Targeted delivery of indinavir to HIV-1 primary reservoirs with immunoliposomes

Novel Nanotechnology-Based Approaches for Targeting HIV Reservoirs

Highly active anti-retroviral therapy (HAART) is prescribed for HIV infection and, to a certain extent, limits the infection’s spread. However, it cannot completely eradicate the latent virus in remote and cellular reservoir areas, and due to the complex nature of the infection, the total eradication of HIV is difficult to achieve. Furthermore, monotherapy and multiple therapies are not of much help. Hence, there is a dire need for novel drug delivery strategies that may improve efficacy, decrease side effects, reduce dosing frequency, and improve patient adherence to therapy. Such a novel strategy could help to target the reservoir sites and eradicate HIV from different biological sanctuaries. In the current review, we have described HIV pathogenesis, the mechanism of HIV replication, and different biological reservoir sites to better understand the underlying mechanisms of HIV spread. Further, the review deliberates on the challenges faced by the current conventional drug delivery systems and introduces some novel drug delivery strategies that have been explored to overcome conventional drug delivery limitations. In addition, the review also summarizes several nanotechnology-based approaches that are being explored to resolve the challenges of HIV treatment by the virtue of delivering a variety of anti-HIV agents, either as combination therapies or by actively targeting HIV reservoir sites.

Current Development of Nano-Drug Delivery to Target Macrophages

Macrophages are the most important innate immune cells that participate in various inflammation-related diseases. Therefore, macrophage-related pathological processes are essential targets in the diagnosis and treatment of diseases. Since nanoparticles (NPs) can be preferentially taken up by macrophages, NPs have attracted most attention for specific macrophage-targeting. In this review, the interactions between NPs and the immune system are introduced to help understand the pharmacokinetics and biodistribution of NPs in immune cells. The current design and strategy of NPs modification for specific macrophage-targeting are investigated and summarized.

Nanoparticle-based strategies to target HIV-infected cells

Antiretroviral drugs employed for the treatment of human immunodeficiency virus (HIV) infections have remained largely ineffective due to their poor bioavailability, numerous adverse effects, modest uptake in infected cells, undesirable drug-drug interactions, the necessity for long-term drug therapy, and lack of access to tissues and reservoirs. Nanotechnology-based interventions could serve to overcome several of these disadvantages and thereby improve the therapeutic efficacy of antiretrovirals while reducing the morbidity and mortality due to the disease. However, attempts to use nanocarriers for the delivery of anti-retroviral drugs have started gaining momentum only in the past decade. This review explores in-depth the various nanocarriers that have been employed for the treatment of HIV infections highlighting their merits and possible demerits.

Advanced Nanomaterials for Preparedness Against (Re-)Emerging Viral Diseases

While the coronavirus disease (COVID-19) accounts for the current global pandemic, the emergence of other unknown pathogens, named "Disease X," remains a serious concern in the future. Emerging or re-emerging pathogens continue to pose significant challenges to global public health. In response, the scientific community has been urged to create advanced platform technologies to meet the ever-increasing needs presented by these devastating diseases with pandemic potential. This review aims to bring new insights to allow for the application of advanced nanomaterials in future diagnostics, vaccines, and antiviral therapies, thereby addressing the challenges associated with the current preparedness strategies in clinical settings against viruses. The application of nanomaterials has advanced medicine and provided cutting-edge solutions for unmet needs. Herein, an overview of the currently available nanotechnologies is presented, highlighting the significant features that enable them to control infectious diseases, and identifying the challenges that remain to be addressed for the commercial production of nano-based products is presented. Finally, to conclude, the development of a nanomaterial-based system using a "One Health" approach is suggested. This strategy would require a transdisciplinary collaboration and communication between all stakeholders throughout the entire process spanning across research and development, as well as the preclinical, clinical, and manufacturing phases.

Nanomedicine based approaches for combating viral infections

Millions of people die each year from viral infections across the globe. There is an urgent need to overcome the existing gap and pitfalls of the current antiviral therapy which include increased dose and dosing frequency, bioavailability challenges, non-specificity, incidences of resistance and so on. These stumbling blocks could be effectively managed by the advent of nanomedicine. Current review emphasizes over an enhanced understanding of how different lipid, polymer and elemental based nanoformulations could be potentially and precisely used to bridle the said drawbacks in antiviral therapy. The dawn of nanotechnology meeting vaccine delivery, role of RNAi therapeutics in antiviral treatment regimen, various regulatory concerns towards clinical translation of nanomedicine along with current trends and implications including unexplored research avenues for advancing the current drug delivery have been discussed in detail.

Lipid Nanocarriers for Anti-HIV Therapeutics: A Focus on Physicochemical Properties and Biotechnological Advances

Since HIV was first identified, and in a relatively short period of time, AIDS has become one of the most devastating infectious diseases of the 21st century. Classical antiretroviral therapies were a major step forward in disease treatment options, significantly improving the survival rates of HIV-infected individuals. Even though these therapies have greatly improved HIV clinical outcomes, antiretrovirals (ARV) feature biopharmaceutic and pharmacokinetic problems such as poor aqueous solubility, short half-life, and poor penetration into HIV reservoir sites, which contribute to the suboptimal efficacy of these regimens. To overcome some of these issues, novel nanotechnology-based strategies for ARV delivery towards HIV viral reservoirs have been proposed. The current review is focused on the benefits of using lipid-based nanocarriers for tuning the physicochemical properties of ARV to overcome biological barriers upon administration. Furthermore, a correlation between these properties and the potential therapeutic outcomes has been established. Biotechnological advancements using lipid nanocarriers for RNA interference (RNAi) delivery for the treatment of HIV infections were also discussed.

Surface Biomodification of Liposomes and Polymersomes for Efficient Targeted Drug Delivery

Chemotherapy has seen great progress in the development of performant treatment strategies. Nanovesicles such as liposomes and polymersomes demonstrated great potential in cancer therapy. However, these nanocarriers deliver their content passively, which faces a lot of constraints during blood circulation. The main challenge resides in degradation and random delivery to normal tissues. Hence, targeting drug delivery using specific molecules (such as antibodies) grafted over the surface of these nanocarriers came as the answer to overcome many problems faced before. The advantage of using antibodies is their antigen/antibody recognition, which provides a high level of specificity to reach treatment targets. This review discusses the many techniques of nanocarrier functionalization with antibodies. The aim is to recognize the various approaches by describing their advantages and deficiencies to create the most suitable drug delivery platform. Some methods are more suitable for other applications rather than drug delivery, which can explain the low success of some proposed targeted nanocarriers. In here, a critical analysis of how every method could impact the recognition and targeting capacity of some nanocarriers (liposomes and polymersomes) is discussed to make future research more impactful and advance the field of biomedicine further.

