Transcriptomics Analysis of Porcine Caudal Dorsal Root Ganglia in Tail Amputated Pigs Shows Long-Term Effects on Many Pain-Associated Genes

Tail amputation by tail docking or as an extreme consequence of tail biting in commercial pig production potentially has serious implications for animal welfare. Tail amputation causes peripheral nerve injury that might be associated with lasting chronic pain. The aim of this study was to investigate the short- and long-term effects of tail amputation in pigs on caudal DRG gene expression at different stages of development, particularly in relation to genes associated with nociception and pain. Microarrays were used to analyse whole DRG transcriptomes from tail amputated and sham-treated pigs 1, 8, and 16 weeks following tail treatment at either 3 or 63 days of age (8 pigs/treatment/age/time after treatment; n = 96). Tail amputation induced marked changes in gene expression (up and down) compared to sham-treated intact controls for all treatment ages and time points after tail treatment. Sustained changes in gene expression in tail amputated pigs were still evident 4 months after tail injury. Gene correlation network analysis revealed two co-expression clusters associated with amputation: Cluster A (759 down-regulated) and Cluster B (273 up-regulated) genes. Gene ontology (GO) enrichment analysis identified 124 genes in Cluster A and 61 genes in Cluster B associated with both “inflammatory pain” and “neuropathic pain.” In Cluster A, gene family members of ion channels e.g., voltage-gated potassium channels (VGPC) and receptors e.g., GABA receptors, were significantly down-regulated compared to shams, both of which are linked to increased peripheral nerve excitability after axotomy. Up-regulated gene families in Cluster B were linked to transcriptional regulation, inflammation, tissue remodeling, and regulatory neuropeptide activity. These findings, demonstrate that tail amputation causes sustained transcriptomic expression changes in caudal DRG cells involved in inflammatory and neuropathic pain pathways.

Determination of stable reference genes for RT-qPCR expression data in mechanistic pain studies on pig dorsal root ganglia and spinal cord

RNA expression levels for genes of interest must be normalised with appropriate reference or "housekeeping" genes that are stably expressed across samples and treatments. This study determined the most stable reference genes from a panel of 6 porcine candidate genes: beta actin (ACTB), beta-2-microglobulin (B2M), eukaryotic elongation factor 1 gamma-like protein (eEF-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), succinate dehydrogenase complex subunit A (SDHA), Ubiquitin C (UBC) in sacral dorsal root ganglia and spinal cord samples collected from 16 tail docked pigs (2/3rds of tail amputated) 1, 4, 8 and 16weeks after tail injury (4 pigs/time point). Total RNA from pooled samples was measured by SYBRgreen real-time quantitative PCR. Cycle threshold values were analysed using geNorm, BestKeeper and NormFinder PCR analysis software. Average expression stability and pairwise variation values were calculated for each candidate reference gene. GeNorm analysis identified the most stable genes for normalisation of gene expression data to be GAPDH>eEF-1>UBC>B2M>ACTB>SDHA for dorsal root ganglia and ACTB>SDHA>UBC>B2M>GAPDH>eEF-1 for spinal cord samples. Expression stability estimates were verified by BestKeeper and NormFinder analysis. Expression stability varied between genes within and between tissues. Validation of most stably expressed reference genes was performed by normalisation of calcitonin gene related polypeptide beta (CALCB). The results show similar patterns of CALCB expression when the best reference genes selected by all three programs were used. GAPDH, eEF-1 and UBC are suitable reference genes for porcine dorsal root ganglia samples, whereas ACTB, SDHA and UBC are more appropriate for spinal cord samples.

The hamster as a model of human visceral leishmaniasis: progressive disease and impaired generation of nitric oxide in the face of a prominent Th1-like cytokine response

Active human visceral leishmaniasis (VL) is characterized by a progressive increase in visceral parasite burden, cachexia, massive splenomegaly, and hypergammaglobulinemia. In contrast, mice infected with Leishmania donovani, the most commonly studied model of VL, do not develop overt, progressive disease. Furthermore, mice control Leishmania infection through the generation of NO, an effector mechanism that does not have a clear role in human macrophage antimicrobial function. Remarkably, infection of the Syrian hamster (Mesocricetus auratus) with L. donovani reproduced the clinicopathological features of human VL, and investigation into the mechanisms of disease in the hamster revealed striking differences from the murine model. Uncontrolled parasite replication in the hamster liver, spleen, and bone marrow occurred despite a strong Th1-like cytokine (IL-2, IFN-gamma, and TNF/lymphotoxin) response in these organs, suggesting impairment of macrophage effector function. Indeed, throughout the course of infection, inducible NO synthase (iNOS, NOS2) mRNA or enzyme activity in liver or spleen tissue was not detected. In contrast, NOS2 mRNA and enzyme activity was readily detected in the spleens of infected mice. The impaired hamster NOS2 expression could not be explained by an absence of the NOS2 gene, overproduction of IL-4, defective TNF/lymphotoxin production (a potent second signal for NOS2 induction), or early dominant production of the deactivating cytokines IL-10 and TGF-beta. Thus, although a Th1-like cytokine response was prominent, the major antileishmanial effector mechanism that is responsible for control of infection in mice was absent throughout the course of progressive VL in the hamster.

Serological evidence for an inflammatory response in murine scrapie

Transmissible spongiform encephalopathies (TSEs) are initiated by a novel kind of agent that produces characteristic degenerative changes in the brain without a detectable systemic inflammatory response or serological changes. A murine scrapie model was evaluated for changes in plasma concentration of serum amyloid P component (SAP), a protein that is up-regulated in infected and/or injured mice during the acute phase response (APR). C57BL10 and IRW mice inoculated with scrapie brain developed clinical scrapie 125-150 days later. At this time, concentration of plasma SAP increased in most of them. The SAP level increased > or =3-fold in >80% of the scrapie-affected C57BL10 mice and IRW male mice. A similar increase was found in <3% of respective nonscrapie control mice. The up-regulation of mouse SAP during clinical scrapie provides evidence for the activation of a systemic APR in TSE, a serological change that may be clinically useful.

