Browsing by Author "Econs, Michael J."
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Item Autoimmune hyperphosphatemic tumoral calcinosis in a patient with FGF23 autoantibodies(American Society for Clinical Investigation, 2018-12-03) Roberts, Mary Scott; Burbelo, Peter D.; Egli-Spichtig, Daniela; Perwad, Farzana; Romero, Christopher J.; Ichikawa, Shoji; Farrow, Emily; Econs, Michael J.; Guthrie, Lori C.; Collins, Michael T.; Gafni, Rachel I.; Medicine, School of MedicineHyperphosphatemic familial tumoral calcinosis (HFTC)/hyperostosis-hyperphosphatemia syndrome (HHS) is an autosomal recessive disorder of ectopic calcification due to deficiency of or resistance to intact fibroblast growth factor 23 (iFGF23). Inactivating mutations in FGF23, N-acetylgalactosaminyltransferase 3 (GALNT3), or KLOTHO (KL) have been reported as causing HFTC/HHS. We present what we believe is the first identified case of autoimmune hyperphosphatemic tumoral calcinosis in an 8-year-old boy. In addition to the classical clinical and biochemical features of hyperphosphatemic tumoral calcinosis, the patient exhibited markedly elevated intact and C-terminal FGF23 levels, suggestive of FGF23 resistance. However, no mutations in FGF23, KL, or FGF receptor 1 (FGFR1) were identified. He subsequently developed type 1 diabetes mellitus, which raised the possibility of an autoimmune cause for hyperphosphatemic tumoral calcinosis. Luciferase immunoprecipitation systems revealed markedly elevated FGF23 autoantibodies without detectable FGFR1 or Klotho autoantibodies. Using an in vitro FGF23 functional assay, we found that the FGF23 autoantibodies in the patient's plasma blocked downstream signaling via the MAPK/ERK signaling pathway in a dose-dependent manner. Thus, this report describes the first case, to our knowledge, of autoimmune hyperphosphatemic tumoral calcinosis with pathogenic autoantibodies targeting FGF23. Identification of this pathophysiology extends the etiologic spectrum of hyperphosphatemic tumoral calcinosis and suggests that immunomodulatory therapy may be an effective treatment.Item Autosomal Dominant Osteopetrosis(Elsevier, 2023) Polgreen, Lynda E.; Imel, Erik A.; Econs, Michael J.; Medicine, School of MedicineAutosomal dominant osteopetrosis (ADO) is the most common form of osteopetrosis. ADO is characterized by generalized osteosclerosis along with characteristic radiographic features such as a "bone-in-bone" appearance of long bones and sclerosis of the superior and inferior vertebral body endplates. Generalized osteosclerosis in ADO typically results from abnormalities in osteoclast function, due most commonly to mutations in the chloride channel 7 (CLCN7) gene. A variety of debilitating complications can occur over time due to bone fragility, impingement of cranial nerves, encroachment of osteopetrotic bone in the marrow space, and poor bone vascularity. There is a wide spectrum of disease phenotype, even within the same family. Currently, there is no disease specific treatment for ADO, so clinical care focuses on monitoring for disease complications and symptomatic treatment. This review describes the history of ADO, the wide disease phenotype, and potential new therapies.Item Bone Marrow Transplantation as a Therapy for Autosomal Dominant Osteopetrosis Type 2 in Mice(Wiley, 2022) Alam, Imranul; Gerard-O’Riley, Rita L.; Acton, Dena; Hardman, Sara L.; Murphy, Madeline; Alvarez, Marta B.; Blosser, Rachel J.; Sinn, Anthony; Srour, Edward F.; Kacena, Melissa A.; Econs, Michael J.; Medicine, School of MedicineAutosomal dominant osteopetrosis type II (ADO2) is a heritable bone disease of impaired osteoclastic bone resorption caused by missense mutations in the