The prognostic significance of serum viral load, codon 215 reverse transcriptase mutation and CD4+ T cells on progression of HIV disease in a double-blind study of thymopentin

Novel strategy for immunomodulation: Dissolving microneedle array encapsulating thymopentin fabricated by modified two-step molding technology

Thymopentin (TP5) is commonly used in the treatment for autoimmune diseases, with a short plasma half-life (30s) and a long treatment period (7 days to 6 months). It is usually administrated by syringe injection, resulting in compromised patient compliance. Dissolving microneedle array (DMNA) offers a superior approach for transdermal delivery of biological macromolecules, as it allows painless penetration through the stratum corneum and generates minimal biohazardous waste after dissolving in the skin. Despite recent advances in DMNA as a novel approach for transdermal drug delivery, problem of insufficient mechanical strength remains to be solved. In this study, TP5-loaded DMNA (TP5-DMNA) was uniquely developed using a modified two-step molding technology. The higher mechanical strength was furnished by employing bovine serum albumin (BSA) as a co-material to fabricate the needles. The obtained TP5-DMNA containing BSA displayed better skin penetration and higher drug loading efficiency than that without BSA. The in vivo pharmacodynamics study demonstrated that TP5-DMNA had comparative effect on immunomodulation to intravenous injection of TP5, in terms of ameliorating the CD4+/CD8+ ratio, SOD activity and MDA value to the basal level. Only mild irritation was observed at the site of administration. These results suggest that the novel TP5-DMNA utilizing BSA provides an alternative approach for convenient and safe transdermal delivery of TP5, which is a promising administration strategy for future clinical application.

Investigation Into Efficiency of a Novel Glycol Chitosan-Bestatin Conjugate to Protect Thymopoietin Oligopeptides From Enzymatic Degradation

In this study, a novel glycol chitosan (GCS)-bestatin conjugate was synthesized and evaluated to demonstrate its efficacy in protecting thymopoietin oligopeptides from aminopeptidase-mediated degradation. Moreover, the mechanism and relative susceptibility of three thymopoietin oligopeptides, thymocartin (TP4), thymopentin (TP5), and thymotrinan (TP3), to enzymatic degradation were investigated and compared at the molecular level. Initial investigations indicated that formation of the GCS-bestatin conjugate, with a substitution degree of 7.0% (moles of bestatin per mole of glycol glucosamine unit), could significantly protect all 3 peptides from aminopeptidase-mediated degradation in a concentration-dependent manner. The space hindrance and loss of one pair of hydrogen bonds, resulting from the covalent conjugation of chitosan with bestatin, did not affect the specific interaction between bestatin and aminopeptidase. Moreover, TP4 displayed a higher degradation clearance compared with those of TP5 and TP3 under the same experimental conditions. The varying levels of susceptibility of these 3 peptides to aminopeptidase (TP4 > TP5 > TP3) were closely related to differences in their binding energies to enzyme, which mainly involved Van der Waals forces and electrostatic interactions, as supported by the results of molecular dynamics simulations. These results suggest that GCS-bestatin conjugate might be useful in the delivery of thymopoietin oligopeptides by mucosal routes, and that TP3 and TP5 are better alternatives to TP4 for delivery because of their robust resistance against enzymatic degradation.

Synthetic modifications of the immunomodulating peptide thymopentin to confer anti-mycobacterial activity

Effective global control of tuberculosis (TB) is increasingly threatened by the convergence of multidrug-resistant TB and the human immunodeficiency virus (HIV) infection. TB/HIV coinfections exert a tremendous burden on the host's immune system, and this has prompted the clinical use of immunomodulators to enhance host defences as an alternative therapeutic strategy. In this study, we modified the clinically used synthetic immunomodulatory pentapeptide, thymopentin (TP-5, RKDVY), with six arginine residues (RR-6, RRRRRR) at the N- and C-termini to obtain the cationic peptides, RR-11 (RKDVYRRRRRR-NH₂) and RY-11 (RRRRRRRKDVY-NH₂), respectively. The arginine residues conferred anti-mycobacterial activity to TP-5 in the peptides as shown by effective minimum inhibitory concentrations of 125 mg/L and killing efficiencies of >99.99% against both rifampicin-susceptible and -resistant Mycobacterium smegmatis. The immunomodulatory action of the peptides remained unaffected as shown by their ability to stimulate TNF-α production in RAW 264.7 mouse macrophage cells. A distinct change in surface morphology after peptide treatment was observed in scanning electron micrographs, while confocal microscopy and dye leakage studies suggested bacterial membrane disruption by the modified peptides. The modified peptides were non-toxic and did not cause hemolysis of rat red blood cells up to a concentration of 2000 mg/L. Moreover, RY-11 showed synergism with rifampicin and reduced the effective concentration of rifampicin, while preventing the induction of rifampicin resistance. The synthetic peptides may have a potential application in both immunocompetent and immunocompromised TB patients.

