Substrains Of Mice Research Articles

Toll-like receptor 4-defective C3H/HeJ mice are not more susceptible than other C3H substrains to infection with Mycobacterium tuberculosis.

Mycobacterium tuberculosis produces a variety of molecules capable of activating Toll-like receptors, a family of pattern recognition receptors expressed by macrophages and a variety of other cells. To determine whether Toll-like receptor 4 (TLR4) was critical in resistance to M. tuberculosis infection, we compared the morbidity and mortality of TLR4-defective C3H/HeJ mice to those of TLR4-sufficient C3H mouse substrains. TLR4-defective C3H/HeJ mice and TLR4-sufficient C3H/HeSnJ, C3HeB/FeJ, and C3H/HeOuJ mice were infected by the aerosol route with M. tuberculosis. TLR4-defective C3H/HeJ mice had levels of cytokines in their bronchoalveolar lavage fluids and in vitro mycobacterial antigen-specific recall responses similar to those of other C3H mouse substrains. In addition, bacterial replication and long-term survival of mice following infection appeared to be independent of TLR4. Interestingly, C3HeB/FeJ mice were significantly more susceptible to M. tuberculosis infection, indicating that genetic heterogeneity among inbred C3H mouse substrains modifies resistance to infection. Therefore, cautious interpretation is required when the C3H/HeJ strain is used as a model of a TLR4-defective mouse strain, as there are significant allelic differences between C3H/HeJ and other C3H mouse substrains in response to M. tuberculosis infection. With this caveat, our data indicate that TLR4 may not be required for optimal immunity of mice to M. tuberculosis.

Taenia crassiceps cysticercosis: immune response in susceptible and resistant BALB/c mouse substrains.

Taenia crassiceps can naturally and experimentally infect rodents in which they reproduce by budding. Differences in the susceptibility to T. crassiceps cysticercosis were found between two BALB/c substrains: BALB/cAnN (susceptible) and BALB/cJ (resistant). In chimeric mice, resistance was transferred to susceptible mice with bone marrow cells from the resistant mice, which argues in favor of an immune mediation of the resistant phenotype. To further explore the immune response that could underlie these differences in susceptibility, the specific cellular immune response elicited by the parasite was explored in both substrains. An increased proliferative response and IL-2 levels were induced by cysticercal antigens only in splenocytes from resistant mice. A decrease in the percentage of CD4(+) (11.1%), CD8(+) (17.5%) was found in splenocytes from susceptible BALB/cAnN mice. A study of the TCRV beta repertoire revealed a significant decrease in V beta 2 in both CD4(+) and CD8(+) splenocytes only in the susceptible BALB/cAnN strain.

Anti-Inflammatory and Chondroprotective Effect of TSG-6 (Tumor Necrosis Factor-α-Stimulated Gene-6) in Murine Models of Experimental Arthritis

Tumor necrosis factor-alpha (TNF-alpha)-stimulated gene-6 (TSG-6) is up-regulated by various cytokines and growth factors. TSG-6 binds to hyaluronan in inflamed synovial tissue and forms a complex with a serine protease inter-alpha-trypsin inhibitor (IalphaI), increasing the protease inhibitory effect of IalphaI >100-fold. The TSG-6/IalphaI complex then blocks serine proteases, including the plasminogen-plasmin activation, probably the most important component in the activation processes of matrix metalloproteinases. To gain insight into the mechanisms of TSG-6 action in arthritis, we have used an autoimmune murine model (proteoglycan-induced arthritis) for systemic, and a monoarticular form of arthritis (antigen-induced arthritis) for local treatment of arthritis with recombinant mouse TSG-6 (rmTSG-6). Intravenous injection of rmTSG-6 induced a dramatic reduction of edema in acutely inflamed joints by immobilizing CD44-bound hyaluronan and, in long-term treatment, protected cartilage from degradation and blocked subchondral and periosteal bone erosion in inflamed joints. The intra-articular injection of a single dose (100 microg) of rmTSG-6 exhibited a strong chondroprotective effect for up to 5 to 7 days, preventing cartilage proteoglycan from metalloproteinase-induced degradation. In contrast, rmTSG-6 did not postpone the onset, nor reduce the incidence of arthritis. We were unable to detect any significant differences between control and rmTSG-6-treated animals when various serum markers (including pro- and anti-inflammatory cytokines, auto- and heteroantibody productions) or antigen-specific T-cell responses were compared, nor when the expressions of numerous cell surface receptors or adhesion molecules were measured. TSG-6 seems to play a critical negative regulatory feed-back function in inflammation, especially in arthritic processes.

