DNA-dependent targeting of cell nuclei by a lupus autoantibody

A lupus-derived autoantibody that binds to intracellular RNA activates cGAS-mediated tumor immunity and can deliver RNA into cells

Nucleic acid-mediated signaling triggers an immune response that is believed to be central to the pathophysiology of autoimmunity in systemic lupus erythematosus (SLE). Here, we found that a cell-penetrating, SLE-associated antiguanosine autoantibody may present therapeutic opportunities for cancer treatment. The autoantibody entered cells through a nucleoside salvage-linked pathway of membrane transit that avoids endosomes and lysosomes and bound to endogenous RNA in live cells. In orthotopic models of glioblastoma, the antibody localized to areas adjacent to necrotic tumor cells and promoted animal survival in a manner that depended on T cells. Mechanistic studies revealed that antibody binding to nucleic acids activated the cytoplasmic pattern recognition receptor cyclic GMP-AMP synthase (cGAS), thereby stimulating immune signaling and cGAS-dependent cytotoxicity. Moreover, the autoantibody could carry and deliver functional RNA into tumor, brain, and muscle tissues in live mice when administered locally. The findings establish a collaborative autoantibody-nucleic acid interaction that is translatable to strategies for nonviral gene delivery and immunotherapy.

Next-generation cell-penetrating antibodies for tumor targeting and RAD51 inhibition

Monoclonal antibody therapies for cancer have demonstrated extraordinary clinical success in recent years. However, these strategies are thus far mostly limited to specific cell surface antigens, even though many disease targets are found intracellularly. Here we report studies on the humanization of a full-length, nucleic acid binding, monoclonal lupus-derived autoantibody, 3E10, which exhibits a novel mechanism of cell penetration and tumor specific targeting. Comparing humanized variants of 3E10, we demonstrate that cell uptake depends on the nucleoside transporter ENT2, and that faster cell uptake and superior in vivo tumor targeting are associated with higher affinity nucleic acid binding. We show that one human variant retains the ability of the parental 3E10 to bind RAD51, serving as a synthetically lethal inhibitor of homology-directed repair in vitro. These results provide the basis for the rational design of a novel antibody platform for therapeutic tumor targeting with high specificity following systemic administration.

Neurological glycogen storage diseases and emerging therapeutics

Glycogen storage diseases (GSDs) comprise a group of inherited metabolic disorders characterized by defects in glycogen metabolism, leading to abnormal glycogen accumulation in multiple tissues, most notably affecting the liver, skeletal muscle, and heart. Recent findings have uncovered the importance of glycogen metabolism in the brain, sustaining a myriad of physiological functions and linking its perturbation to central nervous system (CNS) pathology. This link resulted in classification of neurological-GSDs (n-GSDs), a group of diseases with shared deficits in neurological glycogen metabolism. The n-GSD patients exhibit a spectrum of clinical presentations with common etiology while requiring tailored therapeutic approaches from the traditional GSDs. Recent research has elucidated the genetic and biochemical mechanisms and pathophysiological basis underlying different n-GSDs. Further, the last decade has witnessed some promising developments in novel therapeutic approaches, including enzyme replacement therapy (ERT), substrate reduction therapy (SRT), small molecule drugs, and gene therapy targeting key aspects of glycogen metabolism in specific n-GSDs. This preclinical progress has generated noticeable success in potentially modifying disease course and improving clinical outcomes in patients. Herein, we provide an overview of current perspectives on n-GSDs, emphasizing recent advances in understanding their molecular basis, therapeutic developments, underscore key challenges and the need to deepen our understanding of n-GSDs pathogenesis to develop better therapeutic strategies that could offer improved treatment and sustainable benefits to the patients.

Cathepsin B Nuclear Flux in a DNA-Guided "Antinuclear Missile" Cancer Therapy

Some antinuclear antibodies (ANAs) bind extracellular nucleic acids released into tumor environments and are pulled into the nuclei of live cancer cells through nucleoside salvage pathways, independent of tumor-specific surface antigens. Here we show that ANA nuclear penetration induces nuclear flux by the lysosomal protease cathepsin B and leverage this mechanism to design an antinuclear antibody-drug conjugate (ANADC) with cathepsin B-labile drug linker. The ANADC targets nucleic acid exhaust from necrotic tumors and crosses membrane barriers through nucleoside salvage as a DNA-seeking and tumor agnostic "antinuclear missile" cancer therapy.

Nuclear-penetrating scleroderma autoantibody inhibits topoisomerase 1 cleavage complex formation

The contributions of anti-Topoisomerase 1 (Top1) autoantibodies to the pathophysiology of diffuse cutaneous systemic sclerosis (dcSSc), the most aggressive scleroderma subtype, are unknown. Top1 catalyzes DNA relaxation and unwinding in cell nuclei, a site previously considered inaccessible to antibodies. The discovery of autoantibodies in systemic lupus erythematosus that penetrate nuclei and inhibit DNA repair raised the possibility that nuclear-penetrating autoantibodies contribute to mechanisms of autoimmunity. Here we show that an anti-Top1 autoantibody produced by a single B cell clone from a patient with dcSSc penetrates live cells and localizes into nuclei. Functionally, the autoantibody inhibits formation of the Top1 cleavage complex necessary for DNA nicking, which distinguishes it from cytotoxic camptothecin Top1 inhibitors used in cancer therapy that trap the cleavage complex rather than preventing its formation. Discovery of a patient-derived cell-penetrating scleroderma anti-Top1 autoantibody that inhibits Top1 cleavage complex formation supports the hypothesis that anti-Top1 autoantibodies contribute to cellular dysfunction in dcSSc and offers a valuable antibody reagent resource for future studies on anti-Top1 autoantibody contributions to scleroderma pathophysiology.