Estrogen induces cytokeratin aggregation in primary cultures of Armenian hamster hepatocytes

The effect of estrogen administration to cultured Armenian hamster was studied. Isolated Armenian hamster hepatocytes were cultured in RPMI medium supplemented with beta-estradiol (E2). Beta-estradiol treatment for 24-48 hr induced cytoplasmic inclusion bodies which by immunocytochemistry were positive for cytokeratin (CK) 8, CK 18, and ubiquitin but negative for CK 7 and CK 19. These inclusion bodies appeared as filamentous tangles or amorphous aggregates when observed by electron microscopy. F-actin, tubulin, and desmosomes were not influenced by the presence of the inclusion bodies. Addition of ethanol to culture medium increased the incidence of the inclusion formation. In combination with 0.5% ethanol 1 microM of E2 induced five to six times more inclusion bodies, while the number of inclusion bodies decreased when epidermal growth factor (EGF) was added to the medium in combination with E2. This reduction effect was nullified by treatment with anti-EGF receptor antibody. These findings suggest that E2 treatment to Armenian hamster hepatocytes in vitro induces Mallory body-like inclusions whose incidence can be influenced by addition of ethanol or EGF to the culture medium.

Effect of hamster pregnancy on female protein, a homolog of serum amyloid P component

Pentraxins such as human serum amyloid P component (SAP) and C reactive protein (CRP) represent an ancient family of proteins that are ubiquitous in nature and have evolved with little change in structure or regulation. The pentraxin in the Syrian hamster (Mesocricetus auratus) is unique because it is preferentially expressed in the female at high constitutive levels and accordingly called female protein (FP) or FP(SAP) due to its close homology with human SAP. The high levels of FP in female serum (100-fold greater than male serum) suggested its role in hamster pregnancy, one of the shortest of any eutherian mammal. We determined the serum FP concentration in pregnant Syrian hamsters and found a marked decrease (>80%) at term with the nadir at parturition with subsequent increase. A similar downregulation of FP was found in the normal female Syrian hamster after injury (acute phase response), so in both cases the assumed beneficial effects were achieved with less, rather than more pentraxin, a paradoxical pentraxin response. The fall in serum FP concentration could represent a response to protect the fetus from the high and potentially toxic level of FP normally found in the female, that is harmful because of its association with amyloidosis. An FP that is 97.5% identical to Syrian hamster FP is found in the Turkish hamster (Mesocricetus brandti), although serum levels in females are much lower, and amyloid is very rare. During pregnancy/parturition of Turkish hamsters, the serum level of FP remained remarkably constant. In a more distantly related hamster, the Armenian hamster (Cricetulus migratorius), serum FP actually increased during pregnancy and at parturition in a manner similar to that found in the Armenian hamster during an acute phase response. The heterogeneity of FP kinetics during pregnancy in these three species of hamster indicates pleomorphic gene structure for regulation of their similar FPs, and suggests that this protein may have a different function in the pregnancy of each species.

Estrogen-induced hepatic toxicity and hepatic cancer: differences between two closely related hamster species

AIMS/BACKGROUND

Estrogen is known to affect hepatobiliary function; however, it is unusual for high serum levels of estrogen to actually result in clinically detectable hyperbilirubinemia. Women affected by cholestatic jaundice during pregnancy share this genetic susceptibility with two Cricetulus hamsters, the Armenian hamster (Cricetulus migratorius) and the Chinese hamster (Cricetulus griseus). Nevertheless, the pathophysiologic process responsible for this estrogen induced icterus may be different in women and hamsters. The present study compares various facets of estrogen-induced icterus in these two closely related hamsters.

METHODS

Hamsters were injected with various estrogens and the acute and chronic effects on liver were monitored by measuring changes in serum constituents and by observing changes in hepatic structure as seen grossly and by light and electron microscopy.

RESULTS

In previous studies, hepatic tumors developed in most Armenian hamsters after chronic estrogen treatment, but in the present study, the livers of Chinese hamsters were remarkably free of neoplastic change under similar conditions. Also, when compared with the responses in the Armenian hamsters, signs of hepatic destruction and regeneration were less prevalent in estrogen-treated Chinese hamsters, and they were less susceptible to the effects of estrogen (because larger doses of estrogen were required to produce icterus and the bilirubin levels were lower and of shorter duration). In contrast to the findings in Armenian hamsters, bile canaliculi were severely affected in livers of estrogen-treated Chinese hamsters, and hepatic microvesicular steatosis, indicative of an unusual lipodystrophy caused by estrogen, was prominent. An additional lesion peculiar to the Chinese hamster was striking sinusoidal dilatation, which may be analogous to the oral contraceptive-induced sinusoidal dilatation in humans.

CONCLUSIONS

Although these two hamster species are genetically similar, the genes activated by the estrogen receptor show remarkable heterogeneity when their respective livers are examined. Comparisons within these species may provide information about the specific gene activation responsible for particular pathologic events.

Female protein, amyloidosis, and hormonal carcinogenesis in Turkish hamster: differences from Syrian hamster

The Syrian hamster (Mesocricetus auratus) has been widely used as an experimental animal and is a unique model for three sex hormone-regulated events: 1) estrogen-initiated renal carcinogenesis, 2) sex-limited expression of amyloidosis, a ubiquitous disease, and 3) sex hormone control of a serum amyloid P component (SAP) called female protein (FP). In this study, we evaluated the closely related Turkish hamster (Mesocricetus brandti) for these three events and found some very different responses: 1) estrogen-initiated renal carcinogenesis was not found in Turkish hamster, 2) amyloidosis was not sex limited and actually was a rare disease in the Turkish hamster, and 3) Turkish hamsters did express a sex-limited SAP-FP in serum that was antigenically identical and structurally very similar (97.5%) to Syrian hamster SAP-FP. However, acute phase regulation of SAP-FP synthesis was different, and serum levels of this pentraxin were much lower than those found in the Syrian hamster. On the other hand, in contrast to findings in the Syrian hamster, hepatic tumors were relatively common in normal and especially in estrogen-treated Turkish hamsters. Therefore, although they are closely related, these two Mesocricetus hamster species have markedly dissimilar responses to sex hormones.

