Clinical Results of a Trifocal Toric Intraocular Lens Using the Holladay Total Surgically Induced Astigmatism Formula for Correcting Low Corneal Astigmatism in Japanese Patients.

Purpose: To evaluate the effectiveness and safety of the AcrySof IQ PanOptix toric intraocular lens (IOL) with cylinder power of 1.0 D (TFNT20) in a Japanese population with low corneal astigmatism and compare with historical control data for nontoric IOLs. Setting: Tokyo Dental College Suidobashi Hospital, Tokyo, Japan. Design: Prospective, single-center study. Methods: Patients ≥20 years old received TFNT20 IOL in at least 1 eye based on Alcon Toric calculator (Holladay Total surgically induced astigmatism). Effectiveness endpoints included the percentage of eyes with refractive cylinder ≤0.25 D at 30-60 days after surgery, which was compared with a historical control threshold rate of 29.2% for nontoric IOLs and refractive cylinder ≤0.50 D. Monocular uncorrected distance visual acuity (UDVA; 5 m), uncorrected intermediate visual acuity (UIVA; 60 cm), uncorrected near visual acuity (UNVA; 40 cm), and adverse events were evaluated. Results: Of 41 eyes implanted with TFNT20 IOLs, 37 eyes (90%) achieved refractive cylinder ≤0.25 D at 30-60 days after surgery, demonstrating the superiority of TFNT20 compared with historical data (P<0.0001). Refractive cylinder of ≤0.50 D was achieved by 41 eyes (100%). At 30-60 days, mean ± SD monocular CDVA was -0.15 ± 0.07 logMAR, UDVA was -0.09 ± 0.09 logMAR, UIVA was -0.00 ± 0.07 logMAR, and UNVA was 0.03 ± 0.07 logMAR. Six eyes (15%) had elevated postoperative intraocular pressure, which returned to normal and was not device-related. Conclusion: TFNT20 IOLs successfully reduced postoperative refractive cylinder and provided good distance, intermediate, and near uncorrected VAs in Japanese patients with low corneal astigmatism.

Temperature-controlled porcine eye holder for observing intraocular temperature during cataract surgery.

During cataract surgery, the intraocular temperature changes when irrigating low-temperature fluid and ophthalmic viscosurgical devices (OVDs) are inserted in the anterior chamber, and such a temperature variation affects the unfolding of the intraocular lens (IOL). A porcine eye holder was developed for simulating temperature conditions in clinical surgery by maintaining the ocular temperature close to the body temperature. An aluminum holder was designed to fit porcine eyes and maintain the ocular temperature at approximately 36 °C, while surgery was performed at a room temperature of 20 °C. Intraocular temperature was monitored using a thermocouple sensor placed close to the posterior capsule in the vitreous cavity. Temperatures and microscopic image of the anterior chamber were simultaneously recorded. With the use of the eye holder system, the intraocular temperature unstable during surgery was observed, and there were significant reductions during hydrodissection, irrigation and aspiration, OVD insertion in the capsule, and OVD removal after IOL implantation.

Efficacy of Femtosecond Laser-Assisted Capsulotomy: Experimental Evaluation Using the Zonular Dehiscence Model.

Purpose: The purpose of this study was to evaluate experimentally the efficacy of femtosecond laser (FL)-assisted capsulotomy using an eye model with different degrees of zonular dehiscence (ZD). Methods: An eye model with ZD was created by removing the total iris and including the planned range of the ZD in porcine and human cadaver eyes. FL-assisted capsulotomies (laser group) and manual capsulotomies (manual group) were created for the eye model with 0, 45, 135, 180, and 270 degrees of ZD. The continuity, mean diameter, ellipticity, and decentration of the capsulotomy were evaluated using the captured images. The same evaluation of FL-assisted capsulotomies was done for five human cadaver eyes with 180 degrees of ZD. Results: In the laser group, no differences were seen in the mean diameter, ellipticity, and decentration, although the manual group resulted in significantly larger, ovalized, and decentered capsulotomies with different degrees of ZD (P < 0.001, P < 0.001, and P = 0.0317, respectively). Continuous capsulotomies or capsulotomies with microadhesions were obtained up to 180 degrees of ZD, and incomplete treatment areas were seen in eyes with 270 degrees of ZD. Capsulotomy of the human cadaver eyes with 180 degrees of ZD showed similar results to those of porcine eyes. Conclusions: In this experimental study, FL-assisted capsulotomy showed favorable results in eyes with between 0 and 180 degrees of ZD compared to conventional manual capsulotomy. Translational Relevance: Our experimental model can simulate the capsulotomy in cases with ZD, the results are useful when determining the indication for FL-assisted capsulotomies.

