CCR5 inhibitors: emergence, success, and challenges

CKLF1 interference alleviates IL‑1β‑induced inflammation, apoptosis and degradation of the extracellular matrix in chondrocytes via CCR5

Osteoarthritis (OA) is a type of joint disease with a rising prevalence and incidence among the elderly across the global population. Chemokine-like factor 1 (CKLF1) is a human cytokine, which has been demonstrated to be involved in the progression of multiple human diseases. However, little attention has been paid to the impact of CKLF1 on OA. The present study was designed to identify the role of CKLF1 in OA and to clarify the regulatory mechanism. The expression levels of CKLF1 and its receptor CC chemokine receptor 5 (CCR5) were examined by reverse transcription-quantitative PCR (RT-qPCR) and western blotting. A Cell Counting Kit-8 assay was used to estimate cell viability. The levels and expression of inflammatory factors were determined by ELISA and RT-qPCR, respectively. Apoptosis was investigated by TUNEL assays and the protein levels of apoptosis-related factors were analyzed by western blotting. RT-qPCR and western blotting were used to examine the expression of extracellular matrix (ECM) degradation-associated proteins and ECM components. Dimethylmethylene blue analysis was used to analyze the production of soluble glycosamine sulfate additive. A co-immunoprecipitation assay was used to confirm the protein interaction between CKLF1 and CCR5. The results revealed that CKLF1 expression was increased in IL-1β-exposed murine chondrogenic ATDC5 cells. Furthermore, CKLF1 silencing enhanced the viability of IL-1β-induced ATDC5 cells, while inflammation, apoptosis and degradation of the ECM were reduced. Additionally, CKLF1 knockdown led to decreased CCR5 expression in IL-1β-challenged ATDC5 cells, and CKLF1 bound with CCR5. The enhanced viability, as well as the suppressed inflammation, apoptosis and degradation of the ECM, following CKLF1 knockdown in the IL-1β-induced ATDC5 cells were all restored after CCR5 was overexpressed. In conclusion, CKLF1 might serve a detrimental role in the development of OA by targeting its receptor CCR5.

Reduced CCR5 expression among Uganda HIV controllers

BACKGROUND

Several mechanisms including reduced CCR5 expression, protective HLA, viral restriction factors, broadly neutralizing antibodies, and more efficient T-cell responses, have been reported to account for HIV control among HIV controllers. However, no one mechanism universally accounts for HIV control among all controllers. In this study we determined whether reduced CCR5 expression accounts for HIV control among Ugandan HIV controllers. We determined CCR5 expression among Ugandan HIV controllers compared with treated HIV non-controllers through ex-vivo characterization of CD4 + T cells isolated from archived PBMCs collected from the two distinct groups.

RESULTS

The percentage of CCR5 + CD4 + T cells was similar between HIV controllers and treated HIV non-controllers (ECs vs. NCs, P = 0.6010; VCs vs. NCs, P = 0.0702) but T cells from controllers had significantly reduced CCR5 expression on their cell surface (ECs vs. NCs, P = 0.0210; VCs vs. NCs, P = 0.0312). Furthermore, we identified rs1799987 SNP among a subset of HIV controllers, a mutation previously reported to reduce CCR5 expression. In stark contrast, we identified the rs41469351 SNP to be common among HIV non-controllers. This SNP has previously been shown to be associated with increased perinatal HIV transmission, vaginal shedding of HIV-infected cells and increased risk of death.

CONCLUSION

CCR5 has a non-redundant role in HIV control among Ugandan HIV controllers. HIV controllers maintain high CD4 + T cells despite being ART naïve partly because their CD4 + T cells have significantly reduced CCR5 densities.

Inflammation in Urological Malignancies: The Silent Killer

Several studies have investigated the role of inflammation in promoting tumorigenesis and cancer progression. Neoplastic as well as surrounding stromal and inflammatory cells engage in well-orchestrated reciprocal interactions to establish an inflammatory tumor microenvironment. The tumor-associated inflammatory tissue is highly plastic, capable of continuously modifying its phenotypic and functional characteristics. Accumulating evidence suggests that chronic inflammation plays a critical role in the development of urological cancers. Here, we review the origins of inflammation in urothelial, prostatic, renal, testicular, and penile cancers, focusing on the mechanisms that drive tumor initiation, growth, progression, and metastasis. We also discuss how tumor-associated inflammatory tissue may be a diagnostic marker of clinically significant tumor progression risk and the target for future anti-cancer therapies.

