Familial Hypercholesterolemia in Patients with Acute Coronary Syndrome: Genetic Insights from EXPLORE-J.

AIM: Genetic testing can provide a definitive diagnosis of familial hypercholesterolemia (FH). However, accessibility of genetic testing may be limited in certain countries where it is not considered "standard of care," including Japan. In addition, mutations responsible for FH cannot be identified in approximately 30% of patients. METHODS: EXPLORE-J is a multicenter, prospective, observational study of patients presenting with acute coronary syndrome (ACS). The genetic data were analyzed and adjudicated as pathogenic, indeterminate, or nondetectable pathogenic variant. RESULTS: Of 1,944 patients, 431 underwent genetic screening. Overall, most patients had nonpathogenic variants of LDLR, LDLRAP1, or PCSK9 (n=396, 91.9%). Of the 25 (5.8%) patients with pathogenic variants, variants of the LDLR gene and the PCSK9 gene were seen in 10 and 15 patients, respectively. Indeterminate variants were observed in 10 (2.3%) patients. Of the 431 patients, eight (1.9%) met the criteria for a diagnosis of FH using the Japanese Atherosclerosis Society (JAS) 2017 guidelines. When genetic data were incorporated, 33 (7.7%) patients met the JAS guidelines. No patients with FH pathogenic variants satisfied the JAS clinical criteria for a diagnosis of FH. CONCLUSIONS: The results revealed a higher prevalence of genetic mutations of FH among Japanese patients with ACS and a low sensitivity of the FH diagnostic criteria of the JAS 2017 guidelines. These findings highlight the difficulties of FH diagnosis in patients with ACS in the acute phase and suggest the importance of genetic testing and family history.

Real-world data on the use of insulin glargine 300 U/mL in Japanese patients with type 1 diabetes: twelve-month results from a post-marketing surveillance study (X-STAR study).

BACKGROUND: With limited real-world insulin glargine 300 U/mL (Gla-300) data among Japanese patients with type 1 diabetes mellitus (T1DM) available, the authors describe its effectiveness and safety in Japanese T1DM patients switching to Gla-300. RESEARCH DESIGN AND METHODS: X-STAR was a 12-month prospective, observational, post-marketing study in Japanese patients with diabetes mellitus from 2015 to 2018: insulin-experienced T1DM patients initiating Gla-300 were analyzed. RESULTS: Of 774 patients, mean (±standard deviation) HbA1c (%) and fasting plasma glucose (mg/dL) decreased from 8.27 ± 1.55 to 8.15 ± 1.35 (by -0.12 ± 1.30 [p = 0.013]) and 167.9 ± 92.6 to 153.9 ± 70.9 (by -13.9 ± 103.8 [p = 0.067]) from baseline to month 12, respectively. A total of 16.3% achieved HbA1c <7.0% at month 12. Gla-300 dose increased by 1.13 ± 3.18 U/day (0.02 ± 0.05 U/kg/day) (p < 0.001), with a + 0.22 ± 2.70 (p = 0.037) body-weight change (kg) from baseline 60.83 ± 12.81 to 12-month 61.06 ± 12.89. Adverse drug reactions (ADRs) and serious ADRs occurred in 9.82% and 0.78% of the patients, respectively. Hypoglycemia was the most common ADR (9.30%). In total, 88.9% adhered to Gla-300 administration schedules, whereas <40% adhered to exercise and dietary instructions, respectively. CONCLUSIONS: Gla-300 showed no unprecedented safety concerns for insulin-experienced T1DM patients in Japanese clinical settings. Our results provide insights into strategies for blunted Gla-300 up-titration dose, despite insufficient HbA1c control and lifestyle modification.

Safety and effectiveness of tofogliflozin in Japanese patients with type 2 diabetes mellitus treated in real-world clinical practice: Results of a 36-month post-marketing surveillance study (J-STEP/LT).