Learning behaviour and cerebral protein kinase C, antioxidant status, lipid composition in senescence-accelerated mouse: influence of a phosphatidylcholine–vitamin B12diet

Our objective was to determine whether dietary supplementation with phosphatidylcholine (PC) plus vitamin B12 could afford beneficial effects on biochemical and biophysical events in the brain of senescence-accelerated mouse (SAM) substrain SAMP8. We measured learning behaviour, hippocampal protein kinase C (PKC) activity, cerebral antioxidant status, phospholipid composition and fatty acid composition in 6-month-old SAMP8 and in age-matched controls (SAM substrain SAMR1). In comparison with SAMR1, SAMP8 showed a significant elevation in total grading score of senescence and a significant decline in acquisition SAMP8 had a lower hippocampal PKC activity and cerebral PKC-beta mRNA abundance than SAMR1. SAMP8 had increased cerebral lipid peroxide levels and proportion of sphingomyelin, and a lower proportion of 20 : 4n-6 and 22 : 6n-3 in cerebral phosphtidylethanolamine than SAMR1. SAMP8 fed the PC combined with vitamin B12 diet had an increased PKC activity and a higher proportion of 22 : 6n-3 than SAMP8 fed the control diet. These results indicate the potential benefit of PC combined with vitamin B12 as a dietary supplement.

Variations in susceptibility to proteoglycan‐induced arthritis and spondylitis among C3H substrains of mice: Evidence of genetically acquired resistance to autoimmune disease

Variations in susceptibility to proteoglycan‐induced arthritis and spondylitis among C3H substrains of mice: Evidence of genetically acquired resistance to autoimmune disease

Implications of mouse genotype for phenotype.

Genetic engineering of inbred mice offers the capability to separate interactions of multiple genes that control host resistance to pathogens. An understanding of the negative impact that genetic variability of mouse substrains can have on data is necessary for the design of experiments to dissect out complicated gene interactions.

Colitis induced by enteric bacterial antigen-specific CD4+ T cells requires CD40-CD40 ligand interactions for a sustained increase in mucosal IL-12.

C3H/HeJBir is a mouse substrain that is highly susceptible to colitis. Their CD4+ T cells react to Ags of the commensal enteric bacteria, and the latter can mediate colitis when activated by these Ags and transferred to histocompatible scid recipients. In this study, multiple long-term C3H/HeJBir CD4+ T cell (Bir) lines reactive to commensal enteric bacterial Ags have been generated. All these were Ag specific, pauciclonal, and Th1 predominant; most induced colitis uniformly after transfer to scid recipients. Lesions were focal and marked by increased expression of IL-12p40 and IFN-gamma mRNA and protein. Pathogenic Bir T cell lines expressed CD40 ligand (CD40L) when cultured with Ag-pulsed APCs in vitro. Production of IL-12 was also increased in such cultures, an effect that was Ag- and T cell-dependent and required costimulation by CD40, but not by B7. The two Bir T cell lines that did not induce lesions after transfer failed to significantly express CD40L or increase IL-12 when cultured with Ag-pulsed APCs. Administration of anti-CD40L blocked disease expression induced by pathogenic T cells. We conclude that interactions in the colon mucosa between CD40L-expressing Bir Th1 cells with APCs endogenously loaded with commensal bacterial Ags are critical for sustained increases in local IL-12 production and progression to colitis.

