Search

Tunneling nanotubes (TNTs), also called cytonemes or tumor microtubes, correspond to cellular processes that enable long-range communication. TNTs are plasma membrane extensions that form tubular processes that connect the cytoplasm of two or more cells. TNTs are mostly expressed during the early stages of development and poorly expressed in adulthood. However, in disease conditions such as stroke, cancer, and viral infections such as HIV, TNTs proliferate, but their role is poorly understood. TNTs function has been associated with signaling coordination, organelle sharing, and the transfer of infectious agents such as HIV. Here, we describe the critical role and function of TNTs during HIV infection and reactivation, as well as the use of TNTs for cure strategies.

Only recently, the role of large ionic channels such as Pannexin-1 channels and Connexin hemichannels has been implicated in several physiological and pathological conditions, including HIV infection and associated comorbidities. These channels are in a closed stage in healthy conditions, but in pathological conditions including HIV, Pannexin-1 channels and Connexin hemichannels become open. Our data demonstrate that acute and chronic HIV infection induces channel opening (Pannexin and Connexin channels), ATP release into the extracellular space, and subsequent activation of purinergic receptors in immune and non-immune cells. We demonstrated that Pannexin and Connexin channels contribute to HIV infection and replication, the long-term survival of viral reservoirs, and comorbidities such as NeuroHIV. Here, we discuss the available data to support the participation of these channels in the HIV life cycle and the potential therapeutic approach to prevent HIV-associated comorbidities.

SUMMARYDeciphering the mechanisms underlying viral persistence is critical to achieving a cure for HIV infection. We uncovered molecular signatures of HIV latently-infected CD4+ T cells, identifying the adenosine-producing ectonucleotidase CD73 as a key marker of latent infection. Hypoxic conditioning, reflective of tissue microenvironments, increased the frequency of CD73+ CD4+ T cells and promoted HIV latency. Transcriptomic profiles of CD73+ CD4+ T cells indicated expression phenotypes favoring viral persistence, immune evasion, and cell survival. Further, we demonstrate that CD73+ CD4+ T cells harbor a functional HIV reservoir and are capable of reinitiating productive infection in vitro. Moreover, blocking of the A2A receptor facilitates HIV reactivation in vitro, linking adenosine signaling to viral quiescence. Finally, tissue imaging of lymph nodes from HIV-infected individuals on antiretroviral therapy reveal spatial association between CD73 expression and HIV persistence in vivo. Our findings warrant exploration of the hypoxia-CD73-adenosine axis in curative strategies to promote viral eradication.

SARS-CoV-2, although not being a circulatory virus, spread from the respiratory tract resulting in multiorgan failures and thrombotic complications, the hallmarks of fatal COVID-19. A convergent contributor could be platelets that beyond hemostatic functions can carry infectious viruses. Here, we profiled 52 patients with severe COVID-19 and demonstrated that circulating platelets of 19 out 20 non-survivor patients contain SARS-CoV-2 in robust correlation with fatal outcome. Platelets containing SARS-CoV-2 might originate from bone marrow and lung megakaryocytes (MKs), the platelet precursors, which were found infected by SARS-CoV-2 in COVID-19 autopsies. Accordingly, MKs undergoing shortened differentiation and expressing anti-viral IFITM1 and IFITM3 RNA as a sign of viral sensing were enriched in the circulation of deadly COVID-19. Infected MKs reach the lung concomitant with a specific MK-related cytokine storm rich in VEGF, PDGF and inflammatory molecules, anticipating fatal outcome. Lung macrophages capture SARS-CoV-2-containing platelets in vivo. The virus contained by platelets is infectious as capture of platelets carrying SARS-CoV-2 propagates infection to macrophages in vitro, in a process blocked by an anti-GPIIbIIIa drug. Altogether, platelets containing infectious SARS-CoV-2 alter COVID-19 pathogenesis and provide a powerful fatality marker. Clinical targeting of platelets might prevent viral spread, thrombus formation and exacerbated inflammation at once and increase survival in COVID-19.

