Epigenetic MLH1 silencing concurs with mismatch repair deficiency in sporadic, naturally occurring colorectal cancer in rhesus macaques

BACKGROUND

Naturally occurring colorectal cancers (CRC) in rhesus macaques share many features with their human counterparts and are useful models for cancer immunotherapy; but mechanistic data are lacking regarding the comparative molecular pathogenesis of these cancers.

METHODS

We conducted state-of-the-art imaging including CT and PET, clinical assessments, and pathological review of 24 rhesus macaques with naturally occurring CRC. Additionally, we molecularly characterized these tumors utilizing immunohistochemistry (IHC), microsatellite instability assays, DNAseq, transcriptomics, and developed a DNA methylation-specific qPCR assay for MLH1, CACNA1G, CDKN2A, CRABP1, and NEUROG1, human markers for CpG island methylator phenotype (CIMP). We furthermore employed Monte-Carlo simulations to in-silico model alterations in DNA topology in transcription-factor binding site-rich promoter regions upon experimentally demonstrated DNA methylation.

RESULTS

Similar cancer histology, progression patterns, and co-morbidities could be observed in rhesus as reported for human CRC patients. IHC identified loss of MLH1 and PMS2 in all cases, with functional microsatellite instability. DNA sequencing revealed the close genetic relatedness to human CRCs, including a similar mutational signature, chromosomal instability, and functionally-relevant mutations affecting KRAS (G12D), TP53 (R175H, R273*), APC, AMER1, ALK, and ARID1A. Interestingly, MLH1 mutations were rarely identified on a somatic or germline level. Transcriptomics not only corroborated the similarities of rhesus and human CRCs, but also demonstrated the significant downregulation of MLH1 but not MSH2, MSH6, or PMS2 in rhesus CRCs. Methylation-specific qPCR suggested CIMP-positivity in 9/16 rhesus CRCs, but all 16/16 exhibited significant MLH1 promoter hypermethylation. DNA hypermethylation was modelled to affect DNA topology, particularly propeller twist and roll profiles. Modelling the DNA topology of a transcription factor binding motif (TFAP2A) in the MLH1 promoter that overlapped with a methylation-specific probe, we observed significant differences in DNA topology upon experimentally shown DNA methylation. This suggests a role of transcription factor binding interference in epigenetic silencing of MLH1 in rhesus CRCs.

CONCLUSIONS

These data indicate that epigenetic silencing suppresses MLH1 transcription, induces the loss of MLH1 protein, abrogates mismatch repair, and drives genomic instability in naturally occurring CRC in rhesus macaques. We consider this spontaneous, uninduced CRC in immunocompetent, treatment-naïve rhesus macaques to be a uniquely informative model for human CRC.

Systemic Immune Response to a CD40-Agonist Antibody in Nonhuman Primates

The cell surface molecule CD40 is a member of the tumor necrosis factor receptor superfamily and is broadly expressed by immune cells including B cells, dendritic cells (DC), and monocytes, as well as other normal cells and some malignant cellsCD40 is constitutively expressed on antigen-presenting cells (APCs) and ligation promotes functional maturation leading to an increase in antigen presentation, cytokine production, and a subsequent increase in the activation of antigen specific T cells. It is postulated that CD40 agonists can mediate both T-cell-dependent and T-cell-independent immune mechanisms of tumor regression in mice and patients. In addition, it is believed that CD40 activation also promotes apoptotic death of tumor cells and that the presence of the molecule on the surface of cancer cells is an important factor in the generation of tumor-specific T-cell responses that contribute to tumor cell elimination. Notably, CD40-agonistic therapies were evaluated in patients with solid tumors and hematologic malignancies with reported success as a single agent. Preclinical studies have shown that subcutaneous administration of CD40-agonistic antibodies reduces systemic toxicity and elicits a stronger and localized pharmacodynamic response. Two independent studies in cynomolgus macaque (Macaca fascicularis) studies were performed to further evaluate, potentially immunotoxicological effects associated with drug-induced adverse events seen in human subjects. Studies conducted in monkeys showed that when selicrelumab is administered at doses currently used in clinical trial patients, via subcutaneous injection, it is safe and effective at stimulating a systemic immune response.

The TLR2/TLR6 ligand FSL-1 mitigates radiation-induced hematopoietic injury in mice and nonhuman primates

Thrombocytopenia, hemorrhage, anemia, and infection are life-threatening issues following accidental or intentional radiation exposure. Since few therapeutics are available, safe and efficacious small molecules to mitigate radiation-induced injury need to be developed. Our previous study showed the synthetic TLR2/TLR6 ligand fibroblast stimulating lipopeptide (FSL-1) prolonged survival and provided MyD88-dependent mitigation of hematopoietic acute radiation syndrome (H-ARS) in mice. Although mice and humans differ in TLR number, expression, and function, nonhuman primate (NHP) TLRs are like those of humans; therefore, studying both animal models is critical for drug development. The objectives of this study were to determine the efficacy of FSL-1 on hematopoietic recovery in small and large animal models subjected to sublethal total body irradiation and investigate its mechanism of action. In mice, we demonstrate a lack of adverse effects, an easy route of delivery (subcutaneous) and efficacy in promoting hematopoietic progenitor cell proliferation by FSL-1. NHP given radiation, followed a day later with a single subcutaneous administration of FSL-1, displayed no adversity but showed elevated hematopoietic cells. Our analyses revealed that FSL-1 promoted red blood cell development and induced soluble effectors following radiation exposure. Cytologic analysis of bone marrow aspirates revealed a striking enhancement of mononuclear progenitor cells in FSL-1-treated NHP. Combining the efficacy of FSL-1 in promoting hematopoietic cell recovery with the lack of adverse effects induced by a single administration supports the application of FSL-1 as a viable countermeasure against H-ARS.

Delayed effects of radiation in adipose tissue reflect progenitor damage and not cellular senescence

The pathogenesis of many age-related diseases is linked to cellular senescence, a state of inflammation-inducing, irreversible cell cycle arrest. The consequences and mechanisms of age-associated cellular senescence are often studied using in vivo models of radiation exposure. However, it is unknown whether radiation induces persistent senescence, like that observed in ageing. We performed analogous studies in mice and monkeys, where young mice and rhesus macaques received sub-lethal doses of ionizing radiation and were observed for ~ 15% of their expected lifespan. Assessments of 8-hydroxy-2' -deoxyguanosine (8-OHdG), senescence-associated beta-galactosidase (SAβ-gal), and p16Ink4a and p21 were performed on mitotic and post-mitotic tissues - liver and adipose tissue - 6 months and 3 years post-exposure for the mice and monkeys, respectively. No elevations in 8-OHdG, SA-βgal staining, or p16 Ink4a or p21 gene or protein expression were found in mouse and monkey liver or adipose tissue compared to control animals. Despite no evidence of senescence, progenitor cell dysfunction persisted after radiation exposure, as indicated by lower in situ CD34+ adipose cells (p = 0.03), and deficient adipose stromal vascular cell proliferation (p < 0.05) and differentiation (p = 0.04) ex vivo. Our investigation cautions that employing radiation to study senescence-related processes should be limited to the acute post-exposure period and that stem cell damage likely underpins the dysfunction associated with delayed effects of radiation.