CCL5/CCR5 axis in human diseases and related treatments

To defense harmful stimuli or maintain the immune homeostasis, the body produces and recruits a superfamily of cytokines such as interleukins, interferons, chemokines etc. Among them, chemokines act as crucial regulators in defense systems. CCL5/CCR5 combination is known for facilitating inflammatory responses, as well as inducing the adhesion and migration of different T cell subsets in immune responses. In addition, recent studies have shown that the interaction between CCL5 and CCR5 is involved in various pathological processes including inflammation, chronic diseases, cancers as well as the infection of COVID-19. This review focuses on how CCL5/CCR5 axis participates in the pathological processes of different diseases and their relevant signaling pathways for the regulation of the axis. Moreover, we highlighted the gene therapy and chemotherapy studies for treating CCR5-related diseases, including the ongoing clinical trials. The barriers and perspectives for future application and translational research were also summarized.

Lobostemon trigonus (Thunb.) H. Buek, a medicinal plant from South Africa as a potential natural microbicide against HIV-1

ETHNOPHARMACOLOGICAL RELEVANCE

There have been different methods proposed to prevent the sexual transmission of HIV-1 and many of them have centered on the use of anti-retrovirals as microbicides. Given that a large section of the African population still relies on herbal medicine, Lobostemon trigonus (L. trigonus), a traditionally used medicinal plant in South Africa to treat HIV-1 was further investigated for its potential as a natural microbicide to prevent the sexual transmission of HIV-1.

METHODS

The aerial parts of L. trigonus were oven-dried at 80 °C, ground, extracted with boiling water for 30 min and then filtered. The aqueous extract produced was then bioassayed using different HIV-1 inhibition assays. The active components were purified and chemically profiled using ultra-performance liquid chromatography/quadrupole time-of flight mass spectrometry (UPLC-qTOF-MS). The mechanism of HIV-1 inhibition was determined by fusion arrest assay and time of addition assay. Molecular modelling and molecular dynamic simulations, using Schrödinger, were used to better understand the molecule's mechanism of entry inhibition by evaluating their docking affinity and stability against the gp120 of HIV-1.

RESULTS

The aqueous extract of this plant had a broad spectrum of activity against different subtypes of the virus; neutralizing subtype A, B and C in the TZM-bl cells, with IC₅₀ values ranging from 0.10 to 7.21 μg/mL. The extract was also inhibitory to the virus induced cytopathic effects in CEM-SS cells with an EC₅₀ of 8.9 μg/mL. In addition, it inhibited infection in peripheral blood mononuclear cells (PBMC) and macrophages with IC₅₀ values of 0.97 and 4.4 μg/mL, respectively. In the presence of vaginal and seminal simulants, and in human semen it retained its inhibitory activity albeit with a decrease in efficiency, by about 3-fold. Studies of the mode of action suggested that the extract blocked HIV-1 attachment to target cells. No toxicity was observed when the Lactobacilli strains, L. acidophilus, L. jensenii, and L. crispatus that populate the female genital tract were cultured in the presence of L. trigonus extract. UPLC-qTOF-MS analyses of the purified fraction of the extract, confirmed the presence of six compounds of which four were identified as rosmarinic acid, salvianolic acids B and C and lithospermic acid. The additional molecular dynamic simulations provided further insight into the entry inhibitory characteristics of salvianolic acid B against the HIV-1 gp120, with a stable pose being found within the CD4 binding site.

CONCLUSION

The data suggests that the inhibitory effect of L. trigonus may be due to the presence of organic acids which are known to possess anti-HIV-1 properties. The molecules salvianolic acids B and C have been identified for the first time in L. trigonus species. Our study also showed that the L. trigonus extract blocked HIV-1 attachment to target cells, and that it has a broad spectrum of activity against different subtypes of the virus; thus, justifying further investigation as a HIV-1 microbicide.

Targeting Adrenergic Receptors in Metabolic Therapies for Heart Failure

The heart has a reduced capacity to generate sufficient energy when failing, resulting in an energy-starved condition with diminished functions. Studies have identified numerous changes in metabolic pathways in the failing heart that result in reduced oxidation of both glucose and fatty acid substrates, defects in mitochondrial functions and oxidative phosphorylation, and inefficient substrate utilization for the ATP that is produced. Recent early-phase clinical studies indicate that inhibitors of fatty acid oxidation and antioxidants that target the mitochondria may improve heart function during failure by increasing compensatory glucose oxidation. Adrenergic receptors (α1 and β) are a key sympathetic nervous system regulator that controls cardiac function. β-AR blockers are an established treatment for heart failure and α1A-AR agonists have potential therapeutic benefit. Besides regulating inotropy and chronotropy, α1- and β-adrenergic receptors also regulate metabolic functions in the heart that underlie many cardiac benefits. This review will highlight recent studies that describe how adrenergic receptor-mediated metabolic pathways may be able to restore cardiac energetics to non-failing levels that may offer promising therapeutic strategies.

