Characteristics of Activated Monocyte Phenotype Support R5-Tropic Human Immunodeficiency Virus

Machine learning links different gene patterns of viral infection to immunosuppression and immune-related biomarkers in severe burns

Introduction

Viral infection, typically disregarded, has a significant role in burns. However, there is still a lack of biomarkers and immunotherapy targets related to viral infections in burns.

Methods

Virus-related genes (VRGs) that were extracted from Gene Oncology (GO) database were included as hallmarks. Through unsupervised consensus clustering, we divided patients into two VRGs molecular patterns (VRGMPs). Weighted gene co-expression network analysis (WGCNA) was performed to study the relationship between burns and VRGs. Random forest (RF), least absolute shrinkage and selection operator (LASSO) regression, and logistic regression were used to select key genes, which were utilized to construct prognostic signatures by multivariate logistic regression. The risk score of the nomogram defined high- and low-risk groups. We compared immune cells, immune checkpoint-related genes, and prognosis between the two groups. Finally, we used network analysis and molecular docking to predict drugs targeting CD69 and SATB1. Expression of CD69 and SATB1 was validated by qPCR and microarray with the blood sample from the burn patient.

Results

We established two VRGMPs, which differed in monocytes, neutrophils, dendritic cells, and T cells. In WGCNA, genes were divided into 14 modules, and the black module was correlated with VRGMPs. A total of 65 genes were selected by WGCNA, STRING, and differential expression analysis. The results of GO enrichment analysis were enriched in Th1 and Th2 cell differentiation, B cell receptor signaling pathway, alpha-beta T cell activation, and alpha-beta T cell differentiation. Then the 2-gene signature was constructed by RF, LASSO, and LOGISTIC regression. The signature was an independent prognostic factor and performed well in ROC, calibration, and decision curves. Further, the expression of immune cells and checkpoint genes differed between high- and low-risk groups. CD69 and SATB1 were differentially expressed in burns.

Discussion

This is the first VRG-based signature (including 2 key genes validated by qPCR) for predicting survival, and it could provide vital guidance to achieve optimized immunotherapy for immunosuppression in burns.

Investigating the Effects of Mechanical Stimulation on Retinal Ganglion Cell Spontaneous Spiking Activity

Mechanical forces are increasingly recognized as major regulators of several physiological processes at both the molecular and cellular level; therefore, a deep understanding of the sensing of these forces and their conversion into electrical signals are essential for studying the mechanosensitive properties of soft biological tissues. To contribute to this field, we present a dual-purpose device able to mechanically stimulate retinal tissue and to record the spiking activity of retinal ganglion cells (RGCs). This new instrument relies on combining ferrule-top micro-indentation, which provides local measurements of viscoelasticity, with high-density multi-electrode array (HD-MEAs) to simultaneously record the spontaneous activity of the retina. In this paper, we introduce this instrument, describe its technical characteristics, and present a proof-of-concept experiment that shows how RGC spiking activity of explanted mice retinas respond to mechanical micro-stimulations of their photoreceptor layer. The data suggest that, under specific conditions of indentation, the retina perceive the mechanical stimulation as modulation of the visual input, besides the longer time-scale of activation, and the increase in spiking activity is not only localized under the indentation probe, but it propagates across the retinal tissue.

Raman-Enhanced Spectroscopy Distinguishes Anal Squamous Intraepithelial Lesions in Human Immunodeficiency Virus-Serodiscordant Couples

HIV-positive individuals are at increased risk for precancerous anal squamous intraepithelial lesions (SILs). Anal cytology and digital rectal examination are performed as screening tools, but extensive training and appropriate instruments are required to follow up on an abnormal anal cytology. Thus, novel approaches to SIL evaluation could improve better health care follow-up by efficient and timely diagnosis to offer treatment options. Recently, Raman-enhanced spectroscopy (RESpect) has emerged as a potential new tool for early identification of SIL. RESpect is a noninvasive, label-free, laser-based technique that identifies molecular composition of tissues and cells. HIV-serodiscordant couples had anal biopsies obtained during high-resolution anoscopy. RESpect was performed on the specimens. Principal component analysis of the data identified differences between normal and abnormal tissue as well as HIV-positive and HIV-negative individuals of each couple even with similar pathologies. RESpect has the potential to change the paradigm of anal pathology diagnosis and could provide insight into different pathways leading to SIL in HIV-serodiscordant couples.

