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Cystic fibrosis-related liver disease: Clinical presentations, diagnostic and monitoring approaches in the era of CFTR modulator therapies. J Hepatol 2022; 76:420-434. [PMID: 34678405 DOI: 10.1016/j.jhep.2021.09.042] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/09/2021] [Accepted: 09/30/2021] [Indexed: 12/11/2022]
Abstract
Cystic fibrosis (CF) is the most common autosomal recessive disease in the Caucasian population. Cystic fibrosis-related liver disease (CFLD) is defined as the pathogenesis related to the underlying CFTR defect in biliary epithelial cells. CFLD needs to be distinguished from other liver manifestations that may not have any pathological significance. The clinical/histological presentation and severity of CFLD vary. The main histological presentation of CFLD is focal biliary fibrosis, which is usually asymptomatic. Portal hypertension develops in a minority of cases (about 10%) and may require specific management including liver transplantation for end-stage liver disease. Portal hypertension is usually the result of the progression of focal biliary fibrosis to multilobular cirrhosis during childhood. Nevertheless, non-cirrhotic portal hypertension as a result of porto-sinusoidal vascular disease is now identified increasingly more frequently, mainly in young adults. To evaluate the effect of new CFTR modulator therapies on the liver, the spectrum of hepatobiliary involvement must first be precisely classified. This paper discusses the phenotypic features of CFLD, its underlying physiopathology and relevant diagnostic and follow-up approaches, with a special focus on imaging.
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C-Terminal Domain of Aquaporin-5 Is Required to Pass Its Protein Quality Control and Ensure Its Trafficking to Plasma Membrane. Int J Mol Sci 2021; 22:ijms222413461. [PMID: 34948259 PMCID: PMC8707437 DOI: 10.3390/ijms222413461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/10/2021] [Accepted: 12/12/2021] [Indexed: 01/25/2023] Open
Abstract
Aquaporin-5 (AQP5) is selectively expressed in the apical membrane of exocrine glands, such as salivary, lacrimal, and submucosal glands. It is important for the secretory function of exocrine glands because mice with the knockout of AQP5 exhibit a significant reduction in secretion from these glands. Previous reports indicated that the AQP5 C-terminal domain is crucial for the localization of AQP5 at the plasma membrane, but it remains unclear which motif or amino acid residues in the C-terminal domain are essential for this. In this study, we examined the effects of various AQP5 C-terminal deletions or mutations on the expression of AQP5 on the cell surface. AQP5 C-terminal domain mutants did not localize on the plasma membrane, and Leu262 was shown to be crucial for AQP5′s plasma membrane localization. The mutants localized in the autophagosome or lysosome and showed decreased protein stability via lysosomal degradation. Taking these findings together, our study suggests that the C-terminal domain is required for AQP5 to pass protein quality control and be trafficked to the plasma membrane.
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3
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Liu M, Zaman R, Sawczak V, Periasamy A, Sun F, Zaman K. S-nitrosothiols signaling in cystic fibrosis airways. J Biosci 2021. [DOI: 10.1007/s12038-021-00223-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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4
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Bass R, Brownell JN, Stallings VA. The Impact of Highly Effective CFTR Modulators on Growth and Nutrition Status. Nutrients 2021; 13:2907. [PMID: 34578785 PMCID: PMC8470943 DOI: 10.3390/nu13092907] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/04/2021] [Accepted: 08/18/2021] [Indexed: 02/07/2023] Open
Abstract
Patients with cystic fibrosis (CF) are at increased risk of malnutrition and growth failure due to multiple factors as a result of suboptimal or absent function of the CFTR chloride channel protein. Dysfunctional CFTR contributes to increased energy expenditure, exocrine pancreatic insufficiency causing impaired dietary macronutrient digestion and absorption, intestinal dysbiosis, and impaired bile acid homeostasis. Poor nutritional status as a result of these mechanisms is associated with decreased lung function, worse clinical outcomes, and ultimately, increased mortality. Nutritional interventions addressing these mechanisms, such as pancreatic enzyme-replacement therapy and enteral caloric supplementation, have improved nutritional status and, by association, clinical outcomes. In the last decade, the advent of medications targeting defective CFTR proteins has revolutionized the care of patients with CF by reducing the overall impact of CFTR dysfunction. Below, we summarize the effects of highly effective CFTR modulators on nutritional status overall as well as specific factors including bile acid metabolism, pancreatic function, energy expenditure, and intestinal dysbiosis. The future of CF nutrition care will require a paradigm shift away from focusing on methods addressing CFTR dysfunction such as excess calorie provision and toward an individualized, holistic approach in the context of specific mutations and CFTR-directed therapy.
