Proteomics in Parkinson's disease: An unbiased approach towards peripheral biomarkers and new therapies

Parkinson's disease is the most common neurodegenerative movement disorder, affecting about 6 million people worldwide with a slow progression of the symptoms. Its prevalence is expected to double in the most populated areas within the next two decades, according to increasing aged population. Consequently, Parkinson's disease is a socio-economic trouble and a major challenge for the public health system. Parkinson's disease treatment is merely symptomatic, as clinical symptoms appear when about 70% of the involved neurons are lost and potential disease-modifying/neuroprotective therapies would have no effect. In turn, the availability of an objective measure that allows early diagnosis would strongly impact on the costs that biotech- and pharma-companies will sustain in order to develop disease-modifying therapies. The establishment of suitable models to investigate the mechanisms of Parkinson's disease progression and, on the other hand, the discovery and validation of selective and specific molecular biomarkers for early and differential diagnosis are indeed two important goals for a better management of the disease. In this review, we focus on cellular and animal models of Parkinson's disease by describing their advantages and limitations as useful tools to identify pathogenetic pathways that deserve further exploitation. In parallel, we discuss how proteomics may provide a potent tool to observe altered pathways in models or altered biomarkers in patients with an unbiased, hypothesis-free approach.     

Proteomics in Parkinson's disease: An unbiased approach towards peripheral biomarkers and new therapies

Parkinson's disease is the most common neurodegenerative movement disorder, affecting about 6 million people worldwide with a slow progression of the symptoms. Its prevalence is expected to double in the most populated areas within the next two decades, according to increasing aged population. Consequently, Parkinson's disease is a socio-economic trouble and a major challenge for the public health system. Parkinson's disease treatment is merely symptomatic, as clinical symptoms appear when about 70% of the involved neurons are lost and potential disease-modifying/neuroprotective therapies would have no effect. In turn, the availability of an objective measure that allows early diagnosis would strongly impact on the costs that biotech- and pharma-companies will sustain in order to develop disease-modifying therapies. The establishment of suitable models to investigate the mechanisms of Parkinson's disease progression and, on the other hand, the discovery and validation of selective and specific molecular biomarkers for early and differential diagnosis are indeed two important goals for a better management of the disease. In this review, we focus on cellular and animal models of Parkinson's disease by describing their advantages and limitations as useful tools to identify pathogenetic pathways that deserve further exploitation. In parallel, we discuss how proteomics may provide a potent tool to observe altered pathways in models or altered biomarkers in patients with an unbiased, hypothesis-free approach.     

Anti-inflammatory drugs and atherosclerosis

PURPOSE OF REVIEW: Inflammation contributes to the formation and progression of atherosclerosis and the therapeutic potential of some anti-inflammatory drugs has been evaluated for possible antiatherosclerotic effects. This review will briefly describe the mechanisms underlying the inflammation-atherosclerosis connection, the effect of various anti-inflammatory therapies on atherosclerotic disease and a sampling of the potential targets and agents under evaluation. RECENT FINDINGS: Some agents with anti-inflammatory properties appear to have beneficial effects on atherosclerosis or subsequent risk for cardiovascular events, while others have been disappointing. The anti-inflammatory actions of statins have been linked retrospectively with their favorable effects on atherosclerosis progression and clinical outcomes. The cardiovascular safety of COX-2 inhibitors is being assessed prospectively in patients with atherosclerosis. Potential new therapeutic agents targeting other inflammatory mechanisms and oxidative stress are being evaluated in animal models and clinical trials. SUMMARY: Due to the contributory inflammatory pathways in atherosclerosis, the properties of existing and novel anti-inflammatory agents are being carefully and actively evaluated in cardiovascular disease. Advances in our understanding of both atherosclerosis and the inflammatory contributors may play an important role in future strategies to decrease the incidence of atherosclerotic cardiovascular disease.     

Exploring the role of CD151 in the tumor immune microenvironment: Therapeutic and clinical perspectives

CD151 is a transmembrane protein implicated in tumor progression and has been shown to regulate various cellular and molecular mechanisms contributing to malignancy. More recently, the role of CD151 in the tumor immune microenvironment (TIME) has gained attention as a potential target for cancer therapy. This review aims to explore the role of CD151 in the TIME, focusing on the therapeutic and clinical perspectives. The role of CD151 in regulating the interactions between tumor cells and the immune system will be discussed, along with the current understanding of the molecular mechanisms underlying these interactions. The current state of the development of CD151-targeted therapies and the potential clinical applications of these therapies will also be reviewed. This review provides an overview of the current knowledge on the role of CD151 in the TIME and highlights the potential of CD151 as a therapeutic target for cancer treatment.     

