Villin-1 and Gelsolin Regulate Changes in Actin Dynamics That Affect Cell Survival Signaling Pathways and Intestinal Inflammation

BACKGROUND & AIMS

Cell stress signaling pathways result in phosphorylation of the eukaryotic translation initiation factor 2 subunit alpha (EIF2S1 or EIF2A), which affects regulation of protein translation. Translation reprogramming mitigates stress by activating pathways that result in autophagy and cell death, to eliminate damaged cells. Actin is modified during stress and EIF2A is dephosphorylated to restore homeostasis. It is not clear how actin affects EIF2A signaling. We studied the actin-binding proteins villin 1 (VIL1) and gelsolin (GSN) in intestinal epithelial cells (IECs) to determine whether they respond to cell stress response and affect signaling pathways.

METHODS

We performed studies with mice with disruptions in Vil1 and Gsn (double-knockout mice). Wild-type (WT) mice either were or were not (controls) exposed to cell stressors such as tumor necrosis factor and adherent-invasive Escherichia coli. Distal ileum tissues were collected from mice; IECs and enteroids were cultured and analyzed by histology, immunoblots, phalloidin staining, immunohistochemistry, electron microscopy, and flow cytometry. HT-29 cells were incubated with cell stressors such as DTT, IFN, and adherent-invasive E coli or control agents; cells were analyzed by immunoblots and quantitative polymerase chain reaction. Green fluorescent protein and green fluorescent protein tagged mutant EIF2A were expressed from a lentiviral vector. The mouse immunity-related GTPase (IRGM1) was overexpressed in embryonic fibroblasts from dynamin1 like (DNM1L) protein-knockout mice or their WT littermates. IRGM1 was overexpressed in embryonic fibroblasts from receptor interacting serine/threonine kinase 1-knockout mice or their WT littermates. Human IRGM was overexpressed in human epithelial cell lines incubated with the DNM1L-specific inhibitor Mdivi-1. Mitochondria were analyzed by semi-quantitative confocal imaging. We performed immunohistochemical analyses of distal ileum tissues from 6-8 patients with Crohn's disease (CD) and 6-8 individuals without CD (controls).

RESULTS

In IECs exposed to cell stressors, EIF2A signaling reduced expression of VIL1 and GSN. However, VIL1 and GSN were required for dephosphorylation of EIF2A and recovery from cell stress. In mouse and human IECs, prolonged, unresolved stress was accompanied by continued down-regulation of VIL1 and GSN, resulting in constitutive phosphorylation of EIF2A and overexpression of IRGM1 (or IRGM), which regulates autophagy. Overexpression of IRGM1 (or IRGM) induced cell death by necroptosis, accompanied by release of damage-associated molecular patterns (DAMPs). In double-knockout mice, constitutive phosphorylation of EIF2A and over-expression of IRGM1 resulted in spontaneous ileitis that resembled human CD in symptoms and histology. Distal ileum tissues from patients with CD had lower levels of VIL1 and GSN, increased phosphorylation of EIF2A, increased levels of IRGM and necroptosis, and increased release of nuclear DAMPs compared with controls.

CONCLUSIONS

In studies of intestinal epithelial tissues from patients with CD and embryonic fibroblasts from mice, along with enteroids and human IEC lines, we found that induction of cell stress alters the cytoskeleton in IECs via changes in the actin-binding proteins VIL1 and GSN. Acute changes in actin dynamics increase IEC survival, whereas long-term changes in actin dynamics lead to IEC death and intestinal inflammation. IRGM regulates necroptosis and release of DAMPs to induce gastrointestinal inflammation, linking IRGM activity with CD.