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Affiliation(s)
- Rosara Bass
- Children’s Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, USA
| | - Jefferson N. Brownell
- School of Medicine, University of Pennsylvania Perelman, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; (J.N.B.); (V.A.S.)
| | - Virginia A. Stallings
- School of Medicine, University of Pennsylvania Perelman, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; (J.N.B.); (V.A.S.)
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5
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Yonker LM, Hawley MH, Moschovis PP, Lu M, Kinane TB. Recognizing genetic disease: A key aspect of pediatric pulmonary care. Pediatr Pulmonol 2020; 55:1794-1809. [PMID: 32533909 PMCID: PMC7384240 DOI: 10.1002/ppul.24706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/12/2020] [Indexed: 12/19/2022]
Abstract
Advancement in technology has improved recognition of genetic etiologies of disease, which has impacted diagnosis and management of rare disease patients in the pediatric pulmonary clinic. This review provides an overview of genetic conditions that are likely to present with pulmonary features and require extensive care by the pediatric pulmonologist. Increased familiarity with these conditions allows for improved care of these patients by reducing time to diagnosis, tailoring management, and prompting further investigation into these disorders.
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Affiliation(s)
- Lael M Yonker
- Pulmonary Division, Massachusetts General Hospital for Children, Boston, Massachusetts.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
| | - Megan H Hawley
- Pulmonary Division, Massachusetts General Hospital for Children, Boston, Massachusetts.,Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, Massachusetts
| | - Peter P Moschovis
- Pulmonary Division, Massachusetts General Hospital for Children, Boston, Massachusetts.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
| | - Mengdi Lu
- Pulmonary Division, Massachusetts General Hospital for Children, Boston, Massachusetts.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
| | - T Bernard Kinane
- Pulmonary Division, Massachusetts General Hospital for Children, Boston, Massachusetts.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
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6
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Liou TG. The Clinical Biology of Cystic Fibrosis Transmembrane Regulator Protein: Its Role and Function in Extrapulmonary Disease. Chest 2018; 155:605-616. [PMID: 30359614 DOI: 10.1016/j.chest.2018.10.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 02/07/2023] Open
Abstract
Normal cystic fibrosis (CF) transmembrane regulator (CFTR) protein has multiple functions in health and disease. Many mutations in the CFTR gene produce abnormal or absent protein. CFTR protein dysfunction underlies the classic CF phenotype of progressive pulmonary and GI pathology but may underlie diseases not usually associated with CF. This review highlights selected extrapulmonary disease that may be associated with abnormal CFTR. Increasing survival in CF is associated with increasing incidence of diseases associated with aging. CFTR dysfunction in older individuals may have novel effects on glucose metabolism, control of insulin release, regulation of circadian rhythm, and cancer cell pathophysiology. In individuals who have cancers with acquired CFTR suppression, their tumors may more likely exhibit rapid expansion, epithelial-to-mesenchymal transformation, abnormally reduced apoptosis, and increased metastatic potential. The new modulators of CFTR protein synthesis could facilitate the additional exploration needed to better understand the unfolding clinical biology of CFTR in human disease, even as they revolutionize treatment of patients with CF.
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Affiliation(s)
- Theodore G Liou
- Center for Quantitative Biology, The Adult Cystic Fibrosis Center and the Division of Respiratory, Critical Care and Occupational Pulmonary Medicine, Department of Internal Medicine, School of Medicine, University of Utah, Salt Lake City, UT.
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Sin YY, Price PR, Ballantyne LL, Funk CD. Proof-of-Concept Gene Editing for the Murine Model of Inducible Arginase-1 Deficiency. Sci Rep 2017; 7:2585. [PMID: 28566761 PMCID: PMC5451454 DOI: 10.1038/s41598-017-02927-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 04/28/2017] [Indexed: 12/14/2022] Open
Abstract
Arginase-1 deficiency in humans is a rare genetic disorder of metabolism resulting from a loss of arginase-1, leading to impaired ureagenesis, hyperargininemia and neurological deficits. Previously, we generated a tamoxifen-inducible arginase-1 deficient mouse model harboring a deletion of Arg1 exons 7 and 8 that leads to similar biochemical defects, along with a wasting phenotype and death within two weeks. Here, we report a strategy utilizing the Clustered, Regularly Interspaced, Short Palindromic Repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system in conjunction with piggyBac technology to target and reincorporate exons 7 and 8 at the specific Arg1 locus in attempts to restore the function of arginase-1 in induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (iHLCs) and macrophages in vitro. While successful gene targeted repair was achieved, minimal urea cycle function was observed in the targeted iHLCs compared to adult hepatocytes likely due to inadequate maturation of the cells. On the other hand, iPSC-derived macrophages expressed substantial amounts of "repaired" arginase. Our studies provide proof-of-concept for gene-editing at the Arg1 locus and highlight the challenges that lie ahead to restore sufficient liver-based urea cycle function in patients with urea cycle disorders.
