A pancreatic cancer mouse model with human immunity

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a tumor immune microenvironment (TIME) that promotes resistance to immunotherapy. A preclinical model system that facilitates studies of the TIME and its impact on the responsiveness of human PDAC to immunotherapies remains an unmet need. We report a novel mouse model, which develops metastatic human PDAC that becomes infiltrated by human immune cells recapitulating the TIME of human PDAC. The model may serve as a versatile platform to study the nature of human PDAC TIME and its response to various treatments.

Tumor-resident regulatory T cells in pancreatic cancer express the αvβ5 integrin as a targetable activation marker

Pancreatic ductal adenocarcinoma (PDAC) has abundant immunosuppressive regulatory T cells (Tregs), which contribute to a microenvironment resistant to immunotherapy. Here, we report that Tregs in the PDAC tissue, but not those in the spleen, express the αvβ5 integrin in addition to neuropilin-1 (NRP-1), which makes them susceptible to the iRGD tumor-penetrating peptide, which targets cells positive for αv integrin- and NRP-1. As a result, long-term treatment of PDAC mice with iRGD leads to tumor-specific depletion of Tregs and improved efficacy of immune checkpoint blockade. αvβ5 integrin ⁺ Tregs are induced from both naïve CD4 ⁺ T cells and natural Tregs upon T cell receptor stimulation, and represent a highly immunosuppressive subpopulation of CCR8 ⁺ Tregs. This study identifies the αvβ5 integrin as a marker for activated tumor-resident Tregs, which can be targeted to achieve tumor-specific Treg depletion and thereby augment anti-tumor immunity for PDAC therapy.

Abstract 385: iRGD mediated delivery of neoantigens to enable immunotherapy in integrin b5-rich tumors

Pancreatic duct adenocarcinomas are known for their abundant desmoplastic stroma that acts as a barrier for drug penetration and reduces treatment efficacy. iRGD is a tumor-penetrating peptide that initially targets αv integrins expressed on tumor vasculature with its RGD motif and then is proteolytically processed to expose a CendR motif (R/KXXR/K) that interacts with neuropilin-1 (NRP-1), leading to extravasation. We investigated the mechanism of iRGD tissue penetration and found that iRGD initially targets Carcinoma Associated Fibroblasts (CAFs) and then spreads to the tumor cells in a time dependent manner. CAF targeting was dependent on integrin β5 expression and CAFs induced upregulation of integrin β5 in the adjacent tumor cells in a TGF- β dependent manner. Drugs conjugated or co-administered with iRGD can penetrate deep into tumor tissue, significantly increasing the efficacy of chemotherapeutic agents in a variety of solid tumors. Our recent data shows that KrasLSL-G12D/+ Trp53LSL-R172H/+ Pdx1-Cre (KPC) mice treated with iRGD co-administered with Gemcitabine increased survival compared to drug alone. In addition, we are using iRGD to deliver neoantigens to breast and pancreatic cancers to enable immunotherapy. These tumors have a low mutational burden and a very immunosuppressive microenvironment, rendering them resistant to such therapies. We have used iRGD, to deliver the ovalbumin 257-264 (OVAI) peptide to triple negative breast tumors, followed by adoptive T cell transfer of OT1 CD8 T cells, in order to elicit an antitumor immune response. Our preliminary data showed tumor regression in 70%, and complete response in 42% of the mice treated with iRGD plus OVA1. We are now working on adapting this strategy to pancreatic cancer.

Citation Format: Tatiana Hurtado de Mendoza, Evangeline S. Mose, Gregory P. Botta, Gary B. Braun, Venkata R. Kotamraju, Randall P. French, Kodai Suzuki, Norio Miyamura, Siming Sun, Jay Patel, Tambet Teesalu, Erkki Ruoslahti, Kazuki N. Sugahara, Andrew M. Lowy. iRGD mediated delivery of neoantigens to enable immunotherapy in integrin b5-rich tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 385.

Characterization of mouse embryonic fibroblasts derived from Rassf6 knockout mice shows the implication of Rassf6 in the regulation of NF-κB signaling

RASSF6 is a member of the tumor suppressor Ras association domain family (RASSF) proteins. We have reported using human cancer cell lines that RASSF6 induces apoptosis and cell cycle arrest via p53 and plays tumor suppressive roles. In this study, we generated Rassf6 knockout mice by CRISPR/Cas technology. Contrary to our expectation, Rassf6 knockout mice were apparently healthy. However, Rassf6-null mouse embryonic fibroblasts (MEF) were resistant against ultraviolet (UV)-induced apoptosis/cell cycle arrest and senescence. UV-induced p53-target gene expression was compromised, and DNA repair was delayed in Rassf6-null MEF. More importantly, KRAS active mutant promoted the colony formation of Rassf6-null MEF but not the wild-type MEF. RNA sequencing analysis showed that NF-κB signaling was enhanced in Rassf6-null MEF. Consistently, 7,12-dimethylbenz(a)anthracene (DMBA) induced skin inflammation in Rassf6 knockout mice more remarkably than in the wild-type mice. Hence, Rassf6 deficiency not only compromises p53 function but also enhances NF-κB signaling to lead to oncogenesis.

Tumor-penetrating therapy for β5 integrin-rich pancreas cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterized by marked desmoplasia and drug resistance due, in part, to poor drug delivery to extravascular tumor tissue. Here, we report that carcinoma-associated fibroblasts (CAFs) induce β5 integrin expression in tumor cells in a TGF-β dependent manner, making them an efficient drug delivery target for the tumor-penetrating peptide iRGD. The capacity of iRGD to deliver conjugated and co-injected payloads is markedly suppressed when β5 integrins are knocked out in the tumor cells. Of note, β5 integrin knock-out in tumor cells leads to reduced disease burden and prolonged survival of the mice, demonstrating its contribution to PDAC progression. iRGD significantly potentiates co-injected chemotherapy in KPC mice with high β5 integrin expression and may be a powerful strategy to target an aggressive PDAC subpopulation.