The Biology of Monocytes and Dendritic Cells: Contribution to HIV Pathogenesis

Myeloid cells such as monocytes, dendritic cells (DC) and macrophages (MΦ) are key components of the innate immune system contributing to the maintenance of tissue homeostasis and the development/resolution of immune responses to pathogens. Monocytes and DC, circulating in the blood or infiltrating various lymphoid and non-lymphoid tissues, are derived from distinct bone marrow precursors and are typically short lived. Conversely, recent studies revealed that subsets of tissue resident MΦ are long-lived as they originate from embryonic/fetal precursors that have the ability to self-renew during the life of an individual. Pathogens such as the human immunodeficiency virus type 1 (HIV-1) highjack the functions of myeloid cells for viral replication (e.g., MΦ) or distal dissemination and cell-to-cell transmission (e.g., DC). Although the long-term persistence of HIV reservoirs in CD4+ T-cells during viral suppressive antiretroviral therapy (ART) is well documented, the ability of myeloid cells to harbor replication competent viral reservoirs is still a matter of debate. This review summarizes the current knowledge on the biology of monocytes and DC during homeostasis and in the context of HIV-1 infection and highlights the importance of future studies on long-lived resident MΦ to HIV persistence in ART-treated patients.

Cathepsin B and cystatin B in HIV-seropositive women are associated with infection and HIV-1-associated neurocognitive disorders

OBJECTIVE

HIV-1-associated neurocognitive disorders (HAND) is triggered by immune activation of brain cells and remain prevalent during progressive viral infection despite antiretroviral therapy. Cathepsins and cystatins are lysosomal proteins secreted by macrophages and microglia, and may play important roles in neuroregulatory responses. Our laboratory has shown increased secretion and neurotoxicity of cathepsin B from in-vitro HIV-infected monocyte-derived macrophages, and increased expression in postmortem brain tissue with HIV encephalitis and HAND. We hypothesized that cystatin B and cathepsin B could represent potential biomarkers for HAND.

METHODS

Monocytes, plasma, and cerebrospinal fluid (CSF) from retrospective samples from 63 HIV-seropositive Hispanic women were selected for this study. These were stratified as 27 normal, 14 asymptomatic, and 22 HIV dementia, and as 14 progressors and 17 nonprogressors. Samples were evaluated for cystatins B and C and cathepsin B expression and activity.

RESULTS

Increased cathepsin B and cystatins B and C were found in plasma of HIV-seropositive women. Higher intracellular expression of cathepsin B and cystatin B were found in monocytes from women with HIV-associated dementia (P < 0.05). Significant increase in cystatin B concentration in CSF was found in women with dementia compared with HIV-seropositive asymptomatic women.

CONCLUSION

These results demonstrate that dysregulation of cystatin B-cathepsin B system is operative in HIV-associated neurocognitive impairment and suggests that intracellular expression of cystatin B and cathepsin B in monocytes could be potential candidate biomarkers for HIV dementia, whereas increased cathepsin B and cystatins B and C in plasma are potential candidate markers of chronic HIV-1 activation.

Cognitive performance related to HIV-1-infected monocytes

The effect that HIV type 1 (HIV) has on neurocognition is a dynamic process whereby peripheral events are likely involved in setting the stage for clinical findings. In spite of antiretroviral therapy (ART), patients continue to be at risk for HIV-associated neurocognitive disorders (HAND), which might be related to persistence of inflammation. In a yearly assessment of HIV DNA levels in activated monocytes, increased HIV DNA copies were found in patients with persistent HAND. Furthermore, activated monocytes from patients with high HIV DNA copies secreted more inflammatory cytokines. Since these activated monocytes traffic to the CNS and enter the brain, they may contribute to an inflammatory environment in the CNS that leads to HAND.

The role of lipopolysaccharide as a marker of immune activation in HIV-1 infected patients: a systematic literature review

Background

Recent observational studies suggest a role for lipopolysaccharide (LPS) as a marker of immune activation in HIV-infected patients, with potential repercussions on the effectiveness of antiretroviral regimens.

Object

A systematic review of LPS as a marker of immune activation in HIV-1 infected patients.

Data sources

MEDLINE register of articles and international conference proceedings.

Review methods

Case–control studies comparing the role of plasma LPS as a marker of immune activation in HIV-infected patients versus HIV negative subjects.

Data synthesis

Two hundred and six articles were selected using MEDLINE, plus 51 studies presented at international conferences. Plasma LPS is a marker of immune activation in HIV-infected patients, determining the entry of central memory CD4+ T cells into the replication cycle and finally generating cell death. Plasma LPS probably results from immune-mediated alterations of the intestinal barrier, which can occur soon after HIV seroconversion. LPS is a likely marker of disease progression, as it drives chronic monocyte activation, and some studies suggest that hyperexpression of CCR5 receptors, related to LPS plasma levels, could be responsible for monocyte trafficking in the brain compartment and for the appearance of HIV-associated neurocognitive disorders. Long-term combination antiretroviral therapy (cART) generally reduces LPS concentrations, but rarely to the same levels as in the control group. This phenomenon probably depends on ongoing but incomplete repair of the mucosal barrier. Only in patients achieving maximal viral suppression (i.e. viral load < 2.5 cp/ml) are LPS levels comparable to healthy donors. In successfully treated patients who did not restore CD4+ T cells, one hypothesis is that the degree of residual microbial translocation, measured by LPS, alters the turnover of CD4+ T cells.