Multi-organ targeting of HIV-1 viral reservoirs with etravirine loaded nanostructured lipid carrier: An in-vivo proof of concept

The inadequate bioavailability and toxicity potential of antiretroviral therapy limit their effectiveness in the complete eradication of HIV from viral reservoirs. The penetration of these drugs into the brain is challenging because of the unfavorable physicochemical properties required to cross the membranes, limiting the transport of the drugs. Thus, in the current study, the authors report a nanocarrier-based drug delivery of a highly hydrophobic drug to overcome the existing limitations of the conventional therapies. An explicitly simple approach was used to overcome the limitations of existing anti-HIV therapies. The monophasic hot homogenized solution of lipid, drug, and solubilizer was diluted with the predetermined hot surfactant solution followed by the ultrasonication to generate the polydisperse nanoparticles with the size range of 50-1000 nm. The anti-HIV1 potential of nanostructured lipid carriers of Etravirine on HIV-infected cell lines showed efficacy with an appreciable increase in the therapeutic index as compared with the plain drug. Further, the results obtained from confocal microscopy along with flow cytometry exhibited efficient uptake of the nanocarrier loaded with coumarin-6 in cells. The pharmacokinetics of Etravirine nanostructured carriers was significantly better in all aspects compared to the plain drug solution, which could be attributed to molecular dispersion in the lipid matrix of the nanocarrier. A significant enhancement of Etravirine concentration of several-fold was also observed in the liver, ovary, lymph node, and brain, respectively, as compared to plain drug solution when assessed by biodistribution studies in rats. In conclusion, ETR-NLC systems could serve as a promising approach for simultaneous multi-site targeting and could provide therapeutic benefits for the efficient eradication of HIV/AIDS infections.

Dual engineered gold nanoparticle based synergistic prophylaxis delivery system for HIV/AIDS

HIV is a pandemic and continuously raises problem across the world. This disease puts an immense pressure on treatment modalities. There are only few clinically accepted drugs available for the treatment and few molecules under clinical development. Although, the antiretroviral drugs give reliable and positive response on control of virus replication but during the long treatment, it has been affirmed that there are number of side effects. With recent advancements in biotechnology, nanomaterials such as gold and silver etc. are proving to be a game changer in targeted drug delivery treatment. As gold nanoparticles (AuNPs) are biocompatible natural excipients, a lot of scientists are very eager to investigate more about the immune effects of AuNPs to create a safe and cost effective treatment that could potentially help in the reduction of numerous toxic effects present in the existing treatments of various critical diseases like cancer and HIV etc. In this context, the present hypothesis recommends the use of combination drug delivery strategy based on gold nanoparticles that could pave the way to overcome adverse results of existing delivery techniques of antiretroviral drugs to treat HIV. This review also highlights the fact that a proper development of this gold nanoparticle combination antiretroviral drug delivery approach will not only help to suppress the virus multiplication but also target the viral entry area by attaching with gp120 (glycoprotein 120), and inhibit the binding with CD4 (Cluster of differentiation 4) T cells.

Nanotechnology advances in pathogen- and host-targeted antiviral delivery: multipronged therapeutic intervention for pandemic control

The COVID-19 pandemic's high mortality rate and severe socioeconomic impact serve as a reminder of the urgent need for effective countermeasures against viral pandemic threats. In particular, effective antiviral therapeutics capable of stopping infections in its tracks is critical to reducing infection fatality rate and healthcare burden. With the field of drug delivery witnessing tremendous advancement in the last two decades owing to a panoply of nanotechnology advances, the present review summarizes and expounds on the research and development of therapeutic nanoformulations against various infectious viral pathogens, including HIV, influenza, and coronaviruses. Specifically, nanotechnology advances towards improving pathogen- and host-targeted antiviral drug delivery are reviewed, and the prospect of achieving effective viral eradication, broad-spectrum antiviral effect, and resisting viral mutations are discussed. As several COVID-19 antiviral clinical trials are met with lackluster treatment efficacy, nanocarrier strategies aimed at improving drug pharmacokinetics, biodistributions, and synergism are expected to not only contribute to the current disease treatment efforts but also expand the antiviral arsenal against other emerging viral diseases.

Recent Advancement in Nanotechnology-Based Drug Delivery System Against Viral Infections

In the last few decades, the exponential rise in the incidence of viral infections sets a global health emergency across the world. The biomimetic architecture, the ability to hijack host immune responses, continuous antigen shifting, and drafting are the major critical factors that are responsible for the unavailability of a concrete therapeutic regimen against viral infections. Further, inappropriate pharmacodynamic physicochemical and biological parameters such as low aqueous solubility, poor permeability, high affinity for plasm proteins, short biological half-lives, and fast elimination from the systemic circulation are the major critical factors that govern the suboptimal drug concentration at the target site that leads to the development of drug resistance. To address this issue, nanotechnology-based drug delivery approach is emerged as an altering method to attain the optimal drug concentration at the target site for a prolonged period by integrating the nanoengineering tools in the synthesis of nanoparticles. Nanodimensional configuration with enhanced permeability and retention effect, increased surface-area-to-volume ratio, provision for surface functionalization, etc., are the privileged aspects that make it an effective drug delivery system for dispensing the antiviral therapeutics. However, size, shape, charge, and surface topology of nanoparticles are the greater influential factors that determine target-specific drug delivery, optimum cellular uptake, degree of opsonization by the host immune cells, drug retention time, transcytosis, the extension of biological half-life, in vivo stability, and cytotoxicity. The review will enlighten the elaborative role of nanotechnology-based drug delivery and the major challenging aspect of clinical safety and efficacy.