Pathogenesis and treatment of HIV infection: the cellular, the immune system and the neuroendocrine systems perspective

Infections with HIV represent a great challenge for the development of strategies for an effective cure. The spectrum of diseases associated with HIV ranges from opportunistic infections and cancers to systemic physiological disorders like encephalopathy and neurocognitive impairment. A major progress in controlling HIV infection has been achieved by highly active antiretroviral therapy (HAART). However, HAART does neither eliminate the virus reservoirs in form of latently infected cells nor does it completely reconstitute immune reactivity and physiological status. Furthermore, the failure of the STEP vaccine trial and the only marginal efficacies of the RV144 trial together suggest that the causal relationships between the complex sets of viral and immunological processes that contribute to protection or disease pathogenesis are still poorly understood. Here, we provide an up-to-date overview of HIV-host interactions at the cellular, the immune system and the neuroendocrine systems level. Only by integrating this multi-level knowledge one will be able to handle the systems complexity and develop new methodologies of analysis and prediction for a functional restoration of the immune system and the health of the infected host.

Expression of thymosin alpha1-thymopentin fusion peptide in Pichia pastoris and its characterization

Thymopentin plays an important role in improving imbalanced immune systems of patients, however, it has a limited half-life in plasma. To get more stable and active thymopentin analogs, a fusion thymosin alpha1-thymopentin (Talpha1-TP5) gene was synthesized and cloned into vector pGAPZalphaA. Talpha1-TP5 fusion peptide was expressed in pichia pastoris and purified by metal chelating chromatography and gel filtration chromatography. The circular dichroism spectra (CD) indicated that the secondary structure of Talpha1-TP5 fusion peptide is dominated by a-helix and random coil. In vitro analysis showed that the plasma half-life of Talpha1-TP5 fusion peptide is 140 +/- 14 min, which is longer than that of TP5 (5.6+/-0.7 min) and Talpha1 (127+/-11 min). The in vitro activity assay presented that Talpha1-TP5 fusion peptide has greater activity in promoting proliferation of Kunming mouse splenocytes, and in vivo experiment it showed better activity in promoting the phagocytosis of macrophages and secretion of IL-2 than both Talpha1 and TP5. Our findings suggest that Talpha1-TP5 fusion peptide might be a potential therapeutic agent.

Pharmacokinetics, toxicity of nasal cilia and immunomodulating effects in Sprague-Dawley rats following intranasal delivery of thymopentin with or without absorption enhancers

Thymopentin (TP 5), a synthetic pentapeptide, has been used in clinic as a modulator for immnuodeficiencies through intramuscular administration. The objectives of this study was to investigate the pharmacokinetics using normal rats and toxicity of nasal cilia as well as immunomodulating effects using immunosuppression rats after intranasal delivery of thymopentin with or without an absorption enhancer. The absorption extent of fluorescein isothiocyanate (FITC) labeled TP 5 via nasal delivery at a single dose is significantly improved by incorporating sodium deoxycholate, Brij 35 and chitosan, respectively. FITC-TP 5 can also be absorbed to such an extent ranging from 15 to 28% after intranasal administration of FITC-TP 5 alone, FITC-TP 5 with sodium caprylate, or with bacitracin, respectively. After seven consecutive days multiple dosing, TP 5 formulation with sodium deoxycholate or Brij 35 caused apparently injury to nasal cilia, indicating these two enhancers would not be appropriate for nasal delivery. Results from superoxide dismutase activity, maleic dialdehyde, T-lymphocyte subsets (CD3+, CD4+, CD8+ and CD4+/CD8+ ratio) analyses suggest that all the selected enhancers improve the modulating effects of TP 5 in the immunosuppression rats. On an overall evaluation, intranasal TP 5 alone, TP 5 with chitosan, or TP 5 with bacitracin formulation may be suitable for the future clinical application.