Current Developments on the Role of α1-Adrenergic Receptors in Cognition, Cardioprotection, and Metabolism

The α₁-adrenergic receptors (ARs) are G-protein coupled receptors that bind the endogenous catecholamines, norepinephrine, and epinephrine. They play a key role in the regulation of the sympathetic nervous system along with β and α₂-AR family members. While all of the adrenergic receptors bind with similar affinity to the catecholamines, they can regulate different physiologies and pathophysiologies in the body because they couple to different G-proteins and signal transduction pathways, commonly in opposition to one another. While α₁-AR subtypes (α_1A, α_1B, α_1C) have long been known to be primary regulators of vascular smooth muscle contraction, blood pressure, and cardiac hypertrophy, their role in neurotransmission, improving cognition, protecting the heart during ischemia and failure, and regulating whole body and organ metabolism are not well known and are more recent developments. These advancements have been made possible through the development of transgenic and knockout mouse models and more selective ligands to advance their research. Here, we will review the recent literature to provide new insights into these physiological functions and possible use as a therapeutic target.

HIF-1α is necessary for activation and tumour-promotion effect of cancer-associated fibroblasts in lung cancer

Cancer‐associated fibroblasts (CAFs) activation is crucial for the establishment of a tumour promoting microenvironment, but our understanding of CAFs activation is still limited. In this study, we found that hypoxia‐inducible factor‐1α (HIF‐1α) was highly expressed in CAFs of human lung cancer tissues and mouse spontaneous lung tumour. Accordingly, enhancing the expression of HIF‐1α in fibroblasts via hypoxia induced the conversion of normal fibroblasts into CAFs. HIF‐1α‐specific inhibitor or HIF‐1α knockout (KO) significantly attenuated CAFs activation, which was manifested by the decreased expression of COL1A2 and α‐SMA. In vivo, during tumour formation, the expression of Ki‐67 and proliferating cell nuclear antigen (PCNA) in the tumour tissue with HIF‐1α KO fibroblasts was significantly lower than that of normal fibroblasts. Moreover, HIF‐1α in fibroblasts could activate the NF‐κB signalling pathway and enhance a subsequent secretion of CCL5, thus promoting the tumour growth. In conclusion, our results suggest that HIF‐1α is essential for the activation and tumour‐promotion function of CAFs in lung cancer (LC). And targeting HIF‐1α expression on CAFs may be a promising strategy for LC therapy.

Research Trends and Regulation of CCL5 in Prostate Cancer

Prostate cancer (PCa) is considered as the most common cancer of urologic neoplasms, and its development and prognosis are associated with many factors. Chemokine receptor signaling combine with advances in advanced clinicopathological characteristics have provided new insights into the molecular landscape of prostate cancer. Chemokine (C-C motif) ligand 5 (CCL5) is an important member of the CC subfamily of chemokines. The expression of chemokine CCL5 is positively correlated with poor prognostic features in patients with PCa. Current study suggested that CCL5/CCR5 axis plays a significant role in the proliferation, metastasis, angiogenesis, drug resistance of prostate cancer cells and promotes self-renewal of prostate cancer stem cells (PCSCs). Due to the major domination in CCL5 by prostate cancer and the high cancer-specific mortality with prostate cancer, research on the CCL5/CCR5 axis effective antagonists is widespread application. However, challenges for precision oncology of CCL5/CCR5 axis and effective antagonists in CRPC remain. Herein, we summarized the crucial role of CCL5 in promoting the development of PCa and discussed the antitumor application of the antagonists of CCL5/CCR5 axis.

Discovery of HIV entry inhibitors via a hybrid CXCR4 and CCR5 receptor pharmacophore-based virtual screening approach

Chemokine receptors are key regulators of cell migration in terms of immunity and inflammation. Among these, CCR5 and CXCR4 play pivotal roles in cancer metastasis and HIV-1 transmission and infection. They act as essential co-receptors for HIV and furnish a route to the cell entry. In particular, inhibition of either CCR5 or CXCR4 leads very often the virus to shift to a more virulent dual-tropic strain. Therefore, dual receptor inhibition might improve the therapeutic strategies against HIV. In this study, we aimed to discover selective CCR5, CXCR4, and dual CCR5/CXCR4 antagonists using both receptor- and ligand-based computational methods. We employed this approach to fully incorporate the interaction attributes of the binding pocket together with molecular dynamics (MD) simulations and binding free energy calculations. The best hits were evaluated for their anti-HIV-1 activity against CXCR4- and CCR5-specific NL4.3 and BaL strains. Moreover, the Ca²⁺ mobilization assay was used to evaluate their antagonistic activity. From the 27 tested compounds, three were identified as inhibitors: compounds 27 (CCR5), 6 (CXCR4) and 3 (dual) with IC₅₀ values ranging from 10.64 to 64.56 μM. The binding mode analysis suggests that the active compounds form a salt bridge with the glutamates and π-stacking interactions with the aromatic side chains binding site residues of the respective co-receptor. The presented hierarchical virtual screening approach provides essential aspects in identifying potential antagonists in terms of selectivity against a specific co-receptor. The compounds having multiple heterocyclic nitrogen atoms proved to be relatively more specific towards CXCR4 inhibition as compared to CCR5. The identified compounds serve as a starting point for further development of HIV entry inhibitors through synthesis and quantitative structure-activity relationship studies.