Evaluation of Lens Capsule Stability Using Capsular Tension Ring, Iris Retractor, and Capsule Expander Using a Porcine Model With Zonular Dehiscence.

Purpose: We evaluate the efficacy of capsular tension rings (CTRs), iris retractors (IRs), and capsule expanders (CEs) in stabilizing the lens capsule under different degrees of zonular dehiscence using a porcine model. Methods: We developed an experimental model that can be used to observe the dynamics of lens capsules with different degrees of zonular dehiscence during phacoemulsification and aspiration (PEA). PEA was performed without any aid (control) and with devices. A CTR was used for a dehiscence of 30°, 45°, 60°, 90°, 120°, 150°, and 180° and one to four IRs or one to three CEs were used for a dehiscence of 90°, 120°, and 180°. The retention rate, calculated as the area of the capsular bag during PEA divided by the area before zonular dissection, and the number of lens fragments dropped into the vitreous cavity during PEA were examined and compared among the control and experimental groups. Results: The retention rate increased significantly with the use of devices compared to the control (P < 0.05). The number of dropped lens fragments decreased by one or less with the use of CTR, one IR, or one CE for 90°, two IRs, or one or two CEs for 120°, and three or four IRs, or two or three CEs for 180° of zonular dehiscence. Conclusions: The experimental porcine eye model with zonular dehiscence makes it possible to observe the entire configuration of the lens capsule, and demonstrates differences in the efficacy of capsular bag retention with CTR, IR, and CE.

Functional Role of Lacrimal Gland Fibroblasts in a Mouse Model of Chronic Graft-Versus-Host Disease.

PURPOSE: This study aimed to clarify the mechanisms and assess the characteristics of the chronic graft-versus-host disease (cGVHD) fibrosis in the lacrimal gland (LG) of mice. METHODS: Histopathology of LG tissues was examined by immunohistochemistry and electron microscopy. Cultured fibroblasts derived from the LG were analyzed by phase-contrast microscopy, immunocytochemistry, flow cytometry, proliferation assay, and invasion and migration assays. RESULTS: Cultured murine LG fibroblasts in cGVHD were spindle-shaped and relatively small, whereas those from syngeneic controls were polygon-shaped and relatively large. Flow cytometric analysis showed that the LG fibroblasts in cGVHD had elevated HSP47 levels. The LG fibroblasts in cGVHD also showed increased expression of major histocompatibility complex class II. Furthermore, the proportion of Sca-1PDGFR-α cells among the LG fibroblasts in cGVHD was considerably increased compared with controls. Cell counting kit-8 assays demonstrated that the LG fibroblasts in cGVHD were highly proliferative, and cell invasion assays indicated that they were highly invasive with high migration ability. CONCLUSIONS: LG fibroblasts in cGVHD can be aberrantly activated, thereby eliciting fibrosis by producing excessive extracellular matrix, leading to LG dysfunction in mice.

Objective classification of zonular weakness based on lens movement at the start of capsulorhexis.