chloride channel 7 (CLCN7) gene. Clinical features of ADO2 include fractures, osteomyelitis of jaw, vision loss, and in severe cases, bone marrow failure. Currently, there is no effective therapy for ADO2, and patients usually receive symptomatic treatments. Theoretically, bone marrow transplantation (BMT), which is commonly used in recessive osteopetrosis, could be used to treat ADO2, although the frequency of complications related to BMT is quite high. We created an ADO2 knock-in (p.G213R mutation) mouse model on the 129 genetic background, and their phenotypes mimic the human disease of ADO2. To test whether BMT could restore osteoclast function and rescue the bone phenotypes in ADO2 mice, we transplanted bone marrow cells from 6-8 weeks old male WT donor mice into recipient female ADO2 mice. Also, to determine whether age at the time of transplant may play a role in transplant success, we performed BMT in young (12-week-old) and old (9-month-old) ADO2 mice. Our data indicate that ADO2 mice transplanted with WT marrow achieved more than 90% engraftment up to 6 months post-transplantation at both young and old ages. The in-vivo DXA data revealed that young ADO2 mice transplanted with WT marrow had significantly lower whole body and spine areal bone mineral density (aBMD) at month 6 post-transplantation compared to the ADO2 control mice. The old ADO2 mice also displayed significantly lower whole body, femur and spine aBMD at months 4 and 5 post-transplantation compared to the age-matched control mice. The in-vivo micro-CT data showed that ADO2 experimental mice transplanted with WT marrow had significantly lower BV/TV at months 2 and 4 post-transplantation compared to the ADO2 control mice at young age. In contrast, ADO2 control and experimental mice displayed similar BV/TV values for all post-transplantation time points at old age. In addition, serum CTX was significantly higher at month 2 post-transplantation in both young and old ADO2 experimental mice compared to the ADO2 control mice. Serum P1NP levels in young ADO2 experimental mice were significantly higher at baseline and month 2 post-transplantation compared to the ADO2 control mice. These data suggest that BMT may provide, at least, some beneficial effect at both young and adult ages.Item Bone Mass and Strength are Significantly Improved in Mice Overexpressing Human WNT16 in Osteocytes(Springer, 2017-04) Alam, Imranul; Reilly, Austin M.; Alkhouli, Mohammed; Gerard-O’Riley, Rita L.; Kasipathi, Charishma; Oakes, Dana K.; Wright, Weston B.; Acton, Dena; McQueen, Amie K.; Patel, Bhavmik; Lim, Kyung-Eun; Robling, Alexander G.; Econs, Michael J.; Medicine, School of MedicineRecently, we demonstrated that osteoblast-specific overexpression of human WNT16 increased both cortical and trabecular bone mass and structure in mice. To further identify the cell-specific role of Wnt16 in bone homeostasis, we created transgenic (TG) mice overexpressing human WNT16 in osteocytes using Dmp1 promoter (Dmp1-hWNT16 TG) on C57BL/6 (B6) background. We analyzed bone phenotypes and serum bone biomarkers, performed gene expression analysis and measured dynamic bone histomorphometry in Dmp1-hWNT16 TG and wild-type (WT) mice. Compared to WT mice, Dmp1-hWNT16 TG mice exhibited significantly higher whole-body, spine and femoral aBMD, BMC and trabecular (BV/TV, Tb.N, and Tb.Th) and cortical (bone area and thickness) parameters in both male and female at 12 weeks of age. Femur stiffness and ultimate force were also significantly improved in the Dmp1-hWNT16 TG female mice, compared to sex-matched WT littermates. In addition, female Dmp1-hWNT16 TG mice displayed significantly higher MS/BS, MAR and BFR/BS compared to the WT