The CCL5/CCR5 Axis in Cancer Progression

Tumor cells can “hijack” chemokine networks to support tumor progression. In this context, the C-C chemokine ligand 5/C-C chemokine receptor type 5 (CCL5/CCR5) axis is gaining increasing attention, since abnormal expression and activity of CCL5 and its receptor CCR5 have been found in hematological malignancies and solid tumors. Numerous preclinical in vitro and in vivo studies have shown a key role of the CCL5/CCR5 axis in cancer, and thus provided the rationale for clinical trials using the repurposed drug maraviroc, a CCR5 antagonist used to treat HIV/AIDS. This review summarizes current knowledge on the role of the CCL5/CCR5 axis in cancer. First, it describes the involvement of the CCL5/CCR5 axis in cancer progression, including autocrine and paracrine tumor growth, ECM (extracellular matrix) remodeling and migration, cancer stem cell expansion, DNA damage repair, metabolic reprogramming, and angiogenesis. Then, it focuses on individual hematological and solid tumors in which CCL5 and CCR5 have been studied preclinically. Finally, it discusses clinical trials of strategies to counteract the CCL5/CCR5 axis in different cancers using maraviroc or therapeutic monoclonal antibodies.

Combination of G2-S16 dendrimer/dapivirine antiretroviral as a new HIV-1 microbicide

Aim: To research the synergistic activity of G2-S16 dendrimer and dapivirine (DPV) antiretroviral as microbicide candidate to prevent HIV-1 infection. Materials & methods: We assess the toxicity of DPV on cell lines by MTT assay, the anti-HIV-1 activity of G2-S16 and DPV alone or combined at several fixed ratios. Finally, their ability to inhibit the bacterial growth in vitro was assayed. The analysis of combinatorial effects and the effective concentrations were performed with CalcuSyn software. Conclusion: Our results represent the first proof-of-concept study of G2-S16/DPV combination to develop a safe microbicide.

Macrophage chemoattractants secreted by cancer cells: Sculptors of the tumor microenvironment and another crucial piece of the cancer secretome as a therapeutic target

Beyond their essential role in leukocyte homing in the context of inflammation, chemokines orchestrate the host response to cancer progression. Chemokines are key accelerators in the amplification of inflammatory signals and metastasis in the distal zone of tumors, indicating possible immune editing of tumor cells in the microenvironment. This review summarizes the main macrophage-attracting chemokines secreted from cancer cells and how these mediators can be targeted to improve cancer immunotherapy in multiple cancer types.

Poly(N-vinylcaprolactam) Nanogels with Antiviral Behavior against HIV-1 Infection

Stimuli-responsive nanogels offer promising perspectives for the development of next generation formulations for biomedical applications. In this work, poly(N-vinylcaprolactam) nanogels were synthesized varying the concentration of monomer and crosslinking agent. Thus, the inhibitory effect of poly(N-vinylcaprolactam) nanogels against HIV-1 infection is presented for the first time. In particular, we have demonstrated that one of the synthesized poly(N-vinylcaprolactam) nanogels with initial concentration of 80 mg of vinylcaprolactam and 4% of crosslinking agent shows antiviral behavior against HIV-1 infection since this nanogel inhibits the viral replication in TZM.bl target cells.

Activity and structural analysis of GRL-117C: a novel small molecule CCR5 inhibitor active against R5-tropic HIV-1s

CCR5 is a member of the G-protein coupled receptor family that serves as an essential co-receptor for cellular entry of R5-tropic HIV-1, and is a validated target for therapeutics against HIV-1 infections. In the present study, we designed and synthesized a series of novel small CCR5 inhibitors and evaluated their antiviral activity. GRL-117C inhibited the replication of wild-type R5-HIV-1 with a sub-nanomolar IC₅₀ value. These derivatives retained activity against vicriviroc-resistant HIV-1s, but did not show activity against maraviroc (MVC)-resistant HIV-1. Structural modeling indicated that the binding of compounds to CCR5 occurs in the hydrophobic cavity of CCR5 under the second extracellular loop, and amino acids critical for their binding were almost similar with those of MVC, which explains viral cross-resistance with MVC. On the other hand, one derivative, GRL-10018C, less potent against HIV-1, but more potent in inhibiting CC-chemokine binding, occupied the upper region of the binding cavity with its bis-THF moiety, presumably causing greater steric hindrance with CC-chemokines. Recent studies have shown additional unique features of certain CCR5 inhibitors such as immunomodulating properties and HIV-1 latency reversal properties, and thus, continuous efforts in developing new CCR5 inhibitors with unique binding profiles is necessary.