Electrophoretic polymorphism of a hamster pentraxin, female protein (amyloid P component)

Serum amyloid P protein (SAP) is a ubiquitous vertebrate protein distinguished by its conservative evolution and paucity of polymorphic forms. The SAP homologue in the Syrian hamster (Mesocricetus auratus), called Female Protein [FP(SAP)] is unique because its synthesis is controlled by sex hormones. These observations were limited to the commercially available standard Syrian hamsters that are descendants of three littermates captured in Syria in 1930. The authors examined FP(SAP) expression in nine inbred lines of Syrian hamsters that were derived from 12 wild hamsters captured in 1971. In general, regulation of FP(SAP) was similar in the new wild hamster strains, although a novel electrophoretically slower FP(SAP) was found in three of the strains. The slow FP(SAP) was not distinguished by size, antigenicity, binding capacity, or regulation. The electrophoretic difference was still apparent after deglycosylation. Hybrid offspring coexpressed both fast and slow FP monomers and formed a unique hybrid pentamer that had a new mobility between the fast and slow parent FP(SAP). The origin of this unusual polymorphism could be related to the amyloidogenesis associated with expression of FP(SAP) in the standard Syrian hamster.

Definition of cotton rat immunoglobulins: sigmodon species differ in expression of IgG isotypes and production of respiratory syncytial virus antibody

The cotton rat (Sigmodon species) is the preferred animal model for experiments with a number of human pathogens, especially the respiratory viruses. The cotton rat is classified in the family Cricetidae (with hamsters and gerbils) and is a distant cousin of the common laboratory rat (Rattus) classified in the family Muridae (with the common laboratory mouse, Mus). Antibody reagents that are specific for cotton rat immunoglobulins have not been described. To enhance the usefulness of this model, four immunoglobulins in Sigmodon serum were characterized (IgG1, IgG2, IgA, IgM) and antisera specific for each immunoglobulin were made. Sera from three different species of Sigmodon were examined, S. hispidus (SH), S. arizoni (SA) and S. fulviventer (SF). Although IgA and IgM appeared similar in all three species, the IgG were expressed differently because normal serum levels of IgG2 were deficient in SH when compared with SA and SF and to other rodents. Similarly, IgG2 antibody response to purified protein antigen was deficient in SH although the IgG1 antibody response was superior to that in SF and SA. The three cotton rat species were infected with respiratory syncytial virus, and the kinetics of the antibody response was measured. Neutralizing antibody developed faster and to a higher titre in SH than in SA and SF. The enhanced immunoresponsiveness in SH may compensate for the IgG2 deficiency in SH and these changes appear to be relatively recent events in the evolution of this most populous species of Sigmodon.

Immune response in the hamster: definition of a novel IgG not expressed in all hamster strains

A new IgG isotype is described in serum from Syrian hamsters. This 7S-IgG is called IgG3 and was isolated from IgG1 and IgG2 because of its great affinity for protein A. The unique antigenic determinants of IgG3 were identified with a specific rabbit antisera. IgG3 is the least expressed IgG subclass in Syrian hamsters, but serum levels increase more than 10-fold after immunization or infection. Although found in all tested outbred strains, IgG3 is expressed in only some of the commercially available inbred strains of Syrian hamsters. Five inbred hamster strains were examined, and in three strains (CB, LHC and MHA) IgG3 was not detected in normal serum or in immune serum, indicating serum levels at least 100-fold less than other normal inbred/outbred hamsters. The results of breeding experiments suggests a single gene defect is responsible for this non-expression of IgG3. Immunodeficiency was not associated with this IgG3 deficiency. Selective deficiencies of immunoglobulin classes/subclasses in experimental animals are rare. The evolution of a similar IgG3 deficiency in these three hamster strains during inbreeding suggests a novel and efficient mechanism for regulation of IgG3 synthesis in the Syrian hamster.

Association of rat C-reactive protein and other pentraxins with rat lipoproteins containing apolipoproteins E and A1

C-Reactive protein (CRP) is a member of the pentraxin family of proteins, ubiquitous components of animal serum. This study suggests that, in serum, rat CRP is complexed with lipoprotein and may interact directly with apolipoprotein E. When mixed with diluted rat serum, radiolabeled rat CRP showed a slightly higher sedimentation coefficient (about 15%) than that of the free protein. Elimination of calcium or addition of O-phosphorylethanolamine (O-PE), a low molecular weight compound that binds tightly to rat CRP in a calcium-dependent manner, abolished this difference. Adsorption of rat serum on a rat CRP affinity gel and elution with PE resulted in the isolation of material containing high levels of apolipoproteins E and A1. The affinity-purified preparation interacted with rat CRP and altered the sedimentation coefficient of the latter to the value observed in whole serum. Conversely, rat CRP increased the sedimentation coefficient of the major component of the affinity-purified material or to diluted rat serum, human serum amyloid P (SAP) and hamster female protein (FP), two other members of the pentraxin protein family, also had slightly higher sedimentation coefficients. In contrast, human CRP showed no evidence of an interaction in rat serum or with the affinity-purified proteins. This selectivity coincided with the ability of these pentraxins to bind to O-PE with high affinity. The sedimentation properties of serum lipoproteins, radiolabeled with [3H]cholesterol, also suggested an interaction with rat CRP.(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary structure of the pentraxin female protein in water determined by infrared spectroscopy: effects of calcium and phosphorylcholine

The secondary structure of hamster female protein in aqueous solutions in the presence or absence of calcium and phosphorylcholine has been investigated using Fourier transform infrared spectroscopy. Our present studies provide the first evaluation of the secondary structure of FP and its calcium- and phosphorylcholine-dependent conformational changes. Quantitative analysis indicated that FP is composed of 50% beta-sheet, 11% alpha-helix, 29% beta-turn, and 10% random structures. Calcium- and phosphorylcholine-dependent infrared spectral changes were observed in regions assigned to beta-sheet, alpha-helix, turn, and random structures. The infrared-based secondary structure compositions were used as constraints to compute theoretical locations for the different secondary structures along the amino acid sequence of the FP protein. Two putative calcium-binding sites were proposed for FP (residues 93-109 and 150-168) as well as other members of the pentraxin family on the basis of the theoretical secondary structure predictions and the similarity in sequence between the pentraxins and EF-hand calcium-binding proteins. The changes in protein conformation detected upon binding of calcium and phosphorylcholine provide a mechanism for the effects of these ligands on physiologically important properties of the protein, e.g., activation of complement and association with amyloids.