Epizootic Yersinia enterocolitica in captive African green monkeys (Chlorocebus aethiops sabaeus)

Yersinia enterocolitica is a Gram-negative bacterium that typical results in enterocolitis in humans and poses significant worldwide risks to public health. An outbreak of yersiniosis in the Vervet/African green monkey colony at the WFSM during the winter of 2015-2016 accounted for widespread systemic infection with high morbidity and mortality. Most of the cases had extensive necrosis with suppuration and large colonies of bacilli in the large bowel and associated lymph nodes; however, the small intestine, stomach, and other organs were also regularly affected. Positive cultures of Yersinia enterocolitica were recovered from affected tissues in 20 of the 23 cases. Carrier animals in the colony were suspected as the source of the infection because many clinically normal animals were culture-positive during and after the outbreak. In this study, we describe the gross and histology findings and immune cell profiles in different organs of affected animals. We found increased numbers of myeloid-derived phagocytes and CD11C-positive antigen-presenting cells and fewer adaptive T and B lymphocytes, suggesting an immunocompromised state in these animals. The pathogen-mediated microenvironment may have contributed to the immunosuppression and rapid spread of the infection in the vervets. Further studies in vervets could provide a better understanding of Yersinia-mediated pathogenesis and immunosuppression, which could be fundamental to understanding chronic and systemic inflammatory diseases in humans.

Retrograde Parotid Gland Infusion through Stensen's Duct in a Non-Human Primate for Vectored Gene Delivery

Salivary glands are an attractive tissue target for gene therapy with promising results already leading to human trials. They are inherently capable of secreting proteins into the bloodstream and are easily accessible, making them potentially superior tissue sites for replacement hormone production or vaccination by gene transfer. Suggested methods for gene delivery include transcutaneous injection and retrograde infusion through salivary ducts. We demonstrate how to perform Retrograde Salivary Gland Infusion (RSGI) in non-human primates. We describe the important anatomic landmarks including identification of the parotid papilla, an atraumatic method of cannulating and sealing Stensen's Duct utilizing basic dental tools, polyethylene tubing, and cyanoacrylate, and the appropriate rate of infusion. While this is the least traumatic method of delivery, the method is still limited by the volume able to be delivered (<0.5 mL) and the potential for trauma to the duct and gland. We demonstrate using fluoroscopy that an infusate can be fully delivered into the gland, and further demonstrate by immunohistochemistry the transduction of a typical vector and expression of the delivered gene.

Effects of nitrite and far-red light on coagulation

Nitric oxide, NO, has been explored as a therapeutic agent to treat thrombosis. In particular, NO has potential in treating mechanical device-associated thrombosis due to its ability to reduce platelet activation and due to the central role of platelet activation and adhesion in device thrombosis. Nitrite is a unique NO donor that reduces platelet activation in that it's activity requires the presence of red blood cells whereas NO activity of other NO donors is blunted by red blood cells. Interestingly, we have previously shown that red blood cell mediated inhibition of platelet activation by adenosine diphosophate (ADP) is dramatically enhanced by illumination with far-red light that is likely due to photolysis of red cell surface bound NO congeners. We now report the effects of nitrite, far-red light, and their combination on several measure of blood coagulation using a variety of agonists. We employed turbidity assays in platelet rich plasma, platelet activation using flow cytometry analysis of a fluorescently labeled antibody to the activated platelet fibrinogen binding site, multiplate impedance-based platelet aggregometry, and assessment of platelet adhesion to collagen coated flow-through microslides. In all cases, the combination of far-red light and nitrite treatment decreased measures of coagulation, but in some cases mono-treatment with nitrite or light alone had no effect. Perhaps most relevant to device thrombosis, we observed that platelet adhesions was inhibited by the combination of nitrite and light treatment while nitrite alone and far-red light alone trended to decrease adhesion, but the results were mixed. These results support the potential of combined far-red light and nitrite treatment for preventing thrombosis in extra-corporeal or shallow-tissue depth devices where the far-red light can penetrate. Such a combined treatment could be advantageous due to the localized treatment afforded by far-red light illumination with minimal systemic effects. Given the role of thrombosis in COVID 19, application to treatment of patients infected with SARS Cov-2 might also be considered.

Improved Antitumor Activity of the Fluoropyrimidine Polymer CF10 in Preclinical Colorectal Cancer Models through Distinct Mechanistic and Pharmacologic Properties

Chemotherapy regimens that include 5-fluorouracil (5-FU) are central to colorectal cancer treatment; however, risk/benefit concerns limit 5-FU's use, necessitating development of improved fluoropyrimidine (FP) drugs. In our study, we evaluated a second-generation nanoscale FP polymer, CF10, for improved antitumor activity. CF10 was more potent than the prototype FP polymer F10 and much more potent than 5-FU in multiple colorectal cancer cell lines including HCT-116, LS174T, SW480, and T84D. CF10 displayed improved stability to exonuclease degradation relative to F10 and reduced susceptibility to thymidine antagonism due to extension of the polymer with arabinosyl cytidine. In colorectal cancer cells, CF10 strongly inhibited thymidylate synthase (TS), induced Top1 cleavage complex formation and caused replication stress, while similar concentrations of 5-FU were ineffective. CF10 was well tolerated in vivo and invoked a reduced inflammatory response relative to 5-FU. Blood chemistry parameters in CF10-treated mice were within normal limits. In vivo, CF10 displayed antitumor activity in several colorectal cancer flank tumor models including HCT-116, HT-29, and CT-26. CF10's antitumor activity was associated with increased plasma levels of FP deoxynucleotide metabolites relative to 5-FU. CF10 significantly reduced tumor growth and improved survival (84.5 days vs. 32 days; P < 0.0001) relative to 5-FU in an orthotopic HCT-116-luc colorectal cancer model that spontaneously metastasized to liver. Improved survival in the orthotopic model correlated with localization of a fluorescent CF10 conjugate to tumor. Together, our preclinical data support an early-phase clinical trial of CF10 for treatment of colorectal cancer.

Tumor-targeted 4-1BB agonists for combination with T cell bispecific antibodies as off-the-shelf therapy

Endogenous costimulatory molecules on T cells such as 4-1BB (CD137) can be leveraged for cancer immunotherapy. Systemic administration of agonistic anti-4-1BB antibodies, although effective preclinically, has not advanced to phase 3 trials because they have been hampered by both dependency on Fcγ receptor-mediated hyperclustering and hepatotoxicity. To overcome these issues, we engineered proteins simultaneously targeting 4-1BB and a tumor stroma or tumor antigen: FAP-4-1BBL (RG7826) and CD19-4-1BBL. In the presence of a T cell receptor signal, they provide potent T cell costimulation strictly dependent on tumor antigen-mediated hyperclustering without systemic activation by FcγR binding. We could show targeting of FAP-4-1BBL to FAP-expressing tumor stroma and lymph nodes in a colorectal cancer-bearing rhesus monkey. Combination of FAP-4-1BBL with tumor antigen-targeted T cell bispecific (TCB) molecules in human tumor samples led to increased IFN-γ and granzyme B secretion. Further, combination of FAP- or CD19-4-1BBL with CEA-TCB (RG7802) or CD20-TCB (RG6026), respectively, resulted in tumor remission in mouse models, accompanied by intratumoral accumulation of activated effector CD8⁺ T cells. FAP- and CD19-4-1BBL thus represent an off-the-shelf combination immunotherapy without requiring genetic modification of effector cells for the treatment of solid and hematological malignancies.

Tetravalent dengue DNA vaccine is not immunogenic when delivered by retrograde infusion into salivary glands

Introduction and background

A tetravalent DNA vaccine for Dengue virus is under development but has not yet achieved optimal immunogenicity. Salivary glands vaccination has been reported efficacious in rodents and dogs. We report on a pilot study testing the salivary gland as a platform for a Dengue DNA vaccine in a non-human primate model.

Materials and methods

Four cynomolgus macaques were used in this study. Each macaque was pre-medicated with atropine and sedated with ketamine. Stensen’s duct papilla was cannulated with a P10 polyethylene tube, linked to a 500ul syringe. On the first two infusions, all macaques were infused with 300ul of TVDV mixed with 2 mg of zinc. For the 3rd infusion, to increase transfection into salivary tissue, two animals received 100uL TVDV mixed with 400uL polyethylenimine 1μg/ml (PEI) and the other two animals received 500uL TVDV with zinc. Antibody titers were assessed 4 weeks following the second and third infusion.