Chemical Synthesis and Application of C-Terminally 5-Carboxyfluorescein-labelled Thymopentin as a Fluorescent Probe for Thymopoietin Receptor

Thymopentin (TP5) is a synthetic pentapeptide fragment, which corresponds to position 32 - 36 of thymic polypeptide thymopoietin. Thymopoietin and TP5 display a variety of biological functions, including phenotypic differentiation of T cells and the regulation of immune systems. Previous chemical modification experiments suggested that there was an absolute requirement for N-terminal amino acids to maintain the biological activity of TP5. On the basis of this structure-activity relationship, we designed and synthesized the C-terminally 5-carboxyfluorescein-coupled TP5 (TP5-FAM) as a fluorescent probe for thymopoietin receptor. TP5-FAM could bind to the membrane of human lymphoid cell lines, MOLT-4 cells, in which the thymopoietin receptor is expressed. The binding is specific and saturable (K(d) = 33 microM). TP5 and human splenopentin are nearly equipotent inhibitors of TP5-FAM binding to the thymopoietin receptor, but porcine secretin did not show any significant inhibition of TP5-FAM binding to MOLT-4 cells. Thus, TP5-FAM is suggested to be a potent and biologically active ligand that would be useful for studying the binding and functional characteristics of the human thymopoietin receptor.

Primary genotypic and phenotypic HIV-1 drug resistance in recent seroconverters in Madrid

OBJECTIVE

Transmission of drug-resistant HIV-1 strains is increasing with widespread use of antiretroviral drugs in developed countries. This study examined the prevalence of resistant viruses in recent seroconverters in Madrid, Spain.

DESIGN

HIV isolates from 30 consecutive participants with positive or indeterminate HIV antibody test results and a negative test result at a mean of 6.6 months earlier were examined for HIV drug resistance. All study subjects admitted to having very recently engaged in high-risk practices. All were therapeutically naive and were recruited between 1997 and 1999 in a referring health care facility for sexually transmitted diseases.

METHODS

Population-based sequencing of the viral reverse transcriptase (RT) and protease (PR) regions derived from plasma viral RNA was performed. Phenotypic resistance was assessed by a recombinant virus assay.

RESULTS

Overall prevalence of genotypes associated with reduced susceptibility was 26.7% (8 of 30 participants). Resistance mutations were seen against nucleoside analogues in 7 (23.3%), nonnucleoside reverse transcriptase inhibitors in 1 (3.3%), and protease inhibitors in 2 (6.7%). Zidovudine-resistance mutations M41L and/or T215Y were the commonest, found in 20% (6 of 30 participants). Resistance mutations to at least two antiretroviral families (multidrug-resistance) were detected in 2 (6.7%) study subjects. A median infectious dose (IC50) increase of fourfold for any drug was found in 7 patients, and in 2 was > tenfold for zidovudine (genotype M41L + T215Y) and lamivudine (genotype M184V), respectively.

CONCLUSIONS

Drug-resistant HIV variants were present in over one quarter of individuals recently diagnosed as infected in Madrid, Spain. Therefore, resistance testing at baseline should be considered for the optimal design of first-line antiretroviral combinations.

