CXCR4: a virus's best friend?

CXCR4/CXCL12 blockade therapy; a new horizon in TNBC therapy

The only subtype of breast cancer (BC) without specific therapy is triple-negative breast cancer (TNBC), which represents 15-20% of incidence cases of BC. TNBC encompasses transformed and nonmalignant cells, including cancer-associated fibroblasts (CAF), endothelial vasculature, and tumor-infiltrating cells. These nonmalignant cells, soluble factors (e.g., cytokines), and the extracellular matrix (ECM) form the tumor microenvironment (TME). The TME is made up of these nonmalignant cells, ECM, and soluble components, including cytokines. Direct cell-to-cell contact and soluble substances like cytokines (e.g., chemokines) may facilitate interaction between cancer cells and the surrounding TME. Through growth-promoting cytokines, TME not only enables the development of cancer but also confers therapy resistance. New treatment targets will probably be suggested by comprehending the processes behind tumor development and progression as well as the functions of chemokines in TNBC. In this light, several investigations have shown the pivotal function of the C-X-C motif chemokine ligand 12 (CXCL12 or SDF-1) axis and chemokine receptor type 4 (CXCR4) in the pathophysiology of TNBC. This review provides an overview of the CXCR4/CXCL12 axis' function in TNBC development, metastasis, angiogenesis, and treatment resistance. A synopsis of current literature on targeting the CXCR4/CXCL12 axis for treating and managing TNBC has also been provided.

Identification of the Hub Genes Involved in Chikungunya Viral Infection

Background Chikungunya virus (CHIKV) infection poses a significant global health threat, necessitating a deeper understanding of its molecular mechanisms for effective management and treatment. This study aimed to understand the molecular and genetic mechanisms of CHIKV infection by analyzing microarray expression data. Methodology National Center for Biotechnology Information (NCBI) GEO2R with an adjusted p-value cut-off of <0.05 and |log2FC ≥ 1.5| was used to identify the differentially expressed genes involved in CHIKV infection using microarray data from the Gene Expression Omnibus (GEO) database, followed by enrichment analysis, protein-protein interaction (PPI) network construction, and, finally, hub gene identification. Results Analysis of the microarray dataset revealed 25 highly significant differentially expressed genes (DEGs), including 21 upregulated and four downregulated genes. PPI network analysis elucidated interactions among these DEGs, with hub genes such as ACTB and CTNNB1 exhibiting central roles. Enrichment analysis identified crucial pathways, including leukocyte transendothelial migration, regulation of actin cytoskeleton, and thyroid hormone signaling, implicating their involvement in CHIKV infection. Furthermore, the study highlights potential therapeutic targets such as ACTB and CTNNB1, which showed significant upregulation in infected cells. Conclusions These findings underscore the complex interplay between viral infection and host cellular processes, shedding light on novel avenues for diagnostic marker discovery and advancing antiviral strategies. In this study, we shed light on the molecular and genetic mechanisms of CHIKV infection and the potential role of ACTB and CTNNB1 genes.

CXC chemokine receptor 4 (CXCR4) blockade in cancer treatment

CXC chemokine receptor type 4 (CXCR4) is a member of the G protein-coupled receptors (GPCRs) superfamily and is specific for CXC chemokine ligand 12 (CXCL12, also known as SDF-1), which makes CXCL12/CXCR4 axis. CXCR4 interacts with its ligand, triggering downstream signaling pathways that influence cell proliferation chemotaxis, migration, and gene expression. The interaction also regulates physiological processes, including hematopoiesis, organogenesis, and tissue repair. Multiple evidence revealed that CXCL12/CXCR4 axis is implicated in several pathways involved in carcinogenesis and plays a key role in tumor growth, survival, angiogenesis, metastasis, and therapeutic resistance. Several CXCR4-targeting compounds have been discovered and used for preclinical and clinical cancer therapy, most of which have shown promising anti-tumor activity. In this review, we summarized the physiological signaling of the CXCL12/CXCR4 axis and described the role of this axis in tumor progression, and focused on the potential therapeutic options and strategies to block CXCR4.