Variations in LPS responsiveness among different mouse substrains of C3H lineage and their congenic derivative sublines

Variations in LPS responsiveness among different mouse substrains of C3H lineage and their congenic derivative sublines

IL-5 and Rp105 Signaling Defects in B Cells from Commonly Used 129 Mouse Substrains

The use of 129 strain-derived embryonic stem cell lines for targeted gene mutation in mice has led directly to an expanded use of this inbred strain worldwide. It has been noted, however, that the 129 genetic background can make a significant contribution to the severity of a mutant phenotype. In this study, we reveal a specific defect in the IL-5 and Rp105 responses of B lymphocytes from two widely used 129 mouse substrains. The response to stimulation through surface IgM is also diminished, although to a lesser degree, in these mice. The lesion appears to reduce significantly the expression of the alpha-chain of the IL-5R, but may also influence events downstream of the IL-5R. This phenotype displays a codominant inheritance pattern, and is accompanied by a variable but significant depression of peritoneal B-1 cell numbers in 50% of the mice.

Age-related changes in the brains of senescence-accelerated mice (SAM): association with glial and endothelial reactions.

Twelve substrains of inbred senescence-accelerated mice (SAM) have been developed, among which the SAMP8 and SAMP10 strains show a significant age-related deterioration in learning and memory for passive and active avoidance tasks. These strains have, respectively, a low and high incidence of systemic senile amyloidosis. Although we found no amyloid deposits in their brain parenchyma, a variety of age-related alterations were identified, involving neurons, glia, and vessels in the brain tissues. Here we review the degenerative changes in aged SAMP8 and SAMP10 brains. These changes are generally similar to the pathology of aging human brain and may be characterized by their association with some specific glial reactions.

Differences Between Two Substrains of AB Mice in the Opioid System

Animals from two substrains of AB mice, i.e., ABH/Md and ABG/Md, differ in the occurrence of aggressive behavior. After maturation, male ABH mice regularly exhibited abnormal aggressive behavior making group-housing impossible. In contrast, ABG animals never showed such behavioral patterns. To elucidate the role of opioid mechanisms, we tested the reaction of these animals to morphine in the hot plate test. Moreover, specific DAMGO binding was measured. It was shown that mice from control groups differed significantly in reaction to the thermal stimulus. ABH mice had significantly longer reaction times. With increasing doses of morphine this difference disappeared, suggesting different levels of basal activity in endogenous opioid systems. This is underlined by significantly lower DAMGO binding in aggressive ABH mice. The results suggest that differences in endogenous opioid systems may account for differences in aggressiveness.

Behavioural performance in three substrains of mouse strain 129

Recently, the possibility has been raised that the behavioural abnormalities seen in null-mutant mice might be determined by their genetic background rather than by loss of gene function, especially when the 129 mouse strain is used as supplier for embryonic stem (ES) cells. To examine this issue we tested three 129 mouse substrains (129/J, 129/Ola, 129/Sv-ter/+) and C57BL/6 (B6) in the Morris water maze, the open field, the plus maze and two tests assessing motor co-ordination. We identified only for the 129/J substrain substantial behavioural deficits. These mice are albinos and carry the pink-eyed dilution allele and differed in their basal anxiety level as assessed in the open-field test. They were severely impaired in spatial learning and memory (Morris water maze test), in the Porsolt swim test, which also measures learning and in motor co-ordination. However, the 129/J substrain has not been used as ES cell donor in null-mutant mice where behavioural abnormalities were observed. Instead, mice from 129/Ola and 129/Sv-ter/+ substrains have been commonly used as suppliers for ES cells. These performed normally in most of the tests, including Morris water maze test.

Genetic variation among 129 substrains and its importance for targeted mutagenesis in mice.