Proteomics in human Parkinson's disease research

During the last decades, considerable advances in the understanding of specific mechanisms underlying neurodegeneration in Parkinson's disease have been achieved, yet neither definite etiology nor unifying sequence of molecular events has been formally established. Current unmet needs in Parkinson's disease research include exploring new hypotheses regarding disease susceptibility, occurrence and progression, identifying reliable diagnostic, prognostic and therapeutic biomarkers, and translating basic research into appropriate disease-modifying strategies. The most popular view proposes that Parkinson's disease results from the complex interplay between genetic and environmental factors and mechanisms believed to be at work include oxidative stress, mitochondrial dysfunction, excitotoxicity, iron deposition and inflammation. More recently, a plethora of data has accumulated pinpointing an abnormal processing of the neuronal protein α-synuclein as a pivotal mechanism leading to aggregation, inclusions formation and degeneration. This protein-oriented scenario logically opens the door to the application of proteomic strategies to this field of research. We here review the current literature on proteomics applied to Parkinson's disease research, with particular emphasis on pathogenesis of sporadic Parkinson's disease in humans. We propose the view that Parkinson's disease may be an acquired or genetically-determined brain proteinopathy involving an abnormal processing of several, rather than individual neuronal proteins, and discuss some pre-analytical and analytical developments in proteomics that may help in verifying this concept.     

Advances in developing novel therapeutic strategies for Alzheimer’s disease

Alzheimer’s Disease (AD), the most prevalent neurodegenerative disease of aging, affects one in eight older Americans. Nearly all drug treatments tested for AD today have failed to show any efficacy. There is a great need for therapies to prevent and/or slow the progression of AD. The major challenge in AD drug development is lack of clarity about the mechanisms underlying AD pathogenesis and pathophysiology. Several studies support the notion that AD is a multifactorial disease. While there is abundant evidence that amyloid plays a role in AD pathogenesis, other mechanisms have been implicated in AD such as tangle formation and spread, dysregulated protein degradation pathways, neuroinflammation, and loss of support by neurotrophic factors. Therefore, current paradigms of AD drug design have been shifted from single target approach (primarily amyloid-centric) to developing drugs targeted at multiple disease aspects, and from treating AD at later stages of disease progression to focusing on preventive strategies at early stages of disease development. Here, we summarize current strategies and new trends of AD drug development, including pre-clinical and clinical trials that target different aspects of disease (mechanism-based versus non-mechanism based, e.g. symptomatic treatments, lifestyle modifications and risk factor management).     

Genetics of Parkinson disease: paradigm shifts and future prospects

Parkinson disease is a complex, multifactorial neurodegenerative disease. Although a heritable basis was originally thought unlikely, recent studies have implicated several genes in its pathogenesis, and molecular findings now allow accurate diagnosis and challenge past criteria for defining Parkinson disease. Most importantly, genetic insights provide the rationale for new strategies for prevention or therapy, and have led to animal models of disease in which these strategies can be tested. Neuroprotective therapies can now be designed to slow or halt disease progression in affected subjects and asymptomatic carriers.     

Sensitive fluorescence polarization technique for rapid screening of alpha-synuclein oligomerization/fibrillization inhibitors