Shang-Ke-Huang-Shui and coptisine alleviate osteoarthritis in the knee of monosodium iodoacetate-induced rats through inhibiting CXCR4 signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Shang-Ke-Huang-Shui (SKHS) is a classic traditional Chinese medicine formula originally from the southern China city of Foshan. It has been widely used in the treatment of osteoarthritis (OA) but underlying molecular mechanisms remain unclear.

AIM OF STUDY

Recently, activation of C-X-C chemokine receptor type 4 (CXCR4) signaling has been reported to induce cartilage degradation in OA patients; therefore, inhibition of CXCR4 signaling has becoming a promising approach for OA treatment. The aim of this study was to validate the cartilage protective effect of SKHS and test whether the anti-OA effects of SKHS depend on its inhibition on CXCR4 signaling. Additionally, CXCR4 antagonist in SKHS should be identified and its anti-OA activity should also be tested in vitro and in vivo.

METHODS

The anti-OA effects of SKHS and the newly identified CXCR4 antagonist was evaluated by monosodium iodoacetate (MIA)-induced rats. The articular cartilage surface was examined by hematoxylin and eosin (H&E) staining and Safranin O-Fast Green (S-F) staining whereas the subchondral bone was examined by micro-CT. CXCR4 antagonist screenings were conducted by molecular docking and calcium response assay. The CXCR4 antagonist was characterized by UPLC/MS/MS. The bulk RNA-Seq was conducted to identify CXCR4-mediated signaling pathway. The expression of ADAMTS4,5 was tested by qPCR and Western blot.

RESULTS

SKHS protected rats from MIA-induced cartilage degradation and subchondral bone damage. SKHS also inhibited CXCL12-indcued ADAMTS4,5 overexpression in chondrocytes through inhibiting Akt pathway. Coptisine has been identified as the most potent CXCR4 antagonist in SKHS. Coptisine reduced CXCL12-induced ADAMTS4,5 overexpression in chondrocytes. Furthermore, in MIA-induced OA model, the repaired cartilage and subchondral bone were observed in the coptisine-treated rats.

CONCLUSION

We first report here that the traditional Chinese medicine formula SKHS and its predominate phytochemical coptisine significantly alleviated cartilage degradation as well as subchondral bone damage through inhibiting CXCR4-mediated ADAMTS4,5 overexpression. Together, our work has provided an important insight of the molecular mechanism of SKHS and coptisine for their treatment of OA.

Coronavirus Porcine Epidemic Diarrhea Virus Utilizes Chemokine Interleukin-8 to Facilitate Viral Replication by Regulating Ca2+ Flux

Chemokine production by epithelial cells is crucial for neutrophil recruitment to sites of inflammation during viral infection. However, the effect of chemokine on epithelia and how chemokine is involved in coronavirus infection remains to be fully understood. Here, we identified an inducible chemokine interleukin-8 (CXCL8/IL-8), which could promote coronavirus porcine epidemic diarrhea virus (PEDV) infection in African green monkey kidney epithelial cells (Vero) and Lilly Laboratories cell-porcine kidney 1 epithelial cells (LLC-PK1). IL-8 deletion restrained cytosolic calcium (Ca2+), whereas IL-8 stimulation improved cytosolic Ca2+. The consumption of Ca2+ restricted PEDV infection. PEDV internalization and budding were obvious reductions when cytosolic Ca2+ was abolished in the presence of Ca2+ chelators. Further study revealed that the upregulated cytosolic Ca2+ redistributes intracellular Ca2+. Finally, we identified that G protein-coupled receptor (GPCR)-phospholipase C (PLC)-inositol trisphosphate receptor (IP3R)-store-operated Ca2+ (SOC) signaling was crucial for enhancive cytosolic Ca2+ and PEDV infection. To our knowledge, this study is the first to uncover the function of chemokine IL-8 during coronavirus PEDV infection in epithelia. PEDV induces IL-8 expression to elevate cytosolic Ca2+, promoting its infection. Our findings reveal a novel role of IL-8 in PEDV infection and suggest that targeting IL-8 could be a new approach to controlling PEDV infection. IMPORTANCE Coronavirus porcine epidemic diarrhea virus (PEDV) is a highly contagious enteric coronavirus that caused severe economic losses worldwide, and more effort is needed to develop economical and efficient vaccines to control or eliminate this disease. The chemokine interleukin-8 (CXCL8/IL-8) is indispensable for the activation and trafficking of inflammatory mediators and tumor progression and metastasis. This study evaluated the effect of IL-8 on PEDV infection in epithelia. We found that IL-8 expression improved cytosolic Ca2+ in epithelia, facilitating PEDV rapid internalization and egress. G protein-coupled receptor (GPCR)-phospholipase C (PLC)-inositol trisphosphate receptor (IP3R)-SOC signaling was activated by IL-8, releasing the intracellular Ca2+ stores from endoplasmic reticulum (ER). These findings provide a better understanding of the role of IL-8 in PEDV-induced immune responses, which will help develop small-molecule drugs for coronavirus cure.