Laboratory Guidelines for the Practical Use of HIV Drug Resistance Tests in Patient Follow-Up

HIV drug resistance is one of the major limitations in the successful treatment of HIV-infected patients using currently available antiretroviral combination therapies. When appropriate, drug susceptibility profiles should be taken into consideration in the choice of a specific combination therapy. Guidelines recommending resistance testing in certain circumstances have been issued. Many clinicians have access to resistance testing and will increasingly use these results in their treatment decisions. In this document, we comment on the different methods available, and the relevant issues relating to the clinical application of these tests. Specifically, the following recommendations can be made: (i) genotypic and phenotypic HIV-1 drug resistance analyses can yield complementary information for the clinician. However, insufficient information currently exists as to which approach is preferable in any particular clinical setting; (ii) when HIV-1 drug resistance testing is required, it is recommended that testing be performed on plasma samples obtained before starting, stopping or changing therapy, on samples that have a viral load above the detection limit of the resistance test; (iii) the panel recommends that genotypic and phenotypic HIV-1 drug resistance testing for clinical purposes be performed in a certified laboratory under strict quality control and quality assurance standards; and (iv) the panel recommends that resistance testing laboratories provide clinicians with resistance reports that include a list of drug-related resistance mutations (genotype) and/or a list of drug-related fold resistance values (phenotype), with interpretations of each by an experienced virologist. The interpretation of genotypic and phenotypic analysis is a complex and developing science, and in order to understand HIV-1 drug resistance reports, communication between the requesting clinician and the expert that interpreted the resistance report is recommended.

Comparison of a point mutation assay with a line probe assay for the detection of the major mutations in the HIV-1 reverse transcriptase gene associated with reduced susceptibility to nucleoside analogues

This study compares the performance of a line probe assay (LiPA) for the detection of the major mutations associated with reduced sensitivity to nucleoside analogues with a well characterised point mutation assay (PMA). Plasma samples obtained from patients in a trial of four reverse transcriptase inhibitors (MRC Quattro Trial) were tested by both LiPA and PMA at baseline, 32nd and 64th weeks for the presence of drug resistance associated mutations in the reverse transcriptase (RT) gene. HIV-1 RNA was extracted from plasma by the Boom method and amplified by RT-PCR prior to being tested by LiPA or PMA. Assay discrepancies were further investigated by sequencing of the RT gene. Of 275 samples available from 98 trial subjects, 246 samples were successfully amplified by PCR and analysed by LiPA and PMA for six mutations. Of the 1476 individual codons analysed, LiPA successfully assayed 1444 (97.8%) and PMA gave a result with 1418 (96.1%). LiPA failed to give a result for 32 codons from 22 samples and PMA failed with 58 codons from 38 samples. Gross differences between the two assays, in which one scored a codon as wild-type only and the other as mutant only or vice versa, occurred at 28 codons analysed (1.9%) representing 26 samples from 20 subjects. Sequencing of 22 of the 26 samples confirmed the LiPA result in nine cases, the PMA result in 11 and detected a novel variant at codon 215 in four cases. The PMA and LiPA approach to the detection of the major mutations that are genotypically associated with reduced sensitivity to nucleoside analogues can correctly detect mutations in 97% of the cases.

Managing resistance to anti-HIV drugs: an important consideration for effective disease management

Current recommendations for the treatment of HIV-infected patients advise highly active antiretroviral therapy (HAART) consisting of combinations of 3 or more drugs to provide long-term clinical benefit. This is because only a complete suppression of virus replication will be able to prevent virus drug resistance, the main cause of drug failure. Virus drug resistance may remain a cause of concern in patients who have already received suboptimal mono- or bitherapy, or for patients who do not experience complete shut-down of virus replication under HAART. For these patients, replacement of one combination therapy regimen by another at drug failure, taking into account the existing resistance profile, will be needed. The development of new drugs will remain necessary for those patients who have failed to respond to all currently available drugs, as will be the institution of more effective and less toxic HAART regimens.

The presence of high amounts of HBV-DNA in serum is associated with suppressed costimulatory effects of interleukin 12 on HBV-induced immune response

BACKGROUND/AIMS

The aim of this study was to examine the influence of the viral load on costimulatory effects of rhIL-12 on the hepatitis B virus (HBV)-induced immune response.

METHODS

Peripheral blood mononuclear cells of HBsAg positive patients without cirrhosis were stimulated with HBsAg, HBcAg, preS1Ag and tetanus toxoid in the absence or presence of IL-12 (0.01, 0.1 and 1 ng/ml). Stimulation by alpha-CD3+alpha-CD28, pokeweed mitogen (PWM) and lipopolysaccharide (LPS) were used as controls. Then, proliferation and cytokine production were determined by 3H-thymidine uptake and ELISA after 72 h. The patients were divided into group 1 (n=21): HBV-DNA: not detectable, group 2 (n=13): HBV-DNA: <300 pg/ml, and group 3 (n= 10): HBV-DNA: >300 pg/ml.