Allosteric Modulation of Class A GPCRs: Targets, Agents, and Emerging Concepts

G-protein-coupled receptors (GPCRs) have been tractable drug targets for decades with over one-third of currently marketed drugs targeting GPCRs. Of these, the class A GPCR superfamily is highly represented, and continued drug discovery for this family of receptors may provide novel therapeutics for a vast range of diseases. GPCR allosteric modulation is an innovative targeting approach that broadens the available small molecule toolbox and is proving to be a viable drug discovery strategy, as evidenced by recent FDA approvals and clinical trials. Numerous class A GPCR allosteric modulators have been discovered recently, and emerging trends such as the availability of GPCR crystal structures, diverse functional assays, and structure-based computational approaches are improving optimization and development. This Perspective provides an update on allosterically targeted class A GPCRs and their disease indications and the medicinal chemistry approaches toward novel allosteric modulators and highlights emerging trends and opportunities in the field.

Alternatively-Activated Macrophages Upregulate Mesothelial Expression of P-Selectin to Enhance Adhesion of Ovarian Cancer Cells

Peritoneal metastasis of high-grade serous ovarian cancer (HGSOC) occurs when tumor cells suspended in ascites adhere to mesothelial cells. Despite the strong relationship between metastatic burden and prognosis in HGSOC, there are currently no therapies specifically targeting the metastatic process. We utilized a coculture model and multivariate analysis to examine how interactions between tumor cells, mesothelial cells, and alternatively-activated macrophages (AAM) influence the adhesion of tumor cells to mesothelial cells. We found that AAM-secreted MIP-1β activates CCR5/PI3K signaling in mesothelial cells, resulting in expression of P-selectin on the mesothelial cell surface. Tumor cells attached to this de novo P-selectin through CD24, resulting in increased tumor cell adhesion in static conditions and rolling underflow. C57/BL6 mice treated with MIP-1β exhibited increased P-selectin expression on mesothelial cells lining peritoneal tissues, which enhanced CaOV3 adhesion ex vivo and ID8 adhesion in vivo Analysis of samples from patients with HGSOC confirmed increased MIP-1β and P-selectin, suggesting that this novel multicellular mechanism could be targeted to slow or stop metastasis in HGSOC by repurposing anti-CCR5 and P-selectin therapies developed for other indications.Significance: This study reports novel insights on the peritoneal dissemination occurring during progression of ovarian cancer and has potential for therapeutic intervention.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/13/3560/F1.large.jpg Cancer Res; 78(13); 3560-73. ©2018 AACR.

C-C motif chemokine receptors in gastric cancer

Gastric cancer is the fifth most common cancer and the third leading cause of cancer-associated mortality worldwide. Despite recent advances in molecular and clinical research, patients with gastric cancer at an advanced stage have a dismal prognosis and poor survival rates, and systemic treatment relies predominantly on traditional cytotoxic chemotherapy. To improve patients' quality of life and survival, an improved understanding of the complex molecular mechanisms involved in gastric cancer progression and treatment resistance, and of its clinical application in the development of novel targeted therapies, is urgently required. Chemokines are a group of small chemotactic cytokines that interact with seven-transmembrane G-protein-coupled receptors, and this interaction serves a crucial role in various physiological processes, including organ development and the host immune response, to recruit cells to specific sites in the body. There is also accumulating evidence that chemokines and chemokine receptors (CCRs) contribute to tumor development and progression, as well as metastasis. However, research regarding the functional roles of chemokines and their receptors in cancer is dynamic and context-dependent, and much remains to be elucidated, although various aspects have been explored extensively. In gastric cancer, C-C motif CCRs are involved in the biological behavior of tumor cells, including the processes of growth, invasion and survival, as well as the epithelial-mesenchymal transition. In the present review, attention is given to the clinical relevance of C-C motif CCRs in the development, progression, and metastasis of gastric cancer, particularly CCR7 and CCR5, which have been investigated extensively, as well as their potential therapeutic implications.

TALEN-Mediated Knockout of CCR5 Confers Protection Against Infection of Human Immunodeficiency Virus

Transcription activator-like effector nuclease (TALEN) represents a valuable tool for genomic engineering due to its single-nucleotide precision, high nuclease activity, and low cytotoxicity. We report here systematic design and characterization of 28 novel TALENs targeting multiple regions of CCR5 gene (CCR5-TALEN) which encodes the co-receptor critical for entry of human immunodeficiency virus type I (HIV-1). By systemic characterization of these CCR5-TALENs, we have identified one (CCR5-TALEN-515) with higher nuclease activity, specificity, and lower cytotoxicity compared with zinc-finger nuclease (CCR5-ZFN) currently undergoing clinical trials. Sequence analysis of target cell line GHOST-CCR5-CXCR4 and human primary CD4 T cells showed that the double-strand breaks at the TALEN targeted sites resulted in truncated or nonfunctional CCR5 proteins thereby conferring protection against HIV-1 infection in vitro. None of the CCR5-TALENs had detectable levels of off-target nuclease activity against the homologous region in CCR2 although substantial level was identified for CCR5-ZFN in the primary CD4 T cells. Our results suggest that the CCR5-TALENs identified here are highly functional nucleases that produce protective genetic alterations to human CCR5. Application of these TALENs directly to the primary CD4 T cells and CD34 hematopoietic stem cells (HSCs) of infected individuals could help to create an immune system resistant to HIV-1 infection, recapitulating the success of "Berlin patient" and serving as an essential first step towards a "functional" cure of AIDS.