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Affiliation(s)
- Yuan Yan Sin
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Phillipe R Price
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Laurel L Ballantyne
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Colin D Funk
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
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Yang W, Shen H, Fang G, Li H, Li L, Deng F, Gu W, Li K, Ma L, Gu J, Wang Y. Mutations of rat surfactant protein A have distinct effects on its glycosylation, secretion, aggregation and degradation. Life Sci 2014; 117:47-55. [PMID: 25242514 DOI: 10.1016/j.lfs.2014.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/28/2014] [Accepted: 09/09/2014] [Indexed: 02/05/2023]
Abstract
AIMS Surfactant protein A (SP-A) plays critical roles in the innate immune system and surfactant homeostasis of the lung. Mutations in SP-A2 of the carbohydrate recognition domain (CRD) impair its glycosylation and are associated with pulmonary fibrosis in humans. We aim to examine how mutations in SP-A that impair its glycosylation affect its biological properties and lead to disease. MAIN METHODS We generated rat SP-A constructs with two types of mutations that impair its glycosylation: N-glycosylation site mutations (N21T, N207S and N21T/N207S) and disease-associated CRD mutations (G231V, F198S). We transfected these constructs into Chinese hamster ovary (CHO)-K1 cells and assessed biochemical differences in cellular and secreted wild-type and mutant SP-As by western blot, immunofluorescence, and sensitivity to enzymatic digestion. KEY FINDINGS Mutations of the CRD completely impaired SP-A secretion, whereas mutations of N-glycosylation sites had little effect. Both types of mutations formed nonidet p-40 (NP-40) insoluble aggregates, but the aggregates only from CRD mutations could be partially rescued by a chemical chaperone, 4-phenylbutyrate acid (4-PBA). The majority of CRD mutant SP-A was retained in the endoplasmic reticulum. Moreover, both types of mutations reduced SP-A stability, with CRD mutant SP-A being more sensitive to chymotrypsin digestion. Both types of soluble mutant SP-A could be degraded by the proteasome pathway, while insoluble aggregates could be additionally degraded by the lysosomal pathway. SIGNIFICANCE Our data provide evidence that the differential glycosylation of SP-A may play distinct roles in SP-A secretion, aggregation and degradation which may contribute to familial pulmonary fibrosis caused by SP-A2 mutations.
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Affiliation(s)
- Wenbing Yang
- Department of Pathology, Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Haitao Shen
- Department of Pathology, Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Guodong Fang
- Department of Pathology, Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Hui Li
- Department of Pathology, Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Lan Li
- Department of Pathology, Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Fang Deng
- Department of Pathology, Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Wei Gu
- Department of Pathophysiology, The Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Kangsheng Li
- Department of Microbiology and Immunology, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Lian Ma
- Department of Pediatrics, Second Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong Province, China
| | - Jiang Gu
- Department of Pathology, Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong Province, China
| | - Yongyu Wang
- Department of Pathology, Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong Province, China.
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Monterisi S, Casavola V, Zaccolo M. Local modulation of cystic fibrosis conductance regulator: cytoskeleton and compartmentalized cAMP signalling. Br J Pharmacol 2014; 169:1-9. [PMID: 23072488 DOI: 10.1111/bph.12017] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 09/12/2012] [Accepted: 10/05/2012] [Indexed: 11/28/2022] Open
Abstract
The cystic fibrosis conductance regulator (CFTR) is a cAMP-regulated Cl(-) channel expressed predominantly at the apical membrane of secreting epithelial cells. Mutations in the CFTR gene lead to cystic fibrosis, the most frequent genetic disease in the Caucasian population. The most common mutation, a deletion of phenylalanine at position 508 (F508del), impairs CFTR folding and chloride channel function. Although an intense effort is under way to identify compounds that target the F508del CFTR structural defect and promote its expression and stability at the plasma membrane, so far their clinical efficacy has proven to be poor, highlighting the necessity to better understand the molecular mechanism of CFTR regulation and of the pathogenesis of the disease. Accumulating evidence suggests that the inclusion of the CFTR in macromolecular complexes and its interaction with the cortical cytoskeleton may play a key role in fine-tuning the regulation of channel function. Here we review some recent findings that support a critical role for protein-protein interactions involving CFTR and for the cytoskeleton in promoting local control of channel activity. These findings indicate that compounds that rescue and stabilize CFTR at the apical membrane may not be sufficient to restore its function unless the appropriate intracellular milieu is also reconstituted.
