Review
Abstract
Dietary modification is central to obesity treatment. Weight loss diets are available that include various permutations of energy restriction, macronutrients, foods, and dietary intake patterns. Caloric restriction is the common pathway for weight reduction, but different diets may induce weight loss by varied additional mechanisms, including by facilitating dietary adherence. This narrative Review of meta-analyses and select clinical trials found that lower-calorie diets, compared with higher-calorie regimens, reliably induced larger short-term (<6 months) weight losses, with deterioration of this benefit over the long term (>12 months). Few significant long-term differences in weight loss were observed for diets of varying macronutrient composition, although some regimens were found to have short-term advantages (e.g., low carbohydrate versus low fat). Progress in improving dietary adherence, which is critical to both short- and long-term weight loss, could result from greater efforts to identify behavioral and metabolic phenotypes among dieters.
Authors
Ariana M. Chao, Kerry M. Quigley, Thomas A. Wadden
Abstract
The field of gene therapy has made considerable progress over the past several years. Adeno-associated virus (AAV) vectors have emerged as promising and attractive tools for in vivo gene therapy. Despite the recent clinical successes achieved with recombinant AAVs (rAAVs) for therapeutics, host immune responses against the vector and transgene product have been observed in numerous preclinical and clinical studies. These outcomes have hampered the advancement of AAV gene therapies, preventing them from becoming fully viable and safe medicines. The human immune system is multidimensional and complex. Both the innate and adaptive arms of the immune system seem to play a concerted role in the response against rAAVs. While most efforts have been focused on the role of adaptive immunity and developing ways to overcome it, the innate immune system has also been found to have a critical function. Innate immunity not only mediates the initial response to the vector, but also primes the adaptive immune system to launch a more deleterious attack against the foreign vector. This Review highlights what is known about innate immune responses against rAAVs and discusses potential strategies to circumvent these pathways.
Authors
Manish Muhuri, Yukiko Maeda, Hong Ma, Sanjay Ram, Katherine A. Fitzgerald, Phillip W.L. Tai, Guangping Gao
Abstract
Interferons (IFNs) are pleiotropic cytokines critical for regulation of epithelial cell functions and for immune system regulation. In cancer, IFNs contribute to tumor-intrinsic and -extrinsic mechanisms that determine the quality of antitumor immunity and response to immunotherapy. In this Review, we focus on the different types of tumor IFN sensitivity that determine dynamic tumor-immune interactions and their coevolution during cancer progression and metastasis. We extend the discussion to new evidence supporting immunotherapy-mediated immunoediting and the dual opposing roles of IFNs that lead to immune checkpoint blockade response or resistance. Understanding the intricate dynamic responses to IFN will lead to novel immunotherapeutic strategies to circumvent protumorigenic effects of IFN while exploiting IFN-mediated antitumor immunity.
Authors
Michelle von Locquenghien, Catalina Rozalén, Toni Celià-Terrassa
Abstract
Since the COVID-19 pandemic swept across the globe, researchers have been trying to understand its origin, life cycle, and pathogenesis. There is a striking variability in the phenotypic response to infection with SARS-CoV-2 that may reflect differences in host genetics and/or immune response. It is known that the human epigenome is influenced by ethnicity, age, lifestyle, and environmental factors, including previous viral infections. This review will examine the influence of viruses on the host epigenome. We will describe general lessons and methodologies that can be used to understand how the virus evades the host immune response. We will consider how variation in the epigenome may contribute to heterogeneity in the response to SARS-CoV-2 and may identify a precision medicine approach to treatment.
Authors
Elizabeth J. Hennessy, Garret A. FitzGerald
Abstract
Human coronaviruses (hCoVs) cause severe respiratory illness in the elderly. Age-related impairments in innate immunity and sub-optimal virus-specific T cell and antibody responses are believed to cause severe disease upon respiratory virus infections. This phenomenon has recently received increased attention, as elderly patients are at substantially elevated risk for severe COVID-19 disease and experience increased rates of mortality following SARS-CoV-2 infection compared to younger populations. However, the basis for age-related fatal pneumonia following pathogenic hCoVs is not well understood. In this review article, we provide an overview of our current understanding of hCoV-induced fatal pneumonia in the elderly. We describe host immune response to hCoV infections derived from studies of young and aged animal models, and discuss the potential role of age-associated increases in sterile inflammation (inflammaging) and virus-induced dysregulated inflammation in causing age-related severe disease. We also highlight the existing gaps in our knowledge about virus replication and host immune responses to hCoV infection in young and aged individuals..