Progress and Perspectives on HIV-1 microbicide development

The majority of HIV-1 infections occur via sexual intercourse. Women are the most affected by the epidemic, particularly in developing countries, due to their socio-economic dependence on men and the fact that they are often victims of gender based sexual violence. Despite significant efforts that resulted in the reduction of infection rates in some countries, there is still need for effective prevention methods against the virus. One of these methods for preventing sexual transmission in women is the use of microbicides. In this review we provide a summary of the progress made toward the discovery of affordable and effective HIV-1 microbicides and suggest future directions. We show that there is a wide range of compounds that have been proposed as potential microbicides. Although most of them have so far failed to show protection in humans, there are many promising ones currently in pre-clinical studies and in clinical trials.

Impact of genetic variations in C-C chemokine receptors and ligands on infectious diseases

Chemokine receptors and ligands are crucial for extensive immune response against infectious diseases such as malaria, leishmaniasis, HIV and tuberculosis and a wide variety of other diseases. Role of chemokines are evidenced in the activation and regulation of immune cell migration which is important for immune response against diseases. Outcome of disease is determined by complex interaction among pathogen, host genetic variability and surrounding milieu. Variation in expression or function of chemokines caused by genetic polymorphisms could be associated with attenuated immune responses. Exploration of chemokine genetic polymorphisms in therapeutic response, gene regulation and disease outcome is important. Infectious agents in human host alter the expression of chemokines via epigenetic alterations and thus contribute to disease pathogenesis. Although some fragmentary data are available on chemokine genetic variations and their contribution in diseases, no unequivocal conclusion has been arrived as yet. We therefore, aim to investigate the association of CCR5-CCL5 and CCR2-CCL2 genetic polymorphisms with different infectious diseases, transcriptional regulation of gene, disease severity and response to therapy. Furthermore, the role of epigenetics in genes related to chemokines and infectious disease are also discussed.

Incompatible Natures of the HIV-1 Envelope in Resistance to the CCR5 Antagonist Cenicriviroc and to Neutralizing Antibodies

Cenicriviroc is a CCR5 antagonist which prevents human immunodeficiency virus type 1 (HIV-1) from cellular entry. The CCR5-binding regions of the HIV-1 envelope glycoprotein are important targets for neutralizing antibodies (NAbs), and mutations conferring cenicriviroc resistance may therefore affect sensitivity to NAbs. Here, we used the in vitro induction of HIV-1 variants resistant to cenicriviroc or NAbs to examine the relationship between resistance to cenicriviroc and resistance to NAbs. The cenicriviroc-resistant variant KK652-67 (strain KK passaged 67 times in the presence of increasing concentrations of cenicriviroc) was sensitive to neutralization by NAbs against the V3 loop, the CD4-induced (CD4i) region, and the CD4-binding site (CD4bs), whereas the wild-type (WT) parental HIV-1 strain KKWT from which cenicriviroc-resistant strain KK652-67 was obtained was resistant to these NAbs. The V3 region of KK652-67 was important for cenicriviroc resistance and critical to the high sensitivity of the V3, CD4i, and CD4bs epitopes to NAbs. Moreover, induction of variants resistant to anti-V3 NAb 0.5γ and anti-CD4i NAb 4E9C from cenicriviroc-resistant strain KK652-67 resulted in reversion to the cenicriviroc-sensitive phenotype comparable to that of the parental strain, KKWT. Resistance to 0.5γ and 4E9C was caused by the novel substitutions R315K, G324R, and E381K in the V3 and C3 regions near the substitutions conferring cenicriviroc resistance. Importantly, these amino acid changes in the CCR5-binding region were also responsible for reversion to the cenicriviroc-sensitive phenotype. These results suggest the presence of key amino acid residues where resistance to cenicriviroc is incompatible with resistance to NAbs. This implies that cenicriviroc and neutralizing antibodies may restrict the emergence of variants resistant to each other.

[Immunosuppressives to prevent rejection reactions after allogeneic corneal transplantation]

In order to prevent rejection of an allogeneic corneal transplant after perforating (high risk) keratoplasty, active agents from different classes of pharmacological substances are used, as with solid organ transplantation. In addition to glucocorticoids, antiproliferative agents, small molecule inhibitors and antibodies, those belonging to the group of macrolides with their many derivatives represent an interesting class of substances in this context. As a supplement to cyclosporin A (CSA) the most successful macrolide in transplantation medicine, animal experiments are currently being carried out to test newer macrolide derivatives, such as sanglifehrin A (SFA). This overview describes the classes of drugs and modes of action of currently administered standard medications in the clinical routine and new developments are presented.