The multifaceted roles of the brain glycogen

Glycogen is a biologically essential macromolecule that is directly involved in multiple human diseases. While its primary role in carbohydrate storage and energy metabolism in the liver and muscle is well characterized, recent research has highlighted critical metabolic and non-metabolic roles for glycogen in the brain. In this review, the emerging roles of glycogen homeostasis in the healthy and diseased brain are discussed with a focus on advancing our understanding of the role of glycogen in the brain. Innovative technologies that have led to novel insights into glycogen functions are detailed. Key insights into how cellular localization impacts neuronal and glial function are discussed. Perturbed glycogen functions are observed in multiple disorders of the brain, including where it serves as a disease driver in the emerging category of neurological glycogen storage diseases (n-GSDs). n-GSDs include Lafora disease (LD), adult polyglucosan body disease (APBD), Cori disease, Glucose transporter type 1 deficiency syndrome (G1D), GSD0b, and late-onset Pompe disease (PD). They are neurogenetic disorders characterized by aberrant glycogen which results in devastating neurological and systemic symptoms. In the most severe cases, rapid neurodegeneration coupled with dementia results in death soon after diagnosis. Finally, we discuss current treatment strategies that are currently being developed and have the potential to be of great benefit to patients with n-GSD. Taken together, novel technologies and biological insights have resulted in a renaissance in brain glycogen that dramatically advanced our understanding of both biology and disease. Future studies are needed to expand our understanding and the multifaceted roles of glycogen and effectively apply these insights to human disease.

Pin1-Catalyzed Conformation Changes Regulate Protein Ubiquitination and Degradation

The unique prolyl isomerase Pin1 binds to and catalyzes cis-trans conformational changes of specific Ser/Thr-Pro motifs after phosphorylation, thereby playing a pivotal role in regulating the structure and function of its protein substrates. In particular, Pin1 activity regulates the affinity of a substrate for E3 ubiquitin ligases, thereby modulating the turnover of a subset of proteins and coordinating their activities after phosphorylation in both physiological and disease states. In this review, we highlight recent advancements in Pin1-regulated ubiquitination in the context of cancer and neurodegenerative disease. Specifically, Pin1 promotes cancer progression by increasing the stabilities of numerous oncoproteins and decreasing the stabilities of many tumor suppressors. Meanwhile, Pin1 plays a critical role in different neurodegenerative disorders via the regulation of protein turnover. Finally, we propose a novel therapeutic approach wherein the ubiquitin-proteasome system can be leveraged for therapy by targeting pathogenic intracellular targets for TRIM21-dependent degradation using stereospecific antibodies.

Mendelian randomization analysis reveals a protective association between genetically predicted systemic lupus erythematosus and renal cell carcinoma

Observational studies have suggested that there may be a connection between systemic lupus erythematosus (SLE) and a higher likelihood of developing urological cancers, although the exact cause-effect relationship is still unclear. This study therefore investigated the causal relationship between SLE and urological cancers using the Mendelian randomization (MR) approach. Our primary MR analysis involved using the inverse variance weighted method, which employed an inverse-variance-weighted approach, to examine the causal relationship between SLE and urological conditions. In addition, we performed various sensitivity analyses, such as MR-Egger regression, tests for heterogeneity, and leave-one-out sensitivity tests, to assess the reliability of our results. The findings from our analysis using Two-Sample MR showed that genetically predicted SLE was linked to a reduced likelihood of developing renal cell carcinoma (RCC) (odds ratio = 0.9996, 95% confidence interval = 0.9993-0.9999, P value = .0159). These results suggest a possible protective impact of SLE against RCC. Nevertheless, no substantial correlation was detected between SLE and the likelihood of developing bladder cancer or prostate cancer. Collectively, these findings offer significant fresh perspectives on the possible correlation between SLE and genitourinary malignancies, specifically RCC, which will provide ideas and basis for the treatment of RCC.

Safety assessment, radioiodination and preclinical evaluation of antinuclear antibody as novel medication for prostate cancer in mouse xenograft model

This study aims to provide in vitro and in vivo data to support the utilization of antinuclear antibodies (ANAs) as novel tools for the diagnosis and treatment of prostate cancers. The hematological, biochemical, and histological toxicities of ANAs were assessed at the doses of 5 and 50 μg per mouse. Radiolabeling study was then conducted with ANA and 131I using the chloramine T method, and the biodistribution and treatment efficacy were subsequently investigated in a PC3 xenograft model. No changes in clinical behavior or signs of intoxication, necrosis, or malignancy were observed in ANA-treated mice. 131I-ANA was obtained in very high yield and radiochemical purity, at 94.97 ± 0.98% and 98.56 ± 0.29%, respectively. They achieved immunoreactivity fraction of 0.841 ± 0.17% with PC-3 cells. Levels of radiolabeled ANAs were 1.15-10.14 times higher in tumor tissues than in other examined organs at 24 h post-injection. The tumor growth inhibition rates were 28.33 ± 5.01% in PC3 xenografts mice treated with 131I-ANAs compared with controls and a nearly twofold improvement in median survival was observed. These results demonstrate that radioimmunotherapy of radiolabeled natural ANAs may be an effective treatment for prostate tumors.