Authors
Rudragouda Channappanavar, Stanley Perlman
Abstract
Muscular dystrophies are a heterogeneous group of genetic diseases, characterized by progressive degeneration of skeletal and cardiac muscle. Despite the intense investigation of different therapeutic options, a definitive treatment has not been yet developed for this debilitating class of pathologies. Cell-based therapies in muscular dystrophies have been pursued experimentally for the last three decades. Several cell types with different characteristics and tissues of origin, including myogenic stem and progenitor cells, stromal cells, and pluripotent stem cells, have been investigated over the years and have recently entered in the clinical arena with mixed results. In this review, we will do a roundup of the past attempts and describe the updated status of cell-based therapies aimed at counteracting the skeletal and cardiac myopathy present in dystrophic patients. We will present current challenges, summarize recent progresses, and make recommendations for future research and clinical trials.
Authors
Stefano Biressi, Antonio Filareto, Thomas A. Rando
Abstract
Pulmonary hypertension (PH) is characterized by pulmonary artery remodeling that can subsequently culminate in right heart failure and premature death. Emerging evidence suggests that Hypoxia Inducible Factor (HIF) signaling plays a fundamental and pivotal role in the pathogenesis of PH. This review summarizes the regulation of HIF isoforms and their impact in various PH subtypes, as well as the elaborate conditional and cell specific knockout mouse studies that brought the role of this pathway to light. We also discuss the current preclinical status of pan- and isoform-selective HIF inhibitors, and propose new research areas that may facilitate HIF isoform-specific inhibition as a novel therapeutic strategy for PH and right heart failure.
Authors
Soni Savai Pullamsetti, Argen Mamazhakypov, Norbert Weissmann, Werner Seeger, Rajkumar Savai
Abstract
Epithelial cell dysfunction has emerged as a central component in the pathophysiology of diffuse parenchymal diseases including idiopathic pulmonary fibrosis (IPF). Alveolar type 2 (AT2) cells represent a metabolically active lung cell population important for surfactant biosynthesis and alveolar homeostasis. AT2 cells and other distal lung epithelia, like all eukaryotic cells, contain an elegant quality control (QC) network to respond to intrinsic metabolic and biosynthetic challenges imparted by mutant protein conformers, dysfunctional subcellular organelles, and dysregulated telomeres. Failed AT2 QC components (ubiquitin-proteasome system, unfolded protein response, macroautophagy, mitophagy, and telomere maintenance) result in diverse cellular endophenotypes and molecular signatures including ER stress, defective autophagy, mitochondrial dysfunction, apoptosis, inflammatory cell recruitment, profibrotic signaling, and altered progenitor function that ultimately converge to drive downstream fibrotic remodeling in the IPF lung. As this complex network becomes increasingly better understood, opportunities will emerge to identify targets and therapeutic strategies for IPF.
Authors
Jeremy Katzen, Michael F. Beers
Abstract
Hypoxia-inducible factors (HIFs) and the HIF-dependent cancer hallmarks angiogenesis and metabolic rewiring are well-established drivers of breast cancer aggressiveness, therapy resistance, and poor prognosis. Targeting of HIF and its downstream targets in angiogenesis and metabolism has been unsuccessful so far in the breast cancer clinical setting, with major unresolved challenges residing in target selection, development of robust biomarkers for response prediction, and understanding and harnessing escape mechanisms. This Review discusses the pathophysiological role of HIFs, angiogenesis, and metabolism in breast cancer and the challenges of targeting these features in breast cancer patients. Rational therapeutic combinations, especially with immunotherapy and endocrine therapy, seem most promising in the clinical exploitation of the intricate interplay of HIFs, angiogenesis, and metabolism in breast cancer cells and the tumor microenvironment.
Authors
Ellen C. de Heer, Mathilde Jalving, Adrian L. Harris
Abstract
Hypoxia/HIF-1α- and extracellular adenosine/A2-adenosine receptor-mediated immunosuppression protects tissues from collateral damage by anti-pathogen immune cells. However, this mechanism also protects cancerous tissues by inhibiting anti-tumor immune cells in hypoxic and extracellular adenosine-rich tumors that are the most resistant to current therapies. Here, we explain a conceptually novel, anti-immunosuppressive reasoning to justify strategies using respiratory hyperoxia and oxygenation agents in cancer treatment. Earlier attempts to use oxygenation of tumors as a monotherapy or to improve radiotherapy have failed because oxygenation protocols were not combined with immunotherapies of cancer. In contrast, the proposal for therapeutic use of anti-hypoxic oxygenation described here was motivated by the need to prevent the hypoxia/HIF-1α-driven accumulation of extracellular adenosine to (i) unleash anti-tumor immune cells from inhibition by intracellular cAMP and (ii) prevent immunosuppressive transcription of cAMP response element- and hypoxia response element-containing immunosuppressive gene products (e.g. TGF-β. Using oxygenation agents together with inhibitors of the A2A adenosine receptor may be required to enable the most effective cancer immunotherapy. The emerging outcomes from clinical trials of cancer patients refractory to all other treatments provide support for the molecular and immunological mechanism-based approach to cancer immunotherapy described here.
Authors
Stephen M. Hatfield, Michail V. Sitkovsky
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Copyright © 2021 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)