A Differential Signature of Circulating miRNAs and Cytokines Between COVID-19 and Community-Acquired Pneumonia Uncovers Novel Physiopathological Mechanisms of COVID-19

Coronavirus Disease 2019 (COVID-19) pneumonia is a life-threatening infectious disease, especially for elderly patients with multiple comorbidities. Despite enormous efforts to understand its underlying etiopathogenic mechanisms, most of them remain elusive. In this study, we compared differential plasma miRNAs and cytokines profiles between COVID-19 and other community-acquired pneumonias (CAP). A first screening and subsequent validation assays in an independent cohort of patients revealed a signature of 15 dysregulated miRNAs between COVID-19 and CAP patients. Additionally, multivariate analysis displayed a combination of 4 miRNAs (miR-106b-5p, miR-221-3p, miR-25-3p and miR-30a-5p) that significantly discriminated between both pathologies. Search for targets of these miRNAs, combined with plasma protein measurements, identified a differential cytokine signature between COVID-19 and CAP that included EGFR, CXCL12 and IL-10. Significant differences were also detected in plasma levels of CXCL12, IL-17, TIMP-2 and IL-21R between mild and severe COVID-19 patients. These findings provide new insights into the etiopathological mechanisms underlying COVID-19.

Differential translational regulation of host exosomal proteins play key role in immunomodulation in antimony resistance in Visceral Leishmaniasis: A proteomic profiling study

In host-pathogen interactions, exosomal secretions are crucial for cell to cell communication and have an established role in immunomodulation. Protozoans, including Leishmania, modulates their host vesicular secretions for better survival; although the role of exosomal secretions in unresponsive against sodium antimony gluconate (SAG) has never been documented. In this study, the exosomal proteome of RAW macrophages infected with either SAG responsive (SAG^S) or SAG unresponsive (SAG^R) L. donovani parasites has been compared with uninfected RAW macrophages. Proteins isolated from exosomes were labelled with iTRAQ reagents; followed by subsequent LC-TOF/-MS analysis. In total, 394 proteins (p < 0.05) were identified which were shared common among all sets. Highly differentially expressed proteins were sorted by log2 value -1 and +1 as down regulated and up regulated respectively which yielded 58 proteins in SAG^R and 41 proteins during SAG^S infection. Out of the 58 proteins identified during SAG^R infection, 17 proteins were of immune modulatory function. Network visualization model and pathway analysis revealed the interactions among these proteins via different immunological pathways with reported involvement of some proteins in SAG resistance and host immune modulation. Hence, the differential abundance of immune pathway related proteins in exosomes of infected host during SAG^R infection supports the immune modulatory strategy adopted by SAG resistant parasites for enhanced survival .

Genome-wide expression analysis reveal host genes involved in immediate-early infections of different sheeppox virus strains

This study explored the transcriptome of lamb testis cells infected with sheeppox virus (SPPV) wild strain (WS) and vaccine strain (VS) at an immediate-early time. Most of the differentially expressed genes (DEGs) and differentially expressed highly connected (DEHC) gene network were found to be involved in SPPV-VS infection compared to SPPV-WS. Further, the signaling pathways were mostly involved in SPPV-VS infection than SPPV-WS. SPPV modulates the expression of several important host proteins such as CD40, FAS, ITGβ1, ITGα1, Pak1, Pak2, CD14, ILK leading to viral attachment and entry; immune-related DEGs such as MAPK, JNK, ERK, NFKB, IKB, PI3K, STAT which provide optimal cellular condition for early viral protein expression; and FOXO3, ATF, CDKNA1, TCF, SRF, BDNF which help in inducing apoptosis and MPTP, BAD and Tp53 inhibits apoptosis or cell death at the immediate-early time. The results captured the specific genes and enabled to understand distinct pathogenic mechanisms employed by VS and WS of SPPV.

