Oviduct Infection and Hydrosalpinx in DBA1/j Mice Is Induced by Intracervical but Not Intravaginal Inoculation with Chlamydia muridarum

Intravaginal infection with C. muridarum in mice often results in hydrosalpinx similar to that found in women urogenitally infected with C. trachomatis, making the C. muridarum lower genital tract infection murine model suitable for studying C. trachomatis pathogenesis. To our surprise, DBA1/j mice were highly resistant to hydrosalpinx following an intravaginal infection with C. muridarum although these mice were as susceptible to lower genital tract infection as other mouse strains. A significantly lower level of C. muridarum organisms was recovered from the oviduct of DBA1/j mice, correlating the resistance to hydrosalpinx with reduced ascension of C. muridarum to the oviduct. The DBA1/j resistance to hydrosalpinx was effectively overcome by intracervical inoculation with C. muridarum. The intracervically inoculated DBA1/j mice developed severe hydrosalpinx with the highest levels of live C. muridarum organisms recovered from uterine tissue on day 3 and oviduct tissue on day 7 post inoculation while in intravaginally inoculated DBA1/j mice, the peak of live organism recovery from uterine tissue was delayed to day 7 with no rise in the amount of live organisms recovered from the oviduct. These observations have not only validated the correlation between hydrosalpinx and live organism invasion in the oviduct but also demonstrated that the intracervical inoculation, by promoting rapid chlamydial replication in the uterine epithelial cells and ascension to the oviduct of DBA1/j mice, may be used for further understanding chlamydial pathogenic mechanisms. The above findings also suggest that strategies aimed at reducing tubal infection may be most effective in blocking tubal pathology.     

IL-6-mediated signaling pathways limit Chlamydia muridarum infection and exacerbate its pathogenicity in the mouse genital tract

Chlamydia muridarum induction of mouse hydrosalpinx, depending on both tubal infection and inflammation, has been used for investigating Chlamydia trachomatis pathogenesis. We now report that IL-6 both inhibits C. muridarum infection and exacerbates pathogenicity in the mouse genital tract. When intravaginally inoculated with a high dose of C. muridarum, IL-6-deficient mice developed more extensive genital tract infection with severe hydrosalpinx, suggesting that IL-6 is required for controlling the high dose infection but not essential for C. muridarum-induced pathology. However, at a low dose, IL-6-deficient mice still developed more extensive infection in the genital tract but no longer with significant pathology, suggesting that IL-6 is required for both controlling the low dose infection and exacerbating the low dose infection-induced pathology. The lack of hydrosalpinx in IL-6-deficient mice correlated with significantly reduced inflammatory infiltration in the oviduct tissue and decreased spleen CD4+ and CD8+ T cells that produce TNFα. Thus, IL-6-dependent pathways are important for both limiting chlamydial colonization in the genital tract mucosal tissues regardless of the infection doses and exacerbating chlamydial pathogenicity in the upper genital tract when IL-6-independent pathogenic mechanisms are not yet activated with a low infection dose.     

Variations in the response of five strains of mice to Leishmania mexicana.

Five strains of mice were studied in their ability to support Leishmania mexicana infection. Four strains, AKR, C57BL/6, DBA/2 and NMRI, were relatively resistant to cutaneous leishmaniasis. These strains developed delayed type hypersensitivity responses to leishmanial antigens and produced agglutinating antibodies. On the other hand Balb/c mice, highly susceptible to infection, failed to develop delayed type hypersensitivity responses and showed an impaired production of antibodies. Hybrids produced by mating C57BL/6 males and Balb/c females were no more susceptible than C57BL/6 mice, suggesting that resistance is inherited as a dominant character.     