Parkinson's disease (PD) is characterized by the accumulation of fibrillar alpha-synuclein (alpha-Syn) inclusions known as Lewy bodies (LBs) and Lewy neurites. Mutations in the alpha-Syn gene or extra copies thereof cause familial PD or dementia with LBs (DLB) in rare kindreds, but abnormal accumulations of wildtype alpha-Syn also are implicated in the pathogenesis of sporadic PD, the most common movement disorder. Insights into mechanisms underlying alpha-Syn mediated neurodegeneration link alpha-Syn oligomerization and fibrillization to the onset and progression of PD. Thus, inhibiting alpha-Syn oligomer or fibril formation is a compelling target for discovering disease modifying therapies for PD, DLB, and related synucleinopathies. Although amyloid dyes recognize alpha-Syn fibrils, efficient detection of soluble oligomers remains a challenge. Here, we report a novel fluorescence polarization (FP) technique for examining alpha-Syn assembly by monitoring changes in its relative molecular mass during progression of normal alpha-Syn from highly soluble monomers to higher order multimers and thence insoluble amyloid fibrils. We report that FP is more sensitive than conventional amyloid dye methods for the quantification of mature fibrils, and that FP is capable of detecting oligomeric alpha-Syn, allowing for rapid automated screening of potential inhibitors of alpha-Syn oligomerization and fibrillization. Furthermore, FP can be combined with an amyloid dye in a single assay that simultaneously provides two independent biophysical readouts for monitoring alpha-Syn fibrillization. Thus, this FP method holds potential to accelerate discovery of disease modifying therapies for LB PD, DLB, and related neurodegenerative synucleinopathies.     

New trends in the treatment of bone metastasis

Bone metastasis is often the penultimate harbinger of death for many cancer patients. Bone metastases are often associated with fractures and severe pain resulting in decreased quality of life. Accordingly, effective therapies to inhibit the development or progression of bone metastases will have important clinical benefits. To achieve this goal understanding the mechanisms through which bone metastases develop and progress may provide targets to inhibit the metastases. In the past few years, there have been advances in both understanding the mechanisms through which bone metastases develop and how they impact bone remodeling. Additionally, gains in promising clinical strategies to target bone metastases have been developed. In this prospectus, we will discuss some of these advances.     

Tracking extranigral degeneration in animal models of Parkinson's disease: quest for effective therapeutic strategies

Sporadic Parkinson's disease (PD) is now interpreted as a complex nervous system disorder in which the projection neurons are predominantly damaged. Such an interpretation is based on mapping of Lewy body and Lewy neurite pathology. Symptoms of the human disease are much widespread, which span from pre-clinical non-motor symptoms and clinical motor symptoms to cognitive discrepancies often seen in advanced stages. Existing symptomatic treatments further complicate with overt drug-irresponsive symptoms. PD is better understood by assimilation of extranigral degenerative pathways with nigrostriatal degenerative mechanisms. The term 'extranigral' appeared first in the 1990s to more rigorously define the nigral pathology by process of elimination. However, as clinicians progressively identified PD symptoms unresponsive to the gold standard drug l-DOPA, definitions of PD symptoms were redefined. Non-motor symptoms prodromal to motor symptoms just as pre-clinical to clinical, and conjointly emerged the concept of nigral versus extranigral degeneration in PD. While nigrostriatal degeneration is responsible for the neurobiological substrates of extrapyramydal motor features, extranigral degeneration corroborates a vast majority of other changes in discrete central, peripheral, and enteric nervous system nuclei, which together account for global symptoms of the human disease. As an extranigral site, spinal cord degeneration has also been implicated in PD progression. Interconnected to the upper CNS structures with descending and ascending pathways, spinal neurons participate in movement and sensory circuits, controlling movement and reflexes. Several clinical and in vivo studies have demonstrated signs of parkinsonism-related degenerative processes in spinal cord, which led to recent consideration of spinal cord as an area of potential therapeutic target. In a nutshell, this review explores how the existing animal models can actually reflect the human disease in order to facilitate PD research. Evolution of extranigral degeneration studies has been succinctly revisited, followed by a survey on animal models in light of recent findings in clinical PD. Together, it may help to develop effective therapeutic strategies for PD.     