Swine as models in biomedical research and toxicology testing

Swine are considered to be one of the major animal species used in translational research, surgical models, and procedural training and are increasingly being used as an alternative to the dog or monkey as the choice of nonrodent species in preclinical toxicologic testing of pharmaceuticals. There are unique advantages to the use of swine in this setting given that they share with humans similar anatomic and physiologic characteristics involving the cardiovascular, urinary, integumentary, and digestive systems. However, the investigator needs to be familiar with important anatomic, histopathologic, and clinicopathologic features of the laboratory pig and minipig in order to put background lesions or xenobiotically induced toxicologic changes in their proper perspective and also needs to consider specific anatomic differences when using the pig as a surgical model. Ethical considerations, as well as the existence of significant amounts of background data, from a regulatory perspective, provide further support for the use of this species in experimental or pharmaceutical research studies. It is likely that pigs and minipigs will become an increasingly important animal model for research and pharmaceutical development applications.

Simmondsin for weight loss in rats

OBJECTIVE

To investigate the safety and efficacy for weight loss of simmondsin, a dietary supplement extracted from the seed of the jojoba plant (Simmondsia chinensis).

ANIMALS

Sprague-Dawley male rats were fed various levels of simmondsin for 8 weeks (lean rats) or 16 weeks (high fat-induced obese rats).

MEASUREMENTS

Food intake, body weight and composition, histopathology, hematology parameters.

RESULTS

Simmondsin produced a clear dose-response effect on food intake and body weight. No remarkable histopathologic changes were noted in the liver, kidney and spleen. One lean animal, in the 0.5% group, had approximately a 20% depression in red bone marrow cells. Significant effects on hematology parameters were seen almost exclusively in groups consuming simmondsin at the highest level (0.5%) and these effects appeared to be reversed by removing simmondsin from the diet.

CONCLUSION

Simmondsin at both the 0.15% level and the 0.25% level significantly reduced food intake and body weight without apparent negative effects. At dose levels much higher than therapeutic levels, there seemed to be reversible effects on circulating red and white blood cells. Future studies should determine long-term effects of lower doses on blood cell parameters.

Unusual immunophenotype of a soft tissue sarcoma in a European polecat (Mustela putorius)

The most commonly reported tumors in ferrets are carcinomas, followed by round cell tumors. Soft tissue sarcomas are reported and characterized much less frequently. Because domesticated ferrets (Mustela putorius furo) are direct descendants of European polecats (Mustela putorius), the types and prevalence of tumors are expected to be similar in the two species. Presented here is a case report of unusual immunohistochemical staining characteristics of an abdominal wall leiomyosarcoma in a close relative of domestic ferrets, the European polecat. Sections of tissue were preserved in 10% buffered formalin, embedded in paraffin, and sectioned at 5 mm. Routine staining with hematoxylin and eosin and several immunohistochemical tests were performed to identify the tumor tissue of origin. Although the tumor did not stain with antibody to desmin, further staining for smooth muscle actin was consistent with a smooth muscle origin. To the authors' knowledge, this report is the first description of a leiomyosarcoma in the European polecat. This report emphasizes the importance of using additional secondary markers to accurately diagnose anaplastic tumors.

Radiofrequency ablation of rabbit kidney using liquid electrode: acute and chronic observations

BACKGROUND AND PURPOSE

The percentage of small renal tumors being diagnosed has increased at least five-fold in the last 20 years. The question of how best to treat these lesions remains unanswered. We studied the effectiveness of "wet" radiofrequency (RF) ablation of renal tissue.

MATERIALS AND METHODS

New Zealand white rabbits (N = 48) underwent a 1- or 2-minute ablation of renal parenchyma with a modified insulated spinal needle capable of infusing saline, measuring temperature and impedance, and delivering RF energy. Animals were followed and examined up to 54 days after surgery.

RESULTS

All animals survived for the planned period. Intravenous urograms showed no fistula or urinoma formation and confirmed continued function of the remaining parenchyma. The 1-minute treatments consistently ablated 20% to 25% (average 7 cm) of the tissue, whereas the 2-minute treatments ablated 34% to 36% (average 10 cm). Acutely, there was coagulative necrosis and infiltration of inflammatory cells. Chronically, there were well-demarcated lesions with complete effacement of the tubular epithelium and destruction of the glomeruli.

CONCLUSION

Wet radiofrequency ablation with a liquid electrode can reproducibly create large lesions safely and quickly. The technique may soon become an alternative, minimally invasive therapy for small renal tumors.