Cellular protection from H2O2 toxicity by Fv-Hsp70: protection via catalase and gamma-glutamyl-cysteine synthase

Heat shock proteins (HSPs), especially Hsp70 (HSPA1), have been associated with cellular protection from various cellular stresses including heat, hypoxia-ischemia, neurodegeneration, toxins, and trauma. Endogenous HSPs are often synthesized in direct response to these stresses but in many situations are inadequate in protecting cells. The present study addresses the transduction of Hsp70 into cells providing protection from acute oxidative stress by H2O2. The recombinant Fv-Hsp70 protein and two mutant Fv-Hsp70 proteins minus the ATPase domain and minus the ATPase and terminal lid domains were tested at 0.5 and 1.0 μM concentrations after two different concentrations of H2O2 treatment. All three recombinant proteins protected SH-SY5Y cells from acute H2O2 toxicity. This data indicated that the protein binding domain was responsible for cellular protection. In addition, experiments pretreating cells with inhibitors of antioxidant proteins catalase and gamma-glutamylcysteine synthase (GGCS) before H2O2 resulted in cell death despite treatment with Fv-Hsp70, implying that both enzymes were protected from acute oxidative stress after treatment with Fv-Hsp70. This study demonstrates that Fv-Hsp70 is protective in our experiments primarily by the protein-binding domain. The Hsp70 terminal lid domain was also not necessary for protection.

DNA Oligonucleotides as Antivirals and Vaccine Constituents against SARS Coronaviruses: A Prospective Tool for Immune System Tuning

The SARS-CoV-2 pandemic has demonstrated the need to create highly effective antivirals and vaccines against various RNA viruses, including SARS coronaviruses. This paper provides a short review of innovative strategies in the development of antivirals and vaccines against SARS coronaviruses, with a focus on antisense antivirals, oligonucleotide adjuvants in vaccines, and oligonucleotide vaccines. Well-developed viral genomic databases create new opportunities for the development of innovative vaccines and antivirals using a post-genomic platform. The most effective vaccines against SARS coronaviruses are those able to form highly effective memory cells for both humoral and cellular immunity. The most effective antivirals need to efficiently stop viral replication without side effects. Oligonucleotide antivirals and vaccines can resist the rapidly changing genomic sequences of SARS coronaviruses using conserved regions of their genomes to generate a long-term immune response. Oligonucleotides have been used as excellent adjuvants for decades, and increasing data show that oligonucleotides could serve as antisense antivirals and antigens in vaccine formulations, becoming a prospective tool for immune system tuning.

Post-genomic platform for development of oligonucleotide vaccines against RNA viruses: diamond cuts diamond

The coronavirus pandemic has starkly demonstrated the need to create highly effective vaccines against various viral diseases. The emerging new platforms for vaccine creation (adenovirus vectors and mRNA vaccines) have shown their worth in the fight against the prevention of coronavirus infection. However, adenovirus vectors and mRNA vaccines have a serious disadvantage: as a rule, only the S protein of the coronavirus is presented as an antigen. This tactic for preventing infection allows the ever-mutating virus to escape quickly from the immunity protection provided by such vaccines. Today, viral genomic databases are well-developed, which makes it possible to create new vaccines on a fundamentally new post-genomic platform. In addition, the technology for the synthesis of nucleic acids is currently experiencing an upsurge in demand in various fields of molecular biology. The accumulated experience suggests that the unique genomic sequences of viruses can act as antigens that trigger powerful humoral and cellular immunity. To achieve this effect, the following conditions must be created: the structure of the nucleic acid must be single-stranded, have a permanent 3D nanostructure, and have a unique sequence absent in the vaccinated organism. Oligonucleotide vaccines are able to resist the rapidly changing genomic sequences of RNA viruses by using conserved regions of their genomes to generate a long-term immune response, acting according to the adage that a diamond cuts a diamond. In addition, oligonucleotide vaccines will not contribute to antibody-dependent enhanced infection, since the nucleic acid of the coronavirus is inside the viral particle. It is obvious that new epidemics and pandemics caused by RNA viruses will continue to arise periodically in the human population. The creation of new, safe, and effective platforms for the production of vaccines that can flexibly change and adapt to new subtypes of viruses is very urgent and at this moment should be considered as a strategically necessary task.

Role of the IgG4-related cholangitis autoantigen annexin A11 in cholangiocyte protection

BACKGROUND & AIMS

Annexin A11 was identified as autoantigen in IgG4-related cholangitis (IRC), a B-cell driven disease. Annexin A11 modulates calcium-dependent exocytosis, a crucial mechanism for insertion of proteins into their target membranes. Human cholangiocytes form an apical 'biliary bicarbonate umbrella' regarded as defense against harmful hydrophobic bile acid influx. The bicarbonate secretory machinery comprises the chloride/bicarbonate exchanger AE2 and the chloride channel ANO1. We aimed to investigate the expression and function of annexin A11 in human cholangiocytes and a potential role of IgG1/IgG4-mediated autoreactivity against annexin A11 in the pathogenesis of IRC.