Effect of a neural relay on liver regeneration in mice: activation of serotonin release from the gastrointestinal tract

The development of therapeutic options to promote hepatic regeneration following severe liver injury is essential. While humoral factors have been reported as mechanisms of liver regeneration, the contributions of interorgan communication to liver regeneration have not been reported. In this study, we examined the effect of a neural relay on liver regeneration via activation of serotonin release from the gastrointestinal (GI) tract. Our results demonstrated that the afferent visceral nerve from the liver activates the efferent vagus nerve from the brain, leading to activation of serotonin release from the GI tract and contributing to liver regeneration. While it is difficult to apply these results directly to human health, we believe that this study may represent a step toward developing essential therapeutics to promote liver regeneration.

Endosomal phosphatidylserine is critical for the YAP signalling pathway in proliferating cells

Yes-associated protein (YAP) is a recently discovered growth-promoting transcription coactivator that has been shown to regulate the malignancy of various cancers. How YAP is regulated is not fully understood. Here, we show that one of the factors regulating YAP is phosphatidylserine (PS) in recycling endosomes (REs). We use proximity biotinylation to find proteins proximal to PS. Among these proteins are YAP and multiple proteins related to YAP signalling. Knockdown of ATP8A1 (an RE PS-flippase) or evectin-2 (an RE-resident protein) and masking of PS in the cytoplasmic leaflet of membranes, all suppress nuclear localization of YAP and YAP-dependent transcription. ATP8A1 knockdown increases the phosphorylated (activated) form of Lats1 that phosphorylates and inactivates YAP, whereas evectin-2 knockdown reduces the ubiquitination and increased the level of Lats1. The proliferation of YAP-dependent metastatic cancer cells is suppressed by knockdown of ATP8A1 or evectin-2. These results suggest a link between a membrane phospholipid and cell proliferation.

Age-dependent motor dysfunction due to neuron-specific disruption of stress-activated protein kinase MKK7

c-Jun N-terminal kinase (JNK) is a member of the mitogen-activated protein kinase family and controls various physiological processes including apoptosis. A specific upstream activator of JNKs is the mitogen-activated protein kinase kinase 7 (MKK7). It has been reported that MKK7-JNK signaling plays an important regulatory role in neural development, however, post-developmental functions in the nervous system have not been elucidated. In this study, we generated neuron-specific Mkk7 knockout mice (MKK7 cKO), which impaired constitutive activation of JNK in the nervous system. MKK7 cKO mice displayed impaired circadian behavioral rhythms and decreased locomotor activity. MKK7 cKO mice at 8 months showed motor dysfunctions such as weakness of hind-limb and gait abnormality in an age-dependent manner. Axonal degeneration in the spinal cord and muscle atrophy were also observed, along with accumulation of the axonal transport proteins JNK-interacting protein 1 and amyloid beta precursor protein in the brains and spinal cords of MKK7 cKO mice. Thus, the MKK7-JNK signaling pathway plays important roles in regulating circadian rhythms and neuronal maintenance in the adult nervous system.

The mevalonate pathway regulates primitive streak formation via protein farnesylation

The primitive streak in peri-implantation embryos forms the mesoderm and endoderm and controls cell differentiation. The metabolic cues regulating primitive streak formation remain largely unknown. Here we utilised a mouse embryonic stem (ES) cell differentiation system and a library of well-characterised drugs to identify these metabolic factors. We found that statins, which inhibit the mevalonate metabolic pathway, suppressed primitive streak formation in vitro and in vivo. Using metabolomics and pharmacologic approaches we identified the downstream signalling pathway of mevalonate and revealed that primitive streak formation requires protein farnesylation but not cholesterol synthesis. A tagging-via-substrate approach revealed that nuclear lamin B1 and small G proteins were farnesylated in embryoid bodies and important for primitive streak gene expression. In conclusion, protein farnesylation driven by the mevalonate pathway is a metabolic cue essential for primitive streak formation.

MDCK cells expressing constitutively active Yes-associated protein (YAP) undergo apical extrusion depending on neighboring cell status

Cell competition is a cell-cell interaction by which a cell compares its fitness to that of neighboring cells. The cell with the relatively lower fitness level is the "loser" and actively eliminated, while the cell with the relatively higher fitness level is the "winner" and survives. Recent studies have shown that cells with high Yes-associated protein (YAP) activity win cell competitions but the mechanism is unknown. Here, we report the unexpected finding that cells overexpressing constitutively active YAP undergo apical extrusion and are losers, rather than winners, in competitions with normal mammalian epithelial cells. Inhibitors of metabolism-related proteins such as phosphoinositide-3-kinase (PI3K), mammalian target of rapamycin (mTOR), or p70S6 kinase (p70S6K) suppressed this apical extrusion, as did knockdown of vimentin or filamin in neighboring cells. Interestingly, YAP-overexpressing cells switched from losers to winners when co-cultured with cells expressing K-Ras (G12V) or v-Src. Thus, the role of YAP in deciding cell competitions depends on metabolic factors and the status of neighboring cells.

The PDZ-binding motif of Yes-associated protein is required for its co-activation of TEAD-mediated CTGF transcription and oncogenic cell transforming activity

YAP is a transcriptional co-activator that acts downstream of the Hippo signaling pathway and regulates multiple cellular processes, including proliferation. Hippo pathway-dependent phosphorylation of YAP negatively regulates its function. Conversely, attenuation of Hippo-mediated phosphorylation of YAP increases its ability to stimulate proliferation and eventually induces oncogenic transformation. The C-terminus of YAP contains a highly conserved PDZ-binding motif that regulates YAP's functions in multiple ways. However, to date, the importance of the PDZ-binding motif to the oncogenic cell transforming activity of YAP has not been determined. In this study, we disrupted the PDZ-binding motif in the YAP (5SA) protein, in which the sites normally targeted by Hippo pathway-dependent phosphorylation are mutated. We found that loss of the PDZ-binding motif significantly inhibited the oncogenic transformation of cultured cells induced by YAP (5SA). In addition, the increased nuclear localization of YAP (5SA) and its enhanced activation of TEAD-dependent transcription of the cell proliferation gene CTGF were strongly reduced when the PDZ-binding motif was deleted. Similarly, in mouse liver, deletion of the PDZ-binding motif suppressed nuclear localization of YAP (5SA) and YAP (5SA)-induced CTGF expression. Taken together, our results indicate that the PDZ-binding motif of YAP is critical for YAP-mediated oncogenesis, and that this effect is mediated by YAP's co-activation of TEAD-mediated CTGF transcription.

Common light signaling pathways controlling DNA repair and circadian clock entrainment in zebrafish

UV radiation causes a number of harmful events including growth delay, cell death and ultimately cancer. The reversal of such effects by concomitant exposure to visible light is a conserved mechanism which has been uncovered in many multi-cellular organisms. Here we show that light-dependent UV-tolerance is a cell autonomous phenomenon in zebrafish. In addition, we provide several lines of evidence indicating that light induction of 64PHR, a DNA repair enzyme, and the subsequent light-dependent DNA repair mediated by this enzyme are prerequisites for light-mediated UV tolerance. 64PHR is evolutionary related to and has a high degree of structural similarity to animal CRY, an essential circadian regulator. The zebrafish circadian clock is controlled by a cell-autonomous and light-dependent oscillator, where zCRY1a functions as an important mediator of light entrainment of the circadian clock. In this study, we show that light directly activates MAPK signaling cascades in zebrafish cells and we provide evidence that light-induced activation of these pathways controls the expression of two evolutionary-related genes, z64Phr and zCry1a, revealing that light-dependent DNA repair and the entrainment of circadian clock share common regulatory pathways.

dentification of Fabry’s disease by the screening of a-galactosidase A activity in male and female hemodialysis patients

BACKGROUND

Although previous studies reported that the prevalence of Fabry's disease was 0.16 - 1.2% in hemodialysis (HD) patients based on measurement of a-galactosidase A (alpha-Gal A) activity, few reports detected female patients by the screening for alpha-Gal A. Here we determined the prevalence of Fabry's disease not only in male but also in female HD patients by measuring alpha-Gal A.

METHODS

Plasma alpha-Gal A was measured in 696 consecutive males (n = 401) and females (n = 295) on HD. Patients with low plasma alpha-Gal A were examined for leukocyte alpha-Gal A, and patients with low leukocyte alpha-Gal A underwent alpha-Gal A gene sequence analysis for possible mutations, and family survey.

RESULTS

Among 15 patients with low plasma alpha-Gal A activity, 4 male patients with low leukocyte alpha-Gal A and 1 female patient revealing low plasma alpha-Gal A were detected in 696 HD patients (0.7% of total patients). 3 of these 5 patients were already diagnosed to have the classical type of Fabry's disease. The other 2 patients were newly diagnosed as Fabry's disease, and did not have typical manifestations of Fabry's disease other than renal failure and left ventricular hypertrophy. DNA analysis of these 2 newly diagnosed patients revealed that each had an alpha-Gal missense mutation, previously identified (E66Q, M2961).

CONCLUSION

Fabry's disease should be considered in the etiology of unexplained end-stage renal disease. Not only affected males but also affected females undergoing HD patients can be readily diagnosed by alpha-Gal A activities and gene analysis. These patients and their family members may benefit from enzyme replacement therapy for Fabry's disease.

Distribution of the collagen IV isoforms in human Bruch's membrane

AIMS

To determine the distribution of the alpha1 to alpha6 chains of type IV collagen in Bruch's membrane of the human posterior pole.

METHODS

Cryosections (10 micro m) from 18 human eyes (20 months to 83 years old) were acid treated, blocked with 10% normal goat serum, incubated for 1 hour with monoclonal antibodies against type IV collagen isoform specific peptides at 1:75 dilution, and visualised with an ABC staining kit.

RESULTS

In Bruch's membrane, the alpha1(IV) and alpha2(IV) chains were identified in retinal pigment epithelial (10/18 = 55%) and choriocapillaris basement membranes (18/18 = 100%); the alpha3(IV), alpha4(IV), and alpha5(IV) chains were also found in the retinal pigment epithelial basement membrane (13/18 = 72%). In the choroid, the alpha1(IV) and alpha2(IV) chains were detected in the blood vessels (18/18=100%). The alpha6(IV) chain was not identified in any sections.

CONCLUSION

The heterogeneous distribution of alpha1-2(IV) and alpha3-5(IV) in Bruch's membrane could give insights into the function of this structure in health, ageing, and diseases such as age related macular degeneration.

Heterozygous knockout of the IRS-1 gene in mice enhances obesity-linked insulin resistance: a possible model for the development of type 2 diabetes

Insulin receptor substrate 1 (IRS-1) gene polymorphisms have been identified in type 2 diabetic patients; however, it is unclear how such polymorphisms contribute to the development of diabetes. Here we introduced obesity in heterozygous IRS-1 knockout (IRS-1(+/-)) mice by gold-thioglucose (GTG) injection and studied the impact of reduced IRS-1 expression on obesity-linked insulin resistance. GTG injection resulted in approximately 30% weight gain in IRS-1(+/-) and wild type (WT) mice, compared with saline-injected controls. There was no difference in insulin sensitivity between lean IRS-1(+/-) and lean WT. Elevated fasting insulin levels but no change in fasting glucose were noted in obese IRS-1(+/-) and WT compared with the respective lean controls. Importantly, fasting insulin in obese IRS-1(+/-) was 1.5-fold higher (P<0.05) than in obese WT, and an insulin tolerance test showed a profound insulin resistance in obese IRS-1(+/-) compared with obese WT. The islets of obese IRS-1(+/-) were 1.4-fold larger than those of obese WT. The expression of insulin receptor and IRS-1 and IRS-2 was decreased in obese IRS-1(+/-), which could in part explain the profound insulin resistance in these mice. Our results suggest that IRS-1 is the suspected gene for type 2 diabetes and its polymorphisms could worsen insulin resistance in the presence of other additional factors, such as obesity.