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Affiliation(s)
- Stefania Monterisi
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, UK
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10
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11
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Roomans GM. Pharmacological Approaches to Correcting the Ion Transport Defect in Cystic Fibrosis. ACTA ACUST UNITED AC 2012; 2:413-31. [PMID: 14719993 DOI: 10.1007/bf03256668] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cystic fibrosis (CF) is a lethal genetic disease caused by a mutation in a membrane protein, the cystic fibrosis transmembrane conductance regulator (CFTR), which mainly (but not exclusively) functions as a chloride channel. The main clinical symptoms are chronic obstructive lung disease, which is responsible for most of the morbidity and mortality associated with CF, and pancreatic insufficiency. About 1000 mutations of the gene coding for CFTR are currently known; the most common of these, present in the great majority of the patients (Delta508) results in the deletion of a phenylalanine at position 508. In this mutation, the aberrant CFTR is not transported to the membrane but degraded in the ubiquitin-proteasome pathway. The aim of this review is to give an overview of the pharmacologic strategies currently used in attempts to overcome the ion transport defect in CF. One strategy to develop pharmacologic treatment for CF is to inhibit the breakdown of DeltaF508-CFTR by interfering with the chaperones involved in the folding of CFTR. At least in in vitro systems, this can be accomplished by sodium phenylbutyrate, or S-nitrosoglutathione (GSNO), and also by genistein or benzo[c]quinolizinium compounds. It is also possible to stimulate CFTR or its mutated forms, when present in the plasma membrane, using xanthines, genistein, and various other compounds, such as benzamidizoles and benzoxazoles, benzo[c]quinolizinium compounds or phenantrolines. Experimental results are not always unambiguous, and adverse effects have been incompletely tested. Some clinical tests have been done on sodium phenyl butyrate, GSNO and genistein, mostly in respect to other diseases, and the results demonstrate that these drugs are reasonably well tolerated. Their efficiency in the treatment of CF has not yet been demonstrated, however. An alternative strategy is to compensate for the defective chloride transport by CFTR by stimulation of other chloride channels. This can be done via purinergic receptors. A phase I study using a stable uridine triphosphate analog has recently been completed. A second alternative strategy is to attempt to maintain hydration of the airway mucus by inhibiting Na(+) uptake by the epithelial Na(+) channel using amiloride or stable analogs of amiloride. Clinical tests so far have been inconclusive. A number of other suggestions are currently being explored. The minority of patients with CF who have a stop mutation may benefit from treatment with gentamicin. The difficulties in finding a pharmacologic treatment for CF may be due to the fact that CFTR has additional functions besides chloride transport, and interfering with CFTR biosynthesis or activation implies interference with central cellular processes, which may have undesirable adverse effects.
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Affiliation(s)
- Godfried M Roomans
- Department of Medical Cell Biology, University of Uppsala, Uppsala, Sweden.
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12
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Monterisi S, Favia M, Guerra L, Cardone RA, Marzulli D, Reshkin SJ, Casavola V, Zaccolo M. CFTR regulation in human airway epithelial cells requires integrity of the actin cytoskeleton and compartmentalized cAMP and PKA activity. J Cell Sci 2012; 125:1106-17. [PMID: 22302988 DOI: 10.1242/jcs.089086] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) mutation ΔF508CFTR still causes regulatory defects when rescued to the apical membrane, suggesting that the intracellular milieu might affect its ability to respond to cAMP regulation. We recently reported that overexpression of the Na(+)/H(+) exchanger regulatory factor NHERF1 in the cystic fibrosis (CF) airway cell line CFBE41o-rescues the functional expression of ΔF508CFTR by promoting F-actin organization and formation of the NHERF1-ezrin-actin complex. Here, using real-time FRET reporters of both PKA activity and cAMP levels, we find that lack of an organized subcortical cytoskeleton in CFBE41o-cells causes both defective accumulation of cAMP in the subcortical compartment and excessive cytosolic accumulation of cAMP. This results in reduced subcortical levels and increased cytosolic levels of PKA activity. NHERF1 overexpression in CFBE41o-cells restores chloride secretion, subcortical cAMP compartmentalization and local PKA activity, indicating that regulation of ΔF508CFTR function requires not only stable expression of the mutant CFTR at the cell surface but also depends on both generation of local cAMP signals of adequate amplitude and activation of PKA in proximity of its target. Moreover, we found that the knockdown of wild-type CFTR in the non-CF 16HBE14o-cells results in both altered cytoskeletal organization and loss of cAMP compartmentalization, whereas stable overexpression of wt CFTR in CF cells restores cytoskeleton organization and re-establishes the compartmentalization of cAMP at the plasma membrane. This suggests that the presence of CFTR on the plasma membrane influences the cytoskeletal organizational state and, consequently, cAMP distribution. Our data show that a sufficiently high concentration of cAMP in the subcortical compartment is required to achieve PKA-mediated regulation of CFTR activity.