The CXCR4/SDF-1 Axis in the Development of Facial Expression and Non-somitic Neck Muscles

Trunk and head muscles originate from distinct embryonic regions: while the trunk muscles derive from the paraxial mesoderm that becomes segmented into somites, the majority of head muscles develops from the unsegmented cranial paraxial mesoderm. Differences in the molecular control of trunk versus head and neck muscles have been discovered about 25 years ago; interestingly, differences in satellite cell subpopulations were also described more recently. Specifically, the satellite cells of the facial expression muscles share properties with heart muscle. In adult vertebrates, neck muscles span the transition zone between head and trunk. Mastication and facial expression muscles derive from the mesodermal progenitor cells that are located in the first and second branchial arches, respectively. The cucullaris muscle (non-somitic neck muscle) originates from the posterior-most branchial arches. Like other subclasses within the chemokines and chemokine receptors, CXCR4 and SDF-1 play essential roles in the migration of cells within a number of various tissues during development. CXCR4 as receptor together with its ligand SDF-1 have mainly been described to regulate the migration of the trunk muscle progenitor cells. This review first underlines our recent understanding of the development of the facial expression (second arch-derived) muscles, focusing on new insights into the migration event and how this embryonic process is different from the development of mastication (first arch-derived) muscles. Other muscles associated with the head, such as non-somitic neck muscles derived from muscle progenitor cells located in the posterior branchial arches, are also in the focus of this review. Implications on human muscle dystrophies affecting the muscles of face and neck are also discussed.

Identification of a novel signaling complex containing host chemokine receptor CXCR4, Interleukin-10 receptor, and human cytomegalovirus US27

Human cytomegalovirus (HCMV) is a widespread herpesvirus that establishes latency in myeloid cells and persists by manipulating immune signaling. Chemokine receptor CXCR4 and its ligand CXCL12 regulate movement of myeloid progenitors into bone marrow and out into peripheral tissues. HCMV amplifies CXCL12-CXCR4 signaling through viral chemokine receptor US27 and cmvIL-10, a viral cytokine that binds the cellular IL-10 receptor (IL-10R), but precisely how these viral proteins influence CXCR4 is unknown. We used the proximity ligation assay (PLA) to examine association of CXCR4, IL-10R, and US27 in both transfected and HCMV-infected cells. CXCR4 and IL-10R colocalized to discrete clusters, and treatment with CXCL12 and cmvIL-10 dramatically increased receptor clustering and calcium flux. US27 was associated with CXCR4 and IL-10R in PLA clusters and further enhanced cluster formation and calcium signaling. These results indicate that CXCR4, IL-10R, and US27 form a novel virus-host signaling complex that enhances CXCL12 signaling during HCMV infection.

Epigenetic Regulator miRNA Pattern Differences Among SARS-CoV, SARS-CoV-2, and SARS-CoV-2 World-Wide Isolates Delineated the Mystery Behind the Epic Pathogenicity and Distinct Clinical Characteristics of Pandemic COVID-19

