Functional and clinical consequences of changes to natural killer cell phenotypes driven by chronic cytomegalovirus infections.

Cytomegalovirus (CMV) infections may affect natural killer (NK) cells and are implicated in age-related disorders-notably poor vascular endothelial function. Changes may be greater in renal transplant recipients (RTR) as they have a high burden of CMV and may influence antibody-dependent cellular cytotoxicity (ADCC) responses to viral antigen. We obtained blood mononuclear cells from RTR stable after transplantation (n = 27) and age- and sex-matched controls (n = 28). Natural killer (NK) cells were assessed for expression of CD107a or TNF-α, after stimulation with autologous antibodies bound to CMV glycoprotein B (measuring ADCC) or anti-CD16 (measuring NK cell activation). Alleles of FCRG3A (encoding CD16; rs396991) were determined by the Taqman assay. The vascular endothelial function was assessed using flow-mediated dilatation (FMD) of the brachial artery. Proportions of NK cells expressing CD16 ex vivo were lower in RTR. Frequencies of NK cells expressing NKG2C or LIR-1 or lacking FcRγ were highest in CMV-seropositive RTR. ADCC was affected by rs396991 genotype and CMV gB antibody levels, but not by RTR status or detection of CMV DNA in plasma. Responses of FcRγ-NK cells to anti-CD16 were lower compared to FcRγ+ NK cells. Increased percentages of LIR-1 + and FcRγ- NK cells correlated with lower FMD. In summary, CMV evokes substantial and similar ADCC responses in CMV seropositive RTR and controls. The equivalence may reflect higher titers of CMV reactive antibody in RTR, as NK responses stimulated by ligation of CD16 were lower. NK cells that were LIR-1 + and/or FcRγ- were induced by CMV and correlated inversely with vascular endothelial function.

Characterization of Natural Killer Cells in HIV Patients Beginning Therapy with a High Burden of Cytomegalovirus.

BACKGROUND: Active infections with cytomegalovirus (CMV) increase NK cell expression of the inhibitory receptor LIR-1 and the activating receptor NKG2C in transplant recipients. However, the effects of CMV on NK cells are different in HIV patients stable on antiretroviral therapy (ART) and have not been analyzed in young HIV patients beginning ART. METHODOLOGY: We followed a cohort of 78 Indonesian HIV patients beginning ART. CMV antibodies were measured in plasma before ART (baseline), and after 1, 3, 6, and 12 months. CMV DNA was sought in blood granulocytes at baseline by quantitative PCR assay and a deletion in the NKG2C gene was identified by PCR. NK cell profiles were monitored by flow cytometry in 19 patients stratified by the presence of CMV DNA. Healthy controls (n = 17) were assessed once. RESULTS: All 78 patients were CMV seropositive and 41 had detectable CMV DNA. CMV DNA+ patients had higher proportions of total NK cells and CD16+ NK cells at baseline, but similar expression of LIR-1 and NKp30 on NK cells on ART. However, levels of CMV antibody were inversely related to median LIR-1 expression on NK cells. A dramatic elevation in cells expressing NKG2C was restricted to CMV DNA+ patients heterozygous for the NKG2C deletion. Patients with High NKG2C expression had lower levels of CMV antibodies. CONCLUSION: A subpopulation of NK cells expressing NKG2C was induced by CMV replication in HIV patients heterozygous for a deletion in this gene. Individuals with an abundant NKG2C+ and LIR-1+ NK cells displayed lower levels of CMV reactive antibody.

CMV drives the expansion of highly functional memory T cells expressing NK-cell receptors in renal transplant recipients.