AIMS/INTRODUCTION: Tofogliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor that lowers plasma glucose levels by enhancing urinary glucose excretion. After its approval in Japan in 2014 for the treatment of type 2 diabetes mellitus, we carried out a 3-year prospective observational post-marketing surveillance study in Japanese patients (Japanese Study of Tofogliflozin with Type 2 Diabetes Mellitus Patients/Long Term [J-STEP/LT]). MATERIALS AND METHODS: This surveillance was carried out between September 2014 and February 2019, and recorded safety in terms of adverse drug reactions (ADRs) and ADRs of special interest, and effectiveness in terms of changes in glycated hemoglobin and bodyweight from baseline to last observation carried forward. RESULTS: Of 6,897 patients with type 2 diabetes mellitus registered, 6,711 and 6,451 were analyzed for safety and effectiveness, respectively. ADRs were reported in 846 patients (12.61%), with serious ADRs in 101 patients (1.5%). ADRs of special interest included hypoglycemia (62 patients [0.9%]), polyuria/pollakiuria (90 [1.3%]), volume depletion-related disorders (135 [2.0%]), urinary tract infections (91 [1.4%]), genital infections (117 [1.7%]) and skin diseases (53 [0.8%]). One case of diabetic ketoacidosis was reported. The mean ± standard deviation changes from baseline to last observation carried forward in glycated hemoglobin and bodyweight were -0.68 ± 1.34% (n = 6,158, P < 0.0001) and -3.13 ± 4.67 kg (n = 5,213, P < 0.0001), respectively. CONCLUSIONS: J-STEP/LT, a 3-year, prospective, observational, post-marketing study in Japan, found no unprecedented ADRs, and consistent reductions from baseline in glycated hemoglobin and bodyweight over the observation period. The present results provide further evidence regarding the safety and tolerability of tofogliflozin in Japanese patients with type 2 diabetes mellitus.

Risk of hypoglycemia in Japanese people with type 2 diabetes mellitus who initiated or switched to insulin glargine 300 U/mL: A subgroup analysis of 12-month post-marketing surveillance study (X-STAR study).

AIMS: This study investigated the hypoglycemia risk in people with type 2 diabetes (T2D) who initiated or switched to insulin glargine 300 U/mL (Gla-300) by stratifying them by age and renal function. METHODS: We examined data from 4621 people with T2D (1227 insulin-naïve and 3394 insulin-experienced) of the X-STAR study, a prospective, observational, 12-month study conducted from December 2015 to August 2018 in Japan. Participants were stratified by age (<65, 65 to <75, and ≥75 years) and estimated glomerular filtration rate (eGFR) (≥90, 60 to <90, 30 to <60, and <30 mL/min/1.73 m2). Hypoglycemia was defined according to the Ministry of Health, Labour and Welfare manual of Japan. RESULTS: No apparent increase in the proportion of people who experienced hypoglycemia was found in all subgroups. The proportions were 2.9-3.5% and 2.7-5.2% of insulin-naïve and insulin-experienced people, respectively, for age subgroups, and 2.4-4.7% and 4.6-4.8%, respectively, for eGFR subgroups. The result was similar for HbA1c levels below and at or above 7.0% in all age subgroups. CONCLUSIONS: Our study found no apparent increase in the hypoglycemia risk in people with older age and renal impairment who were administered Gla-300. These results would provide reassuring information on Gla-300 use.

Transcription factor MafB in podocytes protects against the development of focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is a common cause of steroid-resistant nephrotic syndrome. Spontaneous remission of FSGS is rare and steroid-resistant FSGS frequently progresses to renal failure. Many inheritable forms of FSGS have been described, caused by mutations in proteins that are important for podocyte function. Here, we show that a basic leucine zipper transcription factor, MafB, protects against FSGS. MAFB expression was found to be decreased in the podocytes of patients with FSGS. Moreover, conditional podocyte-specific MafB-knockout mice developed FSGS with massive proteinuria accompanied by depletion of the slit diaphragm-related proteins (Nphs1 and Magi2), and the podocyte-specific transcription factor Tcf21. These findings indicate that MafB plays a crucial role in the pathogenesis of FSGS. Consistent with this, adriamycin-induced FSGS and attendant proteinuria were ameliorated by MafB overexpression in the podocytes of MafB podocyte-specific transgenic mice. Thus, MafB could be a new therapeutic target for FSGS.