Insights into the mechanism of inhibition of CXCR4: identification of Piperidinylethanamine analogs as anti-HIV-1 inhibitors

The cellular entry of HIV-1 into CD4(+) T cells requires ordered interactions of HIV-1 envelope glycoprotein with C-X-C chemokine receptor type 4 (CXCR4) receptors. However, such interactions, which should be critical for rational structure-based discovery of new CXCR4 inhibitors, remain poorly understood. Here we first determined the effects of amino acid substitutions in CXCR4 on HIV-1NL 4 - 3 glycoprotein-elicited fusion events using site-directed mutagenesis-based fusion assays and identified 11 potentially key amino acid substitutions, including D97A and E288A, which caused >30% reductions in fusion. We subsequently carried out a computational search of a screening library containing ∼604,000 compounds, in order to identify potential CXCR4 inhibitors. The computational search used the shape of IT1t, a known CXCR4 inhibitor, as a reference and employed various algorithms, including shape similarity, isomer generation, and docking against a CXCR4 crystal structure. Sixteen small molecules were identified for biological assays based on their high shape similarity to IT1t, and their putative binding modes formed hydrogen bond interactions with the amino acids identified above. Three compounds with piperidinylethanamine cores showed activity and were resynthesized. One molecule, designated CX6, was shown to significantly inhibit fusion elicited by X4 HIV-1NL 4 - 3 glycoprotein (50% inhibitory concentration [IC50], 1.9 μM), to inhibit Ca(2+) flux elicited by stromal cell-derived factor 1α (SDF-1α) (IC50, 92 nM), and to exert anti-HIV-1 activity (IC50, 1.5 μM). Structural modeling demonstrated that CX6 bound to CXCR4 through hydrogen bond interactions with Asp97 and Glu288. Our study suggests that targeting CXCR4 residues important for fusion elicited by HIV-1 envelope glycoprotein should be a useful and feasible approach to identifying novel CXCR4 inhibitors, and it provides important insights into the mechanism by which small-molecule CXCR4 inhibitors exert their anti-HIV-1 activities.

Nanotech-derived topical microbicides for HIV prevention: the road to clinical development

More than three decades since its discovery, HIV infection remains one of the most aggressive epidemics worldwide, with more than 35 million people infected. In sub-Saharan Africa, heterosexual transmissions represent nearly 80% of new infections, with 50% of these occurring in women. In an effort to stop the dramatic spread of the HIV epidemic, new preventive treatments, such as microbicides, have been developed. Nanotechnology has revolutionized this field by designing and engineering novel highly effective nano-sized materials as microbicide candidates. This review illustrates the most recent advances in nanotech-derived HIV prevention strategies, as well as the main steps required to translate promising in vitro results into clinical trials.

Synergistic combinations of the CCR5 inhibitor VCH-286 with other classes of HIV-1 inhibitors

Here, we evaluated the in vitro anti-HIV-1 activity of the experimental CCR5 inhibitor VCH-286 as a single agent or in combination with various classes of HIV-1 inhibitors. Although VCH-286 used alone had highly inhibitory activity, paired combinations with different drug classes led to synergistic or additive interactions. However, combinations with other CCR5 inhibitors led to effects ranging from synergy to antagonism. We suggest that caution should be exercised when combining CCR5 inhibitors in vivo.

Increased CXCR4 use of HIV-1 subtype C identified by population sequencing in patients failing antiretroviral treatment compared with treatment-naive patients in Botswana

HIV-1 uses the coreceptors CCR5 and/or CXCR4 for cell entry. Monotropic CCR5-using variants are found early in the infection while CXCR4-using variants may appear after progression to AIDS. CXCR4 use may consist of both monotropic and dualtropic viruses. The viral phenotype is important in evaluating the response to CCR5 inhibitors, a new class of antiviral drugs. The coreceptor use of HIV-1 was investigated using population sequencing in 24 patients from Botswana, carrying HIV-1 subtype C and failing antiretroviral treatment, while 26 treatment-naive patients acted as controls. Single genome sequencing was used to discern minor HIV-1 populations in the treatment-experienced group. The Geno2Pheno method was employed to predict the coreceptor use phenotype from HIV-1 env gp120 V3 DNA sequences. The glycan-charge model adjusted for subtype C was also used for phenotype prediction. The viral phenotype of population sequences was predicted using Geno2Pheno in 24/24 treatment-experienced patients, of whom eight (33%) were predicted to harbor CXCR4-using strains as compared to 2/26 in the treatment-naive group (p=0.03). Single genome sequencing generated 4-23 clones/patient in the treatment-experienced group. Altogether, 90/295 (31%) putative CXCR4-using clones were identified. In 10/24 (42%) treated patients at least one clone was predicted to be CXCR4-using, further increasing the amount of identified treatment-experienced patients with CXCR4 use. Although subtype C is usually associated with comparatively little CXCR4 use, the frequency of CXCR4 use in treatment-experienced patients with subtype C can be higher, which may have implications for the administration of CCR5 inhibitors in this patient group.