Bioluminescence Imaging of Chlamydia muridarum Ascending Infection in Mice

Chlamydial pathogenicity in the upper genital tract relies on chlamydial ascending from the lower genital tract. To monitor chlamydial ascension, we engineered a luciferase-expressing C. muridarum. In cells infected with the luciferase-expressing C. muridarum, luciferase gene expression and enzymatic activity (measured as bioluminescence intensity) correlated well along the infection course, suggesting that bioluminescence can be used for monitoring chlamydial replication. Following an intravaginal inoculation with the luciferase-expressing C. muridarum, 8 of 10 mice displayed bioluminescence signal in the lower with 4 also in the upper genital tracts on day 3 after infection. By day 7, all 10 mice developed bioluminescence signal in the upper genital tracts. The bioluminescence signal was maintained in the upper genital tract in 6 and 2 mice by days 14 and 21, respectively. The bioluminescence signal was no longer detectable in any of the mice by day 28. The whole body imaging approach also revealed an unexpected airway infection following the intravaginal inoculation. Although the concomitant airway infection was transient and did not significantly alter the genital tract infection time courses, caution should be taken during data interpretation. The above observations have demonstrated that C. muridarum can not only achieve rapid ascending infection in the genital tract but also cause airway infection following a genital tract inoculation. These findings have laid a foundation for further optimizing the C. muridarum intravaginal infection murine model for understanding chlamydial pathogenic mechanisms.     

A role for matrix metalloproteinase-9 in pathogenesis of urogenital Chlamydia muridarum infection in mice

Matrix metalloproteinases (MMPs) are a family of host-derived enzymes involved in the turnover of extracellular matrix (ECM) molecules and the processing of cytokines, chemokines and growth factors. We have previously reported that global inhibition of MMP in Chlamydia muridarum urogenital tract infection of susceptible strains of female mice impeded ascension of C. muridarum into the upper genital tract, blunted acute inflammatory responses and reduced the rate of formation of chronic disease. Because we have also observed that MMP-9 (also known as gelatinase B) is expressed in relatively large quantities in susceptible strains of mice in response to infection during acute phases of infection, we explored this further in a more selected fashion. We infected MMP-9 gene knockout mice and wild type controls intravaginally with C. muridarum. Both groups of mice had similar isolation rates from the lower urogenital tract but the absence of MMP-9 resulted in a slightly lower isolation rate in the upper genital tract, blunted acute inflammatory indices in the affected tissues and a reduced rate of formation of hydrosalpinx-a surrogate marker of infertility. These results imply that MMP-9 is involved in pathogenesis of chlamydial infection in this model possibly by amplifying inflammatory responses.     

Host Genetic Background Influences the Response to the Opportunistic Pseudomonas aeruginosa Infection Altering Cell-Mediated Immunity and Bacterial Replication

Pseudomonas aeruginosa is a common cause of healthcare-associated infections including pneumonia, bloodstream, urinary tract, and surgical site infections. The clinical outcome of P. aeruginosa infections may be extremely variable among individuals at risk and patients affected by cystic fibrosis. However, risk factors for P. aeruginosa infection remain largely unknown. To identify and track the host factors influencing P. aeruginosa lung infections, inbred immunocompetent mouse strains were screened in a pneumonia model system. A/J, BALB/cJ, BALB/cAnNCrl, BALB/cByJ, C3H/HeOuJ, C57BL/6J, C57BL/6NCrl, DBA/2J, and 129S2/SvPasCRL mice were infected with P. aeruginosa clinical strain and monitored for body weight and mortality up to seven days. The most deviant survival phenotypes were observed for A/J, 129S2/SvPasCRL and DBA/2J showing high susceptibility while BALB/cAnNCrl and C3H/HeOuJ showing more resistance to P. aeruginosa infection. Next, one of the most susceptible and resistant mouse strains were characterized for their deviant clinical and immunological phenotype by scoring bacterial count, cell-mediated immunity, cytokines and chemokines profile and lung pathology in an early time course. Susceptible A/J mice showed significantly higher bacterial burden, higher cytokines and chemokines levels but lower leukocyte recruitment, particularly neutrophils, when compared to C3H/HeOuJ resistant mice. Pathologic scores showed lower inflammatory severity, reduced intraluminal and interstitial inflammation extent, bronchial and parenchymal involvement and diminished alveolar damage in the lungs of A/J when compared to C3H/HeOuJ. Our findings indicate that during an early phase of infection a prompt inflammatory response in the airways set the conditions for a non-permissive environment to P. aeruginosa replication and lock the spread to other organs. Host gene(s) may have a role in the reduction of cell-mediated immunity playing a critical role in the control of P. aeruginosa infection. These results now provide a basis for mapping genomic regions underlying host susceptibility to P. aeruginosa infection.     