mice. Gene expression analysis demonstrated significantly higher mRNA level of Alp in both male and female Dmp1-hWNT16 TG mice and significantly higher levels of Osteocalcin, Opg and Rankl in the male Dmp1-hWNT16 TG mice in bone tissue compared to sex-matched WT mice. These results indicate that WNT16 plays a critical role for acquisition of both cortical and trabecular bone mass and strength. Strategies designed to use WNT16 as a target for therapeutic interventions will be valuable to treat osteoporosis and other low bone mass conditions.Item The Case | Ectopic calcifications in a child(Nature Publishing Group, 2015-05) Keskar, Vaibhav S.; Imel, Erik A.; Kulkarni, Manjunath; Mane, Swati; Jamale, Tukaram E.; Econs, Michael J.; Hase, Niwrutti K.; Department of Medicine, IU School of MedicineItem Chloroquine increases osteoclast activity in vitro but does not improve the osteopetrotic bone phenotype of ADO2 mice(Elsevier, 2021) Alam, Imranul; Gerard-O’Riley, Rita L.; Acton, Dena; Hardman, Sara L.; Hong, Jung Min; Bruzzaniti, Angela; Econs, Michael J.; Medicine, School of MedicineAutosomal Dominant Osteopetrosis type II (ADO2) is a bone disease of impaired osteoclastic bone resorption that usually results from heterozygous missense mutations in the chloride channel 7 (CLCN7) gene. We created mouse models of ADO2 by introducing a knock-in (p.G213R) mutation in the Clcn7 gene, which is analogous to one of the common mutations (G215R) found in humans. The mutation leads to severe osteopetrosis and lethality in homozygous mice but produces substantial phenotypic variability in heterozygous mice on different genetic backgrounds that phenocopy the human disease of ADO2. ADO2 is an osteoclast-intrinsic disease, and lysosomal enzymes and proteins are critical for osteoclast activity. Chloroquine (CQ) is known to affect lysosomal trafficking, intracellular signaling and the lysosomal and vesicular pH, suggesting it might improve ADO2 osteoclast function. We tested this hypothesis in cell culture studies using osteoclasts derived from wild-type (WT or ADO2+/+) and ADO2 heterozygous (ADO2+/−) mice and found that CQ and its metabolite desethylchloroquine (DCQ), significantly increased ADO2+/− osteoclasts bone resorption activity in vitro, whereas bone resorption of ADO2+/+ osteoclasts was increased only by DCQ. In addition, we exploited our unique animal model of ADO2 on 129 background to identify the effect of CQ for the treatment of ADO2. Female ADO2 mice at 8 weeks of age were treated with 5 doses of CQ (1, 2.5, 5, 7.5 and 10 mg/kg BW/day) via drinking water for 6 months. Bone mineral density and bone micro-architecture were analyzed by longitudinal in-vivo DXA and micro-CT at baseline, 3 and 6 months. Serum bone biomarkers (CTX, TRAP and P1NP) were also analyzed at these time points. CQ treatment at the doses tested failed to produce any significant changes of aBMD, BMC (whole body, femur and spine) and trabecular BV/TV (distal femur) in ADO2 mice compared to the control group (water only). Further, levels of bone biomarkers were not significantly changed due to CQ treatment in these mice. Our findings indicate that while CQ increased osteoclast activity in vitro, it did not improve the osteopetrotic bone phenotypes in ADO2 heterozygous mice.Item Conventional Therapy in Adults With XLH Improves Dental Manifestations, But Not Enthesopathy.