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Affiliation(s)
- Stefania Monterisi
- Department of General and Environmental Physiology, University of Bari, Bari, 70125, Italy
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Antigny F, Norez C, Becq F, Vandebrouck C. CFTR and Ca Signaling in Cystic Fibrosis. Front Pharmacol 2011; 2:67. [PMID: 22046162 PMCID: PMC3200540 DOI: 10.3389/fphar.2011.00067] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 10/11/2011] [Indexed: 11/13/2022] Open
Abstract
Among the diverse physiological functions exerted by calcium signaling in living cells, its role in the regulation of protein biogenesis and trafficking remains incompletely understood. In cystic fibrosis (CF) disease the most common CF transmembrane conductance regulator (CFTR) mutation, F508del-CFTR generates a misprocessed protein that is abnormally retained in the endoplasmic reticulum (ER) compartment, rapidly degraded by the ubiquitin/proteasome pathway and hence absent at the plasma membrane of CF epithelial cells. Recent studies have demonstrated that intracellular calcium signals consequent to activation of apical G-protein-coupled receptors by different agonists are increased in CF airway epithelia. Moreover, the regulation of various intracellular calcium storage compartments, such as ER is also abnormal in CF cells. Although the molecular mechanism at the origin of this increase remains puzzling in epithelial cells, the F508del-CFTR mutation is proposed to be the onset of abnormal Ca2+ influx linking the calcium signaling to CFTR pathobiology. This article reviews the relationships between CFTR and calcium signaling in the context of the genetic disease CF.
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Affiliation(s)
- Fabrice Antigny
- Institut de Physiologie et de Biologie Cellulaires, Université de Poitiers, CNRS Poitiers, France
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Abstract
CD40/CD40 ligand (CD40L) cross-talk plays a key role in B-cell terminal maturation in the germinal centers. Genetic defects affecting CD40 cause a rare form of hyper-immunoglobulin M (IgM) syndrome, a disorder characterized by low or absent serum IgG and IgA, associated with recurrent infections. We previously reported on a few patients with homozygous CD40 mutations resulting in lack or severe reduction of CD40 cell surface expression. Here we characterize the 3 CD40 mutants due to missense mutations or small in-frame deletions, and show that the mutated proteins are synthesized but retained in the endoplasmic reticulum (ER), likely due to protein misfolding. Interestingly, the intracellular behavior and fate differ significantly among the mutants: progressive accumulation of the P2 mutant causes endoplasmic reticulum stress and the activation of an unfolded protein response; the mutant P4 is rather efficiently disposed by the ER-associated degradation pathway, while the P5 mutant partially negotiates transport to the plasma membrane, and is competent for CD40L binding. Interestingly, this latter mutant activates downstream signaling elements when overexpressed in transfected cells. These results give new important insights into the molecular pathogenesis of HIGM disease, and suggest that CD40 deficiency can also be regarded as an ER-storage disease.
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Xu LN, Na WL, Liu X, Hou SG, Lin S, Yang H, Ma TH. Identification of natural coumarin compounds that rescue defective DeltaF508-CFTR chloride channel gating. Clin Exp Pharmacol Physiol 2008; 35:878-83. [PMID: 18430055 DOI: 10.1111/j.1440-1681.2008.04943.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1. Deletion of phenylalanine at position 508 (DeltaF508) of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is the most common mutation causing cystic fibrosis (CF). Effective pharmacological therapy of CF caused by the DeltaF508-CFTR mutation requires the rescue of both intracellular processing and channel gating defects. 2. We identified a class of natural coumarin compounds that can correct the defective DeltaF508-CFTR chloride channel gating by screening a collection of 386 single natural compounds from Chinese medicinal herbs. Screening was performed with an iodide influx assay in Fischer rat thyroid epithelial cells coexpressing DeltaF508-CFTR and an iodide-sensitive fluorescent indicator (YFP-H148Q/I152L). 3. Dose-dependent potentiation of defective DeltaF508-CFTR chloride channel gating by five coumarin compounds was demonstrated by the fluorescent iodide influx assay and confirmed by an Ussing chamber short-circuit current assay. Activation was fully abolished by the specific CFTR inhibitor CFTR(inh)-172. Two potent compounds, namely imperatorin and osthole, have activation K(d) values of approximately 10 micromol/L, as determined by the short-circuit current assay. The active coumarin compounds do not elevate intracellular cAMP levels. Activation of DeltaF508-CFTR by the coumarin compounds requires cAMP agonist, suggesting direct interaction with the mutant CFTR molecule. Kinetics analysis indicated rapid activation of DeltaF508-CFTR by the coumarin compounds, with half-maximal activation of < 5 min. The activating effect was fully reversed for all five active compounds 45 min after washout. 4. In conclusion, the natural coumarin DeltaF508-CFTR activators may represent a new class of natural lead compounds for the development of pharmacological therapies for CF caused by the DeltaF508 mutation.