In healthy conditions, pannexin-1 (Panx-1) channels are in a close state, but in several pathological conditions, including HIV and NeuroHIV, the channel becomes open. However, the mechanism or contribution of Panx-1 channels to the Human Immunodeficiency Virus-1 (HIV) pathogenesis and NeuroHIV are unknown. To determine the contribution of Panx-1 channels to the pathogenesis of NeuroHIV, we used a well-established model of Simian Immunodeficiency Virus (SIV) infection in macaques (Macaca mulatta) in the presence of and absence of a Panx-1 blocker to later examine the synaptic/axonal compromise induced for the virus. Using Golgi's staining, we demonstrated that SIV infection compromised synaptic and axonal structures, especially in the white matter. Blocking Panx-1 channels after SIV infection prevented the synaptic and axonal compromise induced by the virus, especially by maintaining the more complex synapses. Our data demonstrated that targeting Panx-1 channels can prevent and maybe revert brain synaptic compromise induced by SIV infection.

Colorectal cancer (CRC) is the one of the most frequent and deadly cancer worldwide. The regulation mediated by the N6methyladenosine (m6A) demethylase protein called FTO in CRC is quite controversial. As previously studied in obesity and food intake, currently is being linked to stemness, epithelial-mesenchymal transition, chemotherapy resistance and proliferation in colon cancer cells, however, its localization and function in the tumor microenvironment (TME) and how it connects with progression remains unclear. The aim of this study was to evaluate FTO protein in tumor and healthy corresponding tissue from 22 colorectal cancer patients with different histological TNM stages (hTNM) by immunohistochemistry and multiple immunofluorescence analysis; classifying the tumor and stromal FTO localization and associating this data with clinical and histopathological features. As for content, the frequency of FTO+ cells in stromal compartments increases in more invasive stages compared to non-tumor tissue and in tumors with low desmoplasia. Regarding to localization, FTO is mostly nuclear and present in the lamina propria cells in non-tumor tissues and in immune and fibro-immune compartments in the TME, such as T cells, cancer associated fibroblasts and macrophages. In tumor cells, the percentage of FTO+ cells increase in early carcinogenic stages (hTNM I vs healthy tissue) and in moderately differentiated tumors. In addition, nuclear FTO expression increases in normal T cells and fibroblasts with a particular pattern after exposure for 24h to a colon adenocarcinoma cell-derived conditioned media, suggesting FTO activity in the TME interaction following a paracrine signal. In conclusion, the increase of the FTO protein in both tumor and stroma from CRC suggests its participation mediating TME communication. Citation Format: Glauben T. Landskron-Ramos, Antonia L. Domínguez-Beltrando, Mauricio Zambra-Rojas, Antonella Sanguineti, Gonzalo Vasquez, Marjorie De la Fuente, Daniela Simian, Silvana Valdebenito-Silva, Juan Saavedra, Solange Gouet, Ricardo Soto-Rifo, Daniela Sauma, Eliseo Eugenin, Mario Abedrapo, Marcela A. Hermoso, Marcela A. Hermoso. Novel potential role of m6A-demethylase FTO (fat mass and obesity) protein in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1251.