Effectiveness and safety of insulin glargine 300 unit/mL in Japanese type 2 diabetes mellitus patients: a 12-month post-marketing surveillance study (X-STAR study).

BACKGROUND: With limited real-world insulin glargine 300 unit/mL (Gla-300) data available, we assessed the effectiveness and safety of Gla-300 in the Japanese type 2 diabetes mellitus (T2DM) population. RESEARCH DESIGN AND METHODS: X-STAR was a prospective, observational, 12-month post-marketing study of Gla-300 from 2015 to 2018. T2DM patients received Gla-300 as the first insulin (insulin-naïve) or after treatment with another type of insulin (insulin-experienced). RESULTS: We identified 1,227 insulin-naïve and 3,394 insulin-experienced patients. Insulin-naïve group increased the Gla-300 starting dose by 2.80 U/day during 12 months (7.49 to 10.29 U/day). Mean HbA1c reduced by 1.99% (9.82 to 7.83%), and 28.4% showed HbA1c < 7.0%. Insulin-experienced group had a baseline insulin dose of 14.86 U/day, which increased by 0.73 U/day. Mean HbA1c reduced by 0.18% (7.99 to 7.81%), and 24.6% showed HbA1c < 7.0%. Adverse drug reactions occurred in 3.42% (insulin-naïve) and 4.45% (insulin-experienced); symptomatic hypoglycemia (2.93% and 3.86%, respectively) was the most common in both groups. CONCLUSIONS: Gla-300, in clinical practice, provides an effective and safe therapy as HbA1c was reduced/maintained in insulin-naïve/experienced Japanese T2DM patients without new safety signal. This study provides insights into the current Japanese clinical practices where insulin use is delayed and conservative despite relatively low HbA1c achievement.

Fixed-ratio combination of basal insulin and glucagon-like peptide-1 receptor agonists in the treatment of Japanese people with type 2 diabetes: An innovative solution to a complex therapeutic challenge.

Over 10 million people in Japan have known or suspected type 2 diabetes (T2D), and this number is expected to rise. Although many people require therapy escalation because of the progressive nature of T2D, this appears to be suboptimal in Japanese real-world clinical practice. Insulin therapy tends to be introduced only when glycaemic control is very poor (mean glycated haemoglobin >9%). Although basal insulin therapy is effective in reducing fasting plasma glucose (FPG), postprandial plasma glucose often remains uncontrolled. Basal-bolus insulin regimens are complex and carry the risk of weight gain and hypoglycaemia. Recently, fixed-ratio combinations (FRCs) of BI and glucagon-like peptide-1 receptor agonists (GLP-1RAs) have shown efficacy in reducing both FPG and postprandial plasma glucose with a single injection and without increased risk of hypoglycaemia or weight gain. IDegLira, a titratable FRC of insulin degludec (100 U/mL) and liraglutide, is currently available in Japan and the United States/European Union at a ratio of 1 U (unit):0.036 mg. iGlarLixi (insulin glargine 100 U/mL and lixisenatide at a ratio of 1:1 (20 U/20 µg) has recently been approved in Japan. Phase 3 trials in Japan for IDegLira (DUAL Japan) and iGlarLixi (LixiLan JP) have shown that both FRCs are efficacious. This review provides an overview of IDegLira and iGlarLixi (Japanese formulation) and considers their potential use as new therapeutic options to address the clinical need for early glycaemic control in Japanese people with T2D.

Safety and effectiveness of tofogliflozin in Japanese patients with type 2 diabetes mellitus: Results of 24-month interim analysis of a long-term post-marketing study (J-STEP/LT).

