Andras Perl

Bio: Andras Perl is an academic researcher from State University of New York Upstate Medical University. The author has contributed to research in topics: Systemic lupus erythematosus & Lupus erythematosus. The author has an hindex of 59, co-authored 196 publications receiving 14134 citations. Previous affiliations of Andras Perl include Roswell Park Cancer Institute & State University of New York System.

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

Abstract: In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagy-related protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

Abstract: In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Mitochondrial hyperpolarization and ATP depletion in patients with systemic lupus erythematosus.

Abstract: Objective Peripheral blood lymphocytes (PBLs) from systemic lupus erythematosus (SLE) patients exhibit increased spontaneous and diminished activation-induced apoptosis. We tested the hypothesis that key biochemical checkpoints, the mitochondrial transmembrane potential (ΔΨm) and production of reactive oxygen intermediates (ROIs), mediate the imbalance of apoptosis in SLE. Methods We assessed the ΔΨm with potentiometric dyes, measured ROI production with oxidation-sensitive fluorochromes, and monitored cell death by annexin V and propidium iodide staining of lymphocytes, using flow cytometry. Intracellular glutathione levels were measured by high-performance liquid chromatography, while ATP and ADP levels were assessed by the luciferin-luciferase assay. Results Both ΔΨm and ROI production were elevated in the 25 SLE patients compared with the 25 healthy subjects and the 10 rheumatoid arthritis patients. Intracellular glutathione contents were diminished, suggesting increased utilization of reducing equivalents in SLE. H2O2, a precursor of ROIs, increased ΔΨm and caused apoptosis in normal PBLs. In contrast, H2O2-induced apoptosis and ΔΨm elevation were diminished, particularly in T cells, and the rate of necrotic cell death was increased in patients with SLE. The intracellular ATP content and the ATP:ADP ratio were reduced and correlated with the ΔΨm elevation in lupus. CD3:CD28 costimulation led to transient elevation of the ΔΨm, followed by ATP depletion, and sensitization of normal PBLs to H2O2-induced necrosis. Depletion of ATP by oligomycin, an inhibitor of F0F1–ATPase, had similar effects. Conclusion T cell activation and apoptosis are mediated by ΔΨm elevation and increased ROI production. Mitochondrial hyperpolarization and the resultant ATP depletion sensitize T cells for necrosis, which may significantly contribute to inflammation in patients with SLE.

N-acetylcysteine reduces disease activity by blocking mammalian target of rapamycin in T cells from systemic lupus erythematosus patients: A randomized, double-blind, placebo-controlled trial

Abstract: Objective Systemic lupus erythematosus (SLE) patients exhibit T cell dysfunction, which can be regulated through mitochondrial transmembrane potential (Δψm) and mammalian target of rapamycin (mTOR) by glutathione (GSH). This randomized, double-blind, placebo-controlled study was undertaken to examine the safety, tolerance, and efficacy of the GSH precursor N-acetylcysteine (NAC). Methods A total of 36 SLE patients received either daily placebo or 1.2 gm, 2.4 gm, or 4.8 gm of NAC. Disease activity was evaluated monthly by the British Isles Lupus Assessment Group (BILAG) index, the SLE Disease Activity Index (SLEDAI), and the Fatigue Assessment Scale (FAS) before, during, and after a 3-month treatment period. Mitochondrial transmembrane potential and mTOR were assessed by flow cytometry. Forty-two healthy subjects matched to patients for age, sex, and ethnicity were studied as controls. Results NAC up to 2.4 gm/day was tolerated by all patients, while 33% of those receiving 4.8 gm/day had reversible nausea. Placebo or NAC 1.2 gm/day did not influence disease activity. Considered together, 2.4 gm and 4.8 gm NAC reduced the SLEDAI score after 1 month (P = 0.0007), 2 months (P = 0.0009), 3 months (P = 0.0030), and 4 months (P = 0.0046); the BILAG score after 1 month (P = 0.029) and 3 months (P = 0.009); and the FAS score after 2 months (P = 0.0006) and 3 months (P = 0.005). NAC increased Δψm (P = 0.0001) in all T cells, profoundly reduced mTOR activity (P = 0.0009), enhanced apoptosis (P = 0.0004), reversed expansion of CD4−CD8− T cells (mean ± SEM 1.35 ± 0.12-fold change; P = 0.008), stimulated FoxP3 expression in CD4+CD25+ T cells (P = 0.045), and reduced anti-DNA production (P = 0.049). Conclusion This pilot study suggests that NAC safely improves lupus disease activity by blocking mTOR in T lymphocytes.

Rapamycin reduces disease activity and normalizes T cell activation–induced calcium fluxing in patients with systemic lupus erythematosus

Abstract: Objective Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown origin. Current treatment options are often ineffective or poorly tolerated. Recent observations have revealed mitochondrial hyperpolarization and enhanced Ca2+ fluxing in T cells from SLE patients. Rapamycin, a lipophilic macrolide antibiotic that regulates mitochondrial transmembrane potential and Ca2+ fluxing, has been used safely and effectively to treat renal transplant rejection since 1999. In addition, rapamycin has been shown to ameliorate T cell function and to prolong survival in lupus-prone MRL/lpr mice. We therefore undertook the present study to investigate whether rapamycin is beneficial in patients with SLE. Methods Nine patients with clinically active SLE that had been treated unsuccessfully with other immunosuppressive medications began therapy with rapamycin, 2 mg/day orally. Disease activity was assessed with the British Isles Lupus Assessment Group (BILAG) score, SLE Disease Activity Index (SLEDAI), and requirement for prednisone therapy. Mitochondrial transmembrane potential and Ca2+ fluxing were assessed by flow cytometry. Results In patients treated with rapamycin, the BILAG score was reduced by a mean ± SEM of 1.93 ± 0.9 (P = 0.0218), the SLEDAI by 5.3 ± 0.8 (P = 0.00002), and concurrent prednisone use by 26.4 ± 6.7 mg/day (P = 0.0062) compared with pre–rapamycin treatment. While mitochondrial hyperpolarization persisted, pretreatment cytosolic and mitochondrial Ca2+ levels and T cell activation–induced rapid Ca2+ fluxing were normalized in rapamycin-treated patients. Conclusion Rapamycin appears to be a safe and effective therapy for SLE that has been refractory to traditional medications. Mitochondrial dysfunction and Ca2+ fluxing could serve as biomarkers to guide decisions regarding future therapeutic interventions in SLE.

Free Radicals in the Physiological Control of Cell Function

Abstract: At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, how...

Harrison's Principles of Internal Medicine

Abstract: The 11th edition of Harrison's Principles of Internal Medicine welcomes Anthony Fauci to its editorial staff, in addition to more than 85 new contributors. While the organization of the book is similar to previous editions, major emphasis has been placed on disorders that affect multiple organ systems. Important advances in genetics, immunology, and oncology are emphasized. Many chapters of the book have been rewritten and describe major advances in internal medicine. Subjects that received only a paragraph or two of attention in previous editions are now covered in entire chapters. Among the chapters that have been extensively revised are the chapters on infections in the compromised host, on skin rashes in infections, on many of the viral infections, including cytomegalovirus and Epstein-Barr virus, on sexually transmitted diseases, on diabetes mellitus, on disorders of bone and mineral metabolism, and on lymphadenopathy and splenomegaly. The major revisions in these chapters and many

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

Abstract: In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagy-related protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Abstract: Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.