Hamster female protein binding to chromatin, histones and DNA

Hamster female protein (FP) is a member of the family of proteins known as pentraxins which share amino acid sequence homology, cyclic pentameric structure and calcium-dependent binding to ligands. Other members of this family include C-reactive protein (CRP) and serum amyloid P component (SAP), and most species synthesize both CRP and SAP. FP is unusual in that it is apparently the only pentraxin produced in hamsters, it is under hormonal control and it shares binding characteristics with both CRP and SAP. CRP has been defined and isolated by its calcium-dependent binding to pneumococcal C-polysaccharide via phosphocholine (PC) residues. SAP has been isolated by calcium-dependent binding to agarose. FP binds to both PC and agarose. Recently, both SAP and CRP have been found to bind to chromatin in a calcium-dependent manner and involvement of these proteins in the clearance of nuclear material has been proposed. In this paper we test whether FP shares the ability to bind to chromatin and histones, and compare its relative avidities for these ligands. Similar to CRP, FP bound to histones H1 and H2A, and chromatin. FP shared with SAP the ability to bind to DNA. However, FP binding was inhibited by PC for all ligands, whereas SAP binding was not. FP and SAP also failed to compete with each other for binding to DNA. By cross-inhibition FP bound much less well to PC than CRP, but was a very effective inhibitor of CRP binding to H2A. These studies demonstrate that chromatin and histone binding are conserved among these pentraxins. The role of the proposed PC binding site in these binding reactions is discussed.

Immunoglobulin G2 confers protection against Borrelia burgdorferi infection in LSH hamsters

We showed that immune serum and its immunoglobulin fractions, specifically immunoglobulin G2 (IgG2), could confer complete protection to irradiated hamsters challenged with the Lyme disease spirochete. Immune serum and its immunoglobulin fractions also killed Borrelia burgdorferi in vitro. Depletion of complement in vivo abrogated the ability of IgG2 to confer complete protection against B. burgdorferi. Furthermore, the majority of antibody reactivity directed against B. burgdorferi was found in the IgG2 fraction. These findings demonstrate that IgG2 plays an important role in acquired resistance against infection with B. burgdorferi. Additional studies are needed to determine the mechanism(s) by which B. burgdorferi evades host defenses despite the development of an effective borreliacidal antibody response.

A protease-sensitive site in the proposed Ca(2+)-binding region of human serum amyloid P component and other pentraxins

Serum amyloid P component (SAP) is a decamer of 10 identical 25.5-kDa subunits. Limited proteolysis of SAP with alpha-chymotrypsin cleaves the subunit into two fragments of 18 and 7.5 kDa, although the fragments stay together in the decamer under nondenaturing conditions. Proteolysis does not occur in the presence of Ca2+ (10 mM). Cleavage with alpha-chymotrypsin prevents the Ca(2+)-dependent binding of SAP to zymosan extract, nucleosomes, and DNA. The alpha-chymotrypsin cleavage site identified is in a region of SAP that is highly conserved in members of the human C-reactive protein (CRP) family of proteins (pentraxins) to which SAP belongs and is similar to the Ca(2+)-binding site in calmodulin and related Ca(2+)-binding proteins (Nguyen, N.Y., Suzuki, A., Boykins, R.A., & Liu, T.-Y., 1986, J. Biol. Chem. 261, 10456-10465). Treatment of SAP with other proteases (trypsin, Pronase, and Nagarse protease) yields fragmentation patterns upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) that are similar to those obtained with alpha-chymotrypsin. Two other members of the pentraxin family of proteins, hamster female protein and rabbit CRP, also exhibit similar fragmentation patterns on SDS-PAGE when treated with the various proteases. Recently, it has been shown that the homologous protein, human CRP, is cleaved in the same homologous position as cleavage of SAP by alpha-chymotrypsin, resulting in the loss of Ca(2+)-binding (as shown by equilibrium dialysis) and Ca(2+)-dependent binding reactivities (Kinoshita, C.M., Ying, S.-C., Hugli, T.E., Siegel, J.N., Potempa, L.A., Jiang, H.J., Houghten, R.A., & Gewurz, H., 1989, Biochemistry 28, 9840-9848).(ABSTRACT TRUNCATED AT 250 WORDS)

Pentraxin family of proteins interact specifically with phosphorylcholine and/or phosphorylethanolamine

Pentraxins are a family of serum proteins characterized by five identical subunits that are noncovalently linked. The two major types of pentraxins are C-reactive protein (CRP) and serum amyloid P component (SAP). CRP proteins are identified by their calcium-dependent interaction with phosphorylcholine. This study showed that SAP also bound to phosphorylated compounds but had a high specificity for phosphorylethanolamine. Thus, human CRP and SAP show high specificity that is complementary for the related compounds, phosphorylcholine and phosphorylethanolamine, respectively. This relationship suggests a complementary and/or related function for the pentraxins. Pentraxins from other species were also examined. Mouse SAP showed binding interactions and specificity similar to human SAP. Female protein (FP) from hamster and rat CRP showed a hybrid specificity and bound to both phosphorylethanolamine and phosphorylcholine. All of the proteins that bound phosphorylethanolamine also associated with human C4b-binding protein (C4BP). With the exception of human and rat CRP, all the proteins also bound to vesicles containing acidic phospholipids. All of these binding interactions were calcium-dependent and mutually exclusive, suggesting that they involved the same site on the protein. These findings suggest possible ways to examine the function of the pentraxins.

Tamoxifen prevents induction of hepatic neoplasia by zeranol, an estrogenic food contaminant

Zeranol (alpha-zearalanol) is a beta-resorcylic acid lactone (RAL) that has estrogen activity. It is synthesized by molds and is difficult to avoid in human food products. We tested the ability of this mycoestrogen to damage the liver of the Armenian hamster, a rodent that is especially sensitive to hepatotoxic effects of exogenous estrogens. Zeranol induced acute hepatotoxicity and, subsequently, hepatic carcinogenesis; both effects were blocked by tamoxifen, suggesting estrogen receptor mediation. Because zeranol is acting alone as a primary initiator of hepatic neoplasms, this model provides an unusual opportunity to study the pathogenesis of estrogen-initiated tumorigenesis.