Cytomegalovirus (CMV) is a common opportunistic infection encountered in renal transplant recipients (RTRs) and may be reactivated without symptoms at any time post-transplant. We describe how active and latent CMV affect T-cell subsets in RTRs who are stable on maintenance therapy. T-cell responses to CMV were assessed in RTRs (n = 54) >2 years post-transplant, and healthy controls (n = 38). Seven RTRs had CMV DNA detectable in plasma. CMV antibody and DNA aligned with increased proportions of CD8+ T cells and reduced CD4/CD8 ratios. This paralleled an expansion of effector memory T-cell (TEM ), terminally differentiated T-cell (TEMRA ) and CD57+ TEMRA cell populations. Expression of NK-cell receptors, LIR-1 and KLRG1 on CD4+ and CD8+ CD57+ TEM and TEMRA cells correlated with elevated interferon-γ and cytotoxic responses to anti-CD3 and increased cytotoxic responses to CMV phosphoprotein (pp) 65 in RTRs who carried CMV DNA. CD8+ T cells from all CMV seropositive RTRs responded efficiently to CMV immediate early (IE) -1 peptides. The data show that latent and active CMV infection can alter T-cell subsets in RTRs many years after transplantation, and up-regulate T-cell expression of NK-cell receptors. This may enhance effector responses of CD4+ and CD8+ T cells against CMV.

Asymptomatic CMV infections in long-term renal transplant recipients are associated with the loss of FcRγ from LIR-1+ NK cells.

While it is established that cytomegalovirus (CMV) disease affects NK-cell profiles, the functional consequences of asymptomatic CMV replication are unclear. Here, we characterize NK cells in clinically stable renal transplant recipients (RTRs; n = 48) >2 years after transplantation. RTRs and age-matched controls (n = 32) were stratified by their CMV serostatus and the presence of measurable CMV DNA. CMV antibody or CMV DNA influenced expression of NKG2C, LIR-1, NKp30, NKp46, and FcRγ, a signaling adaptor molecule, on CD56dim NK cells. Phenotypic changes ascribed to CMV were clearer in RTRs than in control subjects and affected NK-cell function as assessed by TNF-α and CD107a expression. The most active NK cells were FcRγ- LIR-1+ NKG2C- and displayed high antibody-dependent cell cytotoxicity responses in the presence of immobilized CMV glycoprotein B reactive antibody. However, perforin levels in supernatants from RTRs with active CMV replication were low. Overall we demonstrate that CMV can be reactivated in symptom-free renal transplant recipients, affecting the phenotypic, and functional profiles of NK cells. Continuous exposure to CMV may maintain and expand NK cells that lack FcRγ but express LIR-1.

Evaluation of 4-thiazolidinone derivatives as potential reverse transcriptase inhibitors against HIV-1 drug resistant strains.

Rapid emergence of drug resistance is crucial in management of HIV infection limiting implementation of efficacious drugs in the ART regimen. Designing new molecules against HIV drug resistant strains is utmost essential. Based on the anti-HIV-1 activity, we selected four 4-thiazolidinone derivatives (S009-1908, S009-1909, S009-1911, S009-1912) and studied their interaction with reverse transcriptase (RT) from a panel of 10 clinical isolates (8 nevirapine resistant and two susceptible) using in silico methods, and inhibition pattern using in vitro cell based assays. On the basis of binding affinity observed in in silico analysis, 2-(2-chloro-6-nitrophenyl)-3-(4, 6-dimethylpyridin-2-yl) thiazolidin-4-one (S009-1912) was identified as the lead molecule followed by S009-1908, S009-1909 and S009-1911. The in vitro activity against the same panel was assessed using TZM-bl assay (IC50: 0.4-11.44µg/ml, TI: 4-126) and subsequently in PBMC assay against a nevirapine resistant clinical isolate (IC50: 0.8-6.65µg/ml, TI: 8.31-11.43) and standard strain from NIH ARRRP (IC50: 0.95-3.6µg/ml, TI: 9-26). The study shows analogue with pyrimidin-2-yl amino substitution at N-3 position of thiazolidin-4-one ring (S009-1908, S009-1909, S009-1911) exhibited enhanced activity as compared to pyridin-2-yl substituted derivatives (S009-1912), suggesting the use 4-thiazolidinones for developing potent inhibitors against HIV-1 drug resistant strains.

Rational design and synthesis of novel thiazolidin-4-ones as non-nucleoside HIV-1 reverse transcriptase inhibitors.