METHODS

Expression of annexin A11 in human liver was studied by immunohistochemistry and immunofluorescence. In human control and ANXA11 knockdown H69 cholangiocytes, intracellular pH, AE2 and ANO1 surface expression, and bile acid influx were examined using ratio microspectrofluorometry, cell surface biotinylation, and 22,23-3H-glycochenodeoxycholic acid permeation, respectively. The localization of annexin A11-mEmerald and ANO1-mCherry was investigated by live-cell microscopy in H69 cholangiocytes after incubation with IRC patient serum containing anti-annexin A11 IgG1/IgG4-autoantibodies or disease control serum.

RESULTS

Annexin A11 was strongly expressed in human cholangiocytes, but not hepatocytes. Knockdown of ANXA11 led to reduced plasma membrane expression of ANO1, but not AE2, alkalization of intracellular pH and uncontrolled bile acid influx. High intracellular calcium conditions led to annexin A11 membrane shift and colocalization with ANO1. Incubation with IRC patient serum inhibited annexin A11 membrane shift and reduced ANO1 surface expression.

CONCLUSION

Cholangiocellular annexin A11 mediates apical membrane abundance of the chloride channel ANO1, thereby supporting biliary bicarbonate secretion. Insertion is inhibited by IRC patient serum containing anti-annexin A11 IgG1/IgG4-autoantibodies. Anti-annexin A11 autoantibodies may contribute to the pathogenesis of IRC by weakening the 'biliary bicarbonate umbrella'.

LAY SUMMARY

We previously identified annexin A11 as a specific autoantigen in immunoglobulin G4-related cholangitis (IRC), a B-cell driven disease affecting the bile ducts. Human cholangiocytes are protected against harmful hydrophobic bile acid influx by a defense mechanism referred to as the 'biliary bicarbonate umbrella'. We found that annexin A11 is required for the formation of a robust bicarbonate umbrella. Binding of patient-derived annexin A11 autoantibodies inhibits annexin A11 function, possibly contributing to bile duct damage by weakening the biliary bicarbonate umbrella in patients with IRC.

ENT2 facilitates brain endothelial cell penetration and blood-brain barrier transport by a tumor-targeting anti-DNA autoantibody

The blood-brain barrier (BBB) prevents antibodies from penetrating the CNS and limits conventional antibody-based approaches to brain tumors. We now show that ENT2, a transporter that regulates nucleoside flux at the BBB, may offer an unexpected path to circumventing this barrier to allow targeting of brain tumors with an anti-DNA autoantibody. Deoxymab-1 (DX1) is a DNA-damaging autoantibody that localizes to tumors and is synthetically lethal to cancer cells with defects in the DNA damage response. We found that DX1 penetrated brain endothelial cells and crossed the BBB, and mechanistic studies identify ENT2 as the key transporter. In efficacy studies, DX1 crosses the BBB to suppress orthotopic glioblastoma and breast cancer brain metastases. ENT2-linked transport of autoantibodies across the BBB has potential to be exploited in brain tumor immunotherapy, and its discovery raises hypotheses on actionable mechanisms of CNS penetration by neurotoxic autoantibodies in CNS lupus.

Phosgene: toxicology, animal models, and medical countermeasures

Phosgene is a gas crucial to industrial chemical processes with widespread production (∼1 million tons/year in the USA, 8.5 million tons/year worldwide). Phosgene's high toxicity and physical properties resulted in its use as a chemical warfare agent during the First World War with a designation of CG ('Choky Gas'). The industrial availability of phosgene makes it a compound of concern as a weapon of mass destruction by terrorist organizations. The hydrophobicity of phosgene exacerbates its toxicity often resulting in a delayed toxidrome as the upper airways are moderately irritated; by the time symptoms appear, significant damage has occurred. As the standard of care for phosgene intoxication is supportive therapy, a pressing need for effective therapeutics and treatment regimens exists. Proposed toxicity mechanisms for phosgene based on human and animal exposures are discussed. Whereas intermediary components in the phosgene intoxication pathways are under continued discussion, generation of reactive oxygen species and oxidative stress is a common factor. As animal models are required for the study of phosgene and for FDA approval via the Animal Rule; the status of existing models and their adherence to Haber's Rule is discussed. Finally, we review the continued search for efficacious therapeutics for phosgene intoxication; and present a rapid post-exposure response that places exogenous human heat shock protein 72, in the form of a cell-penetrating fusion protein (Fv-HSP72), into lung tissues to combat apoptosis resulting from oxidative stress. Despite significant progress, additional work is required to advance effective therapeutics for acute phosgene exposure.

Regulation and pharmacological targeting of RAD51 in cancer

Regulation of homologous recombination (HR) is central for cancer prevention. However, too little HR can increase cancer incidence, whereas too much HR can drive cancer resistance to therapy. Importantly, therapeutics targeting HR deficiency have demonstrated a profound efficacy in the clinic improving patient outcomes, particularly for breast and ovarian cancer. RAD51 is central to DNA damage repair in the HR pathway. As such, understanding the function and regulation of RAD51 is essential for cancer biology. This review will focus on the role of RAD51 in cancer and beyond and how modulation of its function can be exploited as a cancer therapeutic.

