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Biomedical subjects

E P Blankenhorn

Publications and source records attributed to E P Blankenhorn.

At least 19 recordsLinked to original sources
PubMed2005

Background and gender effects on survival in the TgN(SOD1-G93A)1Gur mouse model of ALS.

Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disorder. While most cases of ALS are sporadic, 10-15% are familial, and of these 15-20% possess a mutation in the gene that codes for the enzyme Cu/Zn superoxide dismutase (SOD1). In families of ALS patients with specific SOD1 mutations, affected members demonstrate significant heterogeneity of disease and a large variation in age of onset and severity, suggesting that there are genetic modifiers of disease expression. Transgenic mice expressing mutant forms of SOD1 demonstrate symptoms similar to those seen in patients with ALS. We have observed in our colony of G93A SOD1 transgenic mice a milder phenotype in mice in a C57BL/6J background than the C57BL/6JxSJL/J hybrid background used by Jackson Laboratories to maintain their colony. To investigate the effect of genetic background on phenotype, we have constructed congenic lines on two genetic backgrounds, C57BL/6J (B6) and SJL/J (SJL). We report the influence of background and gender on the survival of these congenic lines compared to the hybrid C57BL/6JxSJL/J background. The mean survival of G93A SOD1 mice in the hybrid B6/SJL background was 130 days, with females surviving significantly longer than males. When compared to the hybrid B6/SJL background, the survival of mice in the SJL background significantly decreased, and the gender difference in survival was maintained. On the other hand, mean survival in the B6 background significantly increased, and in contrast to the B6/SJL and SJL backgrounds, there was no difference in survival between males and females. Transgene copy numbers were verified in all animals to ensure that any phenotypic differences observed were not due to alterations in copy number. This is the first report of a shortened lifespan when the G93A SOD1 transgene is placed on the SJL/J background and an increased survival with the loss of gender influences when the transgene is placed on the C57BL/6J background.

Age Factors↗
PubMed2000

Genetic analysis of the influence of pertussis toxin on experimental allergic encephalomyelitis susceptibility: an environmental agent can override genetic checkpoints.

Pertussis toxin (PTX) is a potent ancillary adjuvant used to elicit several different autoimmune diseases, including experimental allergic encephalomyelitis (EAE). To delineate the genetics of PTX effect in EAE, we mapped EAE-modifying (eae-m) loci in cohorts of backcross mice immunized with and without PTX. In this study, we analyzed the genetic basis of EAE susceptibility and severity and the intermediate phenotypes of mononuclear cell infiltration, suppuration, and demyelination. In animals immunized with PTX, one major locus, eae9, controls disease susceptibility and severity. Eae9 also regulates the extent of mononuclear cell infiltration of the spinal cord in male mice. Without PTX, five eae-m loci were noted, including three new loci in intervals on chromosomes 8 (eae14), 10 (eae17), and 18 (eae18). Taken together, these results suggest that eae9 controls the effects of PTX in EAE susceptibility, and is capable of overriding the other genetic checkpoints in the pathogenesis of this disease.

Animals↗
PubMed2000

Molecular characterization and chromosomal localization of mouse Puralpha gene.

Puralpha is a 39-kDa sequence-specific single-stranded DNA/RNA binding protein with the ability to modulate transcription of several genes containing the Pur element in their promoter region. Human and mouse Puralpha exhibit an extraordinary degree of conservation with only two changes at amino acid residues 49 and 306. A 15-kb genomic clone encompassing the mouse Puralpha gene was isolated by screening the mouse genomic library, using a PCR-amplified fragment from human Puralpha cDNA. Results from sequencing analysis confirmed the isolated genomic clone to be Puralpha and not the other members of the Pur family, including Purbeta. Characterization of the mouse Puralpha gene by restriction analysis/Southern blotting and sequencing revealed that the Puralpha gene contains only one intron within the 5' UTR and the open reading frame was intact. Using chromosomal markers, the Puralpha gene was mapped to chromosome 18 in mouse and rat.

Animals↗
PubMed2000

Identification of genetic loci controlling the characteristics and severity of brain and spinal cord lesions in experimental allergic encephalomyelitis.