A detailed understanding of the molecular mechanism of SARS-CoV-2 pathogenesis is still elusive, and there is a need to address its deadly nature and to design effective therapeutics. Here, we present a study that elucidates the interplay between the SARS-CoV and SARS-CoV-2 viruses' and host's miRNAs, an epigenetic regulator, as a mode of pathogenesis; and we explored how the SARS-CoV and SARS-CoV-2 infections differ in terms of their miRNA-mediated interactions with the host and the implications this has in terms of disease complexity. We have utilized computational approaches to predict potential host and viral miRNAs and their possible roles in different important functional pathways. We have identified several putative host antiviral miRNAs that can target the SARS viruses and also predicted SARS viruses-encoded miRNAs targeting host genes. In silico predicted targets were also integrated with SARS-infected human cell microarray and RNA-seq gene expression data. A comparison between the host miRNA binding profiles on 67 different SARS-CoV-2 genomes from 24 different countries with respective country's normalized death count surprisingly uncovered some miRNA clusters, which are associated with increased death rates. We have found that induced cellular miRNAs can be both a boon and a bane to the host immunity, as they have possible roles in neutralizing the viral threat; conversely, they can also function as proviral factors. On the other hand, from over representation analysis, our study revealed that although both SARS-CoV and SARS-CoV-2 viral miRNAs could target broad immune-signaling pathways; only some of the SARS-CoV-2 miRNAs are found to uniquely target some immune-signaling pathways, such as autophagy, IFN-I signaling, etc., which might suggest their immune-escape mechanisms for prolonged latency inside some hosts without any symptoms of COVID-19. Furthermore, SARS-CoV-2 can modulate several important cellular pathways that might lead to the increased anomalies in patients with comorbidities like cardiovascular diseases, diabetes, breathing complications, etc. This might suggest that miRNAs can be a key epigenetic modulator behind the overcomplications amongst the COVID-19 patients. Our results support that miRNAs of host and SARS-CoV-2 can indeed play a role in the pathogenesis which can be further concluded with more experiments. These results will also be useful in designing RNA therapeutics to alleviate the complications from COVID-19.

Uncovering new disease indications for G-protein coupled receptors and their endogenous ligands

Background

The Open Targets Platform integrates different data sources in order to facilitate identification of potential therapeutic drug targets to treat human diseases. It currently provides evidence for nearly 2.6 million potential target-disease pairs. G-protein coupled receptors are a drug target class of high interest because of the number of successful drugs being developed against them over many years. Here we describe a systematic approach utilizing the Open Targets Platform data to uncover and prioritize potential new disease indications for the G-protein coupled receptors and their ligands.

Results

Utilizing the data available in the Open Targets platform, potential G-protein coupled receptor and endogenous ligand disease association pairs were systematically identified. Intriguing examples such as GPR35 for inflammatory bowel disease and CXCR4 for viral infection are used as illustrations of how a systematic approach can aid in the prioritization of interesting drug discovery hypotheses. Combining evidences for G-protein coupled receptors and their corresponding endogenous peptidergic ligands increases confidence and provides supportive evidence for potential new target-disease hypotheses. Comparing such hypotheses to the global pharma drug discovery pipeline to validate the approach showed that more than 93% of G-protein coupled receptor-disease pairs with a high overall Open Targets score involved receptors with an existing drug discovery program.

Conclusions

The Open Targets gene-disease score can be used to prioritize potential G-protein coupled receptors-indication hypotheses. In addition, availability of multiple different evidence types markedly increases confidence as does combining evidence from known receptor-ligand pairs. Comparing the top-ranked hypotheses to the current global pharma pipeline serves validation of our approach and identifies and prioritizes new therapeutic opportunities.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2392-y) contains supplementary material, which is available to authorized users.

Genetic variation of CXCR4 and risk of coronary artery disease: epidemiological study and functional validation of CRISPR/Cas9 system

Cardiovascular diseases (CVDs) remain the leading cause of death worldwide, while coronary artery disease (CAD) account for a large part of CVDs. Vascular CXCR4 could limit atherosclerosis by maintaining arterial integrity. Here, we conducted a population-based, case-control study to evaluate the associations of common genetic variation within the CXCR4 gene (rs2228014, rs117600832, rs2471859, and rs2322864) with CAD risk in a Chinese population. We found that CXCR4 rs2228014 was significantly associated with 1.29-fold increased risk of CAD (A vs G: OR = 1.29; 95% CI = 1.07–1.55; P = 0.007). The subjects with genotype AA (OR = 1.98; 95% CI = 1.03–3.81; P = 0.041) and AG (OR = 1.27; 95% CI = 1.02–1.58; P = 0.030) have higher risk of CAD, compared with those with genotype GG. Furthermore, both in the CAD patients with diabetes and those without diabetes, rs2228014 was significantly associated with increased risk of CAD (P < 0.05). Additionally, we also validated the significant association for rs2322864 (C vs T: OR = 1.20; 95% CI = 1.00–1.44; P = 0.046). Knockout of CXCR4 gene could significantly impair the capacity of cholesterol efflux (P < 0.01). These findings strongly suggest that CXCR4 polymorphisms might contribute to CAD susceptibility, and the exact biological mechanism awaits further research.