HIV has become a chronic disease despite the effective use of anti-retroviral therapy (ART). However, the mechanisms of tissue colonization, viral evolution, generation of viral reservoirs, and compartmentalization are still a matter of debate, and most of the underlying mechanisms behind these are still not well described due to the challenges involved in examining early events of infection at the cellular and molecular level. Thus, there is still an urgent need to explore these areas to develop effective HIV-cure strategies. Here, we describe the early events of tissue colonization and compartmentalization as well as the role of tunneling nanotubes (TNTs)-like structures (TLS) during viral spread in the presence and absence of effective anti-retroviral treatment. To examine these mechanisms, NOD/SCID IL2 RG−/− (NSG) humanized mice were either directly infected with HIV(ADA) or with low numbers of HIV(ADA)-infected leukocytes to limit tissue colonization in the presence and absence of TAK779, an effective CCR5 blocker of HIV-entry. We identify that viral seeding in tissues occurs early in a tissue and cell type-specific manner (24 to 72 h). Reduction in systemic HIV-replication by TAK779 treatment did not affect tissue seeding or spreading, despite reduced systemic viral replication. Tissue associated HIV-infected cells had different properties than cells in the circulation because the virus continues to spread in tissues in a TLS dependent manner, despite ART. Thus, understanding these mechanisms can provide new approaches to enhance the efficacy of existing ART and HIV-infection cure strategy.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly rampaged worldwide, causing a pandemic of coronavirus disease (COVID -19), but the biology of SARS-CoV-2 remains under investigation. We demonstrate that both SARS-CoV-2 spike protein and human coronavirus 229E (hCoV-229E) or its purified S protein, one of the main viruses responsible for the common cold, induce the transient opening of Pannexin-1 (Panx-1) channels in human lung epithelial cells. However, the Panx-1 channel opening induced by SARS-CoV-2 is greater and more prolonged than hCoV-229E/S protein, resulting in an enhanced ATP, PGE2, and IL-1β release. Analysis of lung lavages and tissues indicate that Panx-1 mRNA expression is associated with increased ATP, PGE2, and IL-1β levels. Panx-1 channel opening induced by SARS-CoV-2 spike protein is angiotensin-converting enzyme 2 (ACE-2), endocytosis, and furin dependent. Overall, we demonstrated that Panx-1 channel is a critical contributor to SARS-CoV-2 infection and should be considered as an alternative therapy., Graphical abstract, Cell biology; Molecular physiology; Virology

Cell-to-cell communication is essential for the development and proper function of multicellular systems. We and others demonstrated that tunneling nanotubes (TNT) proliferate in several pathological conditions such as HIV, cancer, and neurodegenerative diseases. However, the nature, function, and contribution of TNT to cancer pathogenesis are poorly understood. Our analyses demonstrate that TNT structures are induced between glioblastoma (GBM) cells and surrounding non-tumor astrocytes to transfer tumor-derived mitochondria. The mitochondrial transfer mediated by TNT resulted in the adaptation of non-tumor astrocytes to tumor-like metabolism and hypoxia conditions. In conclusion, TNT are an efficient cell-to-cell communication system used by cancer cells to adapt the microenvironment to the invasive nature of the tumor.

The major barrier to eradicating Human immunodeficiency virus-1 (HIV) infection is the generation of tissue-associated quiescent long-lasting viral reservoirs refractory to therapy. Upon interruption of anti-retroviral therapy (ART), HIV replication can be reactivated. Within the brain, microglia/macrophages and a small population of astrocytes are infected with HIV. However, the role of astrocytes as a potential viral reservoir is becoming more recognized because of the improved detection and quantification of HIV viral reservoirs. In this report, we examined the infectivity of human primary astrocytes in vivo and in vitro, and their capacity to maintain HIV infection, become latently infected, be reactivated, and transfer new HIV virions into neighboring cells. Analysis of human brain tissue sections obtained from HIV-infected individuals under effective and prolonged ART indicates that a small population of astrocytes has integrated HIV-DNA. In vitro experiments using HIV-infected human primary astrocyte cultures confirmed a low percentage of astrocytes had integrated HIV-DNA, with poor to undetectable replication. Even in the absence of ART, long-term culture results in latency that could be transiently reactivated with histone deacetylase inhibitor, tumor necrosis factor-alpha (TNF-α), or methamphetamine. Reactivation resulted in poor viral production but efficient cell-to-cell viral transfer into cells that support high viral replication. Together, our data provide a new understanding of astrocytes' role as viral reservoirs within the central nervous system (CNS).