Experimental allergic encephalomyelitis (EAE) is the principal genetically determined animal model for multiple sclerosis (MS), the major inflammatory disease of the central nervous system (CNS). Although genetics clearly play a role in susceptibility to MS, attempts to identify the underlying genes have been disappointing. Considerable variation exists between MS patients with regard to the severity of clinical signs, mechanism of demyelination, and location of CNS lesions, confounding the interpretation of genetic data. A mouse-human synteny mapping approach may allow the identification of candidate susceptibility loci for MS based on the location of EAE susceptibility loci. To date, 16 regions of the mouse genome have been identified that control susceptibility or clinical signs of EAE. In this work, we examined the genetic control of histopathological lesions of EAE in an F2 intercross population generated from the EAE susceptible SJL/J and EAE resistant B10.S/DvTe mouse strains. Composite interval mapping was used to identify 10 quantitative trait loci (QTL), including seven newly identified loci controlling the distribution and severity of CNS lesions associated with murine EAE. QTL on chromosome 10 control lesions in the brain, whereas QTL on chromosomes 3, 7, and 12 control lesions in the spinal cord. Furthermore, sexually dimorphic QTL on chromosomes 2, 9, and 11 control CNS lesions in females, whereas QTL on chromosomes 10, 11, 12, 16, and 19 control lesions in males. Our results suggest that the severity and location of CNS lesions in EAE are genetically controlled, and that the genetic component controlling the character and severity of the lesions can be influenced by sex.

Animals↗
PubMed1999

Sequence polymorphisms in the chemokines Scya1 (TCA-3), Scya2 (monocyte chemoattractant protein (MCP)-1), and Scya12 (MCP-5) are candidates for eae7, a locus controlling susceptibility to monophasic remitting/nonrelapsing experimental allergic encephalomyelitis.

Experimental allergic encephalomyelitis (EAE), the principal animal model of multiple sclerosis, is genetically controlled. To date, 13 disease-modifying loci have been identified in the mouse by whole genome scanning using an F2 intercross between EAE-susceptible SJL/J and EAE-resistant B10.S/DvTe mice. Two quantitative trait loci (QTL), eae6 and eae7, on chromosome 11 were identified by classical marker-specific linkage analysis and interval mapping. Both QTL were reported to be associated with severity and duration of clinical signs. eae7 was subsequently shown to be a unique locus controlling the development of monophasic remitting/nonrelapsing EAE. In this study, composite interval mapping resolved eae6 into two linked QTL: eae6a at 0-13 cM is associated with disease severity, and eae6b at 19-28 cM associated with the duration of clinical signs. Additionally, composite interval mapping significantly refined the locations of eae6a, eae6b, and eae7, thereby facilitating systematic candidate gene screening by cDNA sequencing of SJL/J and B10.S/DvTe alleles. Sequence polymorphisms were not seen in Lif and IL12 beta, candidate genes for eae6a and eae6b, respectively. Similarly, cDNA sequence polymorphisms in Nos2, Scya3, Scya4, Scya5, Scya6, Scya7, Scya9, Scya10, and Scya11 were excluded as candidates for eae7. However, multiple sequence polymorphisms resulting in significant amino acid substitutions were identified in Scya1 (TCA-3), Scya2 (monocyte chemoattractant protein (MCP)-1), and Scya12 (MCP-5). Given the role of chemokines in EAE, these sequence polymorphisms are promising candidates for eae7, a locus associated with severity of clinical signs and susceptibility to the shorter, less severe monophasic remitting/nonrelapsing form of disease.

Amino Acid Sequence↗
PubMed1999

Genetic analysis of disease subtypes and sexual dimorphisms in mouse experimental allergic encephalomyelitis (EAE): relapsing/remitting and monophasic remitting/nonrelapsing EAE are immunogenetically distinct.