Pompe Disease: New Developments in an Old Lysosomal Storage Disorder

Pompe disease, also known as glycogen storage disease type II, is caused by the lack or deficiency of a single enzyme, lysosomal acid alpha-glucosidase, leading to severe cardiac and skeletal muscle myopathy due to progressive accumulation of glycogen. The discovery that acid alpha-glucosidase resides in the lysosome gave rise to the concept of lysosomal storage diseases, and Pompe disease became the first among many monogenic diseases caused by loss of lysosomal enzyme activities. The only disease-specific treatment available for Pompe disease patients is enzyme replacement therapy (ERT) which aims to halt the natural course of the illness. Both the success and limitations of ERT provided novel insights in the pathophysiology of the disease and motivated the scientific community to develop the next generation of therapies that have already progressed to the clinic.

Harnessing SLE Autoantibodies for Intracellular Delivery of Biologic Therapeutics

Intracellular delivery of therapeutic antibodies is highly desirable but remains a challenge for biomedical research and the pharmaceutical industry. Approximately two-thirds of disease-associated targets are found inside the cell. Difficulty blocking these targets with available drugs creates a need for technology to deliver highly specific therapeutic antibodies intracellularly. Historically, antibodies have not been believed to traverse the cell membrane and neutralize intracellular targets. Emerging evidence has revealed that anti-DNA autoantibodies found in systemic lupus erythematosus (SLE) patients can penetrate inside the cell. Harnessing this technology has the potential to accelerate the development of drugs against intracellular targets. Here, we dissect the mechanisms of the intracellular localization of SLE antibodies and discuss how to apply these insights to engineer successful cell-penetrating antibody drugs.

DDX5-targeting fully human monoclonal autoantibody inhibits proliferation and promotes differentiation of acute promyelocytic leukemia cells by increasing ROS production

Acute promyelocytic leukemia (APL) therapy involves the compounds cytotoxic to both malignant tumor and normal cells. Relapsed APL is resistant to subsequent chemotherapy. Novel agents are in need to kill APL cells selectively with minimal toxicity. DDX5 has been recognized to be a novel target to suppress acute myeloid leukemia (AML). However, the role of DDX5 remains elusive in APL. Here a DDX5-targeting fully human monoclonal autoantibody named after 2F5 was prepared. It is demonstrated that 2F5 selectively inhibited APL cell proliferation without toxicity to normal neutrophil and tissues. Moreover, 2F5 was confirmed to induce G0/G1 phase arrest in APL cells, and promote APL cell differentiation combined with decreased DDX5 expression and increased reactive oxygen species (ROS) production. Knockdown of DDX5 by siRNA also inhibited proliferation, promoted cell differentiation and enhanced ROS production in APL cells. However, the ROS inhibitor reversed the effects of 2F5 on DDX5 and ROS in APL cells. Thus, we conclude that DDX5-targeting 2F5 inhibits APL cell proliferation, and promotes cell differentiation via induction of ROS. 2F5 showed the therapeutic value of fully human monoclonal autoantibody in APL, which provides a novel and valid approach for treatment of relapse/refractory APL.

Harnessing the Therapeutic Potential of 'Rogue' Antibodies

Therapeutic antibodies have revolutionized modern medicine. At present, antibodies are successfully used for treatment of diverse human diseases, ranging from cancer to viral infections. All clinically approved antibodies rely on highly specific recognition of their target antigen. Antigen-binding promiscuity, binding to autoantigens, and propensity for self-binding (homophilic interaction) are highly undesirable characteristics of antibody drug candidates. Nevertheless, the immune system of all healthy individuals constantly produces and uses large quantities of antibodies that can be classified as inappropriate for development as drugs. Here, I provide arguments that antibodies with 'aberrant' properties have therapeutic potential. They could be useful in certain complex pathological conditions, thus enriching our armamentarium for treatment of human diseases.

Antibody-Mediated Enzyme Therapeutics and Applications in Glycogen Storage Diseases

The use of antibodies as targeting molecules or cell-penetrating tools has emerged at the forefront of pharmaceutical research. Antibody-directed therapies in the form of antibody-drug conjugates, immune modulators, and antibody-directed enzyme prodrugs have been most extensively utilized as hematological, rheumatological, and oncological therapies, but recent developments are identifying additional applications of antibody-mediated delivery systems. A novel application of this technology is for the treatment of glycogen storage disorders (GSDs) via an antibody-enzyme fusion (AEF) platform to penetrate cells and deliver an enzyme to the cytoplasm, nucleus, and/or other organelles. Exciting developments are currently underway for AEFs in the treatment of the GSDs Pompe disease and Lafora disease (LD). Antibody-based therapies are quickly becoming an integral part of modern disease therapeutics.