Role of SDF-1α/CXCR4 signaling pathway in clinicopathological features and prognosis of patients with nasopharyngeal carcinoma

The present study aims to explore the role of stromal cell-derived factor-1α (SDF-1α)/stromal cell-derived factor receptor-4 (CXCR4) signaling pathway to the clinicopathological features and prognosis of patients with nasopharyngeal carcinoma (NPC). From January 2009 to December 2010, 102 patients with NPC and 80 patients with chronic nasopharyngitis were enrolled for the study. Immunohistochemical staining, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blotting were employed to determine the expressions of SDF-1α and CXCR4 proteins in NPC tissues and chronic nasopharyngitis tissues. Chi-square test was conducted to analyze the associations of the expressions of SDF-1α and CXCR4 proteins with the clinicopathological features of NPC patients. Spearman rank correlation analysis was used to analyze the correlation between the SDF-1α protein expression and CXCR4 protein expression. The mRNA and protein expressions of SDF-1α and CXCR4 in NPC tissues were significantly higher than those in chronic nasopharyngitis tissues. The expressions of SDF-1α and CXCR4 proteins showed associations with T staging, N staging, tumor node metastasis (TNM) staging, skull base invasion, and cervical lymph node metastasis of NPC patients. Compared with NPC patients showing negative expressions of SDF-1α and CXCR4 proteins, those with positive expressions of SDF-1α and CXCR4 proteins had a significantly shorter survival time. SDF-1α protein, CXCR4 protein, EBV-IgG status, T staging, N staging, TNM staging, skull base invasion, and cervical lymph node metastasis were independent risk factors for the prognosis of NPC. The findings indicated that SDF-1α/CXCR4 signaling pathway might be associated with the clinicopathological features and prognosis of patients with NPC.

HIV-Associated Cerebellar Dysfunction and Improvement with Aminopyridine Therapy: A Case Report

Apart from infectious causes and cerebellar dysfunction associated with acquired immune deficiency syndrome dementia or HIV-associated neurocognitive disorder, cerebellar dysfunction in HIV-positive individuals has been ascribed to granule cell neuronopathy as well as primary cerebellar atrophy without identifiable etiology. We report the case of a patient with progressive cerebellar dysfunction as the primary manifestation of HIV infection. No symptom improvement was seen under combination antiretroviral therapy, which had been established upon diagnosis, but the patient improved rapidly under 4-aminopyridine treatment, which was recommended 1 year later. Our report, adding to the rather small number of reports of HIV-associated cerebellar atrophy and dysfunction as a primary manifestation of HIV infection, draws attention to HIV as a possible differential etiology of a cerebellar syndrome. Further, rapid improvement of symptom severity under 4-aminopyridine treatment warrants further investigation with longer-term follow-up into the effectiveness of this compound in gait disorder associated with HIV infection.