Age and topographic variation of insulin-like growth factor-binding protein 2 in the human rpe

PURPOSE

Previous studies have shown that insulin-like growth factor-binding protein (IGFBP)-2 is markedly upregulated in senescent RPE cells in vitro, and might therefore be a marker of senescent cells in vivo. This study was conducted to determine whether IGFBP-2 expression in human RPE cells from the macula and periphery varies with age in vivo.

METHODS

Paraformaldehyde (4%)-fixed and optimal cutting temperature (OCT) compound-embedded human eyes from 17 patients were cryosectioned and subjected to high-sensitivity digoxigenin (DIG)-labeled cRNA in situ hybridization to determine the expression of IGFBP-2. Complementary immunohistochemistry experiments using a polyclonal anti-IGFBP-2 antibody were performed to confirm IGFBP-2 protein expression. Specimens were examined by light microscopy, and images were captured with a digital camera. The total numbers of RPE cells and IGFBP-2 mRNA expression-positive RPE cells were counted for each section, and the ratio of labeled RPE cells to total RPE cells counted was calculated for both macular and peripheral regions of each donor.

RESULTS

IGFBP-2 mRNA expression was detected in the ganglion cell layer, inner and outer nuclear layers, and inner segments of photoreceptor cells in all 17 eyes. In 16 of 17 eyes, IGFBP-2 mRNA expression was detected in the RPE. In 11, the ratio of labeled cells to total RPE cells counted per section in the macula was 1.2 times greater than the ratio in the periphery (P = 0.008). The ratio of labeled RPE cells in the macula decreased with age (P = 0.0064). Immunohistochemistry studies for IGFBP-2 confirmed the expression pattern found by in situ hybridization.

CONCLUSIONS

There is a topographical and age-related change in IGFBP-2 expression in RPE cells from human donor eyes. This distribution is likely not to represent senescent RPE cells in vivo.

Drug release from and mechanical properties of press-coated tablets with hydroxypropylmethylcellulose acetate succinate and plasticizers in the outer shell

Dissolution profiles of diltiazem hydrochloride (DIL) contained in core tablets from press-coated (PC) tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) and plasticizers-adsorbent in the outer shell were investigated. Although, on the addition of triethyl citrate (TEC), triacetin (TA), and acetyltriethy citrate (ATEC) as plasticizers, DIL release was suppressed completely in first fluid (pH 1.2) for 10 h, it was not suppressed in HPMCAS on the addition of dibutyl sebacate (DBS) and acetylated monoglyceride. On the other hand, DIL in second fluid (pH 6.8) was released rapidly after a lag time in all the PC tablets. Water-soluble plasticizers such as TEC, TA, and ATEC showed greater compatibility to HPMCAS, and the results were consistent with suppression of DIL release in first fluid. Furthermore, as to PC tablets with HPMCAS and TEC-adsorbent, the DIL release in second fluid did not change after pretreatment in first fluid by the paddle-beads methods. To evaluate the resistance of the outer shell against such a mechanical impact, tablets with HPMCAS, HPMCAS and TEC- or DBS-adsorbent (H, HT, or HD tablets, respectively) were prepared. In compressive load-strain curves after immersion in first fluid, wet crushing strength was lower in the order of HT > H > HD tablets. Also, the curves of HT tablets at 3 and 21 h after immersion were quite different from those of other tablets, and it was hard to find crushing points. These results suggested that the resistance of the outer shell was due to plastic deformation properties involving some interaction between HPMCAS and TEC.

Effect of magnesium stearate or calcium stearate as additives on dissolution profiles of diltiazem hydrochloride from press-coated tablets with hydroxypropylmethylcellulose acetate succinate in the outer shell

Effect of magnesium stearate (MgSt) or calcium stearate (CaSt) on the dissolution profiles of diltiazem hydrochloride in the core of press-coated (PC) tablets with an outer shell composed of hydroxypropylmethylcellulose acetate succinate (HPMCAS) was evaluated by porosity and changes in IR spectra of tablets. In JP first fluid (pH 1.2), the lag time increased with decreasing porosity and was greatest by the addition of MgSt to HPMCAS. While, in JP second fluid (pH 6.8), it increased with decreasing porosity by the addition of CaSt, but hardly changed by the addition of MgSt. Thus, using tablets prepared with the same composition as the outer shell, the changes in IR spectra and uptake amount of the dissolution media after immersion in first fluid and second fluid were determined. The results suggested that some physicochemical interaction occur between MgSt and HPMCAS in tablets with HPMCAS and MgSt and the uptake increased markedly in each dissolution medium. These phenomena seem to cause a prolongation of lag time in first fluid but a shortening of it in second fluid in PC tablets with HPMCAS and MgSt. In contrast, CaSt and HPMCAS did not show such interactions and increased the hydrophobic properties of the outer shell. Consequently, the lag time was only slightly prolonged in first fluid, however, markedly prolonged in second fluid due to suppression of second fluid penetration into micro pores in the outer shell and HPMCAS gel formation on the surface in PC tablets with HPMCAS and CaSt.