An effective cell-penetrating antibody delivery platform

Despite their well-recognized success in the clinic, antibodies generally do not penetrate cellular membranes to target intracellular molecules, many of which underlie incurable diseases. Here we show that covalently conjugating phosphorothioated DNA oligonucleotides to antibodies enabled their efficient cellular internalization. Antibody cell penetration was partially mediated by membrane potential alteration. Moreover, without an antigen to bind, intracellular levels of the modified antibodies underwent cellular clearance, which involved efflux and lysosomal degradation, enabling detection of intended intracellular molecules as tested in fibroblasts, tumor cells, and T cells. This target-dependent cellular retention of modified antibodies extended to in vivo studies. Both local and systemic administrations of low doses of modified antibodies effectively inhibited intracellular targets, such as transcription factors Myc, interferon regulatory factor 4, and tyrosine-protein kinase SRC, and expression of their downstream genes in tumors, resulting in tumor cell apoptosis and tumor growth inhibition. This simple modification enables the use of antibodies to detect and modulate intracellular molecules in both cultured living cells and in whole animals, forming the foundation for a new paradigm for antibody-based research, diagnostics, and therapeutics.

Anti-double Stranded DNA Antibodies: Origin, Pathogenicity, and Targeted Therapies

Systemic lupus erythematosus (SLE) is characterized by high-titer serological autoantibodies, including antibodies that bind to double-stranded DNA (dsDNA). The origin, specificity, and pathogenicity of anti-dsDNA antibodies have been studied from a wider perspective. These autoantibodies have been suggested to contribute to multiple end-organ injuries, especially to lupus nephritis, in patients with SLE. Moreover, serum levels of anti-DNA antibodies fluctuate with disease activity in patients with SLE. By directly binding to self-antigens or indirectly forming immune complexes, anti-dsDNA antibodies can accumulate in the glomerular and tubular basement membrane. These autoantibodies can also trigger the complement cascade, penetrate into living cells, modulate gene expression, and even induce profibrotic phenotypes of renal cells. In addition, the expression of suppressor of cytokine signaling 1 is reduced by anti-DNA antibodies simultaneously with upregulation of profibrotic genes. Anti-dsDNA antibodies may even participate in the pathogenesis of SLE by catalyzing hydrolysis of certain DNA molecules or peptides in cells. Recently, anti-dsDNA antibodies have been explored in greater depth as a therapeutic target in the management of SLE. A substantial amount of data indicates that blockade of pathogenic anti-dsDNA antibodies can prevent or even reverse organ damage in murine models of SLE. This review focuses on the recent research advances regarding the origin, specificity, classification, and pathogenicity of anti-dsDNA antibodies and highlights the emerging therapies associated with them.

Challenges in treating Pompe disease: an industry perspective

Pompe disease is a rare inherited metabolic disorder of defective lysosomal glycogen catabolism due to a deficiency in acid alpha-glucosidase (GAA). Alglucosidase alfa enzyme replacement therapy (ERT) using recombinant human GAA (rhGAA ERT) is the only approved treatment for Pompe disease. Alglucosidase alfa has provided irrefutable clinical benefits, but has not been an optimal treatment primarily due to poor drug targeting of ERT to skeletal muscles. Several critical factors contribute to this inefficiency. Some are inherent to the anatomy of the body that cannot be altered, while others may be addressed with better drug design and engineering. The knowledge gained from alglucosidase alfa ERT over the past 2 decades has allowed us to better understand the challenges that hinder its effectiveness. In this review, we detail the problems which must be overcome for improving drug targeting and clinical efficacy. These same issues may also impact therapeutic enzymes derived from gene therapies, and thus, have important implications for the development of next generation therapies for Pompe.

Targeted Intracellular Delivery of Antibodies: The State of the Art

A dominant area of antibody research is the extension of the use of this mighty experimental and therapeutic tool for the specific detection of molecules for diagnostics, visualization, and activity blocking. Despite the ability to raise antibodies against different proteins, numerous applications of antibodies in basic research fields, clinical practice, and biotechnology are restricted to permeabilized cells or extracellular antigens, such as membrane or secreted proteins. With the exception of small groups of autoantibodies, natural antibodies to intracellular targets cannot be used within living cells. This excludes the scope of a major class of intracellular targets, including some infamous cancer-associated molecules. Some of these targets are still not druggable via small molecules because of large flat contact areas and the absence of deep hydrophobic pockets in which small molecules can insert and perturb their activity. Thus, the development of technologies for the targeted intracellular delivery of antibodies, their fragments, or antibody-like molecules is extremely important. Various strategies for intracellular targeting of antibodies via protein-transduction domains or their mimics, liposomes, polymer vesicles, and viral envelopes, are reviewed in this article. The pitfalls, challenges, and perspectives of these technologies are discussed.

A lupus anti-DNA autoantibody mediates autocatalytic, targeted delivery of nanoparticles to tumors

Strategies to target nanoparticles to tumors that rely on surface modification with ligands that bind molecules overexpressed on cancer cells or the tumor neovasculature suffer from a major limitation: with delivery of toxic agents the amount of molecules available for targeting decreases with time; consequently, the efficiency of nanoparticle delivery is reduced. To overcome this limitation, here we propose an autocatalytic tumor-targeting mechanism based on targeting extracellular DNA (exDNA). exDNA is enriched in the tumor microenviroment and increases with treatment with cytotoxic agents, such as doxorubicin (DOX), due to release of DNA by dying tumor cells. We tested this approach using poly(lactic-co-glycolic acid) (PLGA) nanoparticles surface-conjugated with fragments of 3E10 (3E10EN), a lupus anti-DNA autoantibody. We demonstrated that 3E10EN-conjugated nanoparticles bound to DNA and preferentially localized to tumors in vivo. The efficiency of tumor localization of 3E10EN-conjugated, DOX-loaded nanoparticles increased with time and subsequent treatments, demonstrating an autocatalytic effect. 3E10EN-conjugated DOX-loaded nanoparticles exhibited a significant anti-tumor effect that was superior to all controls. This work demonstrates the promise of autocatalytic drug delivery mechanisms and establishes proof of concept for a new anti-DNA autoantibody-based approach for enhancing delivery of nanoparticles to tumors.