Architectured Therapeutic and Diagnostic Nanoplatforms for Combating SARS-CoV-2: Role of Inorganic, Organic, and Radioactive Materials

Although extensive research is being done to combat SARS-CoV-2, we are yet far away from a robust conclusion or strategy. With an increased amount of vaccine research, nanotechnology has found its way into vaccine technology. Researchers have explored the use of various nanostructures for delivering the vaccines for enhanced efficacy. Apart from acting as delivery platforms, multiple studies have shown the application of inorganic nanoparticles in suppressing the growth as well as transmission of the virus. The present review gives a detailed description of various inorganic nanomaterials which are being explored for combating SARS-CoV-2 along with their role in suppressing the transmission of the virus either through air or by contact with inanimate surfaces. The review further discusses the use of nanoparticles for development of an antiviral coating that may decrease adhesion of SARS-CoV-2. A separate section has been included describing the role of nanostructures in biosensing and diagnosis of SARS-CoV-2. The role of nanotechnology in providing an alternative therapeutic platform along with the role of radionuclides in SARS-CoV-2 has been described briefly. Based on ongoing research and commercialization of this nanoplatform for a viral disease, the nanomaterials show the potential in therapy, biosensing, and diagnosis of SARS-CoV-2.

Application of a Scavenger Receptor A1-Targeted Polymeric Prodrug Platform for Lymphatic Drug Delivery in HIV

We have developed a macromolecular prodrug platform based on poly(l-lysine succinylated) (PLS) that targets scavenger receptor A1 (SR-A1), a receptor expressed by myeloid and endothelial cells. We demonstrate the selective uptake of PLS by murine macrophage, RAW 264.7 cells, which was eliminated upon cotreatment with the SR-A inhibitor polyinosinic acid (poly I). Further, we observed no uptake of PLS in an SR-A1-deficient RAW 264.7 cell line, even after 24 h incubation. In mice, PLS distributed to lymphatic organs following i.v. injection, as observed by ex vivo fluorescent imaging, and accumulated in lymph nodes following both i.v. and i.d. administrations, based on immunohistochemical analysis with high-resolution microscopy. As a proof-of-concept, the HIV antiviral emtricitabine (FTC) was conjugated to the polymer's succinyl groups via ester bonds, with a drug loading of 14.2% (wt/wt). The prodrug (PLS-FTC) demonstrated controlled release properties in vitro with a release half-life of 15 h in human plasma and 29 h in esterase-inhibited plasma, indicating that drug release occurs through both enzymatic and nonenzymatic mechanisms. Upon incubation of PLS-FTC with human peripheral blood mononuclear cells (PBMCs), the released drug was converted to the active metabolite FTC triphosphate. In a pharmacokinetic study in rats, the prodrug achieved ∼7-19-fold higher concentrations in lymphatic tissues compared to those in FTC control, supporting lymphatic-targeted drug delivery. We believe that the SR-A1-targeted macromolecular PLS prodrug platform has extraordinary potential for the treatment of infectious diseases.

Nanomaterials Designed for Antiviral Drug Delivery Transport across Biological Barriers

Viral infections are a major global health problem, representing a significant cause of mortality with an unfavorable continuously amplified socio-economic impact. The increased drug resistance and constant viral replication have been the trigger for important studies regarding the use of nanotechnology in antiviral therapies. Nanomaterials offer unique physico-chemical properties that have linked benefits for drug delivery as ideal tools for viral treatment. Currently, different types of nanomaterials namely nanoparticles, liposomes, nanospheres, nanogels, nanosuspensions and nanoemulsions were studied either in vitro or in vivo for drug delivery of antiviral agents with prospects to be translated in clinical practice. This review highlights the drug delivery nanosystems incorporating the major antiviral classes and their transport across specific barriers at cellular and intracellular level. Important reflections on nanomedicines currently approved or undergoing investigations for the treatment of viral infections are also discussed. Finally, the authors present an overview on the requirements for the design of antiviral nanotherapeutics.

Pharmaceutical Approaches to HIV Treatment and Prevention

Human immunodeficiency virus (HIV) infection continues to pose a major infectious disease threat worldwide. It is characterized by the depletion of CD4+ T cells, persistent immune activation, and increased susceptibility to secondary infections. Advances in the development of antiretroviral drugs and combination antiretroviral therapy have resulted in a remarkable reduction in HIV-associated morbidity and mortality. Antiretroviral therapy (ART) leads to effective suppression of HIV replication with partial recovery of host immune system and has successfully transformed HIV infection from a fatal disease to a chronic condition. Additionally, antiretroviral drugs have shown promise for prevention in HIV pre-exposure prophylaxis and treatment as prevention. However, ART is unable to cure HIV. Other limitations include drug-drug interactions, drug resistance, cytotoxic side effects, cost, and adherence. Alternative treatment options are being investigated to overcome these challenges including discovery of new molecules with increased anti-viral activity and development of easily administrable drug formulations. In light of the difficulties associated with current HIV treatment measures, and in the continuing absence of a cure, the prevention of new infections has also arisen as a prominent goal among efforts to curtail the worldwide HIV pandemic. In this review, the authors summarize currently available anti-HIV drugs and their combinations for treatment, new molecules under clinical development and prevention methods, and discuss drug delivery formats as well as associated challenges and alternative approaches for the future.

Targeted microbicides for preventing sexual HIV transmission

Sexual transmission remains one of the most significant hurdles in the fight against HIV infection. The use of vaginal or rectal microbicides has been proposed for topical pre-exposure prophylaxis but available results from clinical trials of candidate products have been, at best, less than optimal. While waiting for the first product to get regulatory approval, novel approaches are being explored in order to enhance efficacy, as well as to assure safety. Strategies involving specific delivery of antiviral agents to key players involved in the early steps of sexual transmission have the potential to help achieving such purposes. Engineering systems that allow targeting cells, tissues or other biological structures of interest may provide a way to modulate local pharmacokinetics of promising microbicide molecules and, thus, maximize protection. This concise review discusses the identification and use of potential targets for such purpose, while detailing on several examples of targeted systems engineered as potential microbicide candidates. Furthermore, remaining challenges and hints for future work in the field of targeted microbicides are addressed.