Experimental allergic encephalomyelitis (EAE) is the principal animal model of multiple sclerosis (MS), the major inflammatory disease of the central nervous system. Murine EAE is generally either an acute monophasic or relapsing disease. Because the clinical spectrum of MS is more diverse, the limited range of disease subtypes observed in EAE has raised concern regarding its relevance as a model for MS. During the generation of a large F2 mapping population between the EAE-susceptible SJL/J and EAE-resistant B10.S/DvTe inbred lines, we identified four distinct subtypes of murine EAE resembling clinical subtypes seen in MS. We observed acute progressive, chronic/nonremitting, remitting/relapsing, and monophasic remitting/nonrelapsing EAE. An additional subtype, benign EAE, was identified after histologic examination revealed that some mice had inflammatory infiltrates of the central nervous system, but did not show clinical signs of EAE. Genome exclusion mapping was performed to identify the loci controlling susceptibility to each disease subtype. We report three novel EAE-modifying loci on chromosomes 16, 7, and 13 (eae11-13, respectively). Additionally, unique loci with gender-specific effects govern susceptibility to remitting/relapsing (eae12) and monophasic remitting/nonrelapsing (eae7 and 13) EAE.

Animals↗
PubMed1999

Genetic regulation of long-term nonprogression in E-55+ murine leukemia virus infection in mice.

Certain inbred mouse strains display progression to lymphoma development after infection with E-55+ murine leukemia virus (E-55+ MuLV), while others demonstrate long-term nonprogression. This difference in disease progression occurs despite the fact that E-55+ MuLV causes persistent infection in both immunocompetent BALB/c-H-2(k) (BALB.K) progressor (P) and C57BL/10-H-2(k) (B10.BR) long-term nonprogressor (LTNP) mice. In contrast to immunocompetent mice, immunosuppressed mice from both P and LTNP strains develop lymphomas about 2 months after infection, indicating that the LTNP phenotype is determined by the immune response of the infected mouse. In this study, we used bone marrow chimeras to demonstrate that the LTNP phenotype is associated with the genotype of donor bone marrow and not the recipient microenvironment. In addition, we have mapped a genetic locus that may be responsible for the LTNP trait. Microsatellite-based linkage analysis demonstrated that a non-major histocompatibility complex gene on chromosome 15 regulates long-term survival and is located in the same region as the Rfv3 gene. Rfv3 is involved in recovery from Friend virus-induced leukemia and has been demonstrated to regulate neutralizing virus antibody titers. In our studies, however, both P and LTNP strains produce similar titers of neutralizing and cytotoxic anti-E-55+ MuLV. Therefore, while it is possible that Rfv3 influences the course of E-55+ MuLV infection, it is more likely that the LTNP phenotype in E-55+ MuLV-infected mice is regulated by a different, closely linked gene.

Animals↗
PubMed1999

Non-major histocompatibility complex-linked diabetes susceptibility loci on chromosomes 4 and 13 in a backcross of the DP-BB/Wor rat to the WF rat.

BB rats are used as models of autoimmune human IDDM. Genetic control of IDDM in both species is complex, including both major histocompatibility complex (MHC)-linked and non-MHC-linked genes. DP-BB rats develop IDDM spontaneously. Expression of disease in these animals requires homozygosity at the lyp locus, which causes lymphopenia. All genetic analyses of BB rat diabetes to date have backcrossed to the DP-BB strain or used (DP-BB x non-BB)F2 animals to ensure that a fraction of progeny are homozygous for lyp. Here we report the analysis of a backcross of the DP-BB rat to the histocompatible WF rat. Neither WF nor (WF x DP-BB)F1 animals develop spontaneous IDDM. However, 95% of (WF x DP-BB)F1 rats and a fraction of (WF x DP-BB) x WF backcross animals readily develop IDDM after treatment with polyinosinic:polycytidylic acid and a cytotoxic anti-RT6.1 monoclonal antibody. Using simple sequence length polymorphism analysis, we have mapped loci on chromosomes 4 and 13 that show significant linkage to IDDM expression and insulitis. The susceptibility locus on chromosome 4 is linked to, but not identical to, lyp. We propose a disease model for the BB rat that requires 1) the RT1u MHC haplotype for disease susceptibility, 2) a new locus on chromosome 4 for disease initiation (as measured by insulitis), 3) a new locus on chromosome 13 for disease progression in response to environmental perturbation, and 4) lyp for spontaneous expression of disease.

Animals↗
PubMed1999

Diabetes-prone and diabetes-resistant BB rats share a common major diabetes susceptibility locus, iddm4: additional evidence for a "universal autoimmunity locus" on rat chromosome 4.