A cell-penetrating antibody inhibits human RAD51 via direct binding

RAD51, a key factor in homology-directed repair (HDR), has long been considered an attractive target for cancer therapy, but few specific inhibitors have been found. A cell-penetrating, anti-DNA, lupus autoantibody, 3E10, was previously shown to inhibit HDR, sensitize tumors to radiation, and mediate synthetic lethal killing of BRCA2-deficient cancer cells, effects that were initially attributed to its affinity for DNA. However, as the molecular basis for its ability to inhibit DNA repair, we report that 3E10 directly binds to the N-terminus of RAD51, sequesters RAD51 in the cytoplasm, and impedes RAD51 binding to DNA. Further, we generate separation-of-function mutations in the complementarity-determining regions of 3E10 revealing that inhibition of HDR tracks with binding to RAD51 but not to DNA, whereas cell penetration is linked to DNA binding. The consequences of these mutations on putative 3E10 interactions with RAD51 and DNA are correlated with in silico molecular modeling. Taken together, the results identify 3E10 as a novel inhibitor of RAD51 by direct binding, accounting for its ability to suppress HDR and providing the molecular basis to guide pre-clinical development of 3E10 as an anti-cancer agent.

The roles and applications of autoantibodies in progression, diagnosis, treatment and prognosis of human malignant tumours

The existence of autoantibodies towards an individual's own proteins or nucleic acids has been established for more than 100years, and for a long period, these autoantibodies have been believed to be closely associated with autoimmune diseases. However, in recent years, researchers have become more interested in the role and application of autoantibodies in progression, diagnosis, treatment and prognosis of human malignant tumours. Over the past few decades, numerous epidemiological studies have shown that the risk of certain cancers is significantly altered (increased or decreased) in patients with autoimmune diseases, which suggests that autoantibodies may play either promoting or suppressing roles in cancer progression. The idea that autoantibodies are directly involved in tumour progression gains special support by the findings that some antibodies secreted by a variety of cancer cells can promote their proliferation and metastasis. Because the cancer cells generate cell antigenic changes (neoantigens), which trigger the immune system to produce autoantibodies, serum autoantibodies against tumour-associated antigens have been established as a novel type of cancer biomarkers and have been extensively studied in different types of cancer. The autoantibodies as biomarkers in cancer diagnosis are not only more sensitive and specific than antigens, but also could appear before clinical evidences of the tumours, thus disclosing them. The observations that cancer risk is lower in patients with some autoimmune diseases suggest that certain autoantibodies may be protective from certain cancers. Moreover, the presence of autoantibodies in healthy individuals implies that it could be safe to employ autoantibodies to treat cancer. Of note, an autoantibodies derived from lupus murine model received much attention due to their selective cytotoxicity for malignant tumour cell without harming normal ones. These studies showed the therapeutic value of autoantibodies in cancer. In this review, we revisited the pathological or protective role of autoantibodies in cancer progression, summarize the application of autoantibodies in cancer diagnosis and prognosis, and discuss the value of autoantibodies in cancer therapy. The studies established to date suggest that autoantibodies not only regulate cancer progression but also promise to be valuable instruments in oncological diagnosis and therapy.

Cardioprotective Effects of HSP72 Administration on Ischemia-Reperfusion Injury

BACKGROUND

Although early reperfusion is the most desirable intervention after ischemic myocardial insult, it may add to damage through oxidative stress.

OBJECTIVES

This study investigated the cardioprotective effects of a single intravenous dose of heat shock protein-72 (HSP72) coupled to a single-chain variable fragment (Fv) of monoclonal antibody 3E10 (3E10Fv) in a rabbit ischemia-reperfusion model. The Fv facilitates rapid transport of HSP72 into cells, even with intact membranes.

METHODS

A left coronary artery occlusion (40 min) reperfusion (3 h) model was used in 31 rabbits. Of these, 12 rabbits received the fusion protein (Fv-HSP72) intravenously. The remaining 19 control rabbits received a molar equivalent of 3E10Fv alone (n = 6), HSP72 alone (n = 6), or phosphate-buffered saline (n = 7). Serial echocardiographic examinations were performed to assess left ventricular function before and after reperfusion. Micro-single-photon emission computed tomography imaging of ^99mTc-labeled annexin-V was performed with micro-computed tomography scanning to characterize apoptotic damage in vivo, followed by gamma counting of the excised myocardial specimens to quantify cell death. Histopathological characterization of the myocardial tissue and sequential cardiac troponin I measurements were also undertaken.