Immunoliposomes: A review on functionalization strategies and targets for drug delivery

Nanoparticles, especially liposomes, have gained prominence in the field of drug delivery for the treatment of human diseases, particularly cancer; they provide several advantages, including controlled drug release, protection of the drug against degradation, improved pharmacokinetics, long circulation, and passive targeting to tumors and inflammatory sites due to the enhanced permeability and retention effect. The functionalization of liposomes with monoclonal antibodies or antibody fragments to generate immunoliposomes has emerged as a promising strategy for targeted delivery to and uptake by cells overexpressing the antigens to these antibodies, with a consequent reduction in side effects. In this review, we address functionalization strategies for the non-covalent and covalent attachment of monoclonal antibodies and their fragments to liposomal surfaces. The main reaction occurs between the sulfhydryl groups of thiolated antibodies and maleimide-containing liposomes. Furthermore, we explore the main targeting possibilities with these ligands for the treatment of a variety of pathologies, including HER2- and EGFR-positive cancers, inflammatory and cardiovascular diseases, infectious diseases, and autoimmune and neurodegenerative diseases, which have not previously been reviewed together. Overall, many studies have shown selective delivery of immunoliposomes to target cells, with promising in vivo results, particularly for cancer treatment. Although clinical trials have been conducted, immunoliposomes have not yet received clinical approval. However, immunoliposomes are promising formulations that are expected to become available for therapeutic use after clinical trials prove their safety and efficacy, and after scaling issues are resolved.

Past, Present, and Future Drug Delivery Systems for Antiretrovirals

The human immunodeficiency virus has infected millions of people and the epidemic continues to grow rapidly in some parts of the world. Antiretroviral (ARV) therapy has provided improved treatment and prolonged the life expectancy of patients. Moreover, there is growing interest in using ARVs to protect against new infections. Hence, ARVs have emerged as our primary strategy in combating the virus. Unfortunately, several challenges limit the optimal performance of these drugs. First, ARVs often require life-long use and complex dosing regimens. This results in low patient adherence and periods of lapsed treatment manifesting in drug resistance. This has prompted the development of alternate dosage forms such as vaginal rings and long-acting injectables that stand to improve patient adherence. Another problem central to therapeutic failure is the inadequate penetration of drugs into infected tissues. This can lead to incomplete treatment, development of resistance, and viral rebound. Several strategies have been developed to improve drug penetration into these drug-free sanctuaries. These include encapsulation of drugs in nanoparticles, use of pharmacokinetic enhancers, and cell-based drug delivery platforms. In this review, we discuss issues surrounding ARV therapy and their impact on drug efficacy. We also describe various drug delivery-based approaches developed to overcome these issues.

Biophysical characterization of small molecule antiviral-loaded nanolipogels for HIV-1 chemoprophylaxis and topical mucosal application

Nanocarriers are versatile vehicles for drug delivery, and emerging as platforms to formulate and deliver multiple classes of antiretroviral (ARV) drugs in a single system. Here we describe the fabrication of hydrogel-core and lipid-shell nanoparticles (nanolipogels) for the controlled loading and topical, vaginal delivery of maraviroc (MVC) and tenofovir disoproxil fumarate (TDF), two ARV drugs with different mechanisms of action that are used in the treatment of HIV. The nanolipogel platform was used to successfully formulate MVC and TDF, which produced ARV drug-loaded nanolipogels that were characterized for their physical properties and antiviral activity against HIV-1 BaL in cell culture. We also show that administration of these drug carriers topically to the vaginal mucosa in a murine model leads to antiviral activity against HIV-1 BaL in cervicovaginal lavages. Our results suggest that nanolipogel carriers are promising for the encapsulation and delivery of hydrophilic small molecule ARV drugs, and may expand the nanocarrier systems being investigated for HIV prevention or treatment.

STATEMENT OF SIGNIFICANCE

Topical, mucosal intervention of HIV is a leading strategy in the efforts to curb the spread of viral infection. A significant research thrust in the field has been to characterize different dosage forms for formulation of physicochemically diverse antiretroviral drugs. Nanocarriers have been used to formulate and deliver small molecule and protein drugs for a range of applications, including ARV drugs for HIV treatment. The broad significance of our work includes evaluation of lipid-shell, hydrogel-core nanoparticles for formulation and topical, vaginal delivery of two water-soluble antiretroviral drugs. We have characterized these nanocarriers for their physical properties and their biological activity against HIV-1 infection in vitro, and demonstrated the ability to deliver drug-loaded nanocarriers in vivo.

Nanodrug formulations to enhance HIV drug exposure in lymphoid tissues and cells: clinical significance and potential impact on treatment and eradication of HIV/AIDS

Although oral combination antiretroviral therapy effectively clears plasma HIV, patients on oral drugs exhibit much lower drug concentrations in lymph nodes than blood. This drug insufficiency is linked to residual HIV in cells of lymph nodes. While nanoformulations improve drug solubility, safety and delivery, most HIV nanoformulations are intended to extend plasma levels. A stable nanodrug combination that transports, delivers and accumulates in lymph nodes is needed to clear HIV in lymphoid tissues. This review discusses limitations of current oral combination antiretroviral therapy and advances in anti-HIV nanoformulations. A 'systems approach' has been proposed to overcome these limitations. This concept has been used to develop nanoformulations for overcoming drug insufficiency, extending cell and tissue exposure and clearing virus for treating HIV/AIDS.

Development of HIV reservoir targeted long acting nanoformulated antiretroviral therapies

Human immunodeficiency virus (HIV) infection commonly results in a myriad of comorbid conditions secondary to immune deficiency. Infection also affects broad organ system function. Although current antiretroviral therapy (ART) reduces disease morbidity and mortality through effective control of peripheral viral load, restricted infection in HIV reservoirs including gut, lymphoid and central nervous system tissues, is not eliminated. What underlies these events is, in part, poor ART penetrance into each organ across tissue barriers, viral mutation and the longevity of infected cells. We posit that one means to improve these disease outcomes is through nanotechnology. To this end, this review discusses a broad range of cutting-edge nanomedicines and nanomedicine platforms that are or can be used to improve ART delivery. Discussion points include how polymer-drug conjugates, dendrimers, micelles, liposomes, solid lipid nanoparticles and polymeric nanoparticles can be harnessed to best yield cell-based delivery systems. When completely developed, such nanomedicine platforms have the potential to clear reservoirs of viral infection.