PURPOSE: To quantify zonular weakness based on lens movement at the start of continuous curvilinear capsulorhexis (CCC) and establish a classification system for it. SETTING: Kozawa Eye Hospital and Diabetes Center, Mito, Japan. DESIGN: Retrospective interventional case series. METHODS: We examined 402 consecutive eyes of 316 patients who underwent CCC, phacoemulsification and aspiration (PEA), and intraocular lens (IOL) implantation. The movement of the lens capsule was measured using images from video recordings of the CCC procedure. Zonular weakness was classified based on the shifted distance: Grade I, less than 0.20 mm; Grade II, 0.20-0.39 mm; and Grade III, greater than 0.40 mm. For each of these grades, we examined the use of the capsule stabilization device during PEA, the surgical procedure for lens removal, and IOL fixation. RESULTS: We classified 276 eyes (68.6%) as Grade I, 102 eyes (25.4%) as Grade II, and 24 eyes (6.0%) as Grade III. As the grade increased, the use of the capsule stabilization device in PEA and scleral suture fixation of IOL increased. CONCLUSIONS: Zonular weakness was quantified by measuring the movement of the lens capsule. An objective classification of zonular weakness based on lens movement may be useful for selecting the appropriate device and procedure during cataract surgery.

Safety and Efficacy of Two Trabecular Micro-Bypass Stents as the Sole Procedure in Japanese Patients with Medically Uncontrolled Primary Open-Angle Glaucoma: A Pilot Case Series.

Purpose. To evaluate efficacy and safety of a trabecular micro-bypass stent system when used as the sole procedure in Japanese patients with medically uncontrolled primary open-angle glaucoma (POAG). Design. Prospective nonrandomized interventional pilot study. Methods. Ten eyes of 10 Japanese patients with medically uncontrolled POAG taking three ocular hypotensive medications were treated using only the implantation of two iStent trabecular micro-bypass stents. Each patient continued to take the same ocular hypotensive medications used preoperatively throughout the study. Intraocular pressure (IOP) and endothelial cell density (ECD) were determined at baseline and at 1, 3, and 6 months postoperatively. Best-corrected visual acuity (BCVA) was measured at baseline and 6 months after surgery. Results. Mean IOP was 22.0 ± 3.0 mmHg at baseline and 16.9 ± 3.6 mmHg at 6 months, which represented a mean reduction of 5.1 mmHg or 23.2%. No significant changes were observed in the ECD and BCVA. Complications that occurred during the early postoperative period included hyphema, peripheral anterior synechiae, and occlusion of the stent by the iris. Conclusion. Implantation of two trabecular micro-bypass stents as the sole procedure in Japanese POAG patients effectively reduced IOP and exhibited a favorable safety profile. Clinical Trials Registration number is UMIN000004002.

MHC-compatible bone marrow stromal/stem cells trigger fibrosis by activating host T cells in a scleroderma mouse model.

Fibrosis of organs is observed in systemic autoimmune disease. Using a scleroderma mouse, we show that transplantation of MHC compatible, minor antigen mismatched bone marrow stromal/stem cells (BMSCs) play a role in the pathogenesis of fibrosis. Removal of donor BMSCs rescued mice from disease. Freshly isolated PDGFRα(+) Sca-1(+) BMSCs expressed MHC class II following transplantation and activated host T cells. A decrease in FOXP3(+) CD25(+) Treg population was observed. T cells proliferated and secreted IL-6 when stimulated with mismatched BMSCs in vitro. Donor T cells were not involved in fibrosis because transplanting T cell-deficient RAG2 knock out mice bone marrow still caused disease. Once initially triggered by mismatched BMSCs, the autoimmune phenotype was not donor BMSC dependent as the phenotype was observed after effector T cells were adoptively transferred into naïve syngeneic mice. Our data suggest that minor antigen mismatched BMSCs trigger systemic fibrosis in this autoimmune scleroderma model.

Tissue Renin-Angiotensin System in Lacrimal Gland Fibrosis in a Murine Model of Chronic Graft-Versus-Host Disease.