RESULTS

After stimulation with only HBV antigens, the highest amounts of IL-10 were found in group 3, while interferon (IFN)-gamma was rarely detectable. After stimulation with IL-12 and HBV antigens, strong costimulatory effects on IFN-gamma production, as well as proliferation, were observed in all patients except individuals from group 3. With regard to antigen-unrelated stimulation, significantly lower amounts of LPS-induced IFN-gamma production and alpha-CD3+28 induced proliferative responses, but higher amounts of LPS-induced IL-10 were observed in group 3.

CONCLUSIONS

These data suggest that the presence of high amounts of HBV-DNA in serum is associated with suppressed co-stimulatory and regulatory effects of IL-12 on the immune response to HBV antigens. This may be one explanation for the poor response to immunostimulating therapy in patients with a high viral load.

Zidovudine therapy and HIV type 1 mutations in children with symptomatic HIV type 1 infection: effect of switching to didanosine or zidovudine plus didanosine therapy. Italian Multicenter Study Group on HIV Mutations in Children

Type and prevalence of zidovudine (ZDV) resistance mutations in HIV-1-infected children in clinically stable condition and on ZDV monotherapy were analyzed to evaluate the effect of switching to didanosine (ddI) monotherapy or to ZDV plus ddI on the pattern of mutations and on the clinical outcome. Monthly clinical and laboratory controls for HIV-1 infection status were performed; at enrollment and every 4 to 6 months after treatment randomization mutant proviral sequences were evaluated in all the children, whereas viral burden was performed only in a small subgroup of patients randomly selected in each of the three treatment groups. ZDV resistance-associated proviral DNA mutations were defined as low-level resistance (LLR) mutations or medium/high-level resistance (MHLR) mutations; clinical outcome was considered as stable or deteriorating. Results showed that at entry into the study the duration of ZDV therapy was significantly correlated with the presence of mutations, and that the level of resistance given by mutations was associated with the severity both of symptoms and immunodeficiency. After randomization to treatment, in patients with mutations that confer LLR a better clinical outcome with ddI monotherapy than with ZDV plus ddI and ZDV alone was observed in the subsequent 6 months, whereas in patients with mutations that confer MHLR no significant difference among the three treatment groups was found. Data showed also that levels of viral burden at the time of changing therapy are related to clinical outcome if measured by plasma viral load. These results suggest that genotypic resistance assays, together with viral load, may prove useful for rational treatment decisions both at the start of therapy and with failure.

The sequential occurrence of pol 215 and pol 41 zidovudine resistance mutations is associated in an additive fashion with low CD4 cell counts and high plasma and cellular HIV viral load

We report on a cross-sectional study of virological and immunological surrogate markers of HIV infection in 115 patients for whom a determination of the pol 215 and pol 41 zidovudine (ZDV) resistance mutations had been described between January 1995 and February 1996. The patients received ZDV alone or a combination of ZDV and zalcitabine or didanosine. A total of 55, 15 and 45 patients exhibited a wild (W), a mixed (MIX) or a mutant (M) genotype at codon pol 215, respectively; 85, 10 and 20 patients exhibited a W, a MIX or a M genotype at codon pol 41, respectively. Patients exhibiting the pol 215 M genotype had lower CD4 cells, higher plasma viral load and higher proviral burden than patients exhibiting the pol 215 W genotype. Patients who had variants exhibiting both pol 215 M and pol 41 M or MIX genotypes had significantly worsened surrogate marker values than patients having variants only carrying the pol 215 M genotype. These observations demonstrate that the two mutations additively associate with pejorative surrogate markers.