AIMS/INTRODUCTION: Tofogliflozin is a potent and highly selective sodium-glucose cotransporter 2 inhibitor, and is currently used to treat patients with type 2 diabetes mellitus. We designed a 3-year study of tofogliflozin in patients with type 2 diabetes mellitus to evaluate the safety and effectiveness in routine clinical practice. The 3- and 12-month interim analysis showed tofogliflozin was well-tolerated, safe and clinically effective. Here, we report the results of the 24-month interim analysis. MATERIALS AND METHODS: This is a 3-year prospective, observational and multicenter post-marketing study (Japanese Study of Tofogliflozin with Type 2 Diabetes Mellitus Patients/Long Term). RESULTS: Of the 6,897 patients enrolled, 6,712 and 6,461 patients were analyzed for the safety and effectiveness of tofogliflozin, respectively. During the 24-month observation period, the incidence rates of adverse drug reactions (ADRs) and serious adverse drug reactions were 11.25 and 1.21%, respectively. As to adverse drug reactions of special interest, the incidence rates of hypoglycemia, polyuria/pollakiuria, volume depletion-related events, urinary tract infections and genital infection were 0.83, 1.28, 1.46, 1.18 and 1.62%, respectively. Renal disorders, and cardiovascular and cerebrovascular disorders occurred in 0.63 and 0.76% of the patients, respectively. Glycated hemoglobin A1c and bodyweight decreased significantly by -0.70% (P < 0.0001) and -2.95 kg (P < 0.0001), respectively, from baseline to week 104 (last observation carried forward). CONCLUSIONS: Significant safety concerns have not been observed, and clinical benefit including a long-term reduction in glycated hemoglobin A1c over a 104-week (24 months) observation period with weight loss was suggested in this 24-month interim analysis of the 3-year Japanese Study of Tofogliflozin with Type 2 Diabetes Mellitus Patients/Long Term in routine clinical practice.

Inhibition of epidermal growth factor receptor stimulates prolactin expression in primary culture of the mouse pituitary gland.

The roles of epidermal growth factor (EGF) in the regulation of prolactin (PRL) gene expression in the normal pituitary gland remain poorly understood. In the present study, the effects of EGF and an inhibitor of the EGF receptor, erlotinib, on PRL gene expression were examined both in the pituitary tumour cell line GH3 and in a primary culture of the mouse pituitary gland under similar experimental conditions. The results showed that EGF stimulated PRL expression in GH3 cells, but not in normal cells. Erlotinib was found to counteract EGF in GH3 cells inhibiting the PRL expression enhanced by EGF. By contrast, erlotinib induced an elevation in the PRL mRNA levels in the primary culture of the adult pituitary gland and the initiation of PRL production in the culture of the foetal pituitary gland in which PRL production had not yet occurred. Western blot analyses showed that EGF induced and erlotinib inhibited the activation of extracellular regulated protein kinase equally in GH3 and normal cells. These results suggest that the consequences of EGF receptor activation in normal PRL cells contradict those in adenomatous PRL cells.

Neuron-specific Mafb knockout causes growth retardation accompanied by an impaired growth hormone/insulin-like growth factor I axis.

Mammalian postnatal growth is regulated primarily by the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. MafB is a basic leucine zipper (bZip) transcription factor that has pleiotropic functions. Although MafB plays a critical role in fetal brain development, such as in guidance for hindbrain segmentation, its postnatal role in neurons remains to be elucidated. To investigate this, we used neuron-specific Mafb conditional knockout (cKO) mice. In addition to an approximately 50% neonatal viability, the Mafb cKO mice exhibited growth retardation without apparent signs of low energy intake. Notably, serum IGF-I levels of these mice in the postnatal stage were lower than those of control mice. They seemed to have a neuroendocrine dysregulation, as shown by the upregulation of serum GH levels in the resting state and an inconsistent secretory response of GH upon administration of growth hormone-releasing hormone. These findings reveal that neuronal MafB plays an important role in postnatal development regulated by the GH/IGF-I axis.

Myosin Id localizes in dendritic spines through the tail homology 1 domain.