MicroRNAs in cancer drug resistance: Basic evidence and clinical applications

Development of drug resistance has considerably limited the efficacy of cancer treatments, including chemotherapy and targeted therapies. Hence, understanding the molecular mechanisms underpinning the innate or the acquired resistance to these therapies is critical to improve drug efficiency and clinical outcomes. Several studies have implicated microRNAs (miRNA) in this process. MiRNAs repress gene expression by specific binding to complementary sequences in the 3' region of target messenger RNAs (mRNAs), followed by target mRNA degradation or blocked translation. By targeting molecules specific to a particular pathway within tumor cells, the new generation of cancer treatment strategies has shown significant advantages over conventional chemotherapy. However, the long-term efficacy of targeted therapies often remains poor, because tumor cells develop resistance to such therapeutics. Targeted therapies often involve monoclonal antibodies (mAbs), such as those blocking the ErB/HER tyrosine kinases, epidermal growth factor receptor (cetuximab) and HER2 (trastuzumab), and those inhibiting vascular endothelial growth factor receptor signaling (e.g., bevacizumab). Even though these are among the most used agents in tumor medicine, clinical response to these drugs is reduced due to the emergence of drug resistance as a result of toxic effects in the tumor microenvironment. Research on different types of human cancers has revealed that aberrant expression of miRNAs promotes resistance to the aforementioned drugs. In this study, we review the mechanisms of tumor cell resistance to mAb therapies and the role of miRNAs therein. Emerging treatment strategies combine therapies using innovative miRNA mimics or antagonizers with conventional approaches to maximize outcomes of patients with cancer.     

The role of the estrogen in neuroprotection: implications for neurodegenerative diseases

In trying to rectify the differences in the risk, onset, and progression of neurodegenerative diseases between men and women, the gonadal hormone estrogen has been the primary focus of investigation for many years. Although this gender difference may encompass disparate and overlapping reasons, estrogen and signaling events mediated by its receptor have been shown to be neuroprotective in a number of neurodegenerative disease models such as Alzheimer's, Parkinson's, and Schizophrenia. Although data from human studies remains highly controversial, a large body of research findings suggests that this hormone plays a pivotal role in retarding and preventing the formation of neurodegenerative diseases through its receptor. By activating common intracellular signaling pathways and initiating "cross talk" with neurotrophins, estrogen plays an influential role in neuronal survival from injuries induced by ischemia or other environmental insults. Gaining a better understanding of these estrogen receptor mediated neuroprotective mechanisms may lead to new therapeutic strategies for the treatment or prevention of neurodegenerative diseases.     

Donor cell transplantation for myocardial disease: does it complement current pharmacological therapies?

Heart failure secondary to ischemic heart disease, hypertension, and myocardial infarction is a common cause of death in developed countries. Although pharmacological therapies are very effective, poor prognosis and shorter life expectancy of heart disease patients clearly indicate the need for alternative interventions to complement the present therapies. Since the progression of heart disease is associated with the loss of myocardial cells, the concept of donor cell transplantation into host myocardium is emerging as an attractive strategy to repopulate the damaged tissue. To this end, a number of donor cell types have been tested for their ability to increase the systolic function of diseased hearts in both experimental and clinical settings. Although initial clinical trials with bone marrow stem cells are encouraging, long-term consequences of such interventions are yet to be rigorously examined. While additional laboratory studies are required to address several issues in this field, there is also a clear need for further characterization of drug interactions with donor cells in these interventions. Here, we provide a brief summary of current pharmacological and cell-based therapies for heart disease. Further, we discuss the potential of various donor cell types in myocardial repair, mechanisms underlying functional improvement in cell-based therapies, as well as potential interactions between pharmacological and cell-based therapies.     

The evolving biology of cell reprogramming

Modern stem cell biology has achieved a transformation that was thought by many to be every bit as unattainable as the ancient alchemists' dream of transforming base metals into gold. Exciting opportunities arise from the process known as 'cellular reprogramming' in which cells can be reliably changed from one tissue type to another. This is enabling novel approaches to more deeply investigate the fundamental basis of cell identity. In addition, new opportunities have also been created to study (perhaps even to treat) human genetic and degenerative diseases. Specific cell types that are affected in inherited disease can now be generated from easily accessible cells from the patient and compared with equivalent cells from healthy donors. The differences in cellular phenotype between the two may then be identified, and assays developed to establish therapies that prevent the development or progression of disease symptoms. Cellular reprogramming also has the potential to create new cells to replace those whose death or dysfunction causes disease symptoms. For patients suffering from inherited cases of degenerative diseases like Parkinson's disease or amyotrophic lateral sclerosis (also known as motor neuron disease), the future realization of such cell-based therapies would truly be worth its weight in gold. However, before this enormous potential can become a reality, several significant biological and technical challenges must be overcome. Furthermore, to maintain the credibility of the scientific community with the general public, it is important that hope-inspiring advances are not over-hyped. The papers in this issue of the Philosophical Transactions of the Royal Society B: Biological Sciences cover many areas relevant to this topic. In this Introduction, we provide an overall context in which to consider these individual papers.     