Diabetes-prone (DP) BB rats develop autoimmune type 1 diabetes spontaneously. At least five loci are linked to disease expression: the major histocompatibility complex (iddm2), two susceptibility loci (iddm4, iddm5), and, possibly, a resistance locus (iddm3). Spontaneous disease also requires homozygosity for lyp/iddm1, which causes lymphopenia. It has not been determined whether lyp/iddm1 is required for predisposition to diabetes autoimmunity in addition to being required for its spontaneous expression. We analyzed backcross rats segregating for diabetes but not lymphopenia using Wistar-Furth (WF) and diabetes-resistant (DR) BB animals. The latter are nonlymphopenic (lyp+/+) and develop diabetes only in response to immunological perturbants. Treatment of (DR-BB x WF)F1 x WF animals (all lyp+/+) using a standard induction protocol caused type 1 diabetes in 58% of progeny. Expression of type 1 diabetes was strongly linked to iddm4. The results suggest that lyp/iddm1 does not determine the predisposition to autoimmunity in BB rats and that iddm4 is a major diabetogenic locus in both DP- and DR-BB animals. The iddm4 gene maps to a region containing several major autoimmunity loci, including aia2, aia3, and cia3. We propose that BB rat diabetes requires 1) class II RT1u (iddm2) for susceptibility, 2) additional loci for disease initiation and progression in response to perturbants, and 3) lyp for spontaneous disease.

Age of Onset↗
PubMed1998

Genetic analysis of a mammalian wound-healing trait.

Wound healing of mammalian tissue is an essential process in the maintenance of body integrity. The general mechanism of wound healing usually studied in adult mammals is repair, in contrast to the regeneration seen in more primitive vertebrates. We recently have discovered that MRL/MpJ mice, unlike all other strains of mice tested, undergo rapid and complete wound closure that resembles regeneration. Specifically, through-and-through surgical ear hole wounds close without scarring in <4 weeks with normal gross and microanatomic architecture, including chondrogenesis. We also demonstrated that this healing is a heritable trait in inbred mice. In this study, we present results pertaining to its genetic control in progeny segregating for this phenotype. To identify the genetic loci that control the wound closure process, a genome-wide scan was performed on (MRL/MpJ-Faslpr x C57BL/6)F2 and backcross populations. In the primary screens of these populations, quantitative trait loci that control the extent of wound closure were detected on chromosomes 8, 12, and 15 and at two separate locations on chromosome 13. Evidence of further genetic control of healing was found on chromosome 7. All alleles that contribute to full wound closure are derived from the MRL/MpJ-Faslpr parent except for the quantitative trait locus on chromosome 8, which is derived from C57BL/6.

Alleles↗
PubMed1998

New genetic loci that control susceptibility and symptoms of experimental allergic encephalomyelitis in inbred mice.

Experimental allergic encephalomyelitis (EAE), the principal animal model of multiple sclerosis, is a genetically determined phenotype. In this study, analyses of the cumulative disease frequencies in parental, F1 hybrid, and F2 mice, derived from the EAE-susceptible SJL/J strain and the EAE-resistant B10.S/DvTe strain, confirmed that susceptibility to EAE is not inherited as a simple Mendelian trait. Whole genome scanning, using 150 informative microsatellite markers and a panel of 291 affected and 390 unaffected F2 progeny, revealed significant linkage of EAE susceptibility to marker loci on chromosomes 7 (eae4) and 17, distal to H2 (eae5). Quantitative trait loci for EAE severity, duration, and onset were identified on chromosomes 11 (eae6, and eae7), 2 (eae8), 9 (eae9), and 3 (eae10). While each locus reported in this study is important in susceptibility or disease course, interactions between marker loci were not statistically significant in models of genetic control. One locus, eae7, colocalizes to the same region of chromosome II as Orch3 and Idd4, susceptibility loci in autoimmune orchitis and insulin-dependent diabetes mellitus, respectively. Importantly, eae5 and eae7 are syntenic with human chromosomes 6p21 and 17q22, respectively, two regions of potential significance recently identified in human multiple sclerosis genome scans.