Mouse Strain-Dependent Differences in Estrogen Sensitivity During Vaginal Candidiasis

The animal models available for studying the immune response to genital tract infection require induction of a pseudo estrous state, usually achieved by administration of 17-β-estradiol. In our experimental model of vaginal candidiasis, under pseudo estrus, different strains of mice were used. We observed major differences in the clearance of Candida albicans infection among the different strains, ascribable to differing susceptibility to estradiol treatment. In the early phase of infection CD1, BALB/c, C57BL/6 albino and C57BL/6 mice were colonized to similar levels, while in the late phase of infection, BALB/c mice, which are considered genetically resistant to C. albicans infection, exhibited greater susceptibility to vaginal candidiasis than CD1 and C57BL/6 albino strains of mice. This was because estradiol induced “per se” enlarged and fluid-filled uteri, more pronounced in infected mice and consistently more evident in BALB/c and C57BL/6 mice than in CD1 mice. Unlike CD1, BALB/c and C57BL/6 mice showed a heavy fungal colonization of the uterus, even though C57BL/6 mice apparently cleared C. albicans from the vagina. The presence of C. albicans in the vagina and uterus was accompanied by a heavy bacterial load. Collectively these observations prompted us to carry out a careful analysis of estradiol effects in a mouse model of vaginal infection.     

Comparison of urethane-induced sister-chromatid exchanges in various murine strains, and the effect of enzyme inducers

The induction of sister-chromatid exchanges (SCEs) by urethane, 150 and 300 mg/kg administered i.p., was examined in bone-marrow cells of AKR, BALB/c, C3Hf, C57BL/6J and DBA/2 male mice. In all strains, the base-line level of SCE/cell was similar, ranging from 4.3 to 8.7, and the response increased with the dose of urethane. DBA/2 mice were the most susceptible to urethane at both dose levels, with 30.6 SCE/cell after treatment with 300 mg/kg, whereas the response of the other strains was from 17.4 to 21.5 SCE/cell at the same urethane dose. Pretreatment of C57BL/6J and DBA/2 mice with phenobarbital decreased the SCE frequencies induced by urethane, 300 mg/kg, to 70%, whereas a prior administration of beta-naphthoflavone reduced SCE levels in C57BL/6J but not in DBA/2 mice.     

Comparison of pathology in susceptible A/J and resistant C57BL/6J mice after infection with different sub-strains of Plasmodium chabaudi

Susceptible A/J and more resistant C57BL/6J mice were infected with Plasmodium chabaudi chabaudi 54X, P.c. chabaudi AS and Plasmodium chabaudi adami 408XZ. As expected, most C57BL/6J mice survived the infections with the different isolates. But in contrast to previous observations, not all A/J mice succumbed to infection: just over 50% of A/J mice survived infections with P.c. chabaudi 54X, while 80% survived P.c. chabaudi AS. The more virulent parasite, P.c. adami 408XZ, was able to kill all A/J mice and 20% of C57BL/6J mice after an intravenous infection with 10(5) pRBC. A detailed study of four parameters of pathology (body weight, body temperature, blood glucose and RBC counts) in both mouse strains after a P.c. adami 408XZ infection showed similar patterns to those previously reported after infection with P.c. chabaudi AS. These data suggest that environmental factors as well as parasite polymorphisms might influence the severity of malaria between susceptible and resistant mice.     