An in vitro investigation of the suitability of press-coated tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) and hydrophobic additives in the outer shell for colon targeting

To develop a new colon targeting formulation, which can suppress drug release completely during 12 h in the stomach and release the drug rapidly after a lag time of 3+/-1 h in the small intestine, the use of press-coated tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) in the outer shell was investigated. The release of diltiazem hydrochloride (DIL) as a model drug contained in the core tablets in the 1st fluid (pH 1.2) was suppressed by preparing with higher compression force, but the lag time in the 2nd fluid (pH 6.8) could not exceed 1.5 h. Therefore, to improve the dissolution characteristics, the effects of addition of various hydrophobic additives to HPMCAS were examined. All of the additives examined suppressed the release rate in the 1st fluid, and prolonged the lag time in the 2nd fluid compared to HPMCAS alone. However, although none of the additives examined fulfilled all of the desired criteria, magnesium stearate (MgSt) and calcium stearate (CaSt) showed interesting effects; the former suppressed drug release completely in 1st fluid, while the latter markedly prolonged the lag time in 2nd fluid. To integrate the merits of each additive, press-coated tablets with a powder mixture of HPMCAS, MgSt and CaSt in the outer shell (HMC tablets) were prepared and in vitro tests were performed. The results indicated that HMC tablets with a mixing ratio of 80% HPMCAS, 5-15% MgSt and 15-5% CaSt in the outer shell met the desired criteria and the lag time in 2nd fluid could also be controlled from 2 to 9 h. At a mixing ratio of 80% HPMCAS, 10% MgSt and 10% CaSt, the dissolution profiles of DIL in 1st fluid and 2nd fluid were not remarkably affected by agitation intensity, and addition of bile salts, pretreatment time or anticipated higher pH except for pH 6.0, respectively. These results indicated the usefulness of HMC tablets with the desirable functions for colon-targeting formulations.

Lens and retinal changes in the WBN/Kob rat (spontaneously diabetic strain). Electron-microscopic study

Male WBN/Kob rats represent a spontaneously diabetic strain with hyperglycemia, cataracts, nephropathy, neurophathy, pancreatic fibrosis and hyperlipemia. Cataracts and retinal changes in WBN/Kob rats were examined by light and electron microscopy to evaluate the ocular complications. Lens opacity was present in the posterior subcapsular and center of the anterior cortex of male 14-month-old WBN/Kob rats. Light and transmission electron microscopy showed swelling and irregularity of lens fibers. Scanning electron microscopy revealed that lens fibers were irregular and had many granules and bulging processes of various sizes on the cortical side of the opacified region. The nuclear side of the opacified region showed spongy changes and complete absence of lens fibers. Electron microscopy showed retinal degeneration in the photoreceptor outer segments of 1-month-old male WBN/Kob rats. Light microscopy showed thin outer segments and outer nuclear layers in 5-month-old rats, and electron microscopy revealed severe degeneration in the outer segments. The retinas of 11-month-old rats were thinner; the outer plexiform layer was very thin; the photoreceptor cell nuclei in the outer nuclear layer had decreased to one layer and were almost in contact with the inner nuclear layer nuclei, while the visual cells had disappeared. Retinal degeneration had progressed even further in 14-month-old rats, and very few photoreceptor cell nuclei remained. The retinal capillary lumens were small, and their pericytes had thickened basement membranes. The basement membranes of retinal capillaries from WBN/Kob rats were significantly thicker than those from control Wistar rats (p < 0.0001). Although this rat has spontaneous diabetic features, such as cataracts, its retinal changes look more degenerative.

Preparation of enteric coated timed-release press-coated tablets and evaluation of their function by in vitro and in vivo tests for colon targeting

As a new oral drug delivery system for colon targeting, enteric coated timed-release press-coated tablets (ETP tablets) were developed by coating enteric polymer on timed-release press-coated tablets composed of an outer shell of hydroxypropylcellulose and core tablet containing diltiazem hydrochloride (DIL) as a model drug. The results of the in vitro dissolution tests in JP 1st fluid (pH 1.2) and JP 2nd fluid (pH 6.8) indicated that these tablets showed both acid resistance and timed-release. To clarify whether ETP tablets could have been of use in the gastrointestinal tract, ETP tablets with a layer of phenylpropanolamine hydrochloride (PPA) (a marker of gastric emptying) between the enteric coating layer and outer shell were prepared, and were administered to beagle dogs. The gastric emptying time and lag time after gastric emptying were evaluated by determining the times at which PPA and DIL first appeared in the plasma (TFA(PPA) and TFA(DIL), respectively). TFA(PPA) and TFA(DIL) were about 4 and 7 h, respectively. This value of TFA(PPA) indicated that ETP tablets displayed acid resistance in the stomach as well as in JP Ist fluid. Subtraction of TFA(PPA) from TFA(DIL) gave a value of about 3 h which agreed well with the lag time determined by in vitro dissolution test in JP 2nd fluid. Also, the results seemed to be in accordance with the time at which the tablets reached the colon after gastric emptying. Therefore, ETP tablets seemed to be an effective tool for oral site-specific delivery including targeting of the colon.

Choroidal detachment after vitreous surgery

BACKGROUND AND OBJECTIVE

To study the frequency and clinical features of choroidal detachment (CD) after vitreous surgery, because there have been no reports on this problem.

PATIENTS AND METHODS

We studied the clinical features of 14 patients (15 eyes) with CD from a total of 380 patients treated with vitrectomy at the Nagasaki University Hospital from January 1994 to August 1997.

RESULTS

The incidence of CD after vitreous surgery was 3.9% (15/380). The reasons for vitrectomy were 6 retinal detachments, 4 proliferative diabetic retinopathies, and 5 others. During vitrectomy, 4 eyes were treated with scleral buckling, 11 with endolaser photocoagulation, and 3 with cryoretinopexy. Retinal detachment as a postoperative complication was seen in 8 patients, and in 5 of them the retina remained detached after the final treatment.

CONCLUSIONS

CD may be caused by scleral buckling, panphotocoagulation, or stress on the ciliary body. Some patients with CD have a poor outcome.

Retinal capillary changes in Otsuka Long-Evans Tokushima fatty rats (spontaneously diabetic strain). Electron-microscopic study

The Otsuka Long-Evans Tokushima fatty (OLETF) rat is a spontaneously diabetic strain with polyuria, polydipsia and mild obesity. The pathological features of OLETF rats closely resemble those of patients with non-insulin-dependent diabetes mellitus. The purpose of this study is to investigate the retinal capillary changes in the OLETF rat and to confirm the valuability of the OLETF rat as the model of diabetic retinal disease. One-month-old male OLETF rats and age- and sex-matched Long-Evans Tokushima Otsuka (LETO) controls were supplied by Otsuka Pharmaceutical Co. Ltd. (Tokushima, Japan). Body weight and blood sugar levels were measured monthly. Their eyes were enucleated 14 months after birth. Ultrathin sections were made and examined with a transmission electron microscope. According to their location, two kinds of retinal capillaries were differentiated: those in the nerve fiber layer (NFL) and those in the outer plexiform layer (OPL). The image of each capillary was transferred to a computed image analyzer, and basement membrane thickness and the ratio of the pericyte area to total capillary cross-section area were determined. Corrosion casts of retinal vessels were made and examined with scanning electron microscopy (SEM). OLETF rats gained more weight than LETO rats from the beginning, and the difference increased gradually with age. The blood sugar level of OLETF rats was higher than that of LETO rats after 5 months of age. In the retinal capillaries of 14-month-old OLETF rats, basement membranes were significantly thicker (OLETF: 209 +/- 51 nm in NFL, 132 +/- 23 nm in OPL; LETO: 118 +/- 28 nm in NFL, 79 +/- 14 nm in OPL), and the ratio of pericyte area to the capillary cross-section area was significantly lower than that of the controls (OLETF: 0.131 +/- 0.92 in NFL, 0.111 +/- 0.102 in OPL; LETO: 0.288 +/- 0.142 in NFL, 0.198 +/- 0.136 in OPL). The endothelial cell cytoplasm had degenerated. SEM examination of the vascular corrosion cast of a 14-month-old OLETF rat showed caliber irregularity, narrowing, tortuosity and loop formations of capillaries. The morphological changes in the retinal capillaries of OLETF rats were similar to those seen in diabetic patients. The OLETF rat may be a useful animal model for the study of ocular diabetic complications in humans.

Vascular architecture of degenerated retina in WBN/Kob rats: corrosion cast and electron microscopic study

The purpose of the present study is to determine the changes of vascular architecture in the degenerated retina. We used mainly corrosion casts of the retinal vasculature and scanning electron microscopy to obtain a wide three-dimensional view. WBN/Kob rats (a spontaneously diabetic strain) were used because their outer retinas degenerate and become very thin with age. In 15-month-old rats, localized constriction and irregular caliber of the capillaries were evident in the vascular casts. Two layers of capillary network in the retina were maintained, but the capillaries were decreased in number. Numerous loop formations were present in the superficial capillary networks. Neither microaneurysms nor arteriovenous shunts were seen in young and old rats. Transmission electron microscopy revealed that capillary pericytes in the inner and outer plexiform layers had thickened basement membranes and that endothelial cells had many vesicles in their cytoplasm. Thus the retinal capillary changes in WBN/Kob rats are nondiabetic but due to hereditary retinal degeneration, although the systemic and pancreatic abnormalities in this rat strain are diabetic. Even when the retina becomes very thin, two layer capillary networks remain.

A carboxy-terminal truncation of human alpha-galactosidase A in a heterozygous female with Fabry disease and modification of the enzymatic activity by the carboxy-terminal domain. Increased, reduced, or absent enzyme activity depending on number of amino acid residues deleted

Fabry disease is an X-linked disorder of glycosphingolipid metabolism caused by a deficiency of alpha-galactosidase A (alpha-Gal A). We identified a novel mutation of alpha-Gal A gene in a family with Fabry disease, which converted a tyrosine at codon 365 to a stop and resulted in a truncation of the carboxy (C) terminus by 65 amino acid (AA) residues. In a heterozygote of this family, although the mutant and normal alleles were equally transcribed in cultured fibroblasts, lymphocyte alpha-Gal A activity was approximately 30% of the normal control and severe clinical symptoms were apparent. COS-1 cells transfected with this mutant cDNA showed a complete loss of its enzymatic activity. Furthermore, those cotransfected with mutant and wildtype cDNAs showed a lower alpha-Gal A activity than those with wild type alone (approximately 30% of wild type alone), which suggested the dominant negative effect of this mutation and implied the importance of the C terminus for its activity. Thus, we generated mutant cDNAs with various deletion of the C terminus, and analyzed. Unexpectedly, alpha-Gal A activity was enhanced by up to sixfold compared with wild-type when from 2 to 10 AA residues were deleted. In contrast, deletion of 12 or more AA acid residues resulted in a complete loss of enzyme activity. Our data suggest that the C-terminal region of alpha-Gal A plays an important role in the regulation of its enzyme activity.

Analysis of vasopressin receptor type II (V2R) gene in three Japanese pedigrees with congenital nephrogenic diabetes insipidus: identification of a family with complete deletion of the V2R gene

To investigate the association of mutations in the arginine vasopressin receptor type II (V2R) gene with congenital nephrogenic diabetes insipidus (CNDI) in the Japanese, we analyzed the V2R gene, located on the X chromosome, in three Japanese pedigrees with CNDI. In one pedigree, a large deletion spanning the entire coding region of the V2R gene was identified. In another pedigree, a G to A transition responsible for a substitution of Met88 (ATG) for Val88 (GTG) was detected. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis revealed that this was a de novo mutation that had occurred in the proband's mother. Because CNDI was observed only in those with this mutation, the pathogenicity of this mutation seemed clear. In the last pedigree, only a silent mutation at Leu309 (CTA-->CTG) was found. All the individuals studied in this pedigree by allele-specific oligonucloetide-polymerase chain reaction (ASO-PCR) analysis showed a complete association of this mutation to the clinical symptoms. Because the silent mutation detected was unlikely to be a direct cause of CNDI, mutations in other regions of the V2R gene, such as a promoter region or other regulatory regions, may be responsible for the cause of CNDI in this pedigree. Thus, association of the V2R gene abnormality to clinical symptoms of CNDI was confirmed in three Japanese pedigrees, and a strong contribution of the V2R gene mutation to the development of CNDI was suggested.

Molecular scanning of the insulin receptor substrate-1 (IRS-1) gene in Japanese patients with NIDDM: identification of five novel polymorphisms

Since the insulin receptor substrate-1 (IRS-1) is the major substrate of the insulin receptor tyrosine kinase and has been shown to activate phosphatidylinositol (PI) 3-kinase and promote GLUT4 translocation, the IRS-1 gene is a potential candidate for development of non-insulin-dependent diabetes mellitus (NIDDM). In this study, we have identified IRS-1 gene polymorphisms, evaluated their frequencies in Japanese subjects, and analysed the contribution of these polymorphisms to the development of NIDDM. The entire coding region of the IRS-1 gene of 94 subjects (47 NIDDM and 47 control subjects) was screened by polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) analysis. Seven SSCP polymorphisms were identified. These corresponded to two previously identified polymorphisms [Gly971 --> Arg (GGG --> AGG) and Ala804 (GCA --> GCG)] as well as five novel polymorphisms [Pro190 --> Arg (CCC --> CGC), Met209 --> Thr (ATG --> ACG), Ser809 --> Phe (TCT --> TTT), Leu142 (CTT --> CTC), and Gly625 (GGC --> GGT)]. Although the prevalence of each of these polymorphisms was not statistically different between NIDDM and control subjects, the prevalence of the four IRS-1 polymorphisms with an amino acid substitution together was significantly higher in NIDDM than in control subjects (23.4 vs 8.5%, p < 0.05), and two substitutions (Met 209 --> Thr and Ser809 --> Phe) were found only in NIDDM patients. Equilibrium glucose infusion rates during a euglycaemic clamp in NIDDM and control subjects with the IRS-1 polymorphisms decreased by 29.5 and 22.0%, respectively on the average when compared to those in comparable groups without polymorphisms, although they were not statistically significant. Thus, IRS-1 polymorphisms may contribute in part to the insulin resistance and development of NIDDM in Japanese subjects; however, they do not account for the major part of the decrease in insulin-stimulated glucose uptake which is observed in subjects with clinically apparent NIDDM.

Bradykinin enhances GLUT4 translocation through the increase of insulin receptor tyrosine kinase in primary adipocytes: evidence that bradykinin stimulates the insulin signalling pathway

It has been suggested that bradykinin stimulates glucose uptake in experiments in vivo and in cultured cells. However, its mechanism has not yet been fully elucidated. In this study, the effects of bradykinin on the insulin signalling pathway were evaluated in isolated dog adipocytes. The bradykinin receptor binding study revealed that dog adipocytes possessed significant numbers of bradykinin receptors (Kd = 83 pmol/l, binding sites = 1.7 x 10(4) site/ cell). Reverse transcription-polymerase chain reaction amplification showed the mRNA specific for bradykinin B2 receptor in the adipocytes. Bradykinin alone did not increase 2-deoxyglucose uptake in adipocytes; however, in the presence of insulin (10(-7) mol/l) it significantly increased 2-deoxyglucose uptake in a dose-dependent manner. Bradykinin also enhanced insulin stimulated GLUT4 translocation from the intracellular fraction to the cell membrane, and insulin induced phosphorylation of the insulin receptor beta subunit and insulin receptor substrate-1 (IRS-1) without affecting the binding affinities or numbers of cell surface insulin receptors in dog adipocytes. The time-course of insulin stimulated phosphorylation of the insulin receptor beta subunit revealed that phosphorylation reached significantly higher levels at 10 min, and stayed at the higher levels until 120 min in the presence of bradykinin, suggesting that bradykinin delayed the dephosphorylation of the insulin receptor. It is concluded that bradykinin could potentiate insulin induced glucose uptake through GLUT4 translocation. This effect could be explained by the potency of bradykinin to upregulate the insulin receptor tyrosine kinase activity which stimulates phosphorylation of IRS-1, followed by GLUT4 translocation.

Expression of insulin receptor on clonal pancreatic alpha cells and its possible role for insulin-stimulated negative regulation of glucagon secretion

In pancreatic alpha cells, the existence and function of the insulin receptor has not yet been fully established. In this study, to confirm the expression of functional insulin receptors in pancreatic alpha cells, we performed: 1) insulin receptor binding assay, 2) Northern blot analysis and RT-PCR (reverse transcription-polymerase chain reaction) amplification of insulin receptor mRNA, 3) immunocytochemical staining, 4) biosynthetic labelling of insulin receptor protein using [35S]methionine, 5) analysis of insulin-stimulated autophosphorylation of the insulin receptor in glucagon secreting cell lines, In-R1-G9 and alpha TC clone 6 cells. Glucagon secretion decreased with the addition of insulin in both cells. The receptor binding studies using [125I-Tyr-A14] insulin revealed that both cells possessed a significant number of insulin receptors (In-R1-G9:K1 = 2.1 x 10(9) mol/l-1, K2 = 6.2 x 10(7) mol/l-1, R1 = 0.27 x 10(4), R2 = 1.86 x 10(4) sites/cell; alpha TC clone 6: K1 = 2.1 x 10(9) mol/l-1, K2 = 7.3 x 10(7) mol/l-1, R1 = 0.27 x 10(4), R2 = 1.95 x 10(4) sites/cell). Northern blot analysis as well as RT-PCR amplification showed the mRNA specific for insulin receptor in both cells. By immunocytochemical staining using anti-insulin receptor alpha-subunit antibody, positive immunostaining for insulin receptor was observed in both cells. [35S]Methionine labelling of both cells followed by immunoprecipitation using anti-insulin receptor antibody showed the correct size of the insulin receptor protein. The insulin receptor expressed in these cells underwent autophosphorylation by insulin stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect on insulin sensitivity of angiotensin converting enzyme inhibitors with or without a sulphydryl group: bradykinin may improve insulin resistance in dogs and humans