Targeted mutagenesis in mice, a powerful tool for the analysis of gene function and human disease, makes extensive use of 129 mouse substrains. Although all are named 129, we document that outcrossing of these substrains, both deliberate and accidental, has lead to extensive genetic variability among substrains and embryonic stem cells derived from them. This clearer understanding of 129 substrain variability allows consideration of its negative impact on targeting technology, including: homologous recombination frequencies, preparation of inbred animals, and availability of appropriate controls. Based on these considerations we suggest a number of recommendations for future experimental design.

Oxidative status in senescence-accelerated mice.

The lipid peroxidation and activities of antioxidant enzymes were examined in the livers of two substrains of senescence-accelerated mice (SAM): senescence-resistant SAM-R/1 and senescence-prone SAM-P/1. Fluorescent age pigment and conjugated diene levels in both substrains increased gradually with age, but we found higher levels in SAM-P/1 at all ages tested. Differences in the levels of lipid peroxidation products became more marked with age. Among the enzymes studied, only mitochondrial superoxide dismutase (SOD) in SAM-P/1 showed decreased activity in all age groups. The specific mitochondrial SOD in that case was Cu,Zn-SOD. The amount of Cu,Zn-SOD in mitochondrial fractions of SAM-P/1 was only half that of SAM-R/1, whereas there were no apparent differences in the mRNA levels of both SAM groups. Our study indicates that impaired transport of Cu,Zn-SOD into mitochondria after cytosolic synthesis reduces defense against oxidative stress. That reduction may be one of the factors contributing to accelerated senescence in the SAM-P/1.

Control of the thymic microenvironment by growth hormone/insulin-like growth factor-I-mediated circuits.

The thymus gland is a central lymphoid organ in which bone marrow-derived T cell precursors undergo maturation, eventually leading to the migration of positively selected thymocytes to the T-dependent areas of peripheral lymphoid organs. This process occurs under the influence of the thymic microenvironment, by means of secretory polypeptides and cell-cell contacts. The thymic microenvironment is a tridimensional cellular network composed of epithelial cells (its major component), macrophages, dendritic cells, fibroblasts and extracellular matrix elements. The epithelial reticulum is a heterogeneous tissue, in which a particular lymphoepithelial structure has been isolated in vitro: the thymic nurse cell complex, which possibly creates particular microenvironmental conditions for thymocyte differentiation. Additionally, thymic nurse cells are useful tools to study mechanisms involved in intrathymic T cell migration, including neuroendocrine influences. Previous data showed that thymic hormonal function can be modulated by hormones and neuropeptides, including growth hormone. Interestingly, GH acts pleiotropically on the thymic epithelium increasing cell growth and expression of extracellular matrix ligands and receptors, the latter resulting in an enhancement of thymocyte adhesion to the epithelial cells and thymocyte release from thymic nurse cells. The role of GH on thymus development is further stressed by the findings obtained with GH-deficient dwarf mice. Besides the precocious decline in serum thymulin found in these animals, a progressive thymic hypoplasia occurs, with decreased numbers of CD4+CD8+thymocytes, both defects being largely restored by long-term GH treatment. The effects of GH in the thymus are apparently mediated by IGF-1. Enhancement of thymulin secretion induced by GH, as well as the stimulation of thymocyte adhesion to thymic epithelial cells can be prevented in vitro by treatment with antibodies for IGF-I or IGF-I receptor. Moreover, in both systems IGF-I alone can yield similar effects. Also, the enhanced concanavalin-A mitogenic response and IL-6 production by thymocytes observed in GH-treated mice can be detected in animals treated with IGF-I. Lastly, mouse substrains selected for high or low IGF-I circulating levels exhibited differential thymus developmental patterns correlating with IGF-I levels. A further conceptual aspect concerning the GH-IGF-I-mediated control of thymus physiology is the recent demonstration of an intrathymic production of these molecules, leading to the hypothesis that, in addition to the classical endocrine pathway, GH-IGF-I-mediated paracrine and autocrine pathways may also be implicated in the control of thymus physiology. In any case, such control is exerted pleiotropically, with modulation in the expression of several genes in different cell types of the organ. In this respect, it is exciting to imagine a role of GH-IGF-I loops in shaping the intrathymically generated T cell repertoire.