(The Endocrine Society, 2015-10) Econs, Michael J.; Department of Medical and Molecular Genetics, IU School of MedicineItem Cover, Volume 43, Issue 2(Wiley, 2022) Sarafrazi, Soodabeh; Daugherty, Sean C.; Miller, Nicole; Boada, Patrick; Carpenter, Thomas O.; Chunn, Lauren; Dill, Kariena; Econs, Michael J.; Eisenbeis, Scott; Imel, Erik A.; Johnson, Britt; Kiel, Mark J.; Krolczyk, Stan; Ramesan, Prameela; Truty, Rebecca; Sabbagh, Yves; Medicine, School of MedicineThe cover image is based on the Research Article Novel PHEX gene locus-specific database: Comprehensive characterization of vast number of variants associated with X-linked hypophosphatemia (XLH) by Yves Sabbagh et al., https://doi.org/10.1002/humu.24296.Item Dietary phosphate restriction normalizes biochemical and skeletal abnormalities in a murine model of tumoral calcinosis(2011-12) Ichikawa, Shoji; Austin, Anthony M.; Gray, Amie K.; Allen, Matthew R.; Econs, Michael J.Mutations in the GALNT3 gene cause tumoral calcinosis characterized by ectopic calcifications due to persistent hyperphosphatemia. We recently developed Galnt3 knockout mice in a mixed background, which had hyperphosphatemia with increased bone mineral density (BMD) and infertility in males. To test the effect of dietary phosphate intake on their phenotype, Galnt3 knockout mice were generated in the C57BL/6J strain and fed various phosphate diets: 0.1% (low), 0.3% (low normal), 0.6% (normal), and 1.65% (high). Sera were analyzed for calcium, phosphorus, alkaline phosphatase, creatinine, blood urine nitrogen, 1,25-dihydroxyvitamin D, osteocalcin, tartrate-resistant acid phosphatase 5b, and fibroblast growth factor 23 (Fgf23). Femurs were evaluated by dual-energy x-ray absorptiometry, dynamic histomorphometry, and/or microcomputed tomography. Galnt3 knockout mice in C57BL/6J had the same biochemical phenotype observed in our previous study: hyperphosphatemia, inappropriately normal 1,25-dihydroxyvitamin D level, decreased alkaline phosphatase activity, and low intact Fgf23 concentration but high Fgf23 fragments. Skeletal analyses of their femurs revealed significantly high BMD with increased cortical bone area and trabecular bone volume. On all four phosphate diets, Galnt3 knockout mice had consistently higher phosphorus levels and lower alkaline phosphatase and intact Fgf23 concentrations than littermate controls. The low-phosphate diet normalized serum phosphorus, alkaline phosphatase, and areal BMD but failed to correct male infertility in Galnt3 knockout mice. The high-phosphate diet did not increase serum phosphorus concentration in either mutant or control mice due to a compensatory increase in circulating intact Fgf23 levels. In conclusion, dietary phosphate restriction normalizes biochemical and skeletal phenotypes of Galnt3 knockout mice and, thus, can be an effective therapy for tumoral calcinosis.Item Disentangling the genetics of lean mass(Oxford University Press, 2019-02-01) Karasik, David; Zillikens, M. Carola; Hsu, Yi-Hsiang; Aghdassi, Ali; Akesson, Kristina; Amin, Najaf; Barroso, Inês; Bennett, David A.; Bertram, Lars; Bochud, Murielle; Borecki, Ingrid B.; Broer, Linda; Buchman, Aron S.; Byberg, Liisa; Campbell, Harry; Campos-Obando, Natalia; Cauley, Jane A.; Cawthon, Peggy M.; Chambers, John C.; Chen, Zhao; Cho, Nam H.; Choi, Hyung Jin; Chou, Wen-Chi; Cummings, Steven R.; De Groot, Lisette C. P. G. M.; De Jager, Phillip L.; Demuth, Ilja; Diatchenko, Luda; Econs, Michael J.; Eiriksdottir, Gudny; Enneman, Anke W.; Eriksson, Joel; Eriksson, Johan G.; Estrada, Karol; Evans, Daniel S.; Feitosa, Mary F.; Fu, Mao; Gieger, Christian; Grallert, Harald; Gudnason, Vilmundur; Lenore, Launer J.; Hayward, Caroline; Hofman, Albert; Homuth, Georg; Huffman, Kim M.; Husted, Lise B.; Illig, Thomas; Ingelsson, Erik; Ittermann, Till; Jansson, John-Olov; Johnson, Toby; Biffar, Reiner; Jordan, Joanne M.; Jula, Antti; Karlsson, Magnus; Khaw, Kay-Tee; Kilpeläinen, Tuomas O.; Klopp, Norman; Kloth, Jacqueline S. L.; Koller, Daniel L.; Kooner, Jaspal S.; Kraus, William