Interstitial laser hyperthermia model development for minimally invasive therapy of breast carcinoma

BACKGROUND

This investigation describes the preclinical development of a laser fiberoptic interstitial delivery system for the thermal destruction of small breast cancers. We propose adaptation of this technology to stereotactic mammographic instrumentation currently employed for diagnostic core biopsy to thermally ablate a site of disease with maximal treatment efficacy, minimal observable superficial change, reduced patient trauma, and lowered overall treatment costs.

STUDY DESIGN

Laser hyperthermia is a clinical modality that seeks to achieve tumor destruction through controlled tissue heating. The advantage of laser-induced hyperthermia over traditionally used heat sources such as ultrasound, microwave, or radiowave radiation lies in the ability to focus heat localization to the specific tumor tissue site. Neodymium:yttrium aluminum garnet (Nd:YAG) laser light transmitted through a fiberoptic cable to a diffusing quartz tip can induce such temperature increases leading to localized tissue destruction. Because breast cancer occurs with greatest frequency in the mature woman whose breast tissue has undergone glandular involution with fatty replacement, this study concentrates on determining the resultant laser energy heat distribution within fat and fibrofatty tissue. This investigation studied the time-temperature responses of ex vivo human breast and porcine fibrofatty tissue, which led to an in vivo subcutaneous porcine model for the practical demonstration of a laser hyperthermia treatment of small volumes of porcine mammary chain tissue.

RESULTS

Spatial recordings of the resultant temperature fields through time exhibited similar, reproducible thermal profiles in both ex vivo human breast and subcutaneous porcine fat. In vivo laser-produced temperature fields in porcine subcutaneous fat were comparable to those in the ex vivo analyses, and showed a histologically, sharply defined, and controllable volume of necrosis with no injury to adjacent tissues or to overlying skin.

CONCLUSIONS

Interstitially placed, fiberoptically delivered Nd:YAG laser energy is capable of controlled tissue denaturation to a defined volume for the treatment of small breast cancers. It is hoped that this minimally invasive approach, with further investigation and refinement, may lead to the effective treatment of small, well-defined breast cancers that are commonly diagnosed through stereographic mammography and stereotactic core biopsy. The juxtaposition of such a localized treatment modality with these increasingly used diagnostic tools is of considerable promise.

Gracilis or semitendinosus myopathy in 18 dogs

The clinical findings in 18 dogs with gracilis (n = 17) or semitendinosus (n = 1) myopathy are described. Each dog had a similar hind-limb gait abnormality characterized by a shortened stride with a rapid, elastic medial rotation of the paw, internal rotation of the hock and external rotation of the calcaneus [corrected] and internal rotation of the stifle during the mid-to-late swing phase of the stride. Medical management prior to or in lieu of surgery was attempted (n = 8) with no apparent response. Fifteen dogs had one or multiple surgical procedures. Although transection, partial excision, or complete resection of the affected muscle resulted in resolution of lameness following surgery, lameness recurred six weeks to five months (mean, 2.5 months; median, two months) following surgery. Adjunctive medical treatment did not prevent recurrence. Variable replacement of the affected muscle with fibrous connective tissue (predominantly along the caudolateral border of the muscle) was evident grossly, and replacement of myofibers with fibrous connective tissue was confirmed histologically. A definitive etiology could not be established.

Involvement of canine oral papillomavirus in generalized oral and cutaneous verrucosis in a Chinese Shar Pei dog

Severe papillomatosis developed in the oral cavity and spread throughout the haired skin of the trunk and limbs of an 8-month-old female Chinese Shar Pei dog. The dog had received corticosteroids prior to referral, which was associated with the onset of demodecosis and papillomatosis. Papillomavirus structural antigens were detected in biopsies by immunohistochemistry using a panel of monoclonal and polyclonal antibodies. An 8.2-kilobase papillomavirus-specific DNA molecule was detected in the cutaneous lesions by high stringency Southern blot hybridization using a cloned canine oral papillomavirus DNA probe. Restriction enzyme analysis revealed that the virus in the cutaneous lesions was identical to the canine oral papillomavirus. Discontinuation of the steroids combined with the use of a mitocide, antibiotics, and an autogenous vaccine resolved the demodecosis and papillomatosis. This case report suggests that corticosteroid-induced immunosuppression can expand the tissue tropism of papillomaviruses.