Chronic graft-versus-host disease (cGVHD) is a serious complication known to occur after allogeneic hematopoietic stem cell transplantation. Clinical manifestation includes inflammation and fibrosis. Many peripheral tissues are capable of generating the renin-angiotensin system (RAS) components, called the tissue RAS, and have various roles in tissue-specific physiological and pathological functions of inflammation and fibrosis. This article reviews evidence for the presence of the tissue RAS in the normal mouse lacrimal gland, the role of the tissue RAS in the fibrotic pathogenesis of the lacrimal gland in cGVHD model mice, and the effect of angiotensin II receptor blockers on preventing lacrimal gland fibrosis. B10.D2→BALB/c (H-2d) major histocompatibility complex-compatible, minor histocompatibility antigen-mismatched mice were used as a model of cGVHD, which reflects the clinical and pathological symptoms of human cGVHD. We also describe the localization of RAS components in the normal mouse lacrimal gland. In addition, we characterize the inflammatory and fibrotic changes of the lacrimal gland in cGVHD model mice, demonstrate that fibroblasts strongly express angiotensin II, angiotensin II type 1 receptor (AT1R), and angiotensin II type 2 receptor, and show that mRNA expression of angiotensinogen increased in the lacrimal gland of cGVHD model mice. Inhibitory experiments revealed that lacrimal gland fibrosis was suppressed in mice treated with an AT1R blocker, but not in mice treated with an angiotensin II type 2 receptor blocker. Hence, we conclude that the tissue RAS is involved in the fibrotic pathogenesis of the lacrimal gland and that AT1R blockers have a therapeutic effect on lacrimal gland fibrosis in cGVHD model mice.

Long-term rebamipide and diquafosol in two cases of immune-mediated dry eye.

PURPOSE: Two new drugs with mucin-inducing and secretion-promotive effects, rebamipide and diquafosol, were recently approved as topical dry-eye treatments. We report two cases in which the long-term use of mucin-inducing eye drops improved chronic ocular graft-versus-host disease (cGVHD)-related dry eye and ocular cicatricial pemphigoid (OCP)-like disease. CASE REPORTS: Case 1. A 61-year-old woman had cGVHD-related dry eye that resisted traditional medications. Next, we use topical diquafosol in addition to conventional treatments. The patient used diquafosol for 6 months without experiencing any side effects. The symptoms, including dry-eye sensation, ocular pain, foreign body sensation, and photophobia, as well as ocular surface findings including fluorescein and rose bengal scores and tear break-up time (TBUT), partly improved. To further improve the clinical signs and symptoms and decrease chronic inflammation, rebamipide was added to diquafosol. The symptoms, TBUT, and fluorescein and rose bengal scores markedly improved after long-term dual treatment without any side effects for 6 months. Case 2. A 77-year-old woman had OCP-like disease with dry eye. The patient did not improve using the currently available conventional treatments. Next, we use topical rebamipide in addition to conventional treatments. Symptoms including asthenopia, dry-eye sensation, ocular pain, and dull sensation, as well as fluorescein and rose bengal scores and TBUT, partly improved. Specifically, functional visual acuity was markedly improved after commencement of rebamipide. To further improve the clinical signs and symptoms and increase tear film stability and tear film volume, diquafosol was added to rebamipide. The combination of diquafosol and rebamipide worked for the patient. Improvements were seen in several symptoms, fluorescein and rose bengal scores, Schirmer test value, and TBUT without any side effects for 12 months. CONCLUSIONS: Long-term treatment with topical rebamipide and diquafosol can improve dry eye in patients with cGVHD or OCP-like disease.

Possible involvement of epithelial-mesenchymal transition in fibrosis associated with IgG4-related Mikulicz's disease.

OBJECTIVE: Immunoglobulin G4 (IgG4)-related Mikulicz's disease (MD) is a fibrosis-associated inflammatory disease, often accompanied by lacrimal gland swelling. Although much attention has been paid to the inflammatory aspects of this disease, the mechanisms of the fibrotic processes are still unclear. We focused on the fibrotic changes occurring in the lacrimal glands of IgG4-related MD patients, by examining molecules involved in the epithelial-mesenchymal transition (EMT). METHODS: Lacrimal gland tissue specimens were obtained from 3 IgG4-related MD patients and 3 control patients with Sjögren's syndrome (SS). The glands were examined by immunohistochemistry and transmission electron microscopy. RESULTS: Storiform fibrosis, a characteristic of IgG4-related MD, was observed in the lacrimal glands of IgG4-related MD, but rarely in those of SS. Reduced E-cadherin expression, increased phalloidin-stained filamentous actin, and increased α-smooth muscle actin, snail, and heat-shock protein 47 levels were observed in the lacrimal glands of IgG4-related MD compared with those of SS. Transmission electron microscopy revealed an abnormal periodicity of collagen bundles, and basal membrane thickening in the IgG4-related MD compared with that in the SS tissues. CONCLUSION: EMT-like changes were frequently observed in the lacrimal gland epithelia from patients with IgG4-related MD. Thus, EMT may be involved in the pathology of IgG4-related MD fibrosis.