HIV-associated neurological dysfunction is observed in more than half of the HIV-infected population, even in the current antiretroviral era. The mechanisms by which HIV mediates CNS dysfunction are not well understood but have been associated with the presence of long-lasting HIV reservoirs. In the CNS, macrophage/microglia and a small population of astrocytes harbor the virus. However, the low number of HIV-infected cells does not correlate with the high degree of damage, suggesting that mechanisms of damage amplification may be involved. Here, we demonstrate that the survival mechanism of HIV-infected cells and the apoptosis of surrounding uninfected cells is regulated by inter-organelle interactions among the mitochondria/Golgi/endoplasmic reticulum system and the associated signaling mediated by IP(3) and calcium. We identified that latently HIV-infected astrocytes had elevated intracellular levels of IP(3), a master regulator second messenger, which diffuses via gap junctions into neighboring uninfected astrocytes resulting in their apoptosis. In addition, using laser capture microdissection, we confirmed that bystander apoptosis of uninfected astrocytes and the survival of HIV-infected astrocytes were dependent on mitochondrial function, intracellular calcium, and IP(3) signaling. Blocking gap junction channels did not prevent an increase in IP(3) or inter-organelle dysfunction in HIV-infected cells but reduced the amplification of apoptosis into uninfected neighboring cells. Our data provide a mechanistic explanation for bystander damage induced by surviving infected cells that serve as viral reservoirs and provide potential targets for interventions to reduce the devastating consequences of HIV within the brain.

BACKGROUND: Glioblastoma (GBM) is a highly aggressive primary brain tumor. Currently, the suggested line of action is the surgical resection followed by radiotherapy and treatment with the adjuvant temozolomide (TMZ), a DNA alkylating agent. However, the ability of tumor cells to deeply infiltrate the surrounding tissue makes complete resection quite impossible, and in consequence, the probability of tumor recurrence is high, and the prognosis is not positive. GBM is highly heterogeneous and adapts to treatment in most individuals. Nevertheless, these mechanisms of adaption are unknown. RECENT FINDINGS: In this review, we will discuss the recent discoveries in molecular and cellular heterogeneity, mechanisms of therapeutic resistance, and new technological approaches to identify new treatments for GBM. The combination of biology and computer resources allow the use of algorithms to apply artificial intelligence (AI), and machine learning (ML) approaches to identify potential therapeutic pathways and to identify new drug candidates. CONCLUSION: These new approaches will generate a better understanding of GBM pathogenesis and will result in novel treatments to reduce or block the devastating consequences of brain cancers.

Background: In developed countries, Human Immunodeficiency Virus type-1 (HIV-1) infection has become a chronic disease despite the positive effects of anti-retroviral therapies (ART) but still at least half of the HIV infected population shown signs of cognitive impairment. Therefore, biomarkers of HIV cognitive decline are urgently needed. Methods: We analyze the opening of one of the larger channels expressed by humans, pannexin-1 channels, in the uninfected and HIV infected population (n=175). Upon opening several intracellular second messengers are released into the extracellular space including PGE2 and ATP in serum/plasma. We correlated the cognitive status of the patients with circulating levels of both factors upon a visit to the clinic. Findings: Here, we demonstrate that pannexin channels on fresh PBMCs from uninfected individuals are closed. In contrast, all HIV-infected individuals analyzed, even the ones under effective ART, had a spontaneous opening of pannexin-1 channels and increased circulating levels of PGE2 and ATP. These results suggest that even low or undetectable levels of HIV result in chronic inflammation and opening of pannexin-1 channels. Furthermore, we found that circulating levels of ATP, but not PGE2, correlated with the cognitive status of people living with HIV. Interpretation: We propose that circulating levels of ATP could predict CNS compromise and lead to the breakthroughs necessary to detect and prevent brain compromise in the HIV-infected population. Funding Statement: This work was funded by The National Institute of Mental Health grant, MH096625, the National Institute of Neurological Disorders and Stroke, NS105584, and UTMB internal funding (to E.A.E). Research in the Geiger (J.D.G.) laboratory was supported by the National Institute of General Medical Sciences under award numbers P30GM100329 and U54GM115458, the National Institute of Mental Health under award numbers R01MH100972 and R01MH105329, the National Institute of Neurological Diseases and Stroke under award number R01NS065957, and the National Institute of Drug Abuse under award number 2R01DA032444. The NNTC is made possible through funding from the NIMH and NINDS by the following grants: Manhattan HIV Brain Bank (MHBB): U24MH100931; Texas NeuroAIDS Research Center (TNRC): U24MH100930; National Neurological AIDS Bank (NNAB): U24MH100929; California NeuroAIDS Tissue Network (CNTN): U24MH100928; and Data Coordinating Center (DCC): U24MH100925. The authors also acknowledge the New Jersey and New York Blood Center, the Alfred P. Sloan Foundation Minority fellowship (to S.V.) and Mount Sinai NeuroAIDS Disparities Summer Institute, R25 MH080663 (to S.V. trainee). Declaration of Interests: The authors stated: "None." Ethics Approval Statement: Patients gave written, informed consent for the provision of blood for the purposes of HIV research before inclusion in the current CHARTER pilot study. The protocol for blood collection and analysis was approved by the Mount Sinai, Rutgers University and University of Texas Medical Branch Institutional Review Board (Protocol Numbers, Pro20140000794, Pro2012001303, 18-0136, 18-0135, 18-0134).

Chemical and electrical synapses are the two major communication systems that permit cell-to-cell communication within the nervous system. Although most studies are focused on chemical synapses (glutamate, γ-aminobutyric acid, and other neurotransmitters), clearly both types of synapses interact and cooperate to allow the coordination of several cell functions within the nervous system. The pineal gland has limited independent axonal innervation and not every cell has access to nerve terminals. Thus, additional communication systems, such as gap junctions, have been postulated to coordinate metabolism and signaling. Using acutely isolated glands and dissociated cells, we found that gap junctions spread glycogenolytic signals from cells containing adrenoreceptors to the entire gland lacking these receptors. Our data using glycogen and lactate quantification, electrical stimulation, and high-performance liquid chromatography with electrochemical detection, demonstrate that gap junctional communication between cells of the rat pineal gland allows cell-to-cell propagation of norepinephrine-induced signal that promotes glycogenolysis throughout the entire gland. Thus, the interplay of both synapses is essential for coordinating glycogen metabolism and lactate production in the pineal gland.

Currently, a major barrier to curing HIV infection is the generation of tissue-associated, non-replicating, long-lasting viral reservoirs that are refractory to therapy and can be reactivated upon anti-retroviral therapy interruption. One of these reservoirs are latently HIV-infected macrophages. Here, we show that HIV infection of macrophages results in survival of a small population of infected cells that are metabolically altered and characterized by mitochondrial fusion, lipid accumulation, and reduced mitochondrial ATP production. No changes in glycolysis were detected. Metabolic analysis indicated an essential role of succinate and other TCA metabolites in the tricarboxylic acid (TCA) cycle in mediating lipid accumulation and oxidative phosphorylation (OXPHOS) in the mitochondria. Furthermore, we show that while uninfected and HIV infected macrophages use fatty acids and glucose as primary sources of energy, surviving HIV infected macrophages also use glutamine/glutamate as a major energy source, and blocking these new sources of energy resulted in the killing of latent HIV infected macrophages. Together, our data provide a new understanding of the formation, properties, and potential novel ways to eliminate macrophage viral reservoirs.