Analysis of DNA aneuploidy and c-myc oncoprotein content of canine plasma cell tumors using flow cytometry

To derive a method for determining malignant potential of plasma cell tumors, a retrospective analysis of the DNA ploidy and relative p62c-myc oncoprotein content using bivariate flow cytometry was performed on 23 formalin-fixed, paraffin-embedded tissues from 23 dogs. The samples included one tissue each from 17 males and six females 2 to 16 years of age (mean = 7.5 years). Twelve breeds were represented, including three Cocker Spaniels, three Golden Retrievers, and five of mixed breed. Ten of the samples were histologically classified as malignant-plasma cell tumors, and ten specimens were classified as benign. Three samples of plasmacytic inflammation, from two Cocker Spaniels and one Shih Tsu, were included as controls. The ploidy and relative c-myc content data obtained were compared with the histologic grade. A significant difference in ploidy was found between benign and malignant tumors (P < or = 0.05). Five of nine malignant plasma cell tumors were aneuploid; the remainder were diploid (4/9) or tetraploid (1/9). Only one of the benign plasmacytomas was aneuploid (1/10), whereas six were diploid (6/10), and three were tetraploid (3/10). All of the controls were diploid (3/32). When relative amounts of p62c-myc from malignant and benign tumors were compared by flow cytometry, a greater significant difference was established (P < or = 0.01) than bu using aneuploidy alone. Relative values of p62c-myc content ranged from 219 to 553 units in 8/10 malignant plasma cell tumors and from 86 to 392 units in 3/10 benign plasmacytomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Metastatic malignant melanoma in a mandarin duck (Aix galericulata)

A biopsy taken from a mass on the dorsal surface of the bill of an adult female mandarin duck (Aix galericulata) was diagnosed as a malignant melanoma by light microscopy. Two months later, the tumor had enlarged considerably; the duck developed severe dyspnea and was euthanatized. At necropsy, there were metastases to lymphoid tissues in the lower regions of the neck. To our knowledge, this is the first report of a malignant melanoma in a mandarin duck.

Metastasis of a myxoid leiomyosarcoma via the renal and hepatic portal circulation in a sarus crane (Grus antigone)

A 12-year-old female sarus crane (Grus antigone) developed a recurrent proliferative lesion in the subcutaneous tissue of the tarsometatarsus, which failed to respond to medical and surgical therapy. The crane was killed and microscopic examination of the tissues taken at necropsy revealed a myxomatous, poorly-differentiated sarcoma with metastasis to the liver and kidney. Immunohistochemical staining for muscle actin, smooth muscle myosin and vimentin were positive, indicating that the primary and metastatic tumours were leiomyosarcomas. Location of the metastatic lesions in only the portal venous system of the liver and veins of the kidney indicated that the route of metastasis was the portal circulation via the ischiatic vein, caudal mesenteric vein and both the renal-portal shunt and hepatic portal vein. This is the first report of metastatic subcutaneous leiomyosarcoma in an avian species.

Gastric extramedullary plasmacytoma in a dog

A 10-year-old mixed-breed dog was examined because of a 6-week history of daily vomiting and sporadic diarrhea. On gastroscopy, a crateriform mass was observed on the greater curvature of the stomach. Partial gastrectomy and lymphadenectomy of a large mesenteric lymph node was performed. Gastric plasmacytoma with lymph node metastasis was diagnosed by histologic and immunoperoxidase methods, and chemotherapy was initiated with doxorubicin hydrochloride and diphenhydramine hydrochloride. The dog remains clinically normal 30 months after initial diagnosis. Although gastric plasmacytomas are rare in dogs, long-term survival appears to be better with this disease than with other types of gastric neoplasia.