Grading criteria for chronic ocular graft-versus-host disease: comparing the NIH eye score, Japanese dry eye score, and DEWS 2007 score.

Ocular graft-versus-host disease (GVHD) is a common complication after hematopoietic stem cell transplantation (HSCT). Here we compared the diagnostic rates of ocular GVHD, including its severity, prognosis and the agreement, obtained using three grading scales: the National Institutes of Health (NIH) eye score, Japanese dry eye score, and dry eye workshop score, by retrospectively reviewing the records of 82 patients who underwent HSCT. Tear dynamics and ocular surface assessments made 6-9 months after HSCT were used to determine ocular GVHD severity with the three scales. By the three scales, ocular GVHD was diagnosed in 56 patients (68.3%), 51 patients (62.2%), and 52 patients (63.4%), respectively. The Kappa coefficient was calculated to determine the agreement between scales for diagnosing ocular GVHD. The severity progression within two years after onset was also assessed by tear dynamics and ocular surface examination. The patients were categorized as no change, improved, or progressive. The three grading scales showed good agreement (Kappa = 0.87 to 0.97) in diagnosing patients with ocular GVHD, and the scores by all three were significantly associated with the patients' prognosis (p < 0.01). We recommend that multi-center research is needed for further validation and investigation.

Angiotensin II type 1 receptor antagonist attenuates lacrimal gland, lung, and liver fibrosis in a murine model of chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD), a serious complication following allogeneic HSCT (hematopoietic stem cell transplantation), is characterized by systemic fibrosis. The tissue renin-angiotensin system (RAS) is involved in the fibrotic pathogenesis, and an angiotensin II type 1 receptor (AT1R) antagonist can attenuate fibrosis. Tissue RAS is present in the lacrimal gland, lung, and liver, and is known to be involved in the fibrotic pathogenesis of the lung and liver. This study aimed to determine whether RAS is involved in fibrotic pathogenesis in the lacrimal gland and to assess the effect of an AT1R antagonist on preventing lacrimal gland, lung, and liver fibrosis in cGVHD model mice. We used the B10.D2→BALB/c (H-2(d)) MHC-compatible, multiple minor histocompatibility antigen-mismatched model, which reflects clinical and pathological symptoms of human cGVHD. First, we examined the localization and expression of RAS components in the lacrimal glands using immunohistochemistry and quantitative real-time polymerase chain reaction (PCR). Next, we administered an AT1R antagonist (valsartan; 10 mg/kg) or angiotensin II type 2 receptor (AT2R) antagonist (PD123319; 10 mg/kg) intraperitoneally into cGVHD model mice and assessed the fibrotic change in the lacrimal gland, lung, and liver. We demonstrated that fibroblasts expressed angiotensin II, AT1R, and AT2R, and that the mRNA expression of angiotensinogen was greater in the lacrimal glands of cGVHD model mice than in controls generated by syngeneic-HSCT. The inhibition experiment revealed that fibrosis of the lacrimal gland, lung, and liver was suppressed in mice treated with the AT1R antagonist, but not the AT2R antagonist. We conclude that RAS is involved in fibrotic pathogenesis in the lacrimal gland and that AT1R antagonist has a therapeutic effect on lacrimal gland, lung, and liver fibrosis in cGVHD model mice. Our findings point to AT1R antagonist as a possible target for therapeutic intervention in cGVHD.

Presence and physiologic function of the renin-angiotensin system in mouse lacrimal gland.