Plasmid-Encoded Pgp5 Is a Significant Contributor to Chlamydia muridarum Induction of Hydrosalpinx

We have previously shown that the plasmid-encoded Pgp3 is a major virulence factor for C. muridarum induction of hydrosalpinx. We now report that Pgp5 also plays a significant role in the development of hydrosalpinx following C. muridarum induction. Pgp5 deficiency was introduced via either in-frame deletion (CM-Δpgp5) or premature stop codon installation (CM-pgp5S). Mice infected with either CM-Δpgp5 or CM-pgp5S developed hydrosalpinges at significantly reduced levels with an incidence rate of <40% and a mean severity score of 2 or less. In contrast, 80% or more mice developed hydrosalpinx with a severity score of >3 when mice were infected with Pgp5-sufficient C. muridarum (plasmid-competent wild type or plasmid-free C. muridarum transformed with a full plasmid or depleted of pgp7 gene). The attenuated pathogenicity of the Pgp5-deficient C. muridarum correlated with a significantly reduced level of ascending infection in the oviduct tissue despite the similar overall shedding courses between mice infected with Pgp5-deficeint versus sufficient C. muridarum. Furthermore, in the oviducts of mice infected with Pgp5-deficient C. muridarum, significantly lower levels of inflammatory cell infiltration and cytokine production were detected. Thus, Pgp5 is a significant plasmid-encoded virulence factor for C. muridarum pathogenicity in the upper genital tract.     

Varying susceptibility of pulmonary cytokine production to lipopolysaccharide in mice

Objectives: The lipopolysaccharide (LPS)-induced acute lung injury (ALI) model has been widely applied for pathophysiological and pharmacological research. The aim of present study is to understand the variation of acute pulmonary inflammation between mouse strains. Methods: The present study investigated the susceptibility of acute production of inflammatory mediators, e.g. cytokines, chemokines and others, to LPS in C57BL/6J, Balb/cJ, DBA/1J, CD-1, NMRI, DBA/2J, A/J, and C3H/HeN mice. Results: The susceptibility to intra-tracheal challenge with LPS varied between measured variables, durations and strains. General lung hyper-reactive susceptibility to LPS-induced pulmonary production of 6–8 inflammatory mediators followed the order NMRI, Balb/cJ, C3H/HeN, A/J, C57BL/6J, DBA/1J, DBA/2J and CD-1 mice at 4 h, and A/J, C3H/HeN, CD-1, NMRI, C57BL/6J, Balb/cJ, DBA/2J and DBA/1J mice at 24 h. Conclusions: Our data provide information for scientists to consider the proper strain of mice for the measurement of specific inflammatory mediators and to select sensitive or resistant mouse strains for understanding genetic variation in the pathogenesis and for the screening of target-oriented drug development.     

不同品系小鼠对实验感染念珠状链杆菌敏感性的观察

本文通过念珠状链杆菌（Ｓｔｒｅｐｔｏｂａｃｉｌｕｓｍｏｎｉｌｉｆｏｒｍｉｓ,Ｓ．ｍ．）实验感染昆明、Ｃ５７ＢＬ／６Ｊ、ＢＡＬＢ／ｃ、ＩＣＲ、ＮＩＨ、ＤＢＡ共６个品系小鼠,观察其对Ｓ．ｍ．敏感性的差异。其中昆明、Ｃ５７ＢＬ／６Ｊ两个品系在腹腔接种后表现出明显的临床、病理改变。昆明小鼠发病率和死亡率分别为９２％和８０％;Ｃ５７ＢＬ／６Ｊ分别是８０％和１２％。昆明小鼠较之Ｃ５７ＢＬ／６Ｊ小鼠起病急、病情严重,多数动物死于感染的急性期。其余品系的发病率为：ＮＩＨ８％、ＢＡＬＢ／ｃ和ＤＢＡ４％,没有动物死亡;ＩＣＲ在接种后无任何临床病理改变。在实验感染后临床病理改变方面,昆明小鼠和Ｃ５７ＢＬ／６Ｊ小鼠间有较大不同。昆明小鼠以末梢血管淤血、四肢尾部水肿、关节炎、截瘫、腹泻为主,而Ｃ５７ＢＬ／６Ｊ小鼠则以注射部位和其它部位皮下脓肿、化脓性关节炎为主。本研究提示,中国昆明小鼠对Ｓ．ｍ．敏感性最高,可以将其作为“哨兵动物”用于实验大鼠Ｓ．ｍ．的常规监测;不同品系小鼠不仅对实验感染Ｓ．ｍ．的敏感性不同,而且表现出不同的临床病理改变。     