The present study compared the effect on insulin sensitivity of ACE inhibitors with a sulphydryl group (captopril) or those without a sulphydryl group (delapril and enalapril) during the hyperinsulinaemic euglycaemic clamp test in both animal and clinical experiments. A possible contribution of bradykinin to the improvement of insulin sensitivity by ACE-inhibition was also studied. In healthy control and depancreatized dog experiments, administration of captopril either intravenously (3.0 mmol.kg-1) or orally (5.0 mmol.kg-1) increased insulin sensitivity indices and plasma bradykinin concentrations. In comparison, intravenous administration of an active metabolite of delapril (3.0 mmol.kg-1) and oral administration of either delapril or enalapril (5.0 mmol.kg-1) showed slight, but not significant increases in insulin sensitivity indices and plasma bradykinin concentrations. Infusion of a bradykinin antagonist (N-alpha-adamantane-acetyl-D-Arg-[Hyp3,Thi5,8,D-Phe7]-b bradykinin) (0.5 nmol.kg-1 x min-1) abolished the effect of captopril on insulin sensitivity. Furthermore, intravenous administration of bradykinin (0.1 nmol.kg-1 x min-1) increased insulin sensitivity indices. In clinical experiments, insulin sensitivity indices decreased in the following order: normotensive healthy subjects, hypertensive non-diabetic patients, normotensive NIDDM patients and hypertensive NIDDM patients. In these four groups, oral administration of captopril (2.0 mmol.kg-1) significantly increased insulin sensitivity indices, and a concomitant increase in plasma bradykinin concentrations was observed. By contrast, oral administration of enalapril or delapril showed slight, but not significant effects on insulin sensitivity indices and plasma bradykinin concentrations. From these studies, it is concluded that ACE inhibitors with a sulphydryl group have more potent action on the improvement in insulin sensitivity than those without a sulphydryl group.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of carteolol on the electroretinogram in the perfused cat eye

Carteolol, a nonselective beta-antagonist, was administered intra-arterially in perfused cat eyes. Carteolol increased both photopic and scotopic electroretinogram b-wave amplitude dose-dependently and reversibly, but carteolol failed to induce significant changes in the flow rate of perfusate. This study suggests that carteolol may increase selectively the retinal perfusion flow rate, though it did not reflect the total perfusion flow, or carteolol may have an interaction with retinal beta-adrenergic receptors related to the origin of the b-wave. These ideas are supported by carteolol's intrinsic sympathomimetic activity and effects on endothelium of vessels.

Thyroxine-binding globulin variant (TBG-Kumamoto): identification of a point mutation and genotype analysis of its family

Thyroxine-binding globulin (TBG) is the major thyroid hormone transport protein. Several inherited TBG variants resulting in partial or complete TBG deficiencies have been shown to be caused by either one or two nucleotide substitutions, or one nucleotide deletion in the coding regions of the TBG gene. In this report, a Japanese female patient (proband) with hyperthyroid state, whose lower TBG levels did not return to normal under the euthyroid state after treatment was examined. Genomic DNA samples from the proband with thyroxine-binding globulin deficiency (termed TBG-Kumamoto) and her family were subjected to the polymerase chain reaction, and the generated DNA fragments were sequenced. A single nucleotide substitution in the codon for the amino acid 363 of native TBG molecule (CCT to CTT) was found, resulting in the replacement of proline by leucine. It was revealed that the proband was a heterozygote and her father was a hemizygote. The mutation was confirmed by the allele-specific amplification of genomic DNAs from the proband and her father using oligonucleotide primers of normal or mutant residues at the 3' position in the polymerase chain reaction. These results indicate that the abnormality of TBG-Kumamoto is the consequence of this mutation. Genetically, this point mutation observed in TBG-Kumamoto might be classified as a new type of TBG deficiency.

[Effects of carteolol on electroretinograms in isolated perfused cat eye]

Effects of carteolol on ERG b-wave amplitude were investigated in dark adapted isolated perfused cat eyes. Carteolol enhanced ERG b-waves with both strong stimuli that reflect the function of both the rod and cone systems, and weak stimuli that reflect the function of the rod system. These observations suggest the following two ideas i.e.: 1. Carteolol increases the flow in retinal vessels of perfusate. or 2. Carteolol has interaction with retinal beta-adrenergic receptors related to the origin of the ERG b-wave. It is likely that both participate in the intrinsic sympathomimetic activity and the release activity of the endothelium derived relaxing factor of carteolol.

Familial primary hyperparathyroidism: study of the pedigree in three generations

The familial occurrence of primary hyperparathyroidism in which the proband is a 55-year-old man is reported. His 58-year-old sister and 40-year-old brother had undergone partial parathyroidectomy, and histological examination revealed hyperplasia in both cases. Their father and a daughter of the proband had a history of nephrolithiasis. The three siblings showed high levels of plasma parathyroid hormone (even the two postoperative cases). All of them had a history of nephrolithiasis and peptic ulcers. In the proband, image studies did not reveal any abnormality in the neck region. At present, the three cases do not exhibit any abnormalities in the pancreas or the pituitary by imaging studies and endocrine tests.