Kinase signaling pathways as potential targets in the treatment of Parkinson's disease

Parkinson's disease (PD) is a severe, progressive, age-associated, neurodegenerative disorder. Current therapies are symptomatic and not effective at halting or significantly slowing the disease progress. The search for etiologic-based therapies has focused largely on genetic findings made in familial forms of this disease. Mutations of five genes have been unequivocally linked to PD; two of these, LRRK2 and PINK1, encode kinases and as such are attractive tools with which to understand the disease process; furthermore, preliminary functional data suggests that these proteins, or the pathways in which they are involved, are viable therapeutic targets. Here we explore the current data and thoughts regarding LRRK2 and PINK1 and discuss further avenues of research to understand the pathologic effects of mutations at these loci and potential points of therapeutic intervention, such as within these kinases or in associated pathways such as Jun N-terminal kinase and Akt pathways.     

Identification of fatty acid binding proteins as markers associated with the initiation and/or progression of renal cell carcinoma

Renal cell carcinoma (RCC) representing the most common neoplasia of the kidney in Western countries is a histologic diverse disease with an often unpredictable course. The prognosis of RCC is worsened with the onset of metastasis, and the therapies currently available are of limited success for the treatment of metastatic RCC. Although gene expression analyses and other methods are promising tools clarifying and standardizing the pathological classification of RCC, novel innovative molecular markers for the diagnosis, prognosis, and for the monitoring of this disease during therapy as well as potential therapeutic targets are urgently needed. Using proteome-based strategies, a number of RCC-associated markers either over-expressed or down-regulated in tumor lesions in comparison to the normal epithelium have been identified which have been implicated in tumorigenesis, but never linked to the initiation and/or progression of RCC. These include members of the fatty acid binding protein family, which have the potential to serve as diagnostic or prognostic markers for the screening of RCC patients.     

Human Organoids as a Promising Platform for Fighting COVID-19

The coronavirus disease 2019 (COVID-19) global pandemic evoked by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has triggered a major public health problem with significant morbidity and mortality. Understanding the pathogenesis and molecular mechanisms underlying this novel virus is crucial for both fundamental research and clinical trials in order to devise effective therapies and vaccination regimens. Basic research on SARS-CoV-2 largely depends on ex vivo models that allow viral invasion and replication. Organoid models are now emerging as a valuable tool to investigate viral biology and disease progression, serving as an efficient platform to investigate potential therapies for COVID-19. Here, we summarize various human stem cell-derived organoid types employed in SARS-CoV-2 studies. We highlight key findings from these models, including cell tropisms and molecular mechanisms in viral infection. We also describe their use in identifying potential therapeutic agents against SARS-CoV-2. As more and more advanced organoids emerge, they will facilitate the understanding of disease pathogenesis for drug development in this dreaded pandemic.     

Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms

Although targeted therapies are initially effective, resistance inevitably emerges. Several methods, such as genetic analysis of resistant clinical specimens, have been applied to uncover these resistance mechanisms to facilitate follow-up care. Although these approaches have led to clinically relevant discoveries, difficulties in attaining the relevant patient material or in deconvoluting the genomic data collected from these specimens have severely hampered the path towards a cure. To this end, we here describe a tool for expeditious discovery that may guide improvement in first-line therapies and alternative clinical management strategies. By coupling preclinical in vitro or in vivo drug selection with next-generation sequencing, it is possible to identify genomic structural variations and/or gene expression alterations that may serve as functional drivers of resistance. This approach facilitates the spontaneous emergence of alterations, enhancing the probability that these mechanisms may be observed in the patients. In this protocol we provide guidelines to maximize the potential for uncovering single nucleotide variants that drive resistance using adherent lines.     

Ironing out Parkinson's disease: is therapeutic treatment with iron chelators a real possibility?

Levels of iron are increased in the brains of Parkinson's disease (PD) patients compared to age-matched controls. This has been postulated to contribute to progression of the disease via several mechanisms including exacerbation of oxidative stress, initiation of inflammatory responses and triggering of Lewy body formation. In this minireview, we examine the putative role of iron in PD and its pharmacological chelation as a prospective therapeutic for the disease.