The inflammatory chemokine CCL5 and cancer progression

Until recently, inflammatory chemokines were viewed mainly as indispensable “gate keepers” of immunity and inflammation. However, updated research indicates that cancer cells subvert the normal chemokine system and these molecules and their receptors become important constituents of the tumor microenvironment with very different ways to exert tumor-promoting roles. The CCR5 and the CCL5 ligand have been detected in some hematological malignancies, lymphomas, and a great number of solid tumors, but extensive studies on the role of the CCL5/CCR axis were performed only in a limited number of cancers. This review summarizes updated information on the role of CCL5 and its receptor CCR5 in cancer cell proliferation, metastasis, and the formation of an immunosuppressive microenvironment and highlights the development of newer therapeutic strategies aimed to inhibit the binding of CCL5 to CCR5, to inhibit CCL5 secretion, or to inhibit the interactions among tumor cells and the microenvironment leading to CCL5 secretion.

The chemokine system, and its CCR5 and CXCR4 receptors, as potential targets for personalized therapy in cancer

Chemokines and their receptors regulate the trafficking of leukocytes in hematopoiesis and inflammation, and thus are fundamental to the immune integrity of the host. In parallel, members of the chemokine system exert a large variety of functions that dictate processes of cancer development and progression. Chemokines can act as pro-tumoral or anti-tumoral regulators of malignancy by affecting cells of the tumor microenvironment (leukocytes, endothelial cells, fibroblasts) and the tumor cells themselves (migration, invasion, proliferation, resistance to chemotherapy). Several of the chemokines are generally skewed towards the cancer-promoting direction, including primarily the CCR5-CCL5 (RANTES) and the CXCR4-CXCL12 (SDF-1) axes. This review provides a general view of chemokines and chemokine receptors as regulators of malignancy, describing their multi-faceted activities in cancer. The tumor-promoting activities of the CCR5-CCL5 and CXCR4-CXCL12 pathways are enlightened, emphasizing their potential use as targets for personalized therapy. Indeed, novel blockers of chemokines and their receptors are constantly emerging, and two chemokine receptor inhibitors were recently approved for clinical use: Maraviroc for CCR5 and Plerixafor for CXCR4. The review addresses ongoing pre-clinical and clinical trials using these modalities and others in cancer. Then, challenges and opportunities of personalized therapy directed against chemokines and their receptors in malignancy are discussed, demonstrating that such novel personalized cancer therapies hold many challenges, but also offer hope for cancer patients.

P2' benzene carboxylic acid moiety is associated with decrease in cellular uptake: evaluation of novel nonpeptidic HIV-1 protease inhibitors containing P2 bis-tetrahydrofuran moiety

GRL007 and GRL008, two structurally related nonpeptidic human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) containing 3(R),3a(S),6a(R)-bis-tetrahydrofuranylurethane (bis-THF) as the P2 moiety and a sulfonamide isostere consisting of benzene carboxylic acid and benzene carboxamide as the P2' moiety, respectively, were evaluated for their antiviral activity and interactions with wild-type protease (PR(WT)). Both GRL007 (Ki of 12.7 pM with PR(WT)) and GRL008 (Ki of 8.9 pM) inhibited PR(WT) with high potency in vitro. X-ray crystallographic analysis of PR(WT) in complex with GRL007 or GRL008 showed that the bis-THF moiety of both compounds has three direct polar contacts with the backbone amide nitrogen atoms of Asp29 and Asp30 of PR(WT). The P2' moiety of both compounds showed one direct contact with the backbone of Asp30' and a bridging polar contact with Gly48' through a water molecule. Cell-based antiviral assays showed that GRL007 was inactive (50% effective concentration [EC50] of >1 μM) while GRL008 was highly active (EC50 of 0.04 μM) against wild-type HIV-1. High-performance liquid chromatography (HPLC)/mass spectrometry-based cellular uptake assays showed 8.1- and 84-fold higher intracellular concentrations of GRL008 than GRL007 in human MT-2 and MT-4 cell extracts, respectively. Thus, GRL007, in spite of its favorable enzyme-inhibitory activity and protease binding profile, exhibited a lack of antiviral activity in cell-based assays, most likely due to its compromised cellular uptake associated with its P2' benzene carboxylic acid moiety. The anti-HIV-1 potency, favorable toxicity, and binding profile of GRL008 suggest that further optimization of the P2' moiety may improve its antiretroviral features.