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Affiliation(s)
- Li-Na Xu
- Membrane Channel Research Laboratory, North-east Normal University, Changchun 130024, China
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16
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Sidani SM, Kirchhoff P, Socrates T, Stelter L, Ferreira E, Caputo C, Roberts KE, Bell RL, Egan ME, Geibel JP. ΔF508 Mutation Results in Impaired Gastric Acid Secretion. J Biol Chem 2007; 282:6068-74. [PMID: 17178714 DOI: 10.1074/jbc.m608427200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is recognized as a multifunctional protein that is involved in Cl(-) secretion, as well as acting as a regulatory protein. In order for acid secretion to take place a complex interaction of transport proteins and channels must occur at the apical pole of the parietal cell. Included in this process is at least one K(+) and Cl(-) channel, allowing for both recycling of K(+) for the H,K-ATPase, and Cl(-) secretion, necessary for the generation of concentrated HCl in the gastric gland lumen. We have previously shown that an ATP-sensitive potassium channel (K(ATP)) is expressed in parietal cells. In the present study we measured secretagogue-induced acid secretion from wild-type and DeltaF508-deficient mice in isolated gastric glands and whole stomach preparations. Secretagogue-induced acid secretion in wild-type mouse gastric glands could be significantly reduced with either glibenclamide or the specific inhibitor CFTR-inh172. In DeltaF508-deficient mice, however, histamine-induced acid secretion was significantly less than in wild-type mice. Furthermore, immunofluorescent localization of sulfonylurea 1 and 2 failed to show expression of a sulfonylurea receptor in the parietal cell, thus further implicating CFTR as the ATP-binding cassette transporter associated with the K(ATP) channels. These results demonstrate a regulatory role for the CFTR protein in normal gastric acid secretion.
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Affiliation(s)
- Shafik M Sidani
- Department of Surgery, Yale University, New Haven, Connecticut 06520, USA
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17
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Roy J, Denovan-Wright EM, Linsdell P, Cowley EA. Exposure to sodium butyrate leads to functional downregulation of calcium-activated potassium channels in human airway epithelial cells. Pflugers Arch 2006; 453:167-76. [PMID: 17047984 DOI: 10.1007/s00424-006-0128-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Revised: 06/09/2006] [Accepted: 06/22/2006] [Indexed: 11/27/2022]
Abstract
Cystic fibrosis (CF) is caused by genetic mutations that lead to dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. The most common mutation, DeltaF508, causes inefficient trafficking of mutant CFTR protein from the endoplasmic reticulum to the cell membrane. Therapeutic efforts have been aimed at increasing the level of DeltaF508-CFTR protein in the membrane using agents such as sodium butyrate. In this study, we investigated the effects of culturing a human airway epithelial cell line, Calu-3, in the presence of 5 mM sodium butyrate. Within 24 h, butyrate exposure caused a significant decrease in the basal, as well as Ca(2+)-activated, anion secretion by Calu-3 cell monolayers, determined by the change in transepithelial short-circuit current in response to the Ca(2+)-elevating agent thapsigargin. The secretory response to 1-ethyl-2-benzimidazolinone, an activator of the basolateral Ca(2+)-activated K(+) channel KCNN4, was similarly reduced by butyrate treatment. Quantitative PCR revealed that these functional effects were associated with dramatic decreases in mRNA for both KCNN4 and CFTR. Furthermore, the KCNQ1 K(+) channel was upregulated after butyrate treatment. We suggest that prolonged exposure to sodium butyrate downregulates the expression of both KCNN4 and CFTR, leading to a functional loss of Ca(2+)-activated anion secretion. Thus, butyrate may inhibit, rather than stimulate, the anion secretory capacity of human epithelial cells that express wild-type CFTR, particularly in tissues that normally exhibit robust Ca(2+)-activated secretion.
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Affiliation(s)
- Jeremy Roy
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
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Ron I, Horowitz M. ER retention and degradation as the molecular basis underlying Gaucher disease heterogeneity. Hum Mol Genet 2005; 14:2387-98. [PMID: 16000318 DOI: 10.1093/hmg/ddi240] [Citation(s) in RCA: 238] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Gaucher disease (GD), an autosomal recessive disease, is characterized by accumulation of glucosylceramide mainly in cells of the reticuloendothelial system, due to mutations in the acid beta-glucocerebrosidase gene. Some of the patients suffer from neurological symptoms (type 2 and type 3 patients), whereas patients with type 1 GD do not present neurological signs. The disease is heterogeneous even among patients with the same genotype, implicating that a mutation in the glucocerebrosidase gene is required to cause GD but other factors play an important role in the manifestation of the disease. Glucocerebrosidase is a lysosomal enzyme, synthesized on endoplasmic reticulum (ER)-bound polyribosomes and translocated into the ER. Following N-linked glycosylations, it is transported to the Golgi apparatus, from where it is trafficked to the lysosomes. In this study, we tested glucocerebrosidase protein levels, N-glycans processing and intracellular localization in skin fibroblasts derived from patients with GD. Our results strongly suggest that mutant glucocerebrosidase variants present variable levels of ER retention and undergo ER-associated degradation in the proteasomes. The degree of ER retention and proteasomal degradation is one of the factors that determine GD severity.