Stealth anti-CD4 conjugated immunoliposomes with dual antiretroviral drugs--modern Trojan horses to combat HIV

Highly active antiretroviral therapy (HAART) is the currently employed therapeutic intervention against AIDS where a drug combination is used to reduce the viral load. The present work envisages the development of a stealth anti-CD4 conjugated immunoliposomes containing two anti-retroviral drugs (nevirapine and saquinavir) that can selectively home into HIV infected cells through the CD4 receptor. The nanocarrier was characterized using transmission electron microscopy, FTIR, differential scanning calorimetry, particle size and zeta potential. The cell uptake was also evaluated qualitatively using confocal microscopy and quantitatively by flow cytometry. The drug to lipid composition was optimized for maximum encapsulation of the two drugs. Both drugs were found to localize in different regions of the liposome. The release of the reverse transcriptase inhibitor was dominant during the early phases of the release while in the later phases, the protease inhibitor is the major constituent released. The drugs delivered via anti-CD4 conjugated immunoliposomes inhibited viral proliferation at a significantly lower concentration as compared to free drugs. In vitro studies of nevirapine to saquinavir combination at a ratio of 6.2:5 and a concentration as low as 5 ng/mL efficiently blocked viral proliferation suggesting that co-delivery of anti-retroviral drugs holds a greater promise for efficient management of HIV-1 infection.

Infectious Diseases: Need for Targeted Drug Delivery

Infectious diseases are a leading cause of death worldwide, with the constant fear of global epidemics. It is indeed an irony that the reticuloendothelial system (RES), the body’s major defence system, is the primary site for intracellular infections which are more difficult to treat. Pro-inflammatory M1 macrophages play an important role in defence. However, ingenious pathogen survival mechanisms including phagolysosome destruction enable their persistence. Microbial biofilms present additional challenges. Low intracellular drug concentrations, drug efflux by efflux pumps and/or enzymatic degradation, emergence of multi-drug resistance (MDR), are serious limitations of conventional therapy. Targeted delivery using nanocarriers, and passive and active targeting strategies could provide quantum increase in intracellular drug concentration. Receptor mediated endocytosis using appropriate ligands is a viable approach. Liposomes and polymeric/lipidic nanoparticles, dendrimers micelles and micro/nanoemulsions could all be relied upon. Specialised targeting approaches are demonstrated for important diseases like tuberculosis, HIV and Malaria. Application of targeted delivery in the treatment of veterinary infections is exemplified and future possibilities indicated. The chapter thus provides an overview on important aspects of infectious diseases and the challenges therein, while stressing on the promise of targeted drug delivery in augmenting therapy of infectious diseases.

Targeting strategies for delivery of anti-HIV drugs

Human Immunodeficiency Virus (HIV) infection remains a significant cause of mortality globally. Though antiretroviral therapy has significantly reduced AIDS-related morbidity and mortality, there are several drawbacks in the current therapy, including toxicity, drug–drug interactions, development of drug resistance, necessity for long-term drug therapy, poor bio-availability and lack of access to tissues and reservoirs. To circumvent these problems, recent anti-HIV therapeutic research has focused on improving drug delivery systems through drug delivery targeted specifically to host cells infected with HIV or could potentially get infected with HIV. In this regard, several surface molecules of both viral and host cell origin have been described in recent years, that would enable targeted drug delivery in HIV infection. In the present review, we provide a comprehensive overview of the need for novel drug delivery systems, and the successes and challenges in the identification of novel viral and host-cell molecules for the targeted drug delivery of anti-HIV drugs. Such targeted anti-retroviral drug delivery approaches could pave the way for effective treatment and eradication of HIV from the body.

Lipid-calcium phosphate nanoparticles for delivery to the lymphatic system and SPECT/CT imaging of lymph node metastases

A lipid/calcium/phosphate (LCP) nanoparticle (NP) formulation (particle diameter ∼25 nm) with superior siRNA delivery efficiency was developed and reported previously. Here, we describe the successful formulation of (111)In into LCP for SPECT/CT imaging. Imaging and biodistribution studies showed that, polyethylene glycol grafted (111)In-LCP preferentially accumulated in the lymph nodes at ∼70% ID/g in both C57BL/6 and nude mice when the improved surface coating method was used. Both the liver and spleen accumulated only ∼25% ID/g. Larger LCP (diameter ∼67 nm) was less lymphotropic. These results indicate that 25 nm LCP was able to penetrate into tissues, enter the lymphatic system, and accumulate in the lymph nodes via lymphatic drainage due to 1) small size, 2) a well-PEGylated lipid surface, and 3) a slightly negative surface charge. The capability of intravenously injected (111)In-LCP to visualize an enlarged, tumor-loaded sentinel lymph node was demonstrated using a 4T1 breast cancer lymph node metastasis model. Systemic gene delivery to the lymph nodes after IV injection was demonstrated by the expression of red fluorescent protein cDNA. The potential of using LCP for lymphatic drug delivery is discussed.

Nanotechnology: a magic bullet for HIV AIDS treatment

Human immunodeficiency virus (HIV) infection has become devastating in last a few years. Nearly 7400 new infection cases are coming every day. Highly active antiretroviral therapy (HAART), which involves combination of at least three antiretroviral (ARV) drugs, has been used to extend the life span of the HIV-infected patients. HAART has played an important role to reduce mortality rate in the developed countries but in the developing countries condition is still worst with millions of people being infected by this disease. For the improvement of the situation, nanotechnology-based drug system has been explored for the HIV therapeutics. Nanosystems used for HIV therapeutics offer some unique advantage like enhancement of bioavailability, water solubility, stability, and targeting ability of ARV drugs. Main nanotechnology-based systems explored for HIV therapeutics are liposomes, nanoparticles, niosomes, polymeric micelles, and dendrimers. Present manuscript reviews conventional method of HIV therapeutics and recent advances in the field of nanotechnology-based systems for treatment of HIV-AIDS.