RESULTS

Myocardial annexin-V uptake was 43% lower in the area at risk (p = 0.0003) in Fv-HSP72-treated rabbits compared with control animals receiving HSP72 or 3E10Fv alone. During reperfusion, troponin I release was 42% lower and the echocardiographic left ventricular ejection fraction 27% higher in the Fv-HSP72-treated group compared with control animals. Histopathological analyses confirmed penetration of 3E10Fv-containing molecules into cardiomyocytes in vivo, and treatment with Fv-HSP72 showed fewer apoptotic nuclei compared with control rabbits.

CONCLUSIONS

Single-dose administration of Fv-HSP72 fusion protein at the time of reperfusion reduced myocardial apoptosis by almost one-half and improved left ventricular functional recovery after myocardial ischemia-reperfusion injury in rabbits. It might have potential to serve as an adjunct to early reperfusion in the management of myocardial infarction.

TRIM21 and the Function of Antibodies inside Cells

Therapeutic antibodies targeting disease-associated antigens are key tools in the treatment of cancer and autoimmunity. So far, therapeutic antibodies have targeted antigens that are, or are presumed to be, extracellular. A largely overlooked property of antibodies is their functional activity inside cells. The diverse literature dealing with intracellular antibodies emerged historically from studies of the properties of some autoantibodies. The identification of tripartite motif (TRIM) 21 as an intracellular Fc receptor linking cytosolic antibody recognition to the ubiquitin proteasome system brings this research into sharper focus. We review critically the research related to intracellular antibodies, link this to the TRIM21 effector mechanism, and highlight how this work is exposing the previously restricted intracellular space to the potential of therapeutic antibodies.

The molecular mechanism for nuclear transport and its application

Transportation between the cytoplasm and the nucleoplasm is critical for many physiological and pathophysiological processes including gene expression, signal transduction, and oncogenesis. So, the molecular mechanism for the transportation needs to be studied not only to understand cell physiological processes but also to develop new diagnostic and therapeutic targets. Recent progress in the research of the nuclear transportation (import and export) via nuclear pore complex and four important factors affecting nuclear transport (nucleoporins, Ran, karyopherins, and nuclear localization signals/nuclear export signals) will be discussed. Moreover, the clinical significance of nuclear transport and its application will be reviewed. This review will provide some critical insight for the molecular design of therapeutics which need to be targeted inside the nucleus.

Targeted heat shock protein 72 for pulmonary cytoprotection

Heat shock protein 72 (HSP72) is perhaps the most important member of the HSP70 family of proteins, given that it is induced in a wide variety of tissues and cells to combat stress, particularly oxidative stress. Here, we review independent observations of the critical role this protein plays as a pulmonary cytoprotectant and discuss the merits of developing HSP72 as a therapeutic for rapid delivery to cells and tissues after a traumatic event. We also discuss the fusion of HSP72 to a cell-penetrating single-chain Fv antibody fragment derived from mAb 3E10, referred to as Fv-HSP70. This fusion construct has been validated in vivo in a cerebral infarction model and is currently in testing as a clinical therapeutic to treat ischemic events and as a fieldable medical countermeasure to treat inhalation of toxicants caused by terrorist actions or industrial accidents.

DNA-damaging autoantibodies and cancer: the lupus butterfly theory

Autoantibodies reactive against host DNA are detectable in the circulation of most people with systemic lupus erythematosus (SLE). The long-held view that antibodies cannot penetrate live cells has been disproved. A subset of lupus autoantibodies penetrate cells, translocate to nuclei, and inhibit DNA repair or directly damages DNA. The result of these effects depends on the microenvironment and genetic traits of the cell. Some DNA-damaging antibodies alone have little impact on normal cells, but in the presence of other conditions, such as pre-existing DNA-repair defects, can become highly toxic. These findings raise new questions about autoimmunity and DNA damage, and reveal opportunities for new targeted therapies against malignancies particularly vulnerable to DNA damage. In this Perspectives article, we review the known associations between SLE, DNA damage and cancer, and propose a theory for the effects of DNA-damaging autoantibodies on SLE pathophysiology and cancer risk.

Targeting the replisome with transduced monoclonal antibodies triggers lethal DNA replication stress in cancer cells

Although chemical inhibition of the DNA damage response (DDR) in cancer cells triggers cell death, it is not clear if the fork blockade achieved with inhibitors that neutralise proteins of the replisome is sufficient on its own to overcome the DDR. Monoclonal antibodies to PCNA, which block the DNA elongation process in vitro, have been developed. When these antibodies were transduced into cancer cells, they are able to inhibit the incorporation of nucleoside analogues. When co-delivered with anti-PCNA siRNA, the cells were flattened and the size of their nuclei increased by up to 3-fold, prior to cell death. Analysis of these nuclei by super-resolution microscopy revealed the presence of large numbers of phosphorylated histone H2AX foci. A senescence-like phenotype of the transduced cells was also observed upon delivery of the corresponding Fab molecules or following PCNA gene disruption or when the Fab fragment of an antibody that neutralises DNA polymerase alpha was used. Primary melanoma cells and leukaemia cells that are resistant to chemical inhibitors were similarly affected by these antibody treatments. These results demonstrate that transduced antibodies can trigger a lethal DNA replication stress, which kills cancer cells by abolishing the biological activity of several constituents of the replisome.