Conclusions

LPS is a marker of microbial translocation, responsible for chronic immune activation in HIV-infected patients. Even in successfully treated patients, LPS values are rarely normal. Several studies suggest a role for LPS as a negative predictive marker of immune restoration in patients with blunted CD4 T cell gain.

Microbial translocation in HIV infection: causes, consequences and treatment opportunities

Systemic immune activation is increased in HIV-infected individuals, even in the setting of virus suppression with antiretroviral therapy. Although numerous factors may contribute, microbial products have recently emerged as potential drivers of this immune activation. In this Review, we describe the intestinal damage that occurs in HIV infection, the evidence for translocation of microbial products into the systemic circulation and the pathways by which these products activate the immune system. We also discuss novel therapies that disrupt the translocation of microbial products and the downstream effects of microbial translocation.

Failure to clear intra-monocyte HIV infection linked to persistent neuropsychological testing impairment after first-line combined antiretroviral therapy

HIV-associated neurocognitive disorders (HAND) persist despite plasma HIV RNA suppression with antiretrovirals (ARV). Sequestered reservoirs in the central nervous system and circulating monocytes are theorized to contribute to persistent brain injury. We previously demonstrated that elevated intracellular HIV DNA from circulating cells was associated with HAND in ARV-treated and ARV-naive subjects. We now report that failure to suppress intra-monocyte HIV DNA 3.5 years after initiating ARV is linked to persistent HAND and subjects with dementia are least likely to suppress intra-monocyte HIV DNA at 3.5 years. These findings suggest that antiviral strategies may need to target intra-monocyte HIV DNA.

Serum Hepcidin and Macrophage Iron Correlate With MCP-1 Release and Vascular Damage in Patients With Metabolic Syndrome Alterations

Objective—

Increased body iron stores and hepcidin have been hypothesized to promote atherosclerosis by inducing macrophage iron accumulation and release of cytokines, but direct demonstration in human cells is lacking. The aim of this study was to evaluate the effect of iron on cytokine release in monocytes ex vivo and the correlation with vascular damage and to evaluate the relationship among serum levels of hepcidin, cytokines, and vascular damage in patients with metabolic syndrome alterations.

Methods and Results—

Manipulation of iron status with ferric ammonium citrate and hepcidin-25 induced monocyte chemoattractant protein (MCP)-1 and interleukin-6 in human differentiating monocytes of patients with hyperferritinemia associated with the metabolic syndrome (n=11), but not in subjects with hemochromatosis or HFE mutations impairing iron accumulation (n=15), and the degree of induction correlated with the presence of carotid plaques, detected by echocolor–Doppler. In monocytes of healthy subjects (n=7), iron and hepcidin increased the mRNA levels and release of MCP-1, but not of interleukin-6. In 130 patients with metabolic alterations, MCP-1 levels, as detected by ELISA, were correlated with hepcidin-25 measured by time-of-flight mass spectrometry ( P =0.005) and were an independent predictor of the presence of carotid plaques ( P =0.05).

Conclusion—

Hepcidin and macrophage iron correlate with MCP-1 release and vascular damage in high-risk individuals with metabolic alterations.

Translational research in NeuroAIDS: a neuroimmune pharmacology-related course

Neuroimmune pharmacology (NIP) can be considered a multidisciplinary science where areas of neuroscience, immunology, and pharmacology intersect in neurological disorders. The R25 training program titled "Translational Research in NeuroAIDS and Mental Health (TR-NAMH): An innovative mentoring program to promote diversity in NeuroAIDS Research (R25 MH080661)" at the Johns Hopkins University is a web-based interactive course with the goal to improve the capacity of high quality research by developing mentoring programs for (1) doctoral and postdoctoral candidates and junior faculty from racial and ethnic minorities and (2) non-minority individuals at the same levels, whose research focuses on NeuroAIDS disparity issues such as HIV-associated neurocognitive disorders (HAND). This web-based interactive course overcomes the limitations of traditional education such as access to expert faculty and financial burden of scientists from racial and ethnic minority groups in the field of NeuroAIDS research and NIP and identifies rich nurturing environments for investigators to support their careers. The TR-NAMH program identifies a cadre of talented students and investigators eager to commit to innovative educational and training sessions in NeuroAIDS and NIP. The interplay between NIP changes precipitated by HIV infection in the brain makes the study of HAND an outstanding way to integrate important concepts from these two fields. The course includes activities besides those related to didactic learning such as research training and long-term mentoring; hence, the newly learned topics in NIP are continually reinforced and implemented in real-time experiences. We describe how NIP is integrated in the TR-NAMH program in the context of HAND.