Lymphatic system: a prospective area for advanced targeting of particulate drug carriers

INTRODUCTION

The lymphatic system has a critical role in the immune system's recognition and response to disease and it is an additional circulatory system throughout the entire body. Extensive multidisciplinary investigations have been carried out in the area of lymphatic delivery, and lymphatic targeting has attracted a lot of attention for providing preferential chemotherapy and improving bioavailability of drugs that undergo hepatic first-pass metabolism.

AREAS COVERED

This review focuses on progress in the field of lymphatic therapeutics and diagnosis. Moreover, the anatomy and physiology of the lymphatic system, particulate drug carriers and different physicochemical parameters of both modified and unmodified particulate drug carriers and their effect on lymphatic targeting are addressed.

EXPERT OPINION

Particulate drug carriers have encouraged lymphatic targeting, but there are still challenges in targeting drugs and bioactives to specific sites, maintaining desired action and crossing all the physiological barriers. Lymphatic therapy using drug-encapsulated lipid carriers, especially liposomes and solid lipid nanoparticles, emerges as a new technology to provide better penetration into the lymphatics where residual disease exists. Size is the most important criteria when designing nanocarriers for targeting lymphatic vessels as the transportation of these particles into lymphatic vessels is size dependent. By increasing our understanding of lymphatic transport and uptake, and the role of lymphatics in various diseases, we can design new therapeutics for effective disease control.

Delivery Systems for Lymphatic Targeting

The lymphatic system has a critical role in the immune system’s recognition and response to disease, and it is an additional circulatory system throughout the entire body. Most solid cancers primarily spread from the main site via the tumour’s surrounding lymphatics before haematological dissemination. Targeting drugs to lymphatic system is quite complicated because of its intricate physiology. Therefore, it tends to be an important target for developing novel therapeutics. Currently, nanocarriers have encouraged the lymphatic targeting, but still there are challenges of locating drugs and bioactives to specific sites, maintaining desired action and crossing all the physiological barriers. Lymphatic therapy using drug-encapsulated colloidal carriers especially liposomes and solid lipid nanoparticles emerges as a new technology to provide better penetration into the lymphatics where residual disease exists. Optimising the proper procedure, selecting the proper delivery route and target area and making use of surface engineering tool, better carrier for lymphotropic system can be achieved. Thus, new methods of delivering drugs and other carriers to lymph nodes are currently under investigation.

Enhanced anti-HIV efficacy of indinavir after inclusion in CD4-targeted lipid nanoparticles

BACKGROUND

Combination drug therapy has reduced plasma HIV to undetectable levels; however, drug-sensitive virus persists in patients' lymphoid tissue. We have reported significant lymphoid tissue drug localization with indinavir-associated lipid nanoparticles (LNPs). Our current objective is to evaluate whether additional enhancement is achievable by targeting these particles to CD4-HIV host cells.

METHODS

We characterized 2 peptide-coated (CD4-BP2 and CD4-BP4) drug-associated LNPs and demonstrated CD4-cell specificity. Drug-associated LNPs expressing polyethyleneglycol were exposed on HIV-2-infected cells under dynamic conditions that emulated lymph node physiology for 15, 30, and 60 minutes at concentrations from 0 to 25 μM and evaluated for antiviral activity and cell-associated drug concentrations. The specificity of CD4-mediated enhancement of indinavir LNPs antiviral activity was evaluated by blocking with anti-CD4 antibody.

RESULTS

Inclusion of CD4-binding peptides on LNPs enhanced antiviral activity for all incubation conditions, compared with control particles or soluble drug (eg, 60 minutes exposure, EC50 = 0.12-0.13 vs. 0.46 μM for targeted nanoparticles vs. soluble drug). The CD4-BP4 peptide exhibited higher efficiency in eliciting antiviral activity than CD4-BP2-coated particles (EC50 = 7.5 μM vs. >25 μM at 15 minutes drug exposure). This enhancement seems to be driven by CD4 availability and cell-associated indinavir concentrations, as blocking of CD4 significantly ablated indinavir efficacy in targeted particles and indinavir concentrations reflected the observed anti-HIV activity.

CONCLUSIONS

We constructed CD4-targeted LNPs that provide selective binding and efficient delivery of indinavir to CD4-HIV host cells. Inclusion of polyethyleneglycol in LNPs would minimize immune recognition of peptides. The enhancement of anti-HIV effects is effective even under limited time exposure.

Nanotechnology and the treatment of HIV infection

Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals.

Design and characterization of novel peptide-coated lipid nanoparticles for targeting anti-HIV drug to CD4 expressing cells

Human immunodeficiency virus (HIV) persists in lymph nodes and lymphoid tissues even during aggressive drug treatment, likely due to insufficient drug concentrations at this site. Therefore, to eliminate this residual virus, methods that enhance lymph node drug concentrations are currently being evaluated. Although enhanced drug concentrations in tissue have been achieved with drug-associated lipid nanoparticles, targeting these particles to CD4(+) cells may provide specific delivery of drug to HIV target cells and further enhance drug efficacy. We have evaluated four candidate peptides with reported binding specificity to CD4 for anchoring on lipid nanoparticle preparations previously shown to localize in lymph nodes. Terminal cysteine containing candidate peptides were conjugated to lipid nanoparticles through maleimide-linked phospholipids for targeting to CD4 cells. Using fluorescently labeled lipid nanoparticle binding to cells with varying degree of CD4 expression (CEMx174, Molt-4, Jurkat, and Ramos), we indentified two peptide sequences that provided CD4 selectivity to nanoparticles. These two peptide candidates on lipid nanoparticles bound to cells corresponding to the degree of CD4 expression and in a peptide dose dependent manner. Further, binding of these targeted lipid nanoparticles was CD4 specific, as pre-exposure of CD4(+) cells to anti-CD4 antibodies or free peptides inhibited the binding interactions. These results indicate targeting of lipid nanoparticles for specific binding to CD4 can be accomplished by tagging CD4 binding peptides with peptides, and these results provide a basis for further evaluation of this targeted delivery system to enhance antiviral drug delivery to CD4(+) HIV host cells, particularly those in lymph nodes and lymphoid tissues.