Role of CXC chemokine receptor type 4 as a lactoferrin receptor

Lactoferrin exerts its biological activities by interacting with receptors on target cells, including LDL receptor-related protein-1 (LRP-1/CD91), intelectin-1 (omentin-1), and Toll-like receptor 4 (TLR4). However, the effects mediated by these receptors are not sufficient to fully explain the many functions of lactoferrin. C-X-C-motif cytokine receptor 4 (CXCR4) is a ubiquitously expressed G-protein coupled receptor for stromal cell-derived factor-1 (SDF-1/CXCL12). Lactoferrin was found to be as capable as SDF-1 in blocking infection by an HIV variant that uses CXCR4 as a co-receptor (X4-tropic HIV), suggesting that lactoferrin interacts with CXCR4. We addressed whether CXCR4 acts as a lactoferrin receptor using HaCaT human keratinocytes and Caco-2 human intestinal cells. We found that bovine lactoferrin interacted with CXCR4-containing lipoparticles, and that this interaction was not antagonized by SDF-1. In addition, activation of Akt in response to lactoferrin was abrogated by AMD3100, a small molecule inhibitor of CXCR4, or by a CXCR4-neutralizing antibody, suggesting that CXCR4 functions as a lactoferrin receptor able to mediate activation of the PI3K-Akt signaling pathway. Lactoferrin stimulation mimicked many aspects of SDF-1-induced CXCR4 activity, including receptor dimerization, tyrosine phosphorylation, and ubiquitination. Cycloheximide chase assays indicated that turnover of CXCR4 was accelerated in response to lactoferrin. These results indicate that CXCR4 is a potent lactoferrin receptor that mediates lactoferrin-induced activation of Akt signaling.

Optochemokine Tandem for Light-Control of Intracellular Ca2

An optochemokine tandem was developed to control the release of calcium from endosomes into the cytosol by light and to analyze the internalization kinetics of G-protein coupled receptors (GPCRs) by electrophysiology. A previously constructed rhodopsin tandem was re-engineered to combine the light-gated Ca²⁺-permeable cation channel Channelrhodopsin-2(L132C), CatCh, with the chemokine receptor CXCR4 in a functional tandem protein tCXCR4/CatCh. The GPCR was used as a shuttle protein to displace CatCh from the plasma membrane into intracellular areas. As shown by patch-clamp measurements and confocal laser scanning microscopy, heterologously expressed tCXCR4/CatCh was internalized via the endocytic SDF1/CXCR4 signaling pathway. The kinetics of internalization could be followed electrophysiologically via the amplitude of the CatCh signal. The light-induced release of Ca²⁺ by tandem endosomes into the cytosol via CatCh was visualized using the Ca²⁺-sensitive dyes rhod2 and rhod2-AM showing an increase of intracellular Ca²⁺ in response to light.

Multi-objective active machine learning rapidly improves structure-activity models and reveals new protein-protein interaction inhibitors

Active machine learning puts artificial intelligence in charge of a sequential, feedback-driven discovery process. We present the application of a multi-objective active learning scheme for identifying small molecules that inhibit the protein-protein interaction between the anti-cancer target CXC chemokine receptor 4 (CXCR4) and its endogenous ligand CXCL-12 (SDF-1). Experimental design by active learning was used to retrieve informative active compounds that continuously improved the adaptive structure-activity model. The balanced character of the compound selection function rapidly delivered new molecular structures with the desired inhibitory activity and at the same time allowed us to focus on informative compounds for model adjustment. The results of our study validate active learning for prospective ligand finding by adaptive, focused screening of large compound repositories and virtual compound libraries.

Short Communication: CXCL12 rs1029153 Polymorphism Is Associated with the Sustained Virological Response in HIV/Hepatitis C Virus-Coinfected Patients on Hepatitis C Virus Therapy

The immune response against HIV and hepatitis C virus (HCV) infection partly depends on chemokine-mediated recruitment of specific T cells. CXCL12 polymorphisms have been associated with AIDS progression and survival, but there are no data related to HCV infection. The aim of this study was to determine whether CXCL12 polymorphisms are related so as to achieve sustained virological response (SVR) after HCV therapy with pegylated-interferon-alpha/ribavirin (pegIFN-α/ribavirin) in HIV/HCV-coinfected patients. We carried out a retrospective study in 319 naive patients who started HCV treatment. The CXCL12 (rs266093, rs1029153, and rs1801157) and IL28B (rs12980275) polymorphisms were genotyped by using the GoldenGate assay. Genetic data were analyzed under an additive inheritance model. The overall rates of the SVR were 54.9% (175/319) and 41.5% (90/217) in GT1/4 patients and 83.2% (84/101) in GT2/3 patients. Patients with a favorable CXCL12 rs1029153 T allele had higher SVR rates than patients with the rs1029153 CC genotype (44% CC, 49% CT, and 61.3% TT; p = 0.025). No significant results for the rs266093 and rs1801157 polymorphisms were found. Patients harboring the favorable rs1029153 T allele had significantly increased odds of achieving SVR [adjusted odds ratio (aOR) = 1.55; 95% confidence interval (95% CI) = 1.01; 2.40; p = 0.047]. Moreover, no significant association was found when the study population was stratified by HCV genotype (data not shown), possibly due to the low number of patients in each group. In conclusion, in this study we found that the favorable CXCL12 rs1029153 T allele seems to be related so as to achieve an SVR in HIV/HCV-coinfected patients on pegIFN-α/ribavirin therapy.