Insights into the pathogenesis of inflammatory bowel diseases provided by new rodent models of spontaneous colitis

New molecular techniques that permit over-expression or deletion of targeted genes have created a new class of rodent models of intestinal inflammation. Spontaneous colitis, with variable small bowel, duodenal, and systemic inflammation, develops in transgenic HLA-B27/β2-microglobulin rats; interleukin-2, interleukin-10, transforming growth factor-β1, T cell receptor, and G protein deficient (knockout) mice; the new C3H/HeJ Bir mouse substrain; following transfer of CD45RBhigh lymphocytes into immunodeficient mice; and following bone marrow transplantation into cyclosporin A-treated mice. These models provide the following important insights into the mechanisms of chronic intestinal inflammation: (a) Ubiquitous luminal bacteria have a critical role in induction and perpetuation of chronic intestinal and systemic inflammation in genetically susceptible hosts. (b) Defective immunoregulation, especially immunosuppression, can lead to chronic colitis, (c) Alteration of any of a number of immunoregulatory molecules can induce almost identical phenotypes of intestinal inflammation. (d) Host genetic susceptibility determines the incidence and aggressiveness of disease. (e) The immune system, especially immunoregulatory T lymphocytes, mediates chronic colitis. Results in these models are consistent with the hypothesis that chronic intestinal and related systemic manifestations are the result of an inappropriately aggressive immune response to ubiquitous luminal bacterial constituents, mediated by genetically determined defective immunosuppression. Furthermore, the diverse nature of immunoregulatory defects in these models that share similar clinical manifestations suggests that ulcerative colitis and Crohn's disease are heterogeneous groups of disorders with multiple etiologies.

An inbred epilepsy-prone substrain of BALB/c mice shows absence of the corpus callosum, an abnormal projection to the basal forebrain, and bilateral projections to the thalamus.

BALB/c mice lack a corpus callosum in about 11% of the population. Two inbred substrains of BALB/c mice, epilepsy-prone (EP) and epilepsy-resistant (ER), have been examined to determine whether these substrains differ in regard to corpus callosum morphology. Further, this study addressed the issue of whether misrouted cortical axons form an aberrant pathway instead of the corpus callosum. Initial studies that examined fresh brain tissue of adult animals revealed normal corpora callosa in all ER mice but deficient or absent corpora callosa in all EP mice. Subsequently, Dil crystals were placed in the motor cortices of aldehyde-fixed brains of 2-week-old animals to investigate cortical projections in both inbred substrains of mice. Fluorescent microscopy revealed that all of the ER animals had normal corpora callosa, whereas all EP animals exhibited either reduced corpora callosa (partially callosal) or an absence (acallosal) of this structure. Both acallosal and partially callosal EP mice displayed an extensive, aberrant projection to the basal forebrain as well as bilateral projections to midline and intralaminar thalamic nuclei. The fibers projecting to the basal forebrain arose from the cortex, coursed toward the midline before turning ventrally along the midline, and appeared to terminate in the medial septal nucleus and the nucleus of the diagonal band. ER animals lacked this aberrant cortical projection to the basal forebrain. Electron microscopic results obtained from EP mice indicated that labeled axons in this aberrant pathway formed axosomatic, axodendritic, and axospinous synapses with the neurons in the medial septal/diagonal band complex. The function of the aberrant projection to the basal forebrain remains unknown but it may provide an abnormal excitatory input to a region that provides cholinergic and GABAergic input to the cerebral cortex and hippocampus. The additional projections to midline and contralateral intralaminar thalamic nuclei in EP mice may function to intensify the synchronization of bilateral discharges.