Correlation between antiretroviral resistance mutations, biological parameters, and clinical evolution in zidovudine-treated patients infected with human immunodeficiency virus type 1

To evaluate the correlation between zidovudine (ZDV) resistance mutations of human immunodeficiency virus type 1 (HIV-1), biological parameters, and clinical evolution, 111 HIV-1-infected patients treated with ZDV were studied. Specific mutations at codons 70, 215, and 41 in the HIV-1 reverse transcriptase coding region conferring resistance to ZDV were detected using a selective polymerase chain reaction. The appearance of ZDV resistance mutations was significantly correlated with baseline clinical stage, CD4+ cell count, and viral load, but not with duration of ZDV therapy or p24 antigen level. In univariate analysis, results showed a prognostic role of mutations at codons 215 and 41 for clinical progression to the acquired immune deficiency syndrome (AIDS) or death. In multivariate analysis after controlling for viral load, CD4+ cell count, and clinical stage, the presence of the mutation at codon 215 (but not at codon 41) remained an independent predictor of subsequent clinical evolution.

Evaluation of the presence of 2-LTR HIV-1 unintegrated DNA as a simple molecular predictor of disease progression

In a preliminary cross-sectional analysis of 109 human immunodeficiency virus type 1 (HIV-1)-infected subjects the presence of 2-long terminal repeat (LTR) unintegrated circular HIV-1 DNA in peripheral blood mononuclear cells (PBMC) was found to be associated with both symptomatic infection (P = 0.0037) and low CD4 counts (P = 0.0004). To investigate the prognostic significance of the presence of 2-LTR HIV-1 DNA, a subset of 23 2-LTR-negative and 25 2-LTR-positive asymptomatic individuals were followed up for 12-24 months. The two groups did not differ in terms of baseline CD4 counts, zidovudine (ZDV) therapy, and duration of HIV-1 infection. Longitudinal analysis of CD4 values did not indicate a significantly different CD4 outcome between the two groups. However, when only ZDV-treated subjects were considered, a significant (P = 0.042) decrease in CD4 counts was found at month 24 with respect to baseline in 2-LTR-positive (n = 12) but not in 2-LTR-negative (n = 11) patients. Moreover, when > 40% CD4 loss from baseline and/or development of CDC stage B or C symptoms were considered as indicators of disease progression, there was a significantly higher number of events in the whole 2-LTR-positive group than in the whole 2-LTR-negative group (P = 0.0197 at month 12, P = 0.0299 at month 18, P = 0.0373 at month 24). Thus, the presence of 2-LTR HIV-1 DNA in PBMC merits further investigation as a simple, qualitative, molecular predictor of disease progression and decreased response to antiretroviral therapy.

Zidovudine resistance mutations and human immunodeficiency virus type 1 DNA burden: longitudinal evaluation of six patients under treatment

Zidovudine (ZDV) is by far the most widely used drug to counteract human immunodeficiency virus type 1 (HIV-1) infection, both in monotherapy and in combination therapy regimens. However, the majority of patients under prolonged ZDV therapy have been shown to harbour HIV-1 mutant genomes displaying reduced sensitivity to the drug in vitro. In order to investigate the pathogenic role of in vitro resistance to ZDV, six HIV-1-infected ZDV-treated subjects were evaluated longitudinally (mean follow-up 28.5 months, range 12-39 months) for HIV-1 DNA load in peripheral blood mononuclear cells (PBMC) and for the presence of HIV-1 pol gene mutations responsible for ZDV resistance. Quantitation of HIV-1 DNA was performed by competitive polymerase chain reaction (cPCR) and the pol genotype was determined by direct sequencing of PCR products. All of the six patients developed one or more of the HIV-1 pol mutations known to confer resistance to ZDV in vitro (Met41-->Leu, Asp67-->Asn, Lys70-->Arg, Thr215-->Phe/Tyr, Lys219-->Gln/Glu). A temporal association was found between HIV-1 DNA burden and the level of ZDV resistance, as predicted on the basis of the pol genotype (genotypic resistance). Both virus load and ZDV resistance were inversely correlated with CD4+ cell counts. These results are compatible with a direct in vivo pathogenetic role for pol gene mutations shown to be involved in resistance to ZDV in vitro. Monitoring the degree of genotypic resistance to ZDV and to other antiretroviral drugs should be considered in designing protocols for the management of treated patients.