Results and conclusions

SGRI through Stensen’s duct is a well-tolerated, simple and easy to reproduce procedure. TVDV infused into macaques salivary glands elicited a significantly weaker antibody response than with different delivery methods.

Endometrium and endometriosis tissue mitochondrial energy metabolism in a nonhuman primate model

BACKGROUND

Endometriosis is the growth of uterine lining (endometrium) outside of the uterus. In other chronic inflammatory diseases, mitochondrial dysfunction is suspected of playing a role in disease pathogenesis. However, little is known about endometriosis mitochondrial function or its effects on tissue metabolism. The objectives of this study were to analyze mitochondrial function in nonhuman primate (NHP) endometrium and endometriosis tissue and to identify the metabolic features of these tissues that may contribute to disease.

METHODS

Mitochondrial function in endometriosis tissue and endometrium was measured using mitochondrial respirometry analysis to determine if changes in oxidative phosphorylation exist in endometrium and endometriosis tissue compared to control endometrium from clinically healthy NHPs. Targeted metabolomics and multidimensional statistical analysis were applied to quantify key metabolites in energy and amino acid biosynthesis pathways.

RESULTS

Mitochondrial respirometry assays showed endometrium from NHPs with endometriosis had reduced complex II-mediated oxygen consumption rates (OCR) across all energy states (basal, p = 0.01; state 3, p = 0.02; state 3u, p = 0.04; state 4o, p = 0.008) and endometriosis tissue had reduced state 3, complex I-mediated OCR (p = 0.02) and respiratory control rates (p = 0.01) compared to normal endometrium. Targeted metabolomics performed on tissue revealed carnitine (p = 0.001), creatine phosphate (p = 0.01), NADH (p = 0.0001), FAD (p = 0.001), tryptophan (p = 0.0009), and malic acid (p = 0.005) were decreased in endometriosis tissue compared to normal endometrium samples. FAD (p = 0.004), tryptophan (p = 0.0004) and malic acid (p = 0.03) were significantly decreased in endometrium from NHPs with endometriosis compared to normal endometrium. Significant metabolites identified in endometriosis and endometrium samples from animals with endometriosis were part of amino acid biosynthesis or energy metabolism pathways.

CONCLUSIONS

Here, endometrial mitochondrial energy production and metabolism were decreased in endometrium and endometriosis tissue. Decreased mitochondrial energy production may be due to oxidative stress-induced damage to mitochondrial DNA or membranes, a shift in cell metabolism, or decreased energy substrate; however, the exact cause remains unknown. Additional research is needed to determine the implications of reduced mitochondrial energy production and metabolism on endometriosis and endometrium.

Canine Snake-Eye Myelopathy: Clinical, Magnetic Resonance Imaging, and Pathologic Findings in Four Cases

Intramedullary signal change (ISC) is a non-specific finding that is frequently observed on magnetic resonance imaging (MRI) examinations of the canine spinal cord. ISC can represent a variety of primary pathological processes such as neoplasms or myelitides or secondary changes such as edema, cysts, gliosis, or myelomalacia. An unusual phenotype of ISC is the “snake-eye” myelopathy (SEM), which refers to bilaterally symmetric T2 hyperintensities preferentially affecting the ventral horn gray matter on transverse MR images, which resemble a pair of snake's eyes. The pathophysiology of SEM is poorly understood in humans, and this imaging finding may be associated with cervical spondylotic myelopathy, spinal cord ischemia, ossification of the posterior longitudinal ligament, amyotrophic lateral sclerosis, and Hirayama disease. Here we describe four dogs with cervical MRI examinations consistent with an SEM-like phenotype. All dogs initially presented with a central cord syndrome or tetraparesis referable to a C6-T2 neuroanatomic localization, which was attributed to disc-associated spinal cord compression in three cases, while one dog had the SEM-like phenotype with no identifiable etiology. Once the SEM-like phenotype was present on MRI examinations, dogs demonstrated insidious clinical deterioration despite therapeutic interventions. Deterioration was characterized by lower motor neuron weakness and neurogenic muscle atrophy progressing to paralysis in the thoracic limbs, while neurological functions caudal to the level of the SEM-like lesion remained largely preserved for months to years thereafter. Neuropathological features of the SEM-like phenotype include multisegmental cavitations and poliomyelomalacia of laminae VI-IX of the caudal cervical spinal cord, although the lesion evolved into pan-necrosis of gray matter with extension into the adjacent white matter in one case with an 8 years history of progressive disease. Although the pathophysiology of SEM remains unknown, the topographical distribution and appearance of lesions is suggestive of a vascular disorder. As the SEM-like phenotype was uniformly characterized by longitudinally and circumferentially extensive neuronal necrosis, results of this small case series indicate that dogs with clinical signs of central cord syndrome and the SEM-like phenotype involving the cervicothoracic intumescence on MR examinations have a poor prognosis for the preservation or recovery of thoracic limb motor function.

Transcriptional Profiling of Non-Human Primate Lymphoid Organ Responses to Total-Body Irradiation

The global threat of exposure to radiation and its subsequent outcomes require the development of effective strategies to mitigate immune cell injury. In this study we explored transcriptional and immunophenotypic characteristics of lymphoid organs of a non-human primate model after total-body irradiation (TBI). Fifteen middle-aged adult, ovariectomized, female cynomolgus macaques received a single dose of 0, 2 or 5 Gy gamma radiation. Thymus, spleen and lymph node from three controls and 2 Gy (n = 2) and 5 Gy (n = 2) exposed animals were assessed for molecular responses to TBI through microarray-based transcriptional profiling at day 5 postirradiation, and cellular changes through immunohistochemical (IHC) characterization of markers for B and T lymphocytes and macrophages across all 15 animals at time points up to 6 months postirradiation. Irradiated macaques developed acute hematopoietic syndrome. Analysis of array data at day 5 postirradiation identified transcripts with ≥2-fold difference from control and a false discovery rate (FDR) of Padj < 0.05 in lymph node (n = 666), spleen (n = 493) and thymus (n=3,014). Increasing stringency of the FDR to P < 0.001 reduced the number of genes to 71 for spleen and 379 for thymus. IHC and gene expression data demonstrated that irradiated animals had reduced numbers of T and B lymphocytes along with relative elevations of macrophages. Transcriptional analysis revealed unique patterns in primary and secondary lymphoid organs of cynomolgus macaques. Among the many differentially regulated transcripts, upregulation of noncoding RNAs [MIR34A for spleen and thymus and NEAT1 (NCRNA00084) for thymus] showed potential as biomarkers of radiation injury and targets for mitigating the effects of radiation-induced hematopoietic syndrome-impaired lymphoid reconstitution.

Tumour-specific amplitude-modulated radiofrequency electromagnetic fields induce differentiation of hepatocellular carcinoma via targeting Cav3.2 T-type voltage-gated calcium channels and Ca2+ influx

BACKGROUND

Administration of amplitude modulated 27·12 MHz radiofrequency electromagnetic fields (AM RF EMF) by means of a spoon-shaped applicator placed on the patient's tongue is a newly approved treatment for advanced hepatocellular carcinoma (HCC). The mechanism of action of tumour-specific AM RF EMF is largely unknown.

METHODS

Whole body and organ-specific human dosimetry analyses were performed. Mice carrying human HCC xenografts were exposed to AM RF EMF using a small animal AM RF EMF exposure system replicating human dosimetry and exposure time. We performed histological analysis of tumours following exposure to AM RF EMF. Using an agnostic genomic approach, we characterized the mechanism of action of AM RF EMF.