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Affiliation(s)
- Idit Ron
- Department of Cell Research and Immunology, Tel Aviv University, Ramat Aviv, Israel
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Affiliation(s)
- Steven M Rowe
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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21
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22
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Mousa SA, Fareed J. IBC’s 11th Annual International Symposium: Advances in Anticoagulant, Antithrombotic and Thrombolytic Drugs. Expert Opin Investig Drugs 2005. [DOI: 10.1517/13543784.10.1.157] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
The hydrophobic surfactant proteins, SP-B and SP-C, have important roles in surfactant function. The importance of these proteins in normal lung function is highlighted by the lung diseases associated with abnormalities in their expression. Mutations in the gene encoding SP-B result in severe, fatal neonatal lung disease, and mutations in the gene encoding SP-C are associated with chronic interstitial lung diseases in newborns, older children, and adults. This work reviews the current state of knowledge concerning the lung diseases associated with mutations in the SP-B and SP-C genes, and the potential roles of abnormal SP-B and SP-C expression and genetic variation in these genes in other lung diseases.
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Affiliation(s)
- Lawrence M Nogee
- Division of Neonatology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-3200, USA.
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Kidd JF, Kogan I, Bear CE. Molecular Basis for the Chloride Channel Activity of Cystic Fibrosis Transmembrane Conductance Regulator and the Consequences of Disease-Causing Mutations. Curr Top Dev Biol 2004; 60:215-49. [PMID: 15094300 DOI: 10.1016/s0070-2153(04)60007-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- Jackie F Kidd
- Programme in Structural Biology and Biochemistry Research Institute, Hospital for Sick Children, Department of Physiology, University of Toronto, Toronto Canada M5G 1X8
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Jiang C, Lee ER, Lane MB, Xiao YF, Harris DJ, Cheng SH. Partial correction of defective Cl(-) secretion in cystic fibrosis epithelial cells by an analog of squalamine. Am J Physiol Lung Cell Mol Physiol 2001; 281:L1164-72. [PMID: 11597908 DOI: 10.1152/ajplung.2001.281.5.l1164] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Defective cystic fibrosis (CF) transmembrane conductance regulator (CFTR)-mediated Cl(-) transport across the apical membrane of airway epithelial cells is implicated in the pathophysiology of CF lungs. A strategy to compensate for this loss is to augment Cl(-) transport through alternative pathways. We report here that partial correction of this defect could be attained through the incorporation of artificial anion channels into the CF cells. Introduction of GL-172, a synthetic analog of squalamine, into CFT1 cells increased cell membrane halide permeability. Furthermore, when a Cl(-) gradient was generated across polarized monolayers of primary human airway or Fischer rat thyroid cells in an Ussing chamber, addition of GL-172 caused an increase in the equivalent short-circuit current. The magnitude of this change in short-circuit current was ~30% of that attained when CFTR was maximally stimulated with cAMP agonists. Patch-clamp studies showed that addition of GL-172 to CFT1 cells also increased whole cell Cl(-) currents. These currents displayed a linear current-voltage relationship and no time dependence. Additionally, administration of GL-172 to the nasal epithelium of transgenic CF mice induced a hyperpolarization response to perfusion with a low-Cl(-) solution, indicating restoration of Cl(-) secretion. Together, these results demonstrate that in CF airway epithelial cells, administration of GL-172 is capable of partially correcting the defective Cl(-) secretion.