Salivary gland oncocytes in African hedgehogs (Atelerix albiventris) mimicking cytomegalic inclusion disease

The salivary glands from three African hedgehogs contained multiple foci of cytomegalic cells, which occasionally had a mild to moderate infiltrate of lymphocytes at the periphery. The cytomegalic cells were 35 to 40 microns in diameter with abundant acidophilic granular to hyalin cytoplasm. The nuclei were enlarged with clumped marginalized chromatin and a large, (6 to 8 microns in diameter) central, brightly eosinophilic nucleolus that had the appearance of an inclusion body by light microscopy. Histochemically most of the cytomegalic cells contained cytoplasmic metachromatic granules with Feyrter's thionine inclusion stain. Scattered cells at the periphery of the cytomegalic foci contained periodic acid-Schiff-positive cytoplasmic granules. Ultrastructurally the cytomegalic cells contained numerous tightly-packed, often bizarre, enlarged mitochondria that completely filled the cytoplasm. The nucleus consisted of a dense central core of chromatin associated with the nucleolus and the remaining chromatin was clumped and marginalized. Nuclear and cytoplasmic virions consistent with cytomegalovirus were not present. Histochemical stains of the nucleus for heavy metals were negative. The ultrastructural and histochemical findings of the cytomegalic cells were consistent with oncocytes. Previous reports in the literature of similar cells in the salivary glands of insectivores appear to have been erroneously described as cytomegalovirus infections.

Development of small-cell osteogenic sarcoma after ulnar ostectomy in a dog

A 5-year-old male Saint Bernard was evaluated for vague forelimb lameness. Four and a half years earlier, the dog had undergone left ulnar ostectomy to correct a valgus deformity. Focal bone lysis was evident radiographically at the ostectomy site. Four months later, marked bony swelling was apparent and the dog was bearing partial weight. The dog was euthanatized, and at necropsy, a bone tumor with lung metastasis was found. Microscopically, features of the tumor were compatible with those of small-cell osteogenic sarcoma.

Cloacal papillomas in psittacines

Papilloma-like masses affecting the cloaca of 19 Amazons, 16 macaws, 3 parrots, 1 conure, and 1 parakeet were examined. Papillomatous lesions were characterized by proliferation of the lining epithelium on thin fibrovascular stalks. Carcinoma in situ was diagnosed in the cloaca of a macaw in addition to the other 16 macaws with papillomas. Papillomavirus group-specific antigens were not detected in any of the 41 lesions, using the peroxidase-antiperoxidase technique. The DNA extracts from 6 different frozen papillomas did not contain papillomavirus genomes detectable by Southern blot hybridization, using an African gray parrot cutaneous papillomavirus as a probe. Evidence of an infective agent was not found by electron microscopic examination of 8 of the papillomas. Inoculations of partially purified homogenates of a cloacal papilloma from a yellow-crowned Amazon did not induce lesion formation on cloacal mucosa of an adult yellow-crowned Amazon, green and yellow macaw, sulphur-crested cockatoo, or mollucan cockatoo.

Myopathy in the nyala

Between January 1973 and June 1981, a total of 21 nyalas (Tragelaphus angasi) died with clinical and/or pathologic evidence of myopathy. The main clinical signs were stiffness, inability to rise, and failure to suckle in newborn fawns. Death usually occurred without premonitory signs of disease. Gross lesions were characterized by white or pale patches of skeletal or cardiac muscle. Histologically, acute degeneration or necrosis and mineralization were commonly observed in skeletal muscle. Acute necrosis of the myocardium with or without arteriolar fibrinoid necrosis was usually found in juvenile animals. Interstitial fibrosis of the myocardium with arteriosclerosis was commonly observed in adults. The plasma alpha tocopherol values of 3 affected nyalas ranged from 0.03 to 0.08 mg/dl (mean, 0.05 mg/dl). Unaffected nyalas from the same herd had a range of 0.09 to 0.24 mg/dl (mean, 0.13 mg/dl), which is low enough to be considered clinically deficient. The blood selenium values of the affected nyalas and other nyalas from the same herd ranged from 0.30 to 0.33 ppm (mean, 0.32 ppm), and were considered normal.