FINDINGS

Intrabuccal administration results in systemic delivery of athermal AM RF EMF from head to toe at levels lower than those generated by cell phones held close to the body. Tumour shrinkage results from differentiation of HCC cells into quiescent cells with spindle morphology. AM RF EMF targeted antiproliferative effects and cancer stem cell inhibiting effects are mediated by Ca2+ influx through Cav3·2 T-type voltage-gated calcium channels (CACNA1H) resulting in increased intracellular calcium concentration within HCC cells only.

INTERPRETATION

Intrabuccally-administered AM RF EMF is a systemic therapy that selectively block the growth of HCC cells. AM RF EMF pronounced inhibitory effects on cancer stem cells may explain the exceptionally long responses observed in several patients with advanced HCC. FUND: Research reported in this publication was supported by the National Cancer Institute's Cancer Centre Support Grant award number P30CA012197 issued to the Wake Forest Baptist Comprehensive Cancer Centre (BP) and by funds from the Charles L. Spurr Professorship Fund (BP). DWG is supported by R01 AA016852 and P50 AA026117.

Systemic Iron Deficiency in a Nonhuman Primate Model of Endometriosis

Endometriosis is characterized by endometrial tissue development outside the uterus. Anemia and iron depletion do not commonly accompany endometriosis in women, despite chronic abdominal inflammation and heavy menstrual bleeding. The objective of this study was to examine iron kinetics associated with endometriosis by using a NHP model, to better understand the underlying mechanism of abnormal hematogram values in women with endometriosis. Hematologic data from 46 macaques with endometriosis were examined for signs of iron depletion. Bone marrow, liver, and serum were used to elucidate whether iron loss or inflammation best explained the hematologic findings. Additional serum markers and intestinal biopsies from NHP with and without endometriosis were evaluated for patterns in iron kinetics across the menstrual cycle and for relative dietary iron-absorbing capacity. Almost half of the NHP with endometriosis were anemic. Overall, NHP had decreased RBC counts, increased MCV, increased percentage of reticulocytes, decreased serum hepcidin, and decreased hepatic and bone marrow iron. Intestinal expression of ferroportin 1, a mediator of iron absorption, was increased, indicating that despite high dietary iron, intestinal iron absorption did not compensate for iron losses. We concluded that use of oral iron supplementation alone does not replenish iron stores in endometriosis. Consequently, iron stores should be evaluated in women with endometriosis, even without overt clinical signs of anemia.

Fibronectin Produced by Cerebral Endothelial and Vascular Smooth Muscle Cells Contributes to Perivascular Extracellular Matrix in Late-Delayed Radiation-Induced Brain Injury

Late-delayed radiation-induced brain injury (RIBI) is a major adverse effect of fractionated whole-brain irradiation (fWBI). Characterized by progressive cognitive dysfunction, and associated cerebrovascular and white matter injury, RIBI deleteriously affects quality of life for cancer patients. Despite extensive morphological characterization of the injury, the pathogenesis is unclear, thus limiting the development of effective therapeutics. We previously reported that RIBI is associated with increased gene expression of the extracellular matrix (ECM) protein fibronectin (FN1). We hypothesized that fibronectin contributes to perivascular ECM, which may impair diffusion to the dependent parenchyma, thus contributing to the observed cognitive decline. The goal of this study was to determine the localization of fibronectin in RIBI and further characterize the composition of perivascular ECM, as well as identify the cell of origin for FN1 by in situ hybridization. Briefly, fibronectin localized to the vascular basement membrane of morphologically normal blood vessels from control comparators and animals receiving fWBI, and to the perivascular space of edematous and fibrotic vascular phenotypes of animals receiving fWBI. Additional mild diffuse parenchymal staining in areas of vascular injury suggested blood-brain-barrier disruption and plasma fibronectin extravasation. Perivascular ECM lacked amyloid and contained lesser amounts of collagens I and IV, which localized to the basement membrane. These changes occurred in the absence of alterations in microvascular area fraction or microvessel density. Fibronectin transcripts were rarely expressed in control comparators, and were most strongly induced within cerebrovascular endothelial and vascular smooth muscle cells after fWBI. Our results demonstrate that fibronectin is produced by cerebrovascular endothelial and smooth muscle cells in late-delayed RIBI and contributes to perivascular ECM, which we postulate may contribute to diffusion barrier formation. We propose that pathways that antagonize fibronectin deposition and matrix assembly or enhance degradation may serve as potential therapeutic targets in RIBI.

Labyrinthitis Ossificans in a Cynomolgus Macaque (Macaca fascicularis)

Labyrinthitis is inflammation of the membranous and bony labyrinth of the inner ear. Typical portals of entry includehematogenous spread from the cochlear vasculature, passage of otitis media pathogens through the round window, and mostcommonly, meningogenic spread from the subarachnoid space. The sequela of chronic inner ear inflammation is labyrinthitisossificans, in which inner ear structures are replaced by fibrous and osseous tissues. Labyrinthitis in humans has been reportedconcurrently with infection due to various viruses (for example, varicella-zoster, measles, mumps) and bacteria (for example,Treponema pallidum, Streptococcus pneumoniae) and may be associated with vertebrobasilar ischemia and meningitis. Profoundsensorineural hearing loss is a common, serious complication of this disease. Here, we report a case of labyrinthitisossificans in a cynomolgus macaque (Macaca fascicularis) with a potential infectious etiology. Historically, this animal hadan indwelling femoral intravenous catheter for more than 4 y. He presented with a right-sided head tilt and incoordinationof 2 mo duration. The macaque was treated with NSAID and antibiotics, which corrected the incoordination but not the headtilt. MRI revealed right-sided labyrinthitis, and euthanasia was elected due to clinical signs that were refractory to treatment.Gross pathology was unremarkable, but histopathology revealed chronic labyrinthitis ossificans with local fibroplasia andvestibuloauditory neuritis. We describe here the clinical features, imaging, and histologic lesions of labyrinthitis in a macaque.

Potential therapeutic action of nitrite in sickle cell disease

Sickle cell disease is caused by a mutant form of hemoglobin that polymerizes under hypoxic conditions, increasing rigidity, fragility, calcium influx-mediated dehydration, and adhesivity of red blood cells. Increased red cell fragility results in hemolysis, which reduces nitric oxide (NO) bioavailability, and induces platelet activation and inflammation leading to adhesion of circulating blood cells. Nitric Oxide inhibits adhesion and platelet activation. Nitrite has emerged as an attractive therapeutic agent that targets delivery of NO activity to areas of hypoxia through bioactivation by deoxygenated red blood cell hemoglobin. In this study, we demonstrate anti-platelet activity of nitrite at doses achievable through dietary interventions with comparison to similar doses with other NO donating agents. Unlike other NO donating agents, nitrite activity is shown to be potentiated in the presence of red blood cells in hypoxic conditions. We also show that nitrite reduces calcium associated loss of phospholipid asymmetry that is associated with increased red cell adhesion, and that red cell deformability is also improved. We show that nitrite inhibits red cell adhesion in a microfluidic flow-channel assay after endothelial cell activation. In further investigations, we show that leukocyte and platelet adhesion is blunted in nitrite-fed wild type mice compared to control after either lipopolysaccharide- or hemolysis-induced inflammation. Moreover, we demonstrate that nitrite treatment results in a reduction in adhesion of circulating blood cells and reduced red blood cell hemolysis in humanized transgenic sickle cell mice subjected to local hypoxia. These data suggest that nitrite is an effective anti-platelet and anti-adhesion agent that is activated by red blood cells, with enhanced potency under physiological hypoxia and in venous blood that may be useful therapeutically.