Characterization of the protective antibody response to Borrelia burgdorferi in experimentally infected LSH hamsters

We show that serum obtained from normal hamsters infected with Borrelia burgdorferi can confer complete protection on irradiated recipients challenged with the Lyme spirochete. Borreliacidal activity was detected 7 days after infection, peaked at weeks 3 to 5, and thereafter decreased. Relatively high borreliacidal activity was detected in immune serum at weeks 3 and 5 of infection. The borreliacidal activity did not correlate with antibody used for the serodiagnosis of Lyme disease, which remained elevated throughout experimental infection. Our results also demonstrated that blocking antibody and antigenic variation in B. burgdorferi did not account for the decreasing titer of protective antibody. These findings indicate that protection against reinfection gradually wanes.

Armenian hamster female protein: a pentraxin under complex regulation

The serum of Armenian hamster (Cricetulus migratorius) contains a protein homologous to female protein (FP) that has been characterized in the Syrian (golden) hamster. Of unknown function, FP belongs to a family of proteins (called pentraxins) that have a common ancestral gene and are widely expressed in nature. Whereas serum concentration of FP in Syrian hamsters (SFP) is many fold greater (200- to 300-fold) in females vs. males, Armenian hamster FP (AFP) is only moderately elevated (approximately 3-fold) in female vs. males and only for the fall-winter months of the year. In the Armenian hamster testosterone administration to females or castration of males has no effect on AFP serum levels, whereas in Syrian hamster these treatments change SFP serum concentration to that characteristic of the opposite sex. Some sex steroid control of hepatic AFP synthesis is evident, however, as serum levels decrease after exogenous estrogen treatment. In contrast to Syrian hamster FP, normal levels of AFP are dependent on an intact hypophysial-pituitary axis and also are influenced by the season of the year. As an acute-phase protein, AFP responds in a typical fashion, with increasing serum levels detected in both sexes in contrast to the divergent sex-limited response in Syrian hamsters. Although AFP and SFP are similar structurally, morphologically, and antigenetically and share common binding specificities, the regulation of FP synthesis in Armenian hamster is very different from that previously found in Syrian hamster.

Estrogen induction of hepatocellular carcinomas in Armenian hamsters

Liver tumors were found in most Armenian hamsters (Cricetulus migratorius) injected with on 15-mg pellet of diethylstilbestrol. The tumors were detectable as early as 1 1/2 mo after diethylstilbestrol administration and were usually present as multiple nodules that progressively increased in size. Histologically, the multicentric neoplasms were all hepatocellular carcinomas of varied degrees of differentiation and frequently (42.8%) contained Mallory bodies; preneoplastic lesions were not observed. This hepatocellular carcinoma hamster model is unique because estrogen alone without any other known mutagen is responsible for induction of hepatocellular carcinoma.

Amyloidosis and female protein in the Syrian hamster. Concurrent regulation by sex hormones

Previous results have shown that when compared to male Syrian hamsters, female Syrian hamsters have a distinct predisposition to acquire amyloidosis either normally with aging or experimentally with sodium caseinate or diethylstilbestrol (DES) treatments. In the present study, we tested the influence of testosterone on expression of amyloid to determine if this hormone was solely responsible for the sex-limited amyloidosis of the Syrian hamster. Males deprived of testosterone by castration acquired amyloid at an unusually young age, an age of onset similar to that in female hamsters. Also, the amyloidogenic effect of DES in male Syrian hamsters was inhibited by concomitant injections of testosterone, indicating that estrogens induce amyloid in male hamsters by inhibiting testosterone synthesis. When administered to female hamsters, testosterone inhibited expression of amyloid in aging female Syrian hamsters and extended the life span of this gender. Of the two components of amyloid, the major component Amyloid A-derived fibril or the minor constituent, Amyloid P component, only the P component is under sex hormone control in the Syrian hamster; testosterone inhibits the hepatic synthesis of the P component homologue (called female protein), which is normally expressed 100-200-fold greater in female vs. male Syrian hamster. In general, the serum level of female protein under various experimental conditions correlated with the presence of amyloid and indicated that in the Syrian hamster the P component homologue is of primary importance in the deposition of amyloid.

Antibody response in white-footed mice (Peromyscus leucopus) experimentally infected with the Lyme disease spirochete (Borrelia burgdorferi)

White-footed mice (Peromyscus leucopus), the primary reservoir for Borrelia burgdorferi in the northern midwest and northeastern United States, were experimentally inoculated with an infectious strain or a noninfectious strain of the Lyme disease spirochete and examined for their specific antibody response with the enzyme-linked immunosorbent assay and Western blot (immunoblot) analysis. Immunoglobulin M (IgM) anti-B. burgdorferi antibodies were detected in mice 1 to 2 days after inoculation with either the infectious or noninfectious strain of spirochetes and peaked on days 4 and 5. Mice inoculated with the infectious strain of spirochete had a secondary increase in IgM 21 days after inoculation. Mice also produced both IgG1 and IgG2 antibodies beginning 5 to 7 days after inoculation and they increased in titer until 84 days after inoculation when the experiment was terminated. Western blot analysis of sequential plasma samples from mice inoculated with the infectious strain of spirochete demonstrated the development of IgM, IgG1, and IgG2 antibodies to numerous spirochetal antigens, whereas mice inoculated with the noninfectious strain had reduced blot patterns with antibodies reactive primarily to the 31,000-kilodalton outer surface protein A. Persistent spirochetal infection in some mice, in spite of a strong and diverse antibody response, deserves further investigation.

Synergistic effect of macrophage activation and immune serum, especially IgG2, on resistance to infection with Treponema pallidum ssp. endemicum in hamsters

Experimental studies have indicated that macrophages are involved in the pathogenesis of syphilis. Whether macrophages alone or with immune serum are ultimately responsible for killing of treponemes is disputed. We have demonstrated that BCG-vaccinated hamsters administered normal serum contained fewer treponemes in the inguinal and popliteal lymph nodes than did the nonvaccinated controls. When BCG-vaccinated hamsters were injected with syphilitic immune serum and challenged with Treponema pallidum ssp. endemicum, treponemicidal activity was enhanced. Treponemicidal activity was also detected in BCG-vaccinated hamsters challenged with treponemes treated in vitro with immune serum and its immunoglobulin fractions, especially IgG2. The immune IgG2 fraction had more treponemicidal activity than did the immune IgG1 fraction and the unfractionated immune serum. Our observations indicate an important synergistic role for macrophages and immune serum, especially IgG2, for elimination of T. pallidum ssp. endemicum from the host.