Viral manipulation of the host immune response

Viruses are obligate intracellular parasites that require a host for essential machinery to replicate and ultimately be transmitted to new susceptible hosts. At the same time, the immune system has evolved to protect the human body from invasion by viruses and other pathogens. To counter this, viruses have developed an arsenal of strategies to not only avoid immune detection but to actively manipulate host immune responses to create an environment more favorable for infection. Here, we describe recent advances uncovering novel mechanisms by which viruses skew host immune responses through modulation of cytokine and chemokine signaling networks, interference with antigen presentation and T cell responses, and preventing antibody production.

Function-oriented development of CXCR4 antagonists as selective human immunodeficiency virus (HIV)-1 entry inhibitors

Motivated by the pivotal role of CXCR4 as an HIV entry co-receptor, we herein report a de novo hit-to-lead effort on the identification of subnanomolar purine-based CXCR4 antagonists against HIV-1 infection. Compound 24, with an EC50 of 0.5 nM against HIV-1 entry into host cells and an IC50 of 16.4 nM for inhibition of radioligand stromal-derived factor-1α (SDF-1α) binding to CXCR4, was also found to be highly selective against closely related chemokine receptors. We rationalized that compound 24 complementarily interacted with the critical CXCR4 residues that are essential for binding to HIV-1 gp120 V3 loop and subsequent viral entry. Compound 24 showed a 130-fold increase in anti-HIV activity compared to that of the marketed CXCR4 antagonist, AMD3100 (Plerixafor), whereas both compounds exhibited similar potency in mobilization of CXCR4(+)/CD34(+) stem cells at a high dose. Our study offers insight into the design of anti-HIV therapeutics devoid of major interference with SDF-1α function.

Early mucosal sensing of SIV infection by paneth cells induces IL-1β production and initiates gut epithelial disruption

HIV causes rapid CD4+ T cell depletion in the gut mucosa, resulting in immune deficiency and defects in the intestinal epithelial barrier. Breakdown in gut barrier integrity is linked to chronic inflammation and disease progression. However, the early effects of HIV on the gut epithelium, prior to the CD4+ T cell depletion, are not known. Further, the impact of early viral infection on mucosal responses to pathogenic and commensal microbes has not been investigated. We utilized the SIV model of AIDS to assess the earliest host-virus interactions and mechanisms of inflammation and dysfunction in the gut, prior to CD4+ T cell depletion. An intestinal loop model was used to interrogate the effects of SIV infection on gut mucosal immune sensing and response to pathogens and commensal bacteria in vivo. At 2.5 days post-SIV infection, low viral loads were detected in peripheral blood and gut mucosa without CD4+ T cell loss. However, immunohistological analysis revealed the disruption of the gut epithelium manifested by decreased expression and mislocalization of tight junction proteins. Correlating with epithelial disruption was a significant induction of IL-1β expression by Paneth cells, which were in close proximity to SIV-infected cells in the intestinal crypts. The IL-1β response preceded the induction of the antiviral interferon response. Despite the disruption of the gut epithelium, no aberrant responses to pathogenic or commensal bacteria were observed. In fact, inoculation of commensal Lactobacillus plantarum in intestinal loops led to rapid anti-inflammatory response and epithelial tight junction repair in SIV infected macaques. Thus, intestinal Paneth cells are the earliest responders to viral infection and induce gut inflammation through IL-1β signaling. Reversal of the IL-1β induced gut epithelial damage by Lactobacillus plantarum suggests synergistic host-commensal interactions during early viral infection and identify these mechanisms as potential targets for therapeutic intervention.