Animals↗
PubMed1998

Differences in the immune response during the acute phase of E-55+ murine leukemia virus infection in progressor BALB and long term nonprogressor C57BL mice.

E-55+ murine leukemia virus infection of both progressor (BALB) and long term nonprogressor (C57BL) mouse strains is characterized by an acute and a persistent phase of infection. During the acute phase, progressor strains require CD8+ T cells to decrease virus burden, whereas the long term nonprogressor strains do not. In the present studies the immune response in BALB and C57BL mice during the acute phase of E-55+ murine leukemia virus infection was examined. The results demonstrate that BALB mice produce both IL-4 and IFN-gamma, in contrast to C57BL mice, which produce only IFN-gamma. In BALB mice, IL-4 production results in the absolute requirement for CD8+ T cells to reduce the virus burden during the acute phase of infection. The anti-virus immune response in these mice is IFN-gamma dependent. On the other hand, C57BL mice do not produce IL-4 and, in the absence of both CD8+ T cells and IFN-gamma, still generate an effective anti-virus immune response. Genetic studies suggest that these distinct immune responses are regulated by more than one non-MHC-linked gene. Two candidate regions that may encode this gene(s), located on chromosomes 7 and 19, respectively, were identified by recombinant inbred strain linkage analysis.

Acute Disease↗
PubMed1996

Possible mechanism for the TCR beta-chain associated EAE resistance of LER rats.

LER rats are resistant to the active induction of experimental allergic encephalomyelitis (EAE). The mechanism of their resistance to EAE has yet to be defined, although LER rats are susceptible to adoptively transferred EAE. Genetic analysis of LER and the susceptible LEW rat suggests that a gene linked to the T cell receptor (TCR) beta-chain complex contributes to EAE resistance. This result is consistent with the fact that EAE is a T cell mediated disease and one characterized in EAE-susceptible animals by an oligoclonal TCR V beta 8.2+ response. In this report, analysis of TCR transcripts by reverse transcriptase polymerase chain reaction (RT-PCR) and restriction digestion demonstrates that LER lymph nodes, collected on day 10 post-immunization with myelin basic protein (MBP), express both TCR-V beta 8.2 and other TCR beta chains, usually V beta 8.4, whereas LEW animals demonstrate preferential and almost exclusive use of V beta 8.2 TCR. Fluorescence-activated cell sorting (FACS) analyses of anti-MBP T cells confirm that LER T cells express V beta 8.2 TCR to a lesser degree than LEW T cells. Finally, experiments examining the oligo- or polyclonality of the TCRV beta CDR3 region show that the LER response to MBP is polyclonal, while the LEW response to MBP is oligoclonal. Therefore, the cumulative data on the TCR usage profiles in this report suggest that the choice of TCR variable beta-chain may contribute to the resistance seen in the LER rat.

Alleles↗
PubMed1995

Aod1, the immunoregulatory locus controlling abrogation of tolerance in neonatal thymectomy-induced autoimmune ovarian dysgenesis, maps to mouse chromosome 16.

Mice thymectomized at three days of age (D3Tx) develop during adulthood a variety of organ-specific autoimmune diseases, including autoimmune ovarian dysgenesis (AOD). The phenotypic spectrum of AOD is characterized by the development of anti-ovarian autoantibodies, oophoritis, and atrophy. The D3Tx model of AOD is unique in that disease induction depends exclusively on perturbation of the normal developing immune system, is T-cell-mediated, and is strain specific. For example, D3Tx A/J mice are highly susceptible to AOD, whereas C57BL/6J mice are resistant. After D3Tx, self ovarian antigens, expressed at physiological levels, trigger an autoimmune response capable of eliciting disease. The D3Tx model provides, therefore, the opportunity to focus on the mechanisms of self-tolerance that are relevant to disease pathogenesis. Previous studies indicate that the principal mechanisms involved in AOD susceptibility are genetically controlled and govern developmental processes associated with the induction and maintenance of peripheral tolerance. We report here the mapping of the Aod1 locus to mouse chromosome 16 within a region encoding several loci of immunologic relevance, including scid, Igl1, VpreB, Igll, Igl1r, Mtv6 (Mls-3), Ly-7, Ifnar, and Ifgt.