The novel phospholipid mimetic KPC34 is highly active against preclinical models of Philadelphia chromosome positive acute lymphoblastic leukemia

Philadelphia chromosome positive B cell acute lymphoblastic leukemia (Ph+ ALL) is an aggressive cancer of the bone marrow. The addition of tyrosine kinase inhibitors (TKIs) has improved outcomes but many patients still suffer relapse and novel therapeutic agents are needed. KPC34 is an orally available, novel phospholipid conjugate of gemcitabine, rationally designed to overcome multiple mechanisms of resistance, inhibit the classical and novel isoforms of protein kinase C, is able to cross the blood brain barrier and is orally bioavailable. KPC34 had an IC50 in the nanomolar range against multiple ALL cell lines tested but was lowest for Ph+ lines. In mice bearing either naïve or resistant Ph+ ALL, KPC34 treatment resulted in significantly improved survival compared to cytarabine and gemcitabine. Treatment with KPC34 and doxorubicin was more effective than doxorubicin and cytarabine. Mice with recurrence of their ALL after initial treatment with cytarabine and doxorubicin saw dramatic improvements in hind limb paralysis after treatment with KPC34 demonstrating activity against established CNS disease. Consistent with this KPC34 was better than gemcitabine at reducing CNS leukemic burden. These promising pre-clinical results justify the continued development of KPC34 for the treatment of Ph+ALL.

Abdominal Wall Endometriosis in a Rhesus Macaque (Macaca mulatta)

Endometriosis is the presence of endometrium outside of the uterus. Although endometriosis occurs in both pelvic and extrapelvic locations, extrapelvic locations are less common. The development of abdominal wall or incisional endometriosis in women is associated with gynecologic surgeries and is often misdiagnosed. Because they naturally develop endometriosis similar to women, Old World NHP, including rhesus macaques, provide excellent opportunities for studying endometriosis. Here, we describe a case of abdominal wall endometriosis in a rhesus macaque that had undergone cesarean section. Microscopically, the tissue consisted of pseudocolumnar epithelium-lined glands within a decidualized stroma, which dissected through the abdominal wall musculature and into the adjacent subcutaneous tissue. The stroma was strongly positive for vimentin and CD10 but was rarely, weakly positive for estrogen receptors and negative for progesterone. Close examination of extrapelvic endometriosis in rhesus macaques and other NHP may promote increased understanding of endometriosis in women.

Treatment with a selective histone deacetylase 6 inhibitor decreases lupus nephritis in NZB/W mice

To date, there are 18 histone deacetylase (HDAC) enzymes, divided into four classes, which alter protein function by removing acetyl groups from lysine residues. Prior studies report that non-selective HDAC inhibitors decrease disease in lupus mouse models. Concern for adverse side effects of non-selective HDAC inhibition supports investigation of selective-HDAC inhibition. We hypothesized that a selective HDAC-6 inhibitor (HDAC6i) will alleviate disease in a mouse model of lupus by increasing acetylation of alpha-tubulin. Intraperitoneal injections of the selective HDAC6i ACY-1083 (0.3 mg/kg, 1 mg/kg, or 3 mg/kg), vehicle control, or dexamethasone were administered to 21-week-old, female NZB/W mice, 5 days a week, for 13 weeks. Disease progression was evaluated by proteinuria, serum levels of anti-dsDNA antibody, cytokines and immunoglobulins, and post mortem evaluation of nephritis and T cell populations in the spleen. HDAC6i treatment decreased proteinuria, glomerular histopathology, IgG, and C3 scores when compared to vehicle-treated mice. Within glomeruli of HDAC6i-treated mice, there was increased acetylation of alpha-tubulin and decreased NF-κB. Additionally, HDAC6i decreased serum IL-12/IL-23 and Th17 cells in the spleen. Taken together, these results suggest HDAC-6 inhibition may decrease lupus nephritis in NZB/W mice via mechanisms involving acetylation of alpha-tubulin and decreased NF-κB in glomeruli as well as inhibition of Th17 cells.

Late Effects of Total-Body Gamma Irradiation on Cardiac Structure and Function in Male Rhesus Macaques

Heart disease is an increasingly recognized, serious late effect of radiation exposure, most notably among breast cancer and Hodgkin's disease survivors, as well as the Hiroshima and Nagasaki atomic bomb survivors. The purpose of this study was to evaluate the late effects of total-body irradiation (TBI) on cardiac morphology, function and selected circulating biomarkers in a well-established nonhuman primate model. For this study we used male rhesus macaques that were exposed to a single total-body dose of ionizing gamma radiation (6.5-8.4 Gy) 5.6-9.7 years earlier at ages ranging from ∼3-10 years old and a cohort of nonirradiated controls. Transthoracic echocardiography was performed annually for 3 years on 20 irradiated and 11 control animals. Myocardium was examined grossly and histologically, and myocardial fibrosis/collagen was assessed microscopically and by morphometric analysis of Masson's trichrome-stained sections. Serum/plasma from 27 irradiated and 13 control animals was evaluated for circulating biomarkers of cardiac damage [N-terminal pro B-type natriuretic protein (nt-proBNP) and troponin-I], inflammation (CRP, IL-6, MCP-1, sICAM) and microbial translocation [LPS-binding protein (LBP) and sCD14]. A higher prevalence of histological myocardial fibrosis was observed in the hearts obtained from the irradiated animals (9/14) relative to controls (0/3) (P = 0.04, χ(2)). Echocardiographically determined left ventricular end diastolic and systolic diameters were significantly smaller in irradiated animals (repeated measures ANOVA, P < 0.001 and P < 0.008, respectively). Histomorphometric analysis of trichrome-stained sections of heart tissue demonstrated ∼14.9 ± 1.4% (mean ± SEM) of myocardial area staining for collagen in irradiated animals compared to 9.1 ± 0.9 % in control animals. Circulating levels of MCP-1 and LBP were significantly higher in irradiated animals (P < 0.05). A high incidence of diabetes in the irradiated animals was associated with higher plasma triglyceride and lower HDLc but did not appear to be associated with cardiovascular phenotypes. These results demonstrate that single total-body doses of 6.5-8.4 Gy produced long-term effects including a high incidence of myocardial fibrosis, reduced left ventricular diameter and elevated systemic inflammation. Additional prospective studies are required to define the time course and mechanisms underlying radiation-induced heart disease in this model.

Decidualization of Endometriosis in Macaques

The decidua is the superficial portion of endometrium that transforms, or decidualizes, under the influence of progesterone to nourish the early embryo during pregnancy. Deciduae outside the uterus are found in nearly 100% of human pregnancies. This condition, known as deciduosis, may mimic malignancy, resulting in additional diagnostic procedures that place the mother, baby, or both at risk. Deciduosis has been described in both Old World and New World nonhuman primates in conjunction with pregnancy and after treatment with exogenous progestins. Here the authors present 6 cases of deciduosis associated with endometriotic lesions in female rhesus and cynomolgus macaques (Macaca mulatta and Macaca fascicularis). Full diagnostic necropsies with histologic analyses were performed on all animals. Deciduae were stained with hematoxylin and eosin and by immunohistochemistry for vimentin, CD10, progesterone receptor, estrogen receptor, desmin, cytokeratin, kermix P8, chorionic gonadotropin, human placental lactogen, and calretinin. The most common clinical signs were abdominal pain (4 of 6) and anorexia (2 of 6). At necropsy, macaque uteri were often enlarged or disfigured (4 of 6) with abundant fibrous adhesions (5 of 6). Affected tissue consisted of epithelial-lined cysts and decidualized stroma with scattered gamma/delta T cells. Decidualized stromal cells were large and polyhedral with abundant cytoplasm and round vesicular nuclei. They stained positive for vimentin, CD10, progesterone, and estrogen. In summary, these cases illustrate deciduosis in 6 nonhuman primates with endometriosis. Understanding decidualization in nonhuman primates will aid in elucidating the pathophysiology of deciduosis during pregnancy or endometriosis and potentially lead to new interventions.