Dendritic spines, the postsynaptic compartments at excitatory synapses, are capable of changing their shape and size to modulate synaptic transmission. The actin cytoskeleton and a variety of actin-binding proteins play a critical role in the dynamics of dendritic spines. Class I myosins are monomeric motor proteins that move along actin filaments using the energy of ATP hydrolysis. Of these class I myosins, myosin Id, the mammalian homolog of Drosophila Myo31DF, has been reported to be expressed in neurons, whereas its subcellular localization in neurons remained unknown. Here, we investigated the subcellular localization of myosin Id and determined the domain responsible for it. We found that myosin Id is enriched in the F-actin-rich pseudopodia of HEK293T cells and in the dendritic spines of primary hippocampal neurons. Both deletion and substitution of the tail homology 1 (TH1) domain drastically diminishes its colocalization with F-actin. In addition, the mutant form lacking the TH1 domain is less distributed in dendritic spines than is the full-length form. Taken together, our findings reveal that myosin Id localizes in dendritic spines through the TH1 domain.

Transcription factor MafB may play an important role in secondary hyperparathyroidism.

The transcription factor MafB is essential for development of the parathyroid glands, the expression of which persists after morphogenesis and in adult parathyroid glands. However, the function of MafB in adult parathyroid tissue is unclear. To investigate this, we induced chronic kidney disease (CKD) in wild-type and MafB heterozygote (MafB+/-) mice by feeding them an adenine-supplemented diet, leading to secondary hyperparathyroidism. The elevated serum creatinine and blood urea nitrogen levels in heterozygous and wild-type mice fed the adenine-supplemented diet were similar. Interestingly, secondary hyperparathyroidism, characterized by serum parathyroid hormone elevation and enlargement of parathyroid glands, was suppressed in MafB+/- mice fed the adenine-supplemented diet compared to similarly fed wild-type littermates. Quantitative RT-PCR and immunohistochemical analyses showed that the increased expression of parathyroid hormone and cyclin D2 in mice with CKD was suppressed in the parathyroid glands of heterozygous CKD mice. A reporter assay indicated that MafB directly regulated parathyroid hormone and cyclin D2 expression. To exclude an effect of a developmental anomaly in MafB+/- mice, we analyzed MafB tamoxifen-induced global knockout mice. Hypocalcemia-stimulated parathyroid hormone secretion was significantly impaired in MafB knockout mice. RNA-sequencing analysis indicated PTH, Gata3 and Gcm2 depletion in the parathyroid glands of MafB knockout mice. Thus, MafB appears to play an important role in secondary hyperparathyroidism by regulation of parathyroid hormone and cyclin D2 expression. Hence, MafB may represent a new therapeutic target in secondary hyperparathyroidism.

MafB is a critical regulator of complement component C1q.

The transcription factor MafB is expressed by monocytes and macrophages. Efferocytosis (apoptotic cell uptake) by macrophages is important for inhibiting the development of autoimmune diseases, and is greatly reduced in Mafb-deficient macrophages. Here, we show the expression of the first protein in the classical complement pathway C1q is important for mediating efferocytosis and is reduced in Mafb-deficient macrophages. The efferocytosis defect in Mafb-deficient macrophages can be rescued by adding serum from wild-type mice, but not by adding serum from C1q-deficient mice. By hemolysis assay we also show that activation of the classical complement pathway is decreased in Mafb-deficient mice. In addition, MafB overexpression induces C1q-dependent gene expression and signals that induce C1q genes are less effective in the absence of MafB. We also show that Mafb-deficiency can increase glomerular autoimmunity, including anti-nuclear antibody deposition. These results show that MafB is an important regulator of C1q.

MAFB prevents excess inflammation after ischemic stroke by accelerating clearance of damage signals through MSR1.

Damage-associated molecular patterns (DAMPs) trigger sterile inflammation after tissue injury, but the mechanisms underlying the resolution of inflammation remain unclear. In this study, we demonstrate that common DAMPs, such as high-mobility-group box 1 (HMGB1), peroxiredoxins (PRXs), and S100A8 and S100A9, were internalized through the class A scavenger receptors MSR1 and MARCO in vitro. In ischemic murine brain, DAMP internalization was largely mediated by MSR1. An elevation of MSR1 levels in infiltrating myeloid cells observed 3 d after experimental stroke was dependent on the transcription factor Mafb. Combined deficiency for Msr1 and Marco, or for Mafb alone, in infiltrating myeloid cells caused impaired clearance of DAMPs, more severe inflammation, and exacerbated neuronal injury in a murine model of ischemic stroke. The retinoic acid receptor (RAR) agonist Am80 increased the expression of Mafb, thereby enhancing MSR1 expression. Am80 exhibited therapeutic efficacy when administered, even at 24 h after the onset of experimental stroke. Our findings uncover cellular mechanisms contributing to DAMP clearance in resolution of the sterile inflammation triggered by tissue injury.