A series of novel thiazolidin-4-one analogues, characterized by different substitution patterns at positions C-2 and N-3 of the thiazolidin-4-one scaffold for anti-HIV-1 activity has been investigated. Most of the compounds showed anti-HIV-1 activity at micromolar concentrations when tested in TZM-bl cells in vitro. Among the thirty-three compounds tested, compound 16 was the most potent inhibitor of HIV-1 replication against HIV-1IIIB, HIV-1ADA5, HIV-1UG070 and HIV-1VB59 (EC50=0.02, 0.08, 0.08 and 0.08 µM, respectively) with selectivity index (SI=6940, 1735, 1692 and 1692) against tested viral strains, respectively. The results of the present study suggested that the substitution of the nitro group at 6' position of the C-2 phenyl ring and 4,6-dimethylpyridin-2-yl at the N-3 position of thiazolidin-4-one had a major impact on the anti-HIV-1 activity and was found to lower cytotoxicity. The substitution of the heteroaryl ring with bromo group and bicyclic heteroaryl ring at N-3 thiazolidin-4-one was found to lower anti-HIV-1 activity and increase cytotoxicity. The undertaken docking studies thus facilitated the identification of crucial interactions between the HIV-1 RT enzyme and thiazolidin-4-one inhibitors, which can be used to design new potential inhibitors.

Lead optimization at C-2 and N-3 positions of thiazolidin-4-ones as HIV-1 non-nucleoside reverse transcriptase inhibitors.

Based on rational drug design approach, a series of novel thiazolidin-4-ones bearing different aryl/heteroaryl moieties at position C-2 and N-3 are synthesized and evaluated as potent inhibitors for human immunodeficiency virus type-1 reverse transcriptase enzyme (HIV-1 RT). An in vitro HIV-1 RT assay showed that the compounds 4, 5, 6, 8, 12, 13, 14 and 17 have shown high inhibition of reverse transcriptase (75.41, 95.50, 98.07, 91.24, 85.27, 77.59, 84.11 & 76.49% inhibition) enzyme activity. Further, cell based assay showed that compounds 4, 5, 8 &12 are identified as the best compounds of the series (EC(50) ranged from 0.09 to 0.8 µg/ml and 0.12 to 1.06 µg/ml) against HIV-1 III(B) and HIV-1 ADA5 strains, respectively. Moreover, the compounds which were active against HIV-1 III(B) and HIV-1 ADA5 were also found to be active against primary isolates (EC(50) ranged from 0.10 to 1.55 µg/ml against HIV-1 UG070 and 0.07 to 1.1 µg/ml against HIV-1 VB59), respectively. Structure-activity relationship (SAR) studies demonstrated the importance of the lipophilic bulky substituent pattern on compact heteroaryl ring at N-3, replacement of C4' at C-2 phenyl by trivalent bioisosteric nitrogen and dihalo groups at C-2 aryl/heteroaryl of thiazolidin-4-ones is crucial for anti-HIV-1 activity. Molecular modeling of compounds 4, 5, 8 and 12 in complex with HIV-1 RT demonstrate that there is good correlation of results obtained from SAR studies. Therefore the compounds 4, 5, 8 and 12 may be considered as good candidates for further optimization of anti-HIV-1 activity.

Deciphering Effects of Uncontrolled Cytomegalovirus Replication on Immune Responses in Cytomegalovirus DNA-Positive Renal Transplant Recipients.

Cytomegalovirus (CMV) is a highly prevalent virus and a common cause of morbidity in solid organ transplant patients. It is also known for its long-lasting imprint on the immune system, expanding populations of highly differentiated T cells and natural killer (NK) cells with novel phenotypes. However, it is unclear whether these cells mark success or failure in the management of an active infection. We assessed CMV reactivation in 54 renal transplant recipients (RTRs) by measuring CMV DNA in plasma samples. Function and phenotype of T cells and NK cells were then assessed in seven RTR with detectable CMV DNA. The patient with highest CMV viral load (P1) displayed increased NK cell function and abundant highly differentiated T cells. We compare P1 with the other six patients and review possible scenarios of cross-regulation between NK cells and T cells.