Metabolism of benzo[a]pyrene: Effect of 3-methylcholanthrene pretreatment on metabolism by microsomes from lungs of genetically “responsive” and ”nonresponsive” mice

The metabolism of [¹⁴C]benzo[a]pyrene by microsomes from the lungs of normal and 3-methylcholanthrene-treated DBA/2J, C57BL/6J, and A/HeJ mouse strains was quantitatively analyzed by high-pressure liquid chromatography. The ratio of dihydrodiols of benzo[a]pyrene to total metabolites formed was greater with lung microsomes than with liver microsomes in all three strains. The ratio of epoxide hydrase to monooxygenase activity in mouse lung was shown to be considerably higher than in mouse liver. Benzo[a]pyrene metabolism by control lung microsomes showed some strain differences. C57BL/6J and A/HeJ mice formed twice as much dihydrodiols as a percentage of total metabolism compared to DBA/2J mice. DBA/2J mice produced somewhat less phenol 2 fraction and considerably more quinone 1 and 2 fractions than the other two mouse strains as a percentage of total metabolism. Treatment of C57BL/6J and DBA/2J mice with 3-methylcholanthrene resulted in a 20-fold increase in the metabolism of benzo[a]pyrene, while A/HeJ mice were induced more than 50-fold. The profiles of metabolites from the 3-methylcholanthrene-induced animals were nearly identical in all three mouse strains.     

The DBA.2 mouse is susceptible to disease following infection with a broad, but limited, range of influenza A and B viruses

We assessed the relative susceptibilities to disease of the DBA.2 and C57BL/6 mouse models upon infection with a range of influenza A and B viruses. DBA.2 mice were more susceptible to disease upon inoculation with human H1N1 influenza A virus strains, several swine influenza viruses, and influenza B viruses but were not overtly susceptible to infection with human seasonal H3N2 strains. Hemagglutination inhibition and immunoglobulin isotype profiling indicated that DBA.2 and C57BL/6 mice generate comparable humoral responses upon equivalent 50% mouse lethal dose (MLD(50)) challenges with influenza virus. Our data demonstrate the utility of DBA.2 mice for the elucidation of influenza virus pathogenicity determinants and the testing of influenza vaccines.     

Genetic resistance to lethal Sendai virus pneumonia: virus replication and interferon production in C57BL/6J and DBA/2J mice

Resistant C57BL/6J and susceptible DBA/2J mice were exposed to aerosols of Sendai virus and killed at intervals to 12 days. Lungs were removed and assayed for infectious virus and interferon. Mean virus titers were 6 to 400 times higher in DBA/2J mice than in C57BL/6J mice 3 to 10 days after exposure. Mean interferon titers were 10 to 140 times higher in DBA/2J mice than in C57BL/6J mice 4 to 7 days after exposure. These results suggest that genetic resistance to the lethal effects of Sendai virus is expressed through control of viral replication within the first 72 hours of infection and that early expression of inherited resistance is not regulated by interferon.     

Mouse senile amyloidosis. ASSAM amyloidosis in mice presents universally as a systemic age-associated amyloidosis.

Amyloid deposition in 11 inbred strains of mice (A/J, SJL/J, DDD, C57BL/6J, B10.BR, C57BL/10, B10A/SgSn, C3H/HeMs, B10A(5R), DBA/2 and C57BL/6Cr5/c) was studied using the peroxidase antiperoxidase (PAP) method and antisera against ASSAM and murine protein AA. Among the 170 mice examined, in 77 (45.3%) from the nine strains other than C3H/HeMs and DBA/2, there was evidence of spontaneous amyloid deposits in routine histological sections. Immunohistochemical studies using 54 mice with amyloid deposition, demonstrated ASSAM deposition in 45 mice (83.3%) in all nine strains, although the incidence and intensity of the deposition differed somewhat between strains. SJL/J and A/J had ASSAM deposits from the age of 8 months and the incidence increased with advancing age. In the other seven strains, ASSAM was first deposited at an older age than in the SJL/J and A/J strains. In A J, C57BL/6J, C57BL/10, B10.BR, B10A(5R) and C57BL/6Cr5/c, protein AA often coexisted with ASSAM. The distribution pattern of the ASSAM deposits was similar to that observed among the SAM strains. Thus, ASSAM is an ubiquitously distributed senile amyloid protein in the mouse. Determination of the molecular type of apoA-II, a serum precursor of ASSAM, among all 11 strains using the polymerase chain reaction (PCR) revealed the SAM-P/1 type apoA-II variant in SJL/J and A/J strains with a high susceptibility to ASSAM deposition. We concluded from this study that amino acid substitution in precursor apoA-II may be responsible for the early onset and severe amyloid deposition in the mouse.     

A role for matrix metalloproteinase-9 in pathogenesis of urogenital Chlamydia muridarum infection in mice

Matrix metalloproteinases (MMPs) are a family of host-derived enzymes involved in the turnover of extracellular matrix (ECM) molecules and the processing of cytokines, chemokines and growth factors. We have previously reported that global inhibition of MMP in Chlamydia muridarum urogenital tract infection of susceptible strains of female mice impeded ascension of C. muridarum into the upper genital tract, blunted acute inflammatory responses and reduced the rate of formation of chronic disease. Because we have also observed that MMP-9 (also known as gelatinase B) is expressed in relatively large quantities in susceptible strains of mice in response to infection during acute phases of infection, we explored this further in a more selected fashion. We infected MMP-9 gene knockout mice and wild type controls intravaginally with C. muridarum. Both groups of mice had similar isolation rates from the lower urogenital tract but the absence of MMP-9 resulted in a slightly lower isolation rate in the upper genital tract, blunted acute inflammatory indices in the affected tissues and a reduced rate of formation of hydrosalpinx–a surrogate marker of infertility. These results imply that MMP-9 is involved in pathogenesis of chlamydial infection in this model possibly by amplifying inflammatory responses.     

Streptobacillus moniliformis epizootic in barrier-maintained C57BL/6J mice and susceptibility to infection of different strains of mice

We report a Streptobacillus moniliformis epizootic in barrier-maintained SPF mice. Although various inbred and F1 hybrid strains of mice have been kept in this animal facility, only C57BL/6J Han [corrected] mice showed clinical signs of disease. During the course of the epizootic, 825 breeding animals (approximately 36% of the breeders) died or had to be killed because of severe clinical signs. Although sequential treatment with ampicillin and chlortetracycline gave good therapeutic results, the animal facility was vacated in order to exclude any risk of cross-contamination of the other rodent colonies in our institute. The source and route of transmission of S. moniliformis could not be elucidated. To investigate strain dependent differences experimental infection of different strains of mice with our S. moniliformis isolate was performed. After oral infection only C57BL/6J showed the typical signs of a cervical lymphadenitis and gave an immunological response. BALB/cJ, C3H/He, DBA/2J, CB6F1 and B6D2F1 mice were not affected except in two cases of DBA/2J and B6D2F1 mice where seroconversion was observed. After intravenous infection of C57BL/6J, DBA/2J [corrected] and BALB/cJ all animals showed positive titers in the indirect immunofluorescence test (IIF). One hundred percent of the C57BL/6J, forty percent of the DBA/2J, and none of the BALB/cJ mice developed severe symptoms. The results demonstrate that the susceptibility to streptobacillosis is predominantly influenced by genetic factors.     

Behavior of mice from different strains: modifications produced by noopept

Genotype-dependent behavioral effects were demonstrated in BALB/c, C57BL/6J [Russian character: see text] DBA/2J mice after injections of nootropic drug Noopept. In an elevated plus maze, drug administration induced an increase in the number of enterings into bright arms in BALB/c mice, whereas the opposite effect was observed in C57BL/6J. After the Noopept administration, animals from all the three strains increased the number of active avoidance reactions in stress-inducing slip-funnel test. A significant intensification of exploration behavior was observed in a closed plus-maze in BALB/c and C57BL/6J. The Noopept affected weakly or had no effect on the behavior of DBA/2J mice.