Tamoxifen inhibits estrogen-induced hepatic injury in hamsters

Estrogens have an unusual toxic effect on the liver of two hamster species, the Armenian and the Chinese hamster. The hepatotoxicity was detectable clinically by hyperbilirubinemia and confirmed histologically by the presence of hepatic degenerative-regenerative changes. Administration of tamoxifen with estrogen [either ethynyl estradiol or diethylstilbestrol (DES)] completely abrogated the hepatotoxic effects, suggesting that estrogen receptor (ER) was necessary for estrogen to damage liver. In Armenian hamsters, estrogens decreased hepatic synthesis of female protein (FP); tamoxifen also abolished this DES effect and resulted in a net increase in serum FP levels. DES administration produced higher serum bilirubin levels and lower serum FP levels in females than in males. Paradoxically, tamoxifen blocked these DES effects more effectively and efficiently in females than in males. Estrogens did not injure uteri of Armenian and Chinese hamsters and were nontoxic to livers of other hamsters species, such as Syrian and Turkish. This model provides another perspective of the acute cellular derangement that can be effected by estrogen-ER complex and may indicate a yet unknown mode of ER action.

The role of the female Syrian hamster protein on the interaction between serum lipoproteins and heparin

We have previously shown the effect of phosphorylcholine-binding proteins from rat (PCBP) and rabbit (CRP) on the precipitation of serum lipoproteins by heparin in presence of Ca2+. The present paper describes the effect of a phosphorylcholine-binding protein from the female Syrian hamster (FP) on the lipoprotein precipitation reaction. The precipitation of lipoproteins by heparin was lower in assays using female hamster serum in which FP is a prominent protein, compared with assays with male serum in which FP is present in very low concentration. Depletion of FP from female serum resulted in increased lipoprotein precipitation. The addition of purified FP to assays using human very low density lipoprotein (VLDL) inhibited the precipitation reaction. The precipitation of lipoproteins was also examined using serum from male hamsters treated with diethylstilbestrol and female hamsters treated with testosterone, treatments known to modulate the levels of FP. Results indicate an inverse relationship between serum FP levels from normal and hormone-treated hamsters and the precipitation of lipoproteins from their serum. The partially desialylated FP when added to precipitation assays using human VLDL resulted in reduced inhibition of VLDL precipitation.

Hamster female protein, a pentameric oligomer capable of reassociation and hybrid formation

Syrian hamster female protein (SFP), a serum oligomer composed of five identical subunits, was reassociated in vitro from monomer subunits. The reconstituted pentamer was genuine by morphologic, antigenic, and structural criteria. Another female protein (FP), a homologue from Armenian hamsters (AFP), also reassociated into a pentamer after dissociation with 5 M guanidine hydrochloride. These two FP's hybridized when a mixture of them was dissociated and then reassociated. Differences between the parent FP's were used to show that the recombinant pentamer contained monomer subunits from both SFP and AFP. Reassociation of both FP's was enhanced by increasing FP concentration and also by adding Ca2+ during reassembly. The two FP's differed in their reassociation profile in that SFP was especially efficient in reassembly, whereas AFP was more dependent upon Ca2+. Female protein is a homologue of C-reactive protein and amyloid P component, and all of these proteins (pentraxins) share a similar structure. The in vitro dissociation-reassociation of female protein described herein may reflect an in vivo dissociation-reassociation which is functionally important and a common metabolic feature within this family of proteins.

Effect of immune serum and its immunoglobulin fractions on hamsters challenged with Treponema pallidum ssp. pertenue

Passive transfer of frambesial immune serum is capable of conferring complete protection on hamsters against challenge with Treponema pallidum ssp. pertenue. Treponemicidal activity in the pooled immune serum is relatively high. Immune serum and its immunoglobulin fractions, especially IgG2, also killed T. pallidum ssp. pertenue in vitro. Treponemicidal activity was present only when immune serum was administered to hamsters within a short time (three days) of frambesial challenge. By contrast, administration of pooled immune serum to hamsters infected for more than one week failed to reduce the number and size of lesions and the weight and number of treponemes in the lymph nodes. These results suggest that hamsters can develop the humoral components necessary to protect them against frambesial challenge, but these components are unable to destroy treponemes at the primary foci of infection.

Medroxyprogesterone acetate induces diabetes insipidus in Chinese hamsters

Injection of a synthetic progesterone, medroxyprogesterone acetate (MPA or Depo-ProveraR), a widely used contraceptive, into Chinese hamsters (Cricetulus griseus) induced a profound polyuria with daily output of dilute urine equal to about 50% body weight of the hamster. However, relatively normal ability for renal urine concentration was demonstrated by administration of exogenous vasopressin. Body weight did not increase during onset of MPA-induced polyuria or during interval of vasopressin-induced oliguria, suggesting that primary polydipsia was not etiologic. Administration of this steroid to Chinese hamsters was nontoxic, although these polyuric animals were unusually sensitive to water deprivation. This polyuria was not observed when progesterone alone was injected into Chinese hamsters or when MPA was given to other related hamster species (Armenian, Syrian, Turkish or Djzungarian). The MPA-injected Chinese hamster represents a unique model of vasopressin sensitive diabetes insipidus induced by a steroid in a species-specific fashion.

Complement activation by female protein, the hamster homologue of human C-reactive protein

The capacity of Syrian hamster female protein (FP), a phosphorylcholine (PC)-binding pentraxin, to activate complement was tested in an in vitro system consisting of PC-coupled sheep red blood cells and guinea pig serum as the complement (C) source. FP was demonstrated to fix complement as reflected by hemolysis. Such hemolysis was eliminated by heat treatment (56 degrees C, 30 min) of guinea pig serum and inhibited by PC chloride but not dinitrophenyl lysine. The inability of C4-deficient guinea pig serum to provide lytic activity indicated that lysis proceeded through the classical hemolytic pathway.