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Affiliation(s)
- C Jiang
- Genzyme Corporation, Framingham, Massachusetts 01701-9322, USA
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26
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Galietta LV, Jayaraman S, Verkman AS. Cell-based assay for high-throughput quantitative screening of CFTR chloride transport agonists. Am J Physiol Cell Physiol 2001; 281:C1734-42. [PMID: 11600438 DOI: 10.1152/ajpcell.2001.281.5.c1734] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Drug discovery by high-throughput screening is a promising approach to develop new therapies for the most common lethal genetic disease, cystic fibrosis. Because disease-causing mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) protein produce epithelial cells with reduced or absent Cl(-) permeability, the goal of screening is to identify compounds that restore cell Cl(-) transport. We have developed a rapid, quantitative screening procedure for analysis of CFTR-mediated halide transport in cells with the use of a conventional fluorescence plate reader. Doubly transfected cell lines were generated that express wild-type or mutant CFTR together with a yellow fluorescent protein (YFP)-based halide sensor. CFTR function was assayed from the time course of cell fluorescence in response to extracellular addition of 100 mM I(-) followed by forskolin, resulting in decreased YFP fluorescence due to CFTR-mediated I(-) entry. Cell lines were chosen, and conditions were optimized to minimize basal halide transport to maximize assay sensitivity. In cells cultured on 96-well plastic dishes, the assay gave reproducible halide permeabilities from well to well and could reliably detect a 2% activation of CFTR-dependent halide transport produced by low concentrations of forskolin. Applications of the assay are shown, including comparative dose-dependent CFTR activation by genistein, apigenin, 8-cyclopentyl-1,3-dipropylxanthine, IBMX, 8-methoxypsoralen, and milrinone as well as activation of alternative Cl(-) channels. The fluorescence assay and cell lines should facilitate the screening of novel CFTR activators and the characterization of alternative Cl(-) channels and transporters.
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Affiliation(s)
- L V Galietta
- Department of Medicine and Physiology, Cardiovascular Research Institute, University of California, San Francisco, California 94143-0521, USA
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Roomans GM. Pharmacological treatment of the ion transport defect in cystic fibrosis. Expert Opin Investig Drugs 2001; 10:1-19. [PMID: 11116277 DOI: 10.1517/13543784.10.1.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Cystic fibrosis (CF) is a lethal monogenetic disease characterised by impaired water and ion transport over epithelia. The lung pathology is fatal and causes death in 95% of CF patients. The genetic basis of the disease is a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-regulated chloride channel. The most common mutation, DeltaF508, results in a protein that cannot properly be folded in the endoplasmic reticulum, is destroyed and hence does not reach the apical cell membrane. This paper will discuss those pharmacological approaches that are directed at correcting the defect in ion transport. At present, no clinically effective drug is available, although research has defined areas in which progress might be made. These are the following: (1) the drug 4-phenylbutyrate (4PBA) increases the expression of DeltaF508-CFTR in the cell membrane, probably by breaking the association between DeltaF508-CFTR and a chaperone; (2) a number of xanthines, in particular 8-cyclopentyl-1, 3-dipropylxanthine (CPX), are effective in activating CFTR, presumably by direct binding and also possibly by correcting the trafficking defect; (3) the isoflavone genistein can activate both wild-type and mutant CFTR, probably through direct binding to the channel; (4) purinergic agonists (ATP and UTP) can stimulate chloride secretion via a Ca(2+)-dependent chloride channel and in this way compensate for the defect in CFTR, but stable analogues will be required before this type of treatment has clinical significance; (5) treatment with inhaled amiloride may correct the excessive absorption of Na(+) ions and water by airway epithelial cells that appears connected to the defect in CFTR; although clinical tests have not been very successful so far, amiloride analogues with a longer half-life may give better results. The role of CFTR in bicarbonate secretion has not yet been established with certainty, but correction of the defect in bicarbonate secretion may be important in clinical treatment of the disease. Currently, major efforts are directed at developing a pharmacological treatment of the ion transport defect in CF, but much basic research remains to be done, in particular, with regard to the mechanism by which defective CFTR is removed in the endoplasmic reticulum by the ubiquitin-proteasome pathway, which is a central pathway in protein production and of significance for several other diseases apart from CF.
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Affiliation(s)
- G M Roomans
- Department of Medical Cell Biology, University of Uppsala, Box 571, 75123 Uppsala, Sweden.
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N-substituted acetonitrile inhibitors of cathepsin L. Expert Opin Ther Pat 2001. [DOI: 10.1517/13543776.11.1.149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
LJP-394 is a synthetic biological with immunomodulatory functions. Composed of four double-stranded oligodeoxynucleotides attached to a central branched platform, the drug acts as an anti-"anti-ds-DNA" B-cell toleragen by rendering specific B-lymphocytes unresponsive to immunogen so they do not produce autoantibodies. Extensive animal studies and Phase II clinical trials suggested that the effects of LJP-394 are effective and safe when used as a weekly dose of 100 mg intravenously. Analysis of a multicentre, international Phase II/III clinical trial showed that patients with lupus nephritis and high affinity IgG antibodies to LJP-394 have clinical benefits. This includes increased time to renal flares, reduced number of renal flares, time to institution of high-dose corticosteroids and/or cyclophosphamide and lower anti-ds-DNA levels. A definitive trial is in progress. LJP-394 appears to be free of serious adverse reactions. Though promising, the role of LJP-394 in patients with active, organ-threatening lupus is still not known.
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Affiliation(s)
- D J Wallace
- Clinical Professor of Medicine, Cedars-Sinai/University of California Los Angeles, 8737 Beverly Blvd, Suite 203, Los Angeles, CA 90048, USA.
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