Differences in ethanol-induced behaviors in normal and acatalasemic mice: Systematic examination using a biobehavioral approach

In studies designed to further examine the previously reported involvement of catalase in ethanol-induced effects, we attempted to confirm earlier observations by using normal (C3H-N) and acatalasemic (C3H-A) mice. These mice are identical in every respect and differ only in their catalase activity. Data suggested that the application of 3-amino-1,2,4-triazole (AT), a catalase inhibitor, to both substrains of mice resulted in a proportional decrease in motor activity, thus supporting our earlier observations. We also showed that this effect was specific to ethanol because AT did not have any effect on cocaine-induced motor activity in both substrains. Contrary to the effects of ethanol, these substrains did not differ activity in response to cocaine. In an additional study, we observed that acatalasemic mice differed from the normals in their pattern of voluntary ethanol consumption. Acatalasemic mice consumed more ethanol but only when it was presented in the range of concentrations between 12 and 18%. Finally, we also obtained data suggesting that suggesting that acatalasemic mice have longer duration of sleep time following ethanol administration compared to normals. Catalase activity was measured in both substrains. Results, once again, confirmed earlier data that the substrains differ in this activity and that AT further decreases brain catalase activity in both mice. Finally, when brain homogenates derived from both substrains were incubated with ethanol significant differences in the amount of generated acetaldehyde were found between the two mice strains. Together, these results provide strong support for the involvement of brain catalase in a variety of ethanol-induced behavioral effects.

A behavioral profile of autoimmune lupus-prone MRL mice

Manifestations of the human autoimmune disease systemic lupus erythematosus (SLE) include a number of behavioral and cognitive deficits. The present study asks whether neurobehavioral dysfunction is present also in MRL mice that spontaneously develop most of the fundamental immunological aberrations of SLE. There are two congenic substrains of MRL mice that differ in the time of disease onset: MRL-lpr mice develop lupus early and MRL-+/+ develop the typical signs of disease relatively late in life. The behavior of these substrains was assessed at 7 to 11 weeks of age, a time that coincides with the onset of disease in MRL-lpr mice and the absence of known lupus symptoms in the MRL-+/+ group. When compared to the congenic MRL-+/+ control substrain, MRL-lpr mice were spontaneously less active, traversed a crossbeam slower, and ceased responding to the novelty of a new environment sooner. They were also more reluctant to leave their home base or travel far away from it and perseverated in their response bias during extinction and reversal learning. Immunological status was characterized by moderate proteinuria in both substrains and high titers of antinuclear antibodies in MRL-lpr but not MRL-+/+ mice. Histological analysis revealed minimal or no signs of joint pathology in MRL-lpr mice. Thus, this study shows the presence of behavioral dysfunction in mice with early stages of autoimmune disease and gives support for the idea that MRL mice may provide a useful model of neuro-behavioral dysfunction in SLE. It is suggested that the behavioral profile of MRL-lpr mice may indicate increased “timidity,” related to genetics, autoimmunity, or both.

Genes regulating testis size.

The studies described here provide information about the genetic and morphological bases for the significant differences in testis size among three closely related C57BL mouse substrains: C57BL/6J, C57BL/6ByJ, and C57BL/10J. C57BL/6J mice have normal-size testes while the other two substrains have small-size testes. Genes controlling testis size are postulated to be among the estimated forty genes that differ between the C57BL/6J and C57BL/6ByJ substrains. The number of genes involved in testis size regulation was examined using recombinant inbred mouse strains. An investigation of the role of Y chromosome genes was performed by completing molecular analyses with a mouse Y chromosome-specific probe. Sertoli and germ cell counts provided insight into the morphological basis for the different testis sizes. The experimental results suggest that there are at least two autosomal testis-size genes and that they control testis size by regulating the number of Sertoli cells.