Hamster female protein, a sex-limited pentraxin, is a constituent of Syrian hamster amyloid

Female protein (FP) is a pentraxin of Syrian hamster which is a homologue of two human pentraxins, C-reaction protein (CRP) and amyloid P component (AP). Functionally, FP has been shown to be similar to CRP, although FP has more homology at the amino terminus with AP. The present work investigated amyloid in the Syrian hamster to determine whether FP was involved in a manner analogous to AP. FP was found to be a constituent of Syrian hamster amyloid. This conclusion was based on the following results: (a) FP was consistently detected in amyloid deposits by fluorescent microscopy with specific antisera; (b) The amount of FP extractable from hamster livers directly correlated with the presence of amyloid; and (c) 125I-FP injected intravenously into amyloidotic hamsters rapidly left the intravascular compartment and was found subsequently in amyloid deposits. This unusual alteration of plasma metabolism and amyloid localization of 125I-FP was a characteristic finding in amyloidotic hamsters and was specific for 125I-FP. Therefore, as an amyloid component, FP appears to be functionally similar to human AP. However, FP synthesis is under sex steroid control and the unique sex-limited expression of this pentraxin was associated with an equally novel propensity for deposition of amyloid in female hamsters under normal or experimental conditions. Thus, a high serum level of FP, as found in normal females or diethylstilbestrol-treated males, was associated with enhanced amyloidosis. Although speculative at present, a primary role for serum FP in hamster amyloid deposition may be experimentally approachable by hormonal manipulation of FP synthesis.

Demonstration of Aleutian disease virus-specific lymphocyte response in mink with progressive Aleutian disease: comparison of sapphire and pastel mink infected with different virus strains

Lymphocyte blastogenesis was used to study the antiviral lymphocyte response of sapphire (Aleutian) and pastel (nonAleutian) mink inoculated with Pullman or Utah 1 Aleutian disease virus (ADV). Both mink genotypes developed a virus-specific response when inoculated with Utah 1 ADV. In contrast, after inoculation of Pullman ADV, sapphire mink had a positive virus-specific response, whereas pastel mink did not. Response occurred late after infection (8 wk) and correlated with the development of progressive Aleutian disease (AD). The response to keyhole limpet hemocyanin (KLH) and concanavalin A (Con A) was also determined. Most mink of either genotype, inoculated with either virus strain, maintained an anti-KLH response during disease. Most mink also responded to Con A, although some exhibited suppressed Con A response late in the disease course. These results indicated that mink develop an anti-ADV lymphocyte response during progressive AD and are not immunosuppressed with regard to other antigens or mitogens.

Demonstration of Aleutian disease virus-specific lymphocyte response in mink with progressive Aleutian disease: comparison of sapphire and pastel mink infected with different virus strains

Lymphocyte blastogenesis was used to study the antiviral lymphocyte response of sapphire (Aleutian) and pastel (nonAleutian) mink inoculated with Pullman or Utah 1 Aleutian disease virus (ADV). Both mink genotypes developed a virus-specific response when inoculated with Utah 1 ADV. In contrast, after inoculation of Pullman ADV, sapphire mink had a positive virus-specific response, whereas pastel mink did not. Response occurred late after infection (8 wk) and correlated with the development of progressive Aleutian disease (AD). The response to keyhole limpet hemocyanin (KLH) and concanavalin A (Con A) was also determined. Most mink of either genotype, inoculated with either virus strain, maintained an anti-KLH response during disease. Most mink also responded to Con A, although some exhibited suppressed Con A response late in the disease course. These results indicated that mink develop an anti-ADV lymphocyte response during progressive AD and are not immunosuppressed with regard to other antigens or mitogens.

Diethylstilbestrol-induced jaundice in the Chinese and Armenian hamster

An unusual and impressive hyperbilirubinemia was induced in Chinese hamsters by administration of diethylstilbestrol (DES). This icterus was dose-dependent and affected females more severely than males. However, a similar mortality was detected in both sexes. Another hamster, the Armenian hamster, was even more susceptible to the icteric and lethal effects of DES. The hamster model of DES-induced icterus showed many clinical dissimilarities when compared to the human estrogen-induced jaundice, simple cholestatic jaundice. Furthermore, hepatic pathology was distinctly different as canalicular cholestatic was absent although other degenerative and regenerative hepatocellular changes were present. Livers of Armenian hamsters were more severely affected than were livers from Chinese hamsters and contained Mallory bodies even within 1 week after DES treatment. A modest, nonlethal jaundice also was detected in European hamsters after DES injection, whereas Syrian hamsters were not affected even after larger doses. This unique sensitivity to DES, and the spectrum of sensitivity within these related hamsters (Armenian greater than Chinese greater than European vs. resistant Syrian) provide an interesting model for study of DES effect on hepatic function.

Hamster female protein. A divergent acute phase protein in male and female Syrian hamsters

Normal adult male hamsters have low levels (10-20 micrograms) of female protein (FP) in serum which increase approximately fivefold during an acute phase response. In contrast, normal females have 50- to 100-fold higher serum levels and the acute phase reaction consists of a transient decrease in FP (approximately 50%), followed by a return to normal levels even under adverse conditions such as cortisone treatment (which by itself has a depressing effect on FP levels in normal females). The acute phase response was not inherently associated with gender, as the pattern of response could be changed to that of the opposite sex by appropriate hormonal manipulation. That is, castrated or diethylstilbestrol-treated males with high FP levels showed a female-type response whereas testosterone-treated females with low FP levels showed a male-type response. Studies on catabolism of 125I-FP showed a similar rapid half-life (T1/2, 9-16 h) in normal males and females and indicated that the sex difference in serum concentration was due to greater synthesis of FP in females. The divergent acute phase reaction of serum FP was related directly to changes in the FP synthetic rate (increased in males, decreased in females). As an indicator of serious pathology, a decrease of FP to very low levels in females was associated frequently with impending death.