Downregulation of apelin in the human placental chorionic villi from preeclamptic pregnancies

The role of the endogenous apelin system in pregnancy is not well understood. Apelin's actions in pregnancy are further complicated by the expression of multiple forms of the peptide. Using radioimmunoassay (RIA) alone, we established the expression of apelin content in the chorionic villi of preeclamptic (PRE) and normal pregnant women (NORM) at 36-38 wk of gestation. Total apelin content was lower in PRE compared with NORM chorionic villi (49.7±3.4 vs. 72.3±9.8 fmol/mg protein; n=20-22) and was associated with a trend for lower preproapelin mRNA in the PRE. Further characterization of apelin isoforms by HPLC-RIA was conducted in pooled samples from each group. The expression patterns of apelin peptides in NORM and PRE villi revealed little or no apelin-36 or apelin-17. Pyroglutamate apelin-13 [(Pyr1)-apelin-13] was the predominant form of the peptide in NORM and PRE villi. Angiotensin-converting enzyme 2 (ACE2) activity was higher in PRE villi (572.0±23.0 vs. 485.3±24.8 pmol·mg(-1)·min(-1); n=18-22). A low dose of ANG II (1 nM; 2 h) decreased apelin release in NORM villous explants that was blocked by the ANG II receptor 1 (AT1) antagonist losartan. Moreover, losartan enhanced apelin release above the 2-h baseline levels in both NORM and PRE villi (P<0.05). In summary, these studies are the first to demonstrate the lower apelin content in human placental chorionic villi of PRE subjects using quantitative RIA. (Pyr1)-apelin-13 is the predominant form of endogenous apelin in the chorionic villi of NORM and PRE. The potential mechanism of lower apelin expression in the PRE villi may involve a negative regulation of apelin by ANG II.

HDAC expression and activity is upregulated in diseased lupus-prone mice

Prior studies have shown that pan-HDAC inhibition can decrease disease in lupus mice; however, the mechanisms(s) remain to be elucidated. MRL/MpJ-Fas(lpr) (MRL/lpr) mice develop a lupus-like disease characterized by anti-dsDNA production, lymphoproliferation, and immune complex-mediated glomerulonephritis. Early- and late-disease (12 and 20weeks-of-age respectively) female MRL/lpr mice were compared to age-matched, healthy C57BL/6 mice for HDAC expression and activity in bone marrow (BM) B cells, splenic B and T cells, and glomerular cells. We found that HDAC6 was significantly overexpressed in B cells, splenic T cells and glomerular cells, whereas HDAC9 expression was significantly increased in splenic T cells, BM B cells and glomerular cells. Due to the overexpression of HDAC6, we tested whether treatment with a selective HDAC6 inhibitor (ACY-738) or a pan-HDAC inhibitor (TsA) would decrease HDAC activity. ACY-738 significantly reduced cytoplasmic HDAC activity whereas TsA significantly decreased both nuclear and cytoplasmic HDAC activity. In vitro studies in mesangial cells showed that ACY-738 increased α-tubulin and Hsp90 acetylation resulting in decreased nuclear activation of NF-κB. Treatment of pre-B cells with ACY-738 decreased the Bcl-2:Bax ratio leading to a pro-apoptotic environment. These results suggest that increased HDAC6 expression and activity contribute to SLE pathogenesis, and isoform-selective HDAC inhibitors may prove beneficial in the treatment of SLE by acetylating key signaling and transcription factors in inflammation and cell activation.

The poison oligonucleotide F10 is highly effective against acute lymphoblastic leukemia while sparing normal hematopoietic cells

F10 is an oligonucleotide based on the thymidylate synthase (TS) inhibitory 5-fluorouracil (5-FU) metabolite, 5-fluoro-2'-deoxyuridine-5'-O-monophosphate. We sought to determine the activity of F10 against preclinical models of acute lymphoblastic leukemia (ALL). F10 treatment resulted in robust induction of apoptosis that could not be equaled by 100 fold more 5-FU. F10 was more potent than Ara-C and doxorubicin against a panel of murine and human ALL cells with an average IC₅₀ value of 1.48 nM (range 0.07 to 5.4 nM). F10 was more than 1000 times more potent than 5-FU. In vivo, F10 treatment significantly increased survival in 2 separate syngeneic ALL mouse models and 3 separate xenograft models. F10 also protected mice from leukemia-induced weight loss. In ALL cells made resistant to Ara-C, F10 remained highly active in vitro and in vivo. Using labeled F10, uptake by the ALL cell lines DG75 and SUP-B15 was rapid and profoundly temperature-dependent. Both cell lines demonstrated increased uptake compared to normal murine lineage- depleted marrow cells. Consistent with this decreased uptake, F10 treatment did not alter the ability of human hematopoietic stem cells to engraft in immunodeficient mice.

Molecular and cellular profiling of acute responses to total body radiation exposure in ovariectomized female cynomolgus macaques

PURPOSE

The threat of radiation exposure requires a mechanistic understanding of radiation-induced immune injury and recovery. The study objective was to evaluate responses to ionizing radiation in ovariectomized (surgically post-menopausal) female cynomolgus macaques.

MATERIALS AND METHODS

Animals received a single total-body irradiation (TBI) exposure at doses of 0, 2 or 5 Gy with scheduled necropsies at 5 days, 8 weeks and 24 weeks post-exposure. Blood and lymphoid tissues were evaluated for morphologic, cellular, and molecular responses.

RESULTS

Irradiated animals developed symptoms of acute hematopoietic syndrome, and reductions in thymus weight, thymopoiesis, and bone marrow cellularity. Acute, transient increases in plasma monocyte chemoattractant protein 1 (MCP-1) were observed in 5 Gy animals along with dose-dependent alterations in messenger ribonucleic acid (mRNA) signatures in thymus, spleen, and lymph node. Expression of T cell markers was lower in thymus and spleen, while expression of macrophage marker CD68 (cluster of differentiation 68) was relatively elevated in lymphoid tissues from irradiated animals.

CONCLUSIONS

Ovariectomized female macaques exposed to moderate doses of radiation experienced increased morbidity, including acute, dose-dependent alterations in systemic and tissue-specific biomarkers, and increased macrophage/T cell ratios. The effects on mortality exceeded expectations based on previous studies in males, warranting further investigation.

DMP1β, a splice isoform of the tumour suppressor DMP1 locus, induces proliferation and progression of breast cancer

Our recent work has indicated that the DMP1 locus on 7q21, encoding a haplo-insufficient tumour suppressor, is hemizygously deleted at a high frequency in breast cancer. The locus encodes DMP1α protein, an activator of the p53 pathway leading to cell cycle arrest and senescence, and two other functionally undefined isoforms, DMP1β and DMP1γ. In this study, we show that the DMP1 locus is alternatively spliced in ∼30% of breast cancer cases with relatively decreased DMP1α and increased DMP1β expression. RNA-seq analyses of a publicly available database showed significantly increased DMP1β mRNA in 43-55% of human breast cancers, dependent on histological subtypes. Similarly, DMP1β protein was found to be overexpressed in ∼60% of tumours relative to their surrounding normal tissue. Importantly, alteration of DMP1 splicing and DMP1β overexpression were associated with poor clinical outcomes of the breast cancer patients, indicating that DMP1β may have a biological function. Indeed, DMP1β increased proliferation of non-tumourigenic mammary epithelial cells and knockdown of endogenous DMP1 inhibited breast cancer cell growth. To determine DMP1β's role in vivo, we established MMTV-DMP1β transgenic mouse lines. DMP1β overexpression was sufficient to induce mammary gland hyperplasia and multifocal tumour lesions in mice at 7-18 months of age. The tumours formed were adenosquamous carcinomas with evidence of transdifferentiation and keratinized deposits. Overall, we identify alternative splicing as a mechanism utilized by cancer cells to modulate the DMP1 locus through diminishing DMP1α tumour suppressor expression, while simultaneously up-regulating the tumour-promoting DMP1β isoform.