Summary Glioblastoma (GBM) is the most prevalent and aggressive tumor in the central nervous system. Surgical resection followed by concurrent radiotherapy (ionizing radiation [IR]) and temozolomide (TMZ) is the standard of care for GBM. However, a large subset of patients offer resistance or become adapted to TMZ due mainly to the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT). Thus, alternative mechanisms of MGMT deregulation have been proposed but are heretofore unproven. We show that heterogeneous GBM cells express tunneling nanotubes (TNTs) upon oxidative stress and TMZ/IR treatment. We identified that MGMT protein diffused from resistant to sensitive cells upon exposure to TMZ/IR, resulting in protection against cytotoxic therapy in a TNT-dependent manner. In vivo analysis of resected GBM tumors support our hypothesis that the MGMT protein, but not its mRNA, was associated with TNT biomarkers. We propose that targeting TNT formation could be an innovative strategy to overcome treatment resistance in GBM., Graphical Abstract, Highlights • GBM cells form TNTs in response to ionizing radiation and TMZ treatment • TNTs transfer MGMT protein from resistant to sensitive cells to treatment • MGMT protein transferred via TNTs protect target cells from TMZ and IR treatment • Blocking TNTs and MGMT spread could prevent tumor adaptation to TMZ treatment, Cell Biology; Cancer

Naphthoxazole derivatives are small heterocyclic compounds endowed with outstanding fluorescence properties. In this work, we report a detailed study of the intense white light fluorescence observed in naphthoxazole-quinoline dyads in solvent mixtures including at least a strong hydrogen bonding solvent. The same phenomenon was also studied in inclusion complexes naphthoxazole derivatives-sulfonated-βCD either in aqueous solution as well as in solid phase. A novel mechanism of white molecular fluorescence generation based on solvent-to-fluorophore proton transfer facilitated by ground state hydrogen bonding was characterized. The emission combines both, a blue charge transfer fluorescence emitted by the locally excited singlet state along with a red-shifted emission from a proton transfer complex.

Connexin (Cx) and pannexin (Panx) containing channels - gap junctions (GJs) and hemichannels (HCs) - are present in virtually all cells and tissues. Currently, the role of these channels under physiological conditions is well defined. However, their role in the immune response and pathological conditions has only recently been explored. Data from several laboratories demonstrates that infectious agents, including HIV, have evolved to take advantage of GJs and HCs to improve viral/bacterial replication, enhance inflammation, and help spread toxicity into neighboring areas. In the current review, we discuss the role of Cx and Panx containing channels in immune activation and the pathogenesis of several infectious diseases. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.

Cryptococcus neoformans is an encapsulated yeast-like fungus capable of causing life threatening meningoencephalitis in patients with impaired immunity. This microbe primarily infects the host via inhalation but has the ability to disseminate to the central nervous system (CNS) either as a single cell or inside of macrophages. Upon traversing the blood brain barrier, C. neoformans has the capacity to form biofilm-like structures known as cryptococcomas. Hence, we will discuss the C. neoformans elements contributing to biofilm formation including the fungus’ ability to survive in the acidic environment of a macrophage phagosome and inside of the CNS. The purpose of this mini-review is to instill fresh interest in understanding the importance of biofilms on fungal pathogenesis.

Neoplastic growth and cellular differentiation are critical hallmarks of tumor development. It is well established that cell-to-cell communication between tumor cells and “normal” surrounding cells regulates tumor differentiation and proliferation, aggressiveness, and resistance to treatment. Nevertheless, the mechanisms that result in tumor growth and spread as well as the adaptation of healthy surrounding cells to the tumor environment are poorly understood. A major component of these communication systems is composed of connexin (Cx)-containing channels including gap junctions (GJs), tunneling nanotubes (TNTs), and hemichannels (HCs). There are hundreds of reports about the role of Cx-containing channels in the pathogenesis of cancer, and most of them demonstrate a downregulation of these proteins. Nonetheless, new data demonstrate that a localized communication via Cx-containing GJs, HCs, and TNTs plays a key role in tumor growth, differentiation, and resistance to therapies. Moreover, the type and downstream effects of signals communicated between the different populations of tumor cells are still unknown. However, new approaches such as artificial intelligence (AI) and machine learning (ML) could provide new insights into these signals communicated between connected cells. We propose that the identification and characterization of these new communication systems and their associated signaling could provide new targets to prevent or reduce the devastating consequences of cancer.