E.; Kritchevsky, Stephen; Kutalik, Zoltán; Kuulasmaa, Teemu; Kuusisto, Johanna; Laakso, Markku; Lahti, Jari; Lang, Thomas; Langdahl, Bente L.; Lerch, Markus M.; Lewis, Joshua R.; Lill, Christina; Lind, Lars; Lindgren, Cecilia; Liu, Yongmei; Livshits, Gregory; Ljunggren, Östen; Loos, Ruth J. F.; Lorentzon, Mattias; Luan, Jian'an; Luben, Robert N.; Malkin, Ida; McGuigan, Fiona E.; Medina-Gomez, Carolina; Meitinger, Thomas; Melhus, Håkan; Mellström, Dan; Michaëlsson, Karl; Mitchell, Braxton D.; Morris, Andrew P.; Mosekilde, Leif; Nethander, Maria; Newman, Anne B.; O'Connell, Jeffery R.; Oostra, Ben A.; Orwoll, Eric S.; Palotie, Aarno; Peacock, Munro; Perola, Markus; Peters, Annette; Prince, Richard L.; Psaty, Bruce M.; Räikkönen, Katri; Ralston, Stuart H.; Ripatti, Samuli; Rivadeneira, Fernando; Robbins, John A.; Rotter, Jerome I.; Rudan, Igor; Salomaa, Veikko; Satterfield, Suzanne; Schipf, Sabine; Shin, Chan Soo; Smith, Albert V.; Smith, Shad B.; Soranzo, Nicole; Spector, Timothy D.; Stančáková, Alena; Stefansson, Kari; Steinhagen-Thiessen, Elisabeth; Stolk, Lisette; Streeten, Elizabeth A.; Styrkarsdottir, Unnur; Swart, Karin M. A.; Thompson, Patricia; Thomson, Cynthia A.; Thorleifsson, Gudmar; Thorsteinsdottir, Unnur; Tikkanen, Emmi; Tranah, Gregory J.; Uitterlinden, André G.; Van Duijn, Cornelia M.; Van Schoor, Natasja M.; Vandenput, Liesbeth; Vollenweider, Peter; Völzke, Henry; Wactawski-Wende, Jean; Walker, Mark; Wareham, Nicholas J.; Waterworth, Dawn; Weedon, Michael N.; Wichmann, H-Erich.; Widen, Elisabeth; Williams, Frances M. K.; Wilson, James F.; Wright, Nicole C.; Yerges-Armstrong, Laura M.; Yu, Lei; Zhang, Weihua; Zhao, Jing Hua; Zhou, Yanhua; Nielson, Carrie M.; Harris, Tamara B.; Demissie, Serkalem; Kiel, Douglas P.; Ohlsson, Claes; Medicine, School of MedicineBackground: Lean body mass (LM) plays an important role in mobility and metabolic function. We previously identified five loci associated with LM adjusted for fat mass in kilograms. Such an adjustment may reduce the power to identify genetic signals having an association with both lean mass and fat mass. Objectives: To determine the impact of different fat mass adjustments on genetic architecture of LM and identify additional LM loci. Methods: We performed genome-wide association analyses for whole-body LM (20 cohorts of European ancestry with n = 38,292) measured using dual-energy X-ray absorptiometry) or bioelectrical impedance analysis, adjusted for sex, age, age2, and height with or without fat mass adjustments (Model 1 no fat adjustment; Model 2 adjustment for fat mass as a percentage of body mass; Model 3 adjustment for fat mass in kilograms). Results: Seven single-nucleotide polymorphisms (SNPs) in separate loci, including one novel LM locus (TNRC6B), were successfully replicated in an additional 47,227 individuals from 29 cohorts. Based on the strengths of the associations in Model 1 vs Model 3, we divided the LM loci into those with an effect on both lean mass and fat mass in the same direction and refer to those as "sumo wrestler" loci (FTO and MC4R). In contrast, loci with an impact specifically on LM were termed "body builder" loci (VCAN and ADAMTSL3). Using existing available genome-wide association study databases, LM increasing alleles of SNPs in sumo wrestler loci were associated with an adverse metabolic profile, whereas LM increasing alleles of SNPs in "body builder" loci were associated with metabolic protection. Conclusions: In conclusion, we identified one novel LM locus (TNRC6B). Our results suggest that a genetically determined increase in lean mass might exert either harmful or protective effects on metabolic traits, depending on its relation to fat mass.