Assessment of Multiplate platelet aggregometry using citrate, heparin or hirudin in Rhesus macaques

Electrical impedance aggregometry (EIA) has gained popularity in clinical and research applications. Nonhuman primates are used to study disease and drug-related mechanisms that affect hemostasis, therefore establishing normal EIA parameters are necessary. The anticoagulants sodium heparin, hirudin and sodium citrate and three agonists, ADP, ASPI, and collagen were evaluated. Whole blood from 12 adult male rhesus macaques was collected to evaluate anticoagulants, sodium heparin, hirudin and sodium citrate using three agonists (ADP, ASPI and collagen), on the Multiplate® 5.0 Analyzer. Platelet function was reported for three parameters: Area under the curve (AUC), aggregation, and aggregation velocity. There was a significant difference in mean AUC between citrate and heparin samples, and citrate and hirudin samples regardless of the agonist used. There was no difference in AUC between heparin and hirudin. ADP-activated samples showed an increase in impedance with hirudin samples compared to citrate. Furthermore, heparin and hirudin out-perform citrate as the anticoagulant for EIA in the macaque. Finally, this study demonstrates the utility of the Multiplate® system in this model and provides important insight into anticoagulant choice when using EIA.

Mechanisms of human erythrocytic bioactivation of nitrite

Nitrite signaling likely occurs through its reduction to nitric oxide (NO). Several reports support a role of erythrocytes and hemoglobin in nitrite reduction, but this remains controversial, and alternative reductive pathways have been proposed. In this work we determined whether the primary human erythrocytic nitrite reductase is hemoglobin as opposed to other erythrocytic proteins that have been suggested to be the major source of nitrite reduction. We employed several different assays to determine NO production from nitrite in erythrocytes including electron paramagnetic resonance detection of nitrosyl hemoglobin, chemiluminescent detection of NO, and inhibition of platelet activation and aggregation. Our studies show that NO is formed by red blood cells and inhibits platelet activation. Nitric oxide formation and signaling can be recapitulated with isolated deoxyhemoglobin. Importantly, there is limited NO production from erythrocytic xanthine oxidoreductase and nitric-oxide synthase. Under certain conditions we find dorzolamide (an inhibitor of carbonic anhydrase) results in diminished nitrite bioactivation, but the role of carbonic anhydrase is abrogated when physiological concentrations of CO2 are present. Importantly, carbon monoxide, which inhibits hemoglobin function as a nitrite reductase, abolishes nitrite bioactivation. Overall our data suggest that deoxyhemoglobin is the primary erythrocytic nitrite reductase operating under physiological conditions and accounts for nitrite-mediated NO signaling in blood.

MicroRNA-let-7a expression is increased in the mesangial cells of NZB/W mice and increases IL-6 production in vitro

Recent evidence supports a role for epigenetic alterations in the pathogenesis of systemic lupus erythematosus (SLE). MicroRNAs (miRNAs or miRs) are endogenous epigenetic regulators whose expression is altered in many diseases, including SLE. IL-6 is an inflammatory cytokine produced by mesangial cells during lupus nephritis (LN). IL-6 contains a potential binding site for miRNA-let-7a (let-7a) in its 3' untranslated region (UTR). We found let-7a expression was significantly increased in the mesangial cells of pre-diseased and actively diseased New Zealand Black/White (NZB/W) mice compared to age-matched New Zealand White (NZW) mice. Overexpression of let-7a in vitro increased IL-6 production in stimulated mesangial cells compared to non-transfected controls. Inhibition of let-7a did not significantly affect immune-stimulated IL-6 production. When stimulated mesangial cells overexpressing let-7a were treated with the transcription inhibitor Actinomycin D (ActD), IL-6 was degraded faster, consistent with the direct targeting of the 3' UTR of IL-6 by let-7a. Overexpression of let-7a increased the expression of tristetraprolin (TTP), an RNA-binding protein (RBP) that has 5 potential binding regions in the 3' UTR of IL-6. ActD inhibited the transcription of proteins including TTP that may contribute to the let-7a-mediated increase in immune-stimulated IL-6 production. These data show that NZB/W mice have higher let-7a expression than NZW mice and that increased let-7a expression in vitro increases IL-6 production in stimulated mesangial cells. Further studies examining the role of let-7a expression in inflammation are warranted.

Class I and II histone deacetylase inhibition by ITF2357 reduces SLE pathogenesis in vivo

We sought to determine if a specific class I and II HDAC inhibitor (ITF2357) was able to decrease disease in lupus-prone NZB/W mice through regulation of T cell profiles. From 22 to 38 weeks-of-age, NZB/W and non-lupus NZW mice were treated with ITF2357 (5 mg/kg or 10 mg/kg), or vehicle control. Body weight and proteinuria were measured every 2 weeks, while sera anti-dsDNA and cytokine levels were measured every 4 weeks. Kidney disease was determined by sera IgG levels, immune complex deposition, and renal pathology. T lymphocyte profiles were assessed using flow cytometric analyses. Our results showed that NZB/W mice treated with the 10 mg/kgof ITF2357 had decreased renal disease and inflammatory cytokines in the sera. Treatment with ITF2357 decreased the Th17 phenotype while increasing the percentage of Tregs as well as Foxp3 acetylation. These results suggest that specific HDAC inhibition may decrease disease by altering T cell differentiation and acetylation.

Non-homologous end joining mediated DNA repair is impaired in the NUP98-HOXD13 mouse model for myelodysplastic syndrome

Chromosomal translocations typically impair cell differentiation and often require secondary mutations for malignant transformation. However, the role of a primary translocation in the development of collaborating mutations is debatable. To delineate the role of leukemic translocation NUP98-HOXD13 (NHD13) in secondary mutagenesis, DNA break and repair mechanisms in stimulated mouse B lymphocytes expressing NHD13 were analyzed. Our results showed significantly reduced expression of non-homologous end joining (NHEJ)-mediated DNA repair genes, DNA Pkcs, DNA ligase4, and Xrcc4 leading to cell cycle arrest at G2/M phase. Our results showed that expression of NHD13 fusion gene resulted in impaired NHEJ-mediated DNA break repair.

Non homologous end joining-mediated DNA break repair is impaired in B lymphocytes of aging mice

Aging is an irreversible physiological process characterized by increased risk of diseases, reduced effectiveness of vaccines, and decreased immune responses. One of the most prominent paradigms of aging and age related conditions is the progressive accumulation of un-repaired DNA breaks leading to apoptosis and exhaustion of stem cells. Here we hypothesized that B lymphocytes from old mice have reduced DNA repair mechanisms as a contributing factor for DNA break accumulation. We analyzed class switch recombination (CSR) of naïve B lymphocytes from old and adult mice to delineate the DNA double strand repair mechanisms during aging. In vitro CSR assays and DNA break analysis by labeling phosphorylated histone H2AX showed that old mice had significantly reduced DNA repair efficiency following DNA breaks. Functional efficiency analysis of DNA break repairs using plasmid ligation method showed that B lymphocytes from old mice had poor repair efficiency and increased misrepair of linear plasmid. Diminished DNA repair in old age can contribute to reduced immune cell repertoire and impaired immunity; increased occurrence of cancer; and reduced stem cell reserve.