The loading of labelled antibody-engineered nanoparticles with Indinavir increases its in vitro efficacy against Cryptosporidium parvum

There is much evidence to indicate the ability of Indinavir (IND) to reduce Cryptosporidium parvum infection in both in vitro and in vivo models. However, there are limitations to the administration of IND as such, due to its renal toxicity and the high rate of metabolism and degradation. We aimed to encapsulate IND in biodegradable poly (D,L-lactide-co-glycolide) nanoparticles (Np) and to engineer their surface by conjugation with an anti-Cryptosporidium IgG polyclonal antibody (Ab). Tetramethylrhodamine-labelled Np were loaded with IND and modified by conjugation with an Ab. The IND-loaded modified Np (Ab-TMR-IND-Np) did not show any change, as demonstrated by chemical analysis studies. Simultaneous addition of 50μM Ab-TMR-IND-Np and excysted oocysts to the cell culture resulted in complete inhibition of the infection. In C. parvum-infected cells, the extent to which the infection decreased depended on the duration of treatment with the Ab-TMR-IND-Np. The antibody-engineered Np loaded with IND were able to target C. parvum in infected cells and therefore might represent a novel therapeutic strategy against Cryptosporidium sp. infection. Moreover, the use of Np as an IND delivery device, allows the development of a more appropriate dose formulation thereby reducing the IND side effects.

Activation of latent HIV using drug-loaded nanoparticles

Antiretroviral therapy is currently only capable of controlling HIV replication rather than completely eradicating virus from patients. This is due in part to the establishment of a latent virus reservoir in resting CD4+ T cells, which persists even in the presence of HAART. It is thought that forced activation of latently infected cells could induce virus production, allowing targeting of the cell by the immune response. A variety of molecules are able to stimulate HIV from latency. However no tested purging strategy has proven capable of eliminating the infection completely or preventing viral rebound if therapy is stopped. Hence novel latency activation approaches are required. Nanoparticles can offer several advantages over more traditional drug delivery methods, including improved drug solubility, stability, and the ability to simultaneously target multiple different molecules to particular cell or tissue types. Here we describe the development of a novel lipid nanoparticle with the protein kinase C activator bryostatin-2 incorporated (LNP-Bry). These particles can target and activate primary human CD4+ T-cells and stimulate latent virus production from human T-cell lines in vitro and from latently infected cells in a humanized mouse model ex vivo. This activation was synergistically enhanced by the HDAC inhibitor sodium butyrate. Furthermore, LNP-Bry can also be loaded with the protease inhibitor nelfinavir (LNP-Bry-Nel), producing a particle capable of both activating latent virus and inhibiting viral spread. Taken together these data demonstrate the ability of nanotechnological approaches to provide improved methods for activating latent HIV and provide key proof-of-principle experiments showing how novel delivery systems may enhance future HIV therapy.

Nanoparticulate Delivery Systems for Antiviral Drugs

Nanomedicine opens new therapeutic avenues for attacking viral diseases and for improving treatment success rates. Nanoparticulate-based systems might change the release kinetics of antivirals, increase their bioavailability, improve their efficacy, restrict adverse drug side effects and reduce treatment costs. Moreover, they could permit the delivery of antiviral drugs to specific target sites and viral reservoirs in the body. These features are particularly relevant in viral diseases where high drug doses are needed, drugs are expensive and the success of a therapy is associated with a patient's adherence to the administration protocol.

This review presents the current status in the emerging area of nanoparticulate delivery systems in antiviral therapy, providing their definition and description, and highlighting some peculiar features. The paper closes with a discussion on the future challenges that must be addressed before the potential of nanotechnology can be translated into safe and effective antiviral formulations for clinical use.

Antiretroviral release from poly(DL-lactide-co-glycolide) nanoparticles in mice

OBJECTIVES

Free ritonavir, lopinavir and efavirenz injected intraperitoneally were compared with antiretroviral (AR) nanoparticles (NPs).

METHODS

This is a prospective study in BALB/c mice comparing the pharmacokinetics of free drugs with AR NPs. All animals received free drugs or AR NPs (20 mg/kg) in PBS. In vitro replication assays were used for determination of the anti-HIV efficacy of NP formulations. At specific times (free drugs 0.08, 0.125, 0.25, 0.33, 1, 2 and 3 days; AR NPs 0.125, 0.33, 1, 2, 4, 7, 14, 21, 28, 35 and 42 days) mice were euthanized and serum and organs were harvested for determination of AR concentrations by HPLC. Single treatment of monocyte-derived macrophages (MDMs) infected with HIV-1(ada) compared AR NPs (0.005-0.05 mg/mL) with free efavirenz or lopinavir/ritonavir (0.01-0.1 mg/mL), blank NPs and controls. Results are presented as means ± SEM.

RESULTS

Serum free AR drug concentrations peaked 4 h post-injection (ritonavir 3.9 ± 3.05, lopinavir 3.4 ± 2.5 and efavirenz 1.8 ± 0.63 µg/mL) and were eliminated by 72 h. Poly(dl-lactide-co-glycolide) NP animals had detectable ritonavir, lopinavir and efavirenz concentrations in all tissues for 28 days. Treatment of MDMs with AR NPs resulted in sustained inhibition of HIV-1(ada) replication.

CONCLUSIONS

AR drug concentrations from NPs are sustained for 28 days in vivo and anti-HIV inhibition was comparable to that of free drugs in vitro and could be a sustained treatment for delivery of AR drugs.

Surface modifications of nanocarriers for effective intracellular delivery of anti-HIV drugs

A variety of nanocarriers such as bioconjugates, dendrimers, liposomes, and nanoparticles have been widely evaluated as potential targeted drug delivery systems. Passive targeting of nanoscale carriers is based on a size-flow-filtration phenomenon that is usually limited to tumors, the reticular endothelial system, and possibly lymph nodes (LNs). In fact, targeting the delivery of drugs to pivotal physiological sites such as the lymph nodes has emerged as a promising strategy in treating HIV disease. Ligands for specific cell surface receptors can be displayed on nanocarriers in order to achieve active targeting. The approach has been extensively used preclinically in cancer where certain receptors are over-expressed at various stages of the disease. Unfortunately, markers of HIV infection are lacking and latently infected cells do not show any signs of infection on their surface. However, the disease naturally targets only a few cell types. The HIV receptor CD4, coreceptors (CCR5 and CXCR4), and some receptors relatively specific for macrophages provide potentially valuable surface targets for drug delivery to all susceptible cells in patients infected by HIV. This review focuses on nanoscale targeting with an emphasis on surface modifications of drug delivery nanocarriers for active targeting. A number of related issues, including HIV biology, targets, pharmacokinetics, and intracellular fate as well as literature-cited examples of emerging surface-modified targeted carrier systems are discussed.