MafB is required for development of the hindbrain choroid plexus.

The choroid plexus (ChP) is a non-neural epithelial tissue that produces cerebrospinal fluid (CSF). The ChP differentiates from the roof plate, a dorsal midline structure of the neural tube. However, molecular mechanisms underlying ChP development are poorly understood compared to neural development. MafB is a bZip transcription factor that is known to be expressed in the roof plate. Here we investigated the role of MafB in embryonic development of the hindbrain ChP (hChP) using Mafb-deficient mice. Immunohistochemical analyses revealed that MafB is expressed in the roof plate and early hChP epithelial cells but its expression disappears at a later embryonic stage. We also found that the Mafb-deficient hChP exhibits delayed differentiation and results in hypoplasia compared to the wild-type hChP. Furthermore, the Mafb-deficient hChP exhibits increased apoptotic cell death and decreased proliferating cells at E12.5, an early stage of hChP development. Collectively, our findings reveal that MafB play an important role in promoting hChP development during embryogenesis.

MafB antagonizes phenotypic alteration induced by GM-CSF in microglia.

Microglia are tissue-resident macrophages which are distributed throughout the central nervous system (CNS). Recent studies suggest that microglia are a unique myeloid population distinct from peripheral macrophages in terms of origin and gene expression signature. Granulocyte-macrophage colony-stimulating factor (GM-CSF), a pleiotropic cytokine regulating myeloid development, has been shown to stimulate proliferation and alter phenotype of microglia in vitro. However, how its signaling is modulated in microglia is poorly characterized. MafB, a bZip transcriptional factor, is highly expressed in monocyte-macrophage lineage cells including microglia, although its role in microglia is largely unknown. We investigated the crosstalk between GM-CSF signaling and MafB by analyzing primary microglia. We found that Mafb-deficient microglia grew more rapidly than wild-type microglia in response to GM-CSF. Moreover, the expression of genes associated with microglial differentiation was more downregulated in Mafb-deficient microglia cultured with GM-CSF. Notably, such differences between the genotypes were not observed in the presence of M-CSF. In addition, we found that Mafb-deficient microglia cultured with GM-CSF barely extended their membrane protrusions, probably due to abnormal activation of RhoA, a key regulator of cytoskeletal remodeling. Altogether, our study reveals that MafB is a negative regulator of GM-CSF signaling in microglia. These findings could provide new insight into the modulation of cytokine signaling by transcription factors in microglia.

Generation of insulin-producing cells from the mouse liver using ß cell-related gene transfer including Mafa and Mafb.

Recent studies on the large Maf transcription factors have shown that Mafb and Mafa have respective and distinctive roles in ß-cell development and maturation. However, whether this difference in roles is due to the timing of the gene expression (roughly, expression of Mafb before birth and of Mafa after birth) or to the specific function of each gene is unclear. Our aim was to examine the functional differences between these genes that are closely related to ß cells by using an in vivo model of ß-like cell generation. We monitored insulin gene transcription by measuring bioluminescence emitted from the liver of insulin promoter-luciferase transgenic (MIP-Luc-VU) mice. Adenoviral gene transfers of Pdx1/Neurod/Mafa (PDA) and Pdx1/Neurod/Mafb (PDB) combinations generated intense luminescence from the liver that lasted for more than 1 week and peaked at 3 days after transduction. The peak signal intensities of PDA and PDB were comparable. However, PDA but not PDB transfer resulted in significant bioluminescence on day 10, suggesting that Mafa has a more sustainable role in insulin gene activation than does Mafb. Both PDA and PDB transfers ameliorated the glucose levels in a streptozotocin (STZ)-induced diabetic model for up to 21 days and 7 days, respectively. Furthermore, PDA transfer induced several gene expressions necessary for glucose sensing and insulin secretion in the liver on day 9. However, a glucose tolerance test and liver perfusion experiment did not show glucose-stimulated insulin secretion from intrahepatic ß-like cells. These results demonstrate that bioluminescence imaging in MIP-Luc-VU mice provides a noninvasive means of detecting ß-like cells in the liver. They also show that Mafa has a markedly intense and sustained role in ß-like cell production in comparison with Mafb.