A NUP98-HOXD13 leukemic fusion gene leads to impaired class switch recombination and antibody production

Myelodysplastic syndrome is a clonal process characterized by ineffective hematopoiesis and progression to acute leukemia. Although many myelodysplastic syndrome and leukemic patients have compromised immunity, the role of underlying mutations in regulating immune function is poorly understood. Recent studies show that NUP98-HOXD13 (NHD13) fusion gene results in myelodysplastic syndrome and impairs lymphocyte differentiation in transgenic mice. In our studies, we sought to elucidate the mechanism by which NHD13 affects B-lymphocyte development and function. Based on our preliminary findings that transgenic mice had increased levels of IgM and reduced IgG1 and IgE, we hypothesized that the fusion gene might impair class switch recombination (CSR). Mice were immunologically challenged with dinitrophenol. NHD13 mice showed a marked reduction in B-lymphocyte differentiation in their bone marrow and spleen following dinitrophenol stimulation and had reduced production of dinitrophenol-specific antibodies. Spleen follicles from these mice were small and hypocellular, indicating failure of clonal expansion. When isolated NHD13 B lymphocytes were stimulated in vitro using Escherichia coli lipopolysaccharide or lipopolysaccharide + interleukin-4, they failed to undergo sufficient CSR and proliferation. Taken together, our findings show that expression of NUP98-HOXD13 impairs CSR and reduces the antibody-mediated immune response, in addition to its role in leukemia. Further delineation of the NUP98-HOXD13 transgene may reveal novel pathways involved in CSR.

Heat shock protein 90 inhibition by 17-DMAG lessens disease in the MRL/lpr mouse model of systemic lupus erythematosus

Elevated expression of heat shock protein 90 (HSP90) has been found in kidneys and serum of systemic lupus erythematosus (SLE) patients and MRL/Mp-Fas(lpr)/Fas(lpr) (MRL/lpr) autoimmune mice. We investigated if inhibition of HSP90 would reduce disease in MRL/lpr mice. In vitro, pretreatment of mesangial cells with HSP90 inhibitor Geldanamycin prior to immune-stimulation showed reduced expression of IL-6, IL-12 and NO. In vivo, we found HSP90 expression was elevated in MRL/lpr kidneys when compared to C57BL/6 mice and MRL/lpr mice treated with HSP90 inhibitor 17-DMAG. MRL/lpr mice treated with 17-DMAG showed decreased proteinuria and reduced serum anti-dsDNA antibody production. Glomerulonephritis and glomerular IgG and C3 were not significantly affected by administration of 17-DMAG in MRL/lpr. 17-DMAG increased CD8(+) T cells, reduced double-negative T cells, decreased the CD4/CD8 ratio and reduced follicular B cells. These studies suggest that HSP90 may play a role in regulating T-cell differentiation and activation and that HSP90 inhibition may reduce inflammation in lupus.

Deletion of PPAR-γ in immune cells enhances susceptibility to antiglomerular basement membrane disease

Activation of the nuclear hormone receptor peroxisome proliferator-activated receptor gamma (PPAR-γ) has been shown to be immunoregulatory in autoimmune diseases by inhibiting production of a number of inflammatory mediators. We investigated whether PPAR-γ gene deletion in hematopoietic cells would alter disease pathogenesis in the antiglomerular basement membrane (anti-GBM) mouse model. PPAR-γ^+/+ and PPAR-γ^−/− mice were immunized with rabbit antimouse GBM antibodies and lipopolysaccharide and evaluated for two weeks. Although both the PPAR-γ^+/+ and PPAR-γ^−/− mice had IgG deposition in the glomerulus and showed proteinuria two weeks after injection, glomerular and tubulointerstitial disease in PPAR-γ^−/− mice were significantly more severe compared with the PPAR-γ^+/+ animals. We observed that the PPAR-γ^−/− mice had decreased CD4⁺CD25⁺ regulatory T cells and an increased CD8⁺:CD4⁺ ratio as compared with the PPAR-γ^+/+ mice, suggesting that PPAR-γ has a role in the regulation of T cells. Furthermore, plasma interleukin-6 levels were significantly increased in the PPAR-γ^−/− mice at two weeks as compared with the PPAR-γ^+/+ animals. Taken together, these studies show that the lack of PPAR-γ expression enhances inflammatory renal disease in the anti-GBM antibody-induced glomerulonephritis mouse model and suggests targeting PPAR-γ may have therapeutic efficacy.

Ocular penetration of oral doxycycline in the horse

OBJECTIVE

To investigate intraocular penetration of orally administered doxycycline in the normal equine eye and to compare intraocular and serum doxycycline concentrations. Procedures Six mares were administered doxycycline at 10 mg/kg every 12 h by nasogastric tube for 5 days. Blood, aqueous, and vitreous samples were collected on days 1 and 5. All samples were assayed for doxycycline concentrations. Aqueous and vitreous samples were also assayed for protein quantitation.

RESULTS

Doxycycline was rapidly absorbed after the first dose (T(max) value of 1.42 +/- 1.28 h); and elimination of doxycycline occurred slowly (median t(1/2) = 10.88 h). Doxycycline could not be detected in the aqueous on days 1 and 5, nor could it be detected in the vitreous on day 1. On day 5, the mean vitreous doxycycline concentration was 0.17 +/- 0.04 microg/mL at 2 h after drug administration.

CONCLUSIONS

Repeated oral administration of doxycycline in the horse resulted in steady state serum concentrations of < 1 microg/mL; however, it did not result in appreciable concentrations of drug in the aqueous and vitreous in normal eyes.

Quantification of HTLV-I proviral load in experimentally infected rabbits

BACKGROUND

Levels of proviral load in HTLV-1 infected patients correlate with clinical outcome and are reasonably prognostic. Adaptation of proviral load measurement techniques is examined here for use in an experimental rabbit model of HTLV-1 infection. Initial efforts sought to correlate proviral load with route and dose of inoculation and with clinical outcome in this model. These methods contribute to our continuing goal of using the model to test treatments that alleviate virus infection.

RESULTS

A real-time PCR assay was used to measure proviral load in blood and tissue samples from a series of rabbits infected using HTLV-1 inocula prepared as either cell-free virus particles, infected cells or blood, or by naked DNA injection. Proviral loads from asymptomatically infected rabbits showed levels corresponding to those reported for human patients with clinically silent HTLV-1 infections. Proviral load was comparably increased in 50% of experimentally infected rabbits that developed either spontaneous benign or malignant tumors while infected. Similarly elevated provirus was found in organs of rabbits with experimentally induced acute leukemia/lymphoma-like disease. Levels of provirus in organs taken at necropsy varied widely suggesting that reservoirs of infections exist in non-lymphoid organs not traditionally thought to be targets for HTLV-1.

CONCLUSION

Proviral load measurement is a valuable enhancement to the rabbit model for HTLV-1 infection providing a metric to monitor clinical status of the infected animals as well as a means for the testing of treatment to combat infection. In some cases proviral load in blood did not reflect organ proviral levels, revealing a limitation of this method for monitoring health status of HTLV-1 infected individuals.

Paresis secondary to an extradural hematoma in a Sumatran tiger (Panthera tigris sumatrae)

A 15-yr-old female Sumatran tiger (Panthera tigris sumatrae) was presented to the Boren Veterinary Medical Teaching Hospital at Oklahoma State University with a 3-wk history of progressive hind limb weakness. Neurologic evaluation was limited to review of videotape that demonstrated weakness and ataxia with conscious proprioceptive deficits of the tiger's pelvic limbs. Spinal radiography demonstrated disc space narrowing, and myelography demonstrated a large extradural compressive lesion at the level of L2-3. Computed tomography did not reveal bone involvement. Surgery was performed to decompress the spinal cord and obtain a definitive diagnosis. A right hemilaminectomy was performed after a dorsal approach to the lumbar spine. Histologic examination of the mass revealed a consolidated extradural spinal hematoma, presumed to be secondary to intervertebral disc herniation. Despite incomplete resection of the mass and plastic deformation of the spinal cord, the tiger returned to normal ambulation within 3 wk of surgical decompression.