Nanotechnology-based systems for the treatment and prevention of HIV/AIDS

The HIV/AIDS pandemic is an increasing global burden with devastating health-related and socioeconomic effects. The widespread use of antiretroviral therapy has dramatically improved life quality and expectancy of infected individuals, but limitations of currently available drug regimens and dosage forms, alongside with the extraordinary adapting capacity of the virus, have impaired further success. Alongside, circumventing the escalating number of new infections can only be attained with effective and practical preventative strategies. Recent advances in the field of drug delivery are providing evidence that engineered nanosystems may contribute importantly for the enhancement of current antiretroviral therapy. Additionally, groundwork is also being carried out in the field nanotechnology-based systems for developing preventative solutions for HIV transmission. This manuscript reviews recent advances in the field of nanotechnology-based systems for the treatment and prevention of HIV/AIDS. Particular attention is given to antiretroviral drug targeting to HIV reservoirs and the usefulness of nanosystems for developing topical microbicides and vaccines.

Non-polymeric nano-carriers in HIV/AIDS drug delivery and targeting

Development of an effective drug delivery approach for the treatment of HIV/AIDS is a global challenge. The conventional drug delivery approaches including Highly Active Anti Retroviral Therapy (HAART) have increased the life span of the HIV/AIDS patient. However, the eradication of HIV is still not possible with these approaches due to some limitations. Emergence of polymeric and non-polymeric nanotechnological approaches can be opportunistic in this direction. Polymeric carriers like, dendrimers and nanoparticles have been reported for the targeting of anti HIV drugs. The synthetic pathways as well polymeric framework create some hurdles in their successful formulation development as well as in the possible drug delivery approaches. In the present article, we have discussed the general physiological aspects of the infection along with the relevance of non-polymeric nanocarriers like liposomes, solid lipid nanoparticles (SLN), ethosomes, etc. in the treatment of this disastrous disease.

Combination antiretroviral drugs in PLGA nanoparticle for HIV-1

Background

Combination antiretroviral (AR) therapy continues to be the mainstay for HIV treatment. However, antiretroviral drug nonadherence can lead to the development of resistance and treatment failure. We have designed nanoparticles (NP) that contain three AR drugs and characterized the size, shape, and surface charge. Additionally, we investigated the in vitro release of the AR drugs from the NP using peripheral blood mononuclear cells (PBMCs).

Methods

Poly-(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) containing ritonavir (RTV), lopinavir (LPV), and efavirenz (EFV) were fabricated using multiple emulsion-solvent evaporation procedure. The nanoparticles were characterized by electron microscopy and zeta potential for size, shape, and charge. The intracellular concentration of AR drugs was determined over 28 days from NPs incubated with PBMCs. Macrophages were imaged by fluorescent microscopy and flow cytometry after incubation with fluorescent NPs. Finally, macrophage cytotoxicity was determined by MTT assay.

Results

Nanoparticle size averaged 262 ± 83.9 nm and zeta potential -11.4 ± 2.4. AR loading averaged 4% (w/v). Antiretroviral drug levels were determined in PBMCs after 100 μg of NP in 75 μL PBS was added to media. Intracellular peak AR levels from NPs (day 4) were RTV 2.5 ± 1.1; LPV 4.1 ± 2.0; and EFV 10.6 ± 2.7 μg and continued until day 28 (all AR ≥ 0.9 μg). Free drugs (25 μg of each drug in 25 μL ethanol) added to PBMCs served as control were eliminated by 2 days. Fluorescence microscopy and flow cytometry demonstrated phagocytosis of NP into monocytes-derived macrophages (MDMs). Cellular MTT assay performed on MDMs demonstrated that NPs are not significantly cytotoxic.

Conclusion

These results demonstrated AR NPs could be fabricated containing three antiretroviral drugs (RTV, LPV, EFV). Sustained release of AR from PLGA NP show high drug levels in PBMCs until day 28 without cytotoxicity.

Sustained and specific in vitro inhibition of HIV-1 replication by a protease inhibitor encapsulated in gp120-targeted liposomes

Selective delivery of antiretrovirals to human immunodeficiency virus (HIV) infected cells may reduce toxicities associated with long-term highly active antiretroviral therapy (HAART), may improve therapeutic compliance and delay the emergence of resistance. We developed sterically stabilized pegylated liposomes coated with targeting ligands derived from the Fab' fragment of HIV-gp120-directed monoclonal antibody F105, and evaluated these liposomes as vehicles for targeted delivery of a novel HIV-1 protease inhibitor. We demonstrated that the immunoliposomes were selectively taken up by HIV-1-infected cells and localized intracellularly, enabling the establishment of a cytoplasmic reservoir of protease inhibitor. In antiviral experiments, the drug delivered by the immunoliposomes showed greater and longer antiviral activity than comparable concentrations of free drug or drug encapsulated in non-targeted liposomes. In conclusion, by combining a targeting moiety with drug-loaded liposomes, efficient and specific uptake by non-phagocytic HIV-infected cells was facilitated, resulting in drug delivery to infected cells. This approach to targeted delivery of antiretroviral compounds may enable the design of drug regimens for patients that allow increased therapeutic adherence and less toxic treatment of HIV infection.

Targeted nanomedicines: effective treatment modalities for cancer, AIDS and brain disorders

Novel technology in the nanomedicine field is expected to develop innovative products as targeted drug-delivery approaches. Targeted drug delivery of various drugs for the treatment of cancer, AIDS and brain disorders is the primary research area in which nanomedicines have a major role and need. This review is concerned with emerging targeted nanomedicines (polymeric nanoparticles, solid lipid nanoparticles, polymeric micelles, dendrimers, liposomes, gold nanoparticles and magnetic nanoparticles) and multifunctional carriers capable of combining targeted drug delivery and imaging (polymeric micelles, dendrimers and magnetic nanoparticles) in the field of pharmaceutical applications. The significant toxicity issues associated with these nanomedicines are also explored here.