Epithelial Pten controls acute lung injury and fibrosis by regulating alveolar epithelial cell integrity.

RATIONALE: Injury to alveolar epithelial cells (AECs) and to their repair process is integral to the pathogenesis of acute lung injury (ALI) and idiopathic pulmonary fibrosis (IPF). The mechanisms regulating the integrity of AECs and their intrinsic regulators remain unclear. Pten is a tumor suppressor, and its function in epithelial cells during organ fibrosis is unknown. OBJECTIVES: To determine the role of epithelial Pten in ALI and lung fibrosis. METHODS: Bronchioalveolar epithelium-specific Pten-deleted SP-C-rtTA/(tetO)(7)-Cre/Pten(Δ/Δ) (SOPten(Δ/Δ)) mice were studied by structural, biochemical, and physiologic analyses and compared with wild-type mice. Further mechanistic studies were performed in vivo, in vitro, and on samples from patients with IPF. MEASUREMENTS AND MAIN RESULTS: SOPten(Δ/Δ) mice demonstrated exacerbated alveolar flooding and subsequent augmented lung scarring with enhanced disassembly of tight junctions (TJs) of AECs and degradation of basement membranes. The induction of dominant negative PTEN gene in lung epithelial cells led to augmented transforming growth factor-1-induced disruptions of TJs. Epithelial-derived myofibroblasts were increased in the epithelium-specific Pten-deficient mice. The lungs of bleomycin-treated SOPten(Δ/Δ) mice showed increased pAkt, pS6K, Snail, and matrix metalloproteinase expressions and decreased claudin-4, E-cadherin, and laminin-ß1 expressions. Akt inactivation definitively saved SOPten(Δ/Δ) mice through amelioration of ALI and retention of AEC integrity. We detected a reduction of PTEN expression and AKT hyperactivation in the AECs of human IPF lungs. CONCLUSIONS: Our results highlight epithelial Pten as a crucial gatekeeper controlling ALI and lung fibrosis by modulating AEC integrity, and the Pten/PI3K/Akt pathway as a potential therapeutic target in these intractable diseases.

A novel nonsense mutation in the DMP1 gene in a Japanese family with autosomal recessive hypophosphatemic rickets.

Autosomal recessive hypophosphatemic rickets (ARHR) is an extremely rare disorder of autosomal recessive inheritance, characterized by hypophosphatemia resulting from renal phosphate wasting. Dentin matrix protein 1 (DMP1), a noncollagenous extracellular protein, plays critical roles in bone mineralization and phosphate homeostasis. Recently, loss-of-function mutations in DMP1 gene have been identified as the molecular cause of ARHR. Here, we describe a Japanese family that includes two ARHR-affected siblings carrying a novel mutation of the DMP1 gene. The patients were a 53-year-old woman and a 50-year-old man with short stature and skeletal deformities who were the offspring of a first-cousin marriage. Biochemical examination revealed hypophosphatemia with renal phosphate excretion and low levels of 1,25(OH)(2)D. Serum calcium, parathyroid hormone, and urinary calcium excretion were within the normal range, leading to clinical diagnosis of ARHR. Sequence analysis of peripheral leukocytes from the patients revealed that they carried a novel homozygous nonsense mutation in the DMP1 gene (98G>A, W33X), which leads to a truncated DMP protein with no putative biological function. Unaffected family members were heterozygous for the mutation. This is the first report of a Japanese family with ARHR carrying a novel mutation of the DMP1 gene.