PURPOSE: To investigate the expression, localization, and physiologic function of renin-angiotensin system (RAS) components in the mouse lacrimal gland. METHODS: Lacrimal glands and cultured lacrimal gland fibroblasts from wild-type (WT) BALB/c (H-2(d)) mice were used. Reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry were used to determine the expression and localization of the RAS components, prorenin/renin, angiotensin-converting enzyme (ACE), angiotensin II, angiotensin II type 1 receptor (AT1R), and angiotensin II type 2 receptor (AT2R) in the normal mouse lacrimal gland. To examine the change in tear secretion, mice received ARB (AT1R blocker) or AT2R antagonist. Tear secretion was assessed by cotton thread test before and after drug administration. RESULTS: The mRNAs coding for angiotensinogen, prorenin, ACE, and both AT1R and AT2R were found in normal lacrimal gland tissue and cultured lacrimal gland fibroblasts. Prorenin/renin and ACE were identified in myoepithelial cells around ducts and acini and in blood vessels. Angiotensin II, AT1R, and AT2R were observed in the ducts and interstitial fibroblasts. AT1R and AT2R were also localized in blood vessels. All the cultured lacrimal gland fibroblasts expressed angiotensin II, AT1R, and AT2R. Tear secretion increased in mice that received ARB. CONCLUSIONS: The results are consistent with the hypothesis that a tissue-specific RAS is present in the lacrimal gland, and suggest that fibroblasts are one of the cell types playing a role in the tissue RAS. Tissue RAS might be involved in tissue function of regulating tear secretion in the lacrimal gland.

Morphologic evaluation of meibomian glands in chronic graft-versus-host disease using in vivo laser confocal microscopy.

PURPOSE: To evaluate the morphological changes of the meibomian glands (MGs) using in vivo laser confocal microscopy (CM) in dry eye (DE) patients with chronic graft-versus-host disease (cGVHD). METHODS: Seventeen eyes from 9 patients with a diagnosis of DE associated with cGVHD (DE/cGVHD group; 6 males, 3 females; median 50.5 years) and 16 eyes of 8 hematopoietic stem cell transplantation (HSCT) recipients without DE (non-DE/non-cGVHD group; 5 males, 3 females; median 47.0 years) were enrolled. CM was used to investigate the MG and MG acinar unit density (MGAUD), MG acinar longest diameter (MGALD), MG acinar shortest diameter (MGASD), and the fibrosis grade. Clinical findings of the lid margin were obtained. Tear dynamics, ocular surface vital staining, meibography, and MG expressibility were also examined. Data were compared between the 2 groups using the unpaired t and Mann-Whitney tests. RESULTS: The mean MGAUD value was significantly lower in the DE/cGVHD group than in the non-DE/non-cGVHD group (p=0.01, 57.8±38.3 glands/mm(2), 88.8±26.6 glands/mm(2), respectively), and the mean MGALD and MGASD were significantly shorter in the DE/cGVHD group than in the non-DE/non-cGVHD group (p=0.0018, 37.3±24.4 µm and 60.4±11.8 µm, p=0.0106, 17.7±11.8 µm and 26.6±6.03 µm, respectively). The mean fibrosis grade was significantly higher in the DE/cGVHD group than the non-DE/non-cGVHD group (p<0.0001, 1.39±0.71 grade, 0.06±0.25 grade, respectively). Clinical findings in the lid margin, tear dynamics, and ocular surface findings were significantly worse in the DE/cGVHD group than in the non-DE/non-cGVHD group. CONCLUSIONS: CM clearly depicted the morphological changes of the MG in the DE/cGVHD group, and revealed the severity of the meibomian gland dysfunction. Patients with severe DE after HSCT showed atrophic MG and excessive fibrosis.

Repositioning and scleral fixation of subluxated lenses using a T-shaped capsule stabilization hook.

We describe a T-shaped capsule stabilization hook (modified capsule expander [M-CE]) used for repositioning and scleral fixation of the lens capsule of subluxated lenses. The 5-0 polypropylene device is flexible and attached to a curved needle. The contact portion is bent at 1.25 mm, and the end bifurcates in a T configuration to form a 3.75 mm footpad from which the capsular bag can be suspended. Modified capsule expanders were implanted in 4 eyes of 4 patients with subluxated cataractous lenses and provided excellent support and centration of the intraocular lens (IOL)-capsular bag complex. The IOLs remained well centered and stable. The corrected distance visual acuity improved to at least 20/20 in all patients after surgery. Thus, M-CEs were effective in fixating the lens capsule to the sclera in patients with significant zonular weakness.