Animals↗
PubMed1995

cDNA sequence and differential mRNA regulation of two forms of glial cell line-derived neurotrophic factor in Schwann cells and rat skeletal muscle.

Total RNA from rat Schwann cells grown in culture and adult rat skeletal muscle was reverse transcribed, amplified for glial cell line-derived neurotrophic factor (GDNF) messenger RNA (mRNA) using the polymerase chain reaction (PCR), and the PCR products sequenced. Two forms of GDNF were detected in the PCR step, one of a predicted size (GDNF633) and a second smaller form missing a 78-base pair sequence (GDNF555). Sequence analysis demonstrated that GDNF633 is similar to the published sequence of GDNF differing only at three nucleotides. Southern and Northern blot analyses reveal that the two forms are probably derived from a single RNA species that is alternatively spliced. Interestingly, GDNF633 mRNA was found to be selectively upregulated in denervated rat skeletal muscle at 1-2 weeks following axotomy, providing evidence that the innervation status of the muscle may determine the expression profile of the two alternatively spliced forms. Given these findings, we suggest that GDNF may function as a target-derived trophic factor for neuronal populations innervating skeletal muscle, including sensory neurons and spinal cord motoneurons.

Animals↗
PubMed1995

Cloning of myelin basic protein-reactive T cells from the experimental allergic encephalomyelitis-resistant rat strain, LER.

Rats of the LER inbred strain are resistant to the active induction of experimental allergic encephalomyelitis (EAE), although they are susceptible to adoptively transferred EAE when they are injected with encephalitogenic T cells from EAE-susceptible Lewis rats. The mechanism of resistance remains to be elucidated. We report here that myelin basic protein (MBP)-specific T cells can be cloned from LER rats immunized with MBP, that these CD4+ LER T cells can recognize the encephalitogenic peptide (MBP-EP) and will divide vigorously when it is presented to them, and that these T cells bear V beta 8 + TCR chains. Nevertheless, in contrast to Lewis T cells with the same specificity and TCR beta chains, LER T cells from MBP-EP-specific clones cannot induce EAE when adoptively transferred into naive rats of either strain. Thus, LER T cells can assemble and use a TCR with the canonical encephalitogenic V beta 8.2-D beta-J beta region in response to immunization with MBP, yet they continue to display resistance to EAE.

Amino Acid Sequence↗
PubMed1995

Susceptibility to actively-induced murine experimental allergic encephalomyelitis is not linked to genes of the T cell receptor or CD3 complexes.

The role of the T cell receptor (TCR) in the genetic control of susceptibility to autoimmune demyelinating diseases remains shrouded in controversy. We have used the CXD2 series of recombinant inbred lines (RIL) and a (B10.S/DvTe x SJL/J) x B10.S/DvTe backcross (BC1) population to test for linkage between susceptibility to actively-induced EAE and the different TCR and CD3 loci. The two populations were inoculated for induction of EAE, phenotyped for both clinical and histological parameters of disease, and genotyped using markers flanking the loci of interest in the CXD2 RIL and an SJL/J allele-specific TCR V beta assay in the BC1 mice. Comparisons between the CXD2 strain distribution pattern (SDP) for disease and the SDPs for the chromosomal regions containing the TCR alpha, beta, gamma, delta, and CD3 delta, epsilon, gamma and zeta loci showed no linkage to these loci. Additional tests between EAE susceptibility and several other immunologically important loci for which the SDPs were known also showed no linkage to the minor lymphocyte-stimulating antigen gene Mlsl, Hc, the gene encoding complement component C5, Cd8a, or Cd5. Furthermore, our data from the BC1 mice demonstrate that the Tcrb locus segregates independent of disease and does not modulate disease severity. We conclude that while autoreactive TCRs are undoubtedly necessary for disease pathogenesis, the principle non-MHC-linked loci controlling susceptibility to murine EAE in BALB/c mice are not linked to any of the individual TCR-CD3 complex genes. Similarly, the major disease genes in the SJL/J mouse are not linked to TCR V beta. Our data cannot, however, preclude the possibility that TCR/CD3 alleles are involved in epigenetic phenomena or susceptibility in other mouse strains or animal systems.

Animals↗