disease. Lymph node cell proliferation and IL-4 and interferon-gamma production were also studied. We conclude that peptide T neither prevents nor ameliorates EAE in Lewis rats.

Randomized double-blind placebo-controlled trial of peptide T for HIV-associated cognitive impairment

BACKGROUND

Cognitive impairment is a common consequence of human immunodeficiency virus (HIV) infection, and dementia is one of the diseases that defines the acquired immunodeficiency syndrome. Peptide T (d-ala-peptide-T-amide) has been reported to block the binding of gp120 to brain tissue and to protect neurons from the toxic effects of gp120 in vitro. In pilot studies, administration of peptide T to HIV-positive patients with cognitive impairment was associated with improvement in cognition and constitutional symptoms.

OBJECTIVE

To determine whether the intranasal administration of peptide T would improve cognitive function of HIV-positive patients with cognitive impairment.

PATIENTS AND METHODS

This was a 3-site, double-blind, placebo-controlled trial of peptide T given intranasally at a dosage of 2 mg 3 times a day for 6 months. Participants were HIV-seropositive persons with evidence of cognitive deficits on a screening test battery. Concomitant antiretroviral therapy was allowed. Randomization to the 2 study arms was balanced according to several stratification variables, such as CD4+ cell count, severity of cognitive impairment, and antiretroviral therapy at study entry. A comprehensive neuropsychological (NP) battery, which yielded 23 scores, was administered at baseline and the study end point. The primary outcome measure was a global NP score derived from the 23 standardized scores. The efficacy end point was the change in NP score at 6 months compared with baseline. Secondary efficacy measures were 7 cognitive domain scores and deficit scores of global and domain performance. The patients who completed the baseline and final NP evaluations (after at least 4 months in the randomized treatment arm) were included in the efficacy analyses. Additional analyses were conducted on subgroups of patients according to the CD4+ count and baseline NP deficit. The incidence of NP improvement in the 2 treatment arms was also compared.

RESULTS

There was no statistically significant difference between the peptide T and placebo groups on the global NP change score, the individual domains, or the deficit scores. Because of an imbalance in the baseline CD4+ cell count between treatment arms, analyses were also adjusted for this variable. These CD4+-adjusted analyses suggested (P = .07; analysis of covariance [ANCOVA]) a greater improvement in the peptide T group. Subgroup analyses indicated a treatment effect for patients whose CD4 cell count was above 0.200 x 10(9)/L (200 cells/microL) at baseline. Moreover, peptide T treatment was associated with overall cognitive improvement in patients with baseline global deficit scores of at least 0.5, while overall deterioration was more common among the placebo group (P = .02; Mantel-Haenszel chi(2) test).

CONCLUSIONS

Peptide T was not significantly different from placebo on the study primary end points. However, additional analyses indicated that peptide T may be associated with improved performance in the subgroup of patients with more evident cognitive impairment (ie, NP global deficit score > or = 0.5) or with relatively preserved immunological status (ie, CD4+ cell count > 0.200 x 10(9)/L).

Treatment of early AIDS dementia in intravenous drug users: high versus low dose peptide T

This placebo-controlled, double blind, cross-over study tested the efficacy of two different doses of Peptide T in the treatment of nine intravenous drug users with early AIDS dementia who were also receiving methadone and AZT. Subjects received Peptide T doses of either 15 or 1.5 mg daily for four weeks. Neuropsychological performance improved in four of five patients treated with the high dose, but at the lower dose, three of four patients showed no improvement on Peptide T when compared with placebo. When subjects who received the high dose were compared with those who received the low dose, a significant dose effect was found only during the active phase of the trial even after correction for differences in level of functioning at baseline.

High-performance liquid chromatographic analysis of Peptide T in rabbit plasma with on-line column enrichment

The present paper describes the development of a simple and sensitive analytical method for quantification of Peptide T (PT) in rabbit plasma, using standard analytical equipment and on-line column enrichment, without prior extraction, clean-up or derivatization. The analytical procedure was found to be accurate, precise and linear. The accuracy was 100% (range 97-103%) and the mean precision was 8% (range 3-14%) for all (n=6) concentrations (0, 15, 50, 100 and 200 ng/ml). The total recovery was found to be approximately 80%, and it was found to be dependent upon the injection rate onto the extraction column. The correlation between added and found concentrations was 0.9982, and the limit of detection was estimated to be around 5 ng/ml. The method is therefore found to be suitable for bioavailability studies, involving Peptide T, in rabbits.

Investigation into the intestinal metabolism of [D-Ala1] peptide T amide: implication for oral drug delivery

The anti-AIDS drug, [D-Ala1] Peptide T amide (D-ASTTTNYT.NH2) is an octapeptide which competitively inhibits the attachment of HIV to the receptor CD4 molecule on the T-lymphocyte. The objective of the study is to investigate the degradative process of this peptide and its effective enzyme inhibitors. The metabolites of [D-Ala1] Peptide T amide in rabbit brush-border membrane vesicles at pH 6.5 are ASTT, ASTTTN, YT and Y. The sequential time-course study of each metabolite reveals that enkephalinase (EC 3.4.24.11) plays an important role in the hydrolysis of [D-Ala1] Peptide T amide to ASTT. With the addition of an enkephalinase inhibitor, thiorphan, 85% of degradation was inhibited. Aminopeptidase is also involved in its degradative process and 25% of inhibition was observed by amastatin, an aminopeptidase inhibitor. The results show that no significant difference was observed between the in situ and chronical loop perfusion studies and enzyme activities are somewhat inhibited under acidic conditions in both methods. Approx. 90% of the parent peptide remained when rats were perfused with pH 4.0 peptide solution at a flow rate of 0.123 ml/min, while only 60% was recovered when pH 6.5 peptide solution was applied. The addition of amastatin made a quadrupled increase in the amount of parent peptide recovered. A 117-fold increment was observed when thiorphan was added. The dimensionless wall permeability of this peptide was 1.19 +/- 0.16 when pH 4.0 peptide solution was used during chronical loop perfusion study. Therefore, this study suggests that [D-Ala1] Peptide T amide could be absorbed via small intestine where enzymatic degradation s a rate-limiting step for the absorption of this peptide.

Peptide T improves psoriasis when infused into lesions in nanogram amounts

In each of 14 patients, two small but comparable psoriatic lesions were infused for 2 weeks with either saline or a saline solution of peptide T (as its analog D-ala1-peptide T amide) at 10(-7) mol/L with Alzet osmotic pumps worn extracorporeally. During infusion, lesions were photographed and scored for clinical features of psoriasis on a 9-point scale. After another 7 days, biopsy specimens were taken from the infused sites, and sections were scored for features of psoriasis on a 19-point scale. The differences between means for data from saline- and peptide T-infused lesions were evaluated statistically. Peptide T-infused lesions improved clinically; scores decreased from a mean of 4.35 initially to 1.57 at biopsy, whereas control lesions changed from 4.43 to 3.57 (p less than 0.01 for 1.57 vs 3.57). Histologic scores were also significantly different (5.28 for peptide T vs 10.00 for controls, 0.05 greater than p greater than 0.02). This study provides evidence that intralesionally infused peptide T demonstrates some clearing effect in psoriasis.