Leukocyte subpopulations which amplify or suppress antigen-induced proliferation in Syrian hamsters

The proliferative response of spleen cells, obtained from Syrian hamsters sensitized to hen egg albumin emulsified in complete Freund's adjuvant, is lower in magnitude than the response of draining lymph node cells. In this study, the cellular regulatory mechanisms which may lead to splenic hyporesponsiveness were examined. Although unfractionated spleen cells were not suppressive, the addition of nylon wool nonadherent normal spleen cells to sensitized draining lymph node (target) cells markedly suppressed antigen- but not mitogen-induced proliferation. Suppressor cell activity was not detected in normal lymph nodes. Suppression could be overcome by culturing splenic suppressor plus target cell mixtures in the presence of large quantities of antigen. Suppressor cell activity was radioresistant. In addition to nonadherent suppressor cells, the hamster spleen also contains an adherent cell population(s) which amplified antigen-induced proliferation. Adherent cells with amplifying activity were also present in lymph nodes. The addition of adherent cells abrogated splenic suppression of proliferation. Collectively, these data indicate that the hamster spleen contains both suppressive and amplifying leukocyte subpopulations which may be involved in the regulation of the immune response to certain antigenic stimuli.

Hamster female protein. A new Pentraxin structurally and functionally similar to C-reactive protein and amyloid P component

Female protein (FP), a serum protein present in normal female hamsters was found to be similar to acute-phase reactant, C-reactive protein (CRP) and serum amyloid P component (SAP) in the following ways: (a) hamster FP complexed with phosphorylcholine (PC) in a Ca++-dependent fashion as shown by its isolation from serum by affinity chromatography with PC-Sepharose and selective elution with free PC or EDTA; (b) electron microscopy of FP indicated a pentameric structure similar in size and appearance to other pentraxins; (c) the parent molecule of FP (150,000 mol wt) was composed of five noncovalantly assembled subunits of 30,000 mol wt; and (d) the amino acid analysis and terminal NH2 sequence of FP clearly showed homology with SAP-CRP. Although FP evolved from an ancestral gene common to SAP and CRP, and shares functional, morphological and structural properties with these acute-phase proteins, the biological homology of FP appears quite diverse as this protein is a prominent serum constituent (1-2 mg/ml) of normal female hamsters and under hormonal control (testosterone suppression) in males.

Genetic resistance to the induction of experimental allergic encephalomyelitis in Lewis rats. I. Genetic analysis of an apparent mutant strain with phenotypic resistance to experimental allergic encephalomyelitis

Clinical resistance to the induction of experimental allergic encephalomyelitis was observed in a closed colony of Lewis (designated Le-R) rats. Disease susceptibility in randomly bred animals appeared to increase with increasing age. In the small group of young Le-R rats, which were susceptible, disease onset was delayed, severity of symptoms was reduced, and duration of clinical signs was abbreviated compared to conventional Lewis rats. The severity of histologic neural tissue lesions correlated with clinical observations. Breeding experiments indicated that most Le-R rats were resistant to disease induction regardless of whether their ancestors had been selected for susceptibility or resistance. The F3 generation of resistant lineage was uniformly resistant at all ages tested. Virtually all (Lewis X Le-R)F1 rats of either sex were resistant when challenged at 7-8 wk of age indicating that resistance was a dominant autosomal trait. Approximately half of (F1 X Lewis) backcross rats developed paralytic EAE whereas one-fourth were entirely resistant, suggesting that disease resistance may be mediated by one or two genes. Le-R rats shared at least some of the Lewis rat major histocompatibility antigens. Resistance apparently did not reflect a nonspecific impairment of cellular immune responsiveness. Le-R rats, which had been challenged with myelin basic protein, developed antigen-reactive cells specific for basic protein or its encephalitogenic fragment. Spleen cells obtained from basic protein-sensitized Le-R rats did not adoptively transfer disease into Lewis rats. In contrast, spleen cells obtained from basic protein-sensitized Lewis rats readily transferred disease into both Lewis and Le-R recipients. These data suggest that disease resistance may be a result of an immunologic deficit (or suppressor cell activity) expressed during the differentiation of antigen-reactive cells into disease-inducing effector cells.

Experimental chronic rabies in the cat

Two cats, inoculated with a street rabies virus strain, survived with only some progressive debility and atrophy of musculature in the injected limb for 136 weeks. They had continuously increasing titers of neutralizing antibody in serum and in cerebrospinal fluid, and terminally they had high antibody titers in the brain. Virus was isolated from two brain specimens of one cat obtained at necropsy; isolation was successful only by explant culture and inoculation of explanted tissue into mice. Virus antigen was detected in eight sites in the brain and spinal cord of the same cat by frozen-section immunofluorescence. Lesions in the central nervous system consisted of neuronal degeneration and neuronophagia, associated with the prescence of inclusion bodies and widespread inflammatory cell inflitration into brain and spinal cord parenchyma, perineuronal sites, and perivascular spaces. The inflitrates contained lymphocytes, monocytes-macrophages, and a high proportion of plasma cells. These experimental cases of chronic progressive rabies resembled more closely subacute sclerosing panecephalitis of man than the usual subacute fatal rabies encephalitis of man and other mammalian species.

Antibody development in garter snakes (Thamnophis spp.) experimentally infected with western equine encephalitis virus

Garter snakes (Thamnophis spp.) have been considered to possibly play an important role in the ecology of western equine encephalitis (WEE) virus. Serological tests (hemagglutination-inhibition, complement-fixation, neutralization test in mice, and plaque neutralization) to detect antibody in these reptiles following laboratory exposure t this virus have, in our experience, been unsatisfactory. A new test, the snake globulin precipitation (SGP) test, has been developed and we consider it to be reliable in detecting antibody in WEE virus-infected garter snakes. Antibody has been detected in these snakes over 4.5 years following inoculation with WEE virus. The SGP test should be a valuable tool in obtaining further information regarding the possible role of these cold-blooded vertebrates in the ecology of this important arbovirus.

Deposition of IgA in renal glomeruli of mink affected with Aleutian disease

The glomerular deposition of immunoglobulin (Ig) was studied in sapphire mink affected with terminal Aleutian disease (AD). Fluorescein conjugated Ig-class specific antiserums were used to evaluate and identify the glomerular Ig. Kidneys of all 28 mink with documented AD had deposits of IgA and beta 1 C in a capillary and mesangial distribution. Only 7 of 28 mink had demonstrable glomerular IgG and/or IgM. In addition, interstitial plasma cell infiltrates in 17 of 19 kidneys stained exclusively with anti-IgA. All antiserums used in this study were evaluated for Ig-class specificity by both gel diffusion and agarose-bead techniques. The striking Ig class restriction demonstrated for glomerular Ig deposition in AD is discussed in light of current knowledge of the pathogenesis of AD glomerulopathy.