Foldable acrylic intraocular lens with distended haptics for transscleral fixation.

We describe a foldable acrylic intraocular lens (IOL) with distended haptics suitable for transscleral fixation and the insertion procedure. The IOL has an acrylic optic and poly(methyl methacrylate) haptics with a microscopic indentation 1.3 mm from the tip. Transscleral fixation of the IOL was performed through corneal incisions in 22 eyes, and surgical results were retrospectively assessed. The IOL was sutured firmly in position using the cow-hitch procedure, and there was no suture loosening to the distended haptic. The IOL design provided suitable fixation and may be indicated for bag fixation as well as transscleral fixation.

Impact of transgenic overexpression of SH2-containing inositol 5'-phosphatase 2 on glucose metabolism and insulin signaling in mice.

SH2-containing inositol 5'-phosphatase 2 (SHIP2) is a 5'-lipid phosphatase hydrolyzing the phosphatidylinositol (PI) 3-kinase product PI(3,4,5)P(3) to PI(3,4)P(2) in the regulation of insulin signaling, and is shown to be increased in peripheral tissues of diabetic C57BL/KSJ-db/db mice. To clarify the impact of SHIP2 in the pathogenesis of insulin resistance with type 2 diabetes, we generated transgenic mice overexpressing SHIP2. The body weight of transgenic mice increased by 5.0% (P < 0.05) compared with control wild-type littermates on a normal chow diet, but not on a high-fat diet. Glucose tolerance and insulin sensitivity were mildly but significantly impaired in the transgenic mice only when maintained on the normal chow diet, as shown by 1.2-fold increase in glucose area under the curve over control levels at 9 months old. Insulin-induced phosphorylation of Akt was decreased in the SHIP2-overexpressing fat, skeletal muscle, and liver. In addition, the expression of hepatic mRNAs for glucose-6-phosphatase and phosphoenolpyruvate carboxykinase was increased, that for sterol regulatory element-binding protein 1 was unchanged, and that for glucokinase was decreased. Consistently, hepatic glycogen content was reduced in the 9-month-old transgenic mice. Structure and insulin content were histologically normal in the pancreatic islets of transgenic mice. These results indicate that increased abundance of SHIP2 in vivo contributes, at least in part, to the impairment of glucose metabolism and insulin sensitivity on a normal chow diet, possibly by attenuating peripheral insulin signaling and by altering hepatic gene expression for glucose homeostasis.

Impact of SRC homology 2-containing inositol 5'-phosphatase 2 gene polymorphisms detected in a Japanese population on insulin signaling.

Src homology 2-containing 5'-inositol phosphatase 2 (SHIP2) is known to be one of lipid phosphatases converting PI(3,4,5)P3 to PI(3,4)P2 in the negative regulation of insulin signaling with the fundamental impact on the state of insulin resistance. To clarify the possible involvement of SHIP2 in the pathogenesis of human type 2 diabetes, we examined the relation of human SHIP2 gene polymorphisms to type 2 diabetes in a Japanese population. We identified 10 polymorphisms including four missense mutations. Among them, single nucleotide polymorphism (SNP)3 (L632I) was located in the 5'-phosphatase catalytic region, and SNP5 (N982S) was adjacent to the phosphotyrosine binding domain binding consensus motif in the C terminus. SNP3 was found more frequently in control subjects than in type 2 diabetic patients, suggesting that this mutation might protect from insulin resistance. Transfection study showed that expression of SNP3-SHIP2 inhibited insulin-induced PI(3,4,5)P3 production and Akt2 phosphorylation less potently than expression of wild-type SHIP2 in CHO-IR cells. Insulin-induced tyrosine phosphorylation of SNP5-SHIP2 was decreased compared with that of wild-type SHIP2, resulting in increased Shc/Grb2 association and MAPK activation. These results indicate that the polymorphisms of SHIP2 are implicated, at least in part, in type 2 diabetes, possibly by affecting the metabolic and/or mitogenic insulin signaling in the Japanese population.