Perfluorooctanoic acid-induced immunomodulation in adult C57BL/6J or C57BL/6N female mice

BACKGROUND: Perfluorooctanoic acid (PFOA), an environmentally persistent compound of regulatory concern, has been reported to reduce antibody responses in mice at a single dose. OBJECTIVE: The aim of this study was to evaluate PFOA effects on humoral and cellular immunity using standard assays for assessing immune function, and to derive dose-response data. METHODS: C57BL/6J mice received 0 or 30 mg PFOA/kg/day for 10 days; half of the exposed groups were switched to vehicle and half continued on PFOA for five days. C57BL/6N mice received 0-30 mg/kg/day of PFOA in drinking water for 15 days. Mice were immunized with sheep red blood cells or sensitized to bovine serum albumin in Freund's complete adjuvant on day 10 of exposure; immune responses were determined 1 day post-exposure. RESULTS: We found that 30 mg PFOA/kg/day given for 10 or 15 days reduced IgM synthesis; serum collected 1 day postexposure contained 8.4 x 10(4) or 2.7 x 10(5) ng PFOA/mL, respectively. IgM synthesis was suppressed at exposures > or = 3.75 mg PFOA/kg/day in a dose-dependent manner, and IgG titers were elevated at 3.75 and 7.5 mg PFOA/kg/day. Serum PFOA at 3.75 mg/kg/day was 7.4 x 10(4) ng/mL 1 day postexposure, or 150-fold greater than the levels reported in individuals living near a PFOA production site. Using a second-degree polynomial model, we calculated a benchmark dose of 3 mg/kg/day, with a lower bound (95% confidence limit) of 1.75 mg/kg/day. Cell-mediated function was not affected. CONCLUSIONS: IgM antibodies were suppressed after PFOA exposure. The margin of exposure for reduced IgM antibody synthesis was approximately 150 for highly exposed human populations.     

Chronopharmacology of dapagliflozin-induced antihyperglycemic effects in C57BL/6J mice

Chronopharmacology is the study of the varying responses of drugs to changes in biological timing and endogenous periodicities. The selective sodium-glucose cotransporter 2 inhibitor, dapagliflozin, is a globally prescribed antihyperglycemic drug. Although dapagliflozin is usually administered once a day, the specific intake time is generally not mentioned. Therefore, this study aimed at investigating the diurnal effects of dapagliflozin on high-fat diet (HFD)-induced obesity in mice. Five-week-old male C57BL/6J mice were fed a normal (control) diet or HFD for 10 weeks. During the last 2 weeks, the mice were administered olive oil/ethanol emulsion or dapagliflozin (1 mg/kg, p.o.) in the light or dark phase. At the end of the experiment, the mice were euthanized after an 18 h fasting period, and plasma and tissue samples (epididymal white adipose tissues, liver, and kidney) were collected. Dapagliflozin administration in the light phase significantly decreased plasma glucose levels, insulin levels, adipose adipokines, and decreased the size of adipocytes, compared with the HFD group. In contrast, these parameters remained unchanged in the mice treated during the dark phase. Our data therefore suggests that dapagliflozin portrays definite chronopharmacology, which may provide valuable information on the importance of drug administration timing for maximal pharmacological effects.     

Impaired antigen presention by splenocytes of ethanol-consuming C57BL/6 mice

Excessive alcohol consumption impairs T-cell-dependent immune function. Whether this impairment results from the direct inhibition of helper T (Th) cells or from inhibition of the cells that process and present antigen to Th cells is unclear. The present study examines the effect of dietary alcohol on the ability of spleen cells from C57BL/6 mice to present antigen to T-cell hybridomas. We find that ethanol consumption impairs the ability of spleen cells to present hen egg lysozyme (HEL) in vitro. This impairment was seen for native HEL protein, a hapten-modified HEL, and a peptide bearing a minimal T-cell epitope (HEL 51–60) that requires no additional enzymatic processing. These results suggest that deficiencies in immune responsiveness in alcohol-consuming individuals may include antigen presentation.     

Maternal overnutrition leads to cognitive and neurochemical abnormalities in C57BL/6 mice

Objectives: Epidemiological studies have linked maternal obesity with metabolic as well as psychiatric disorders in the progeny. However, very little is known how maternal overnutrition may affect the cognitive abilities of the offspring.

Methods: Here, we tested the hypothesis whether maternal high-fat diet (HFD) exposure in mice may induce long-term cognitive impairments and neurochemical dysfunctions in the offspring during different age trajectories.

Results: We found that maternal HFD led to cognitive disabilities in adult offspring compared to controls. It was mostly evident in a reference memory and in an associative learning paradigm. More severe and pervasive impairments were evident in the aged adult group across multiple cognitive domains. In addition, adult and aged adult HFD offspring showed potentiation of prepulse inhibition. The cognitive impairments observed at adulthood were associated with attenuations of amino acid levels in the medial prefrontal cortex and the hippocampus regions.

Discussion: Our results suggest that HFD offspring are at an increased risk to develop cognitive deficits, affecting learning and memory processes in adulthood. Furthermore, maternal HFD exposure may facilitate or even drive pathological brain aging mainly in the hippocampal and prefrontal cortex structures that may explain the cognitive deficits observed in the offspring.     

Low-dose whole-body irradiation induced radioadaptive response in C57BL/6 mice

Radioadaptive survival responses after relatively low doses of radiation were investigated in C57BL/6 mice. The 8-week-old mice received whole-body mid-lethal challenging irradiation (5.9 Gy) at various intervals after conditioning whole-body irradiation with 50-400 mGy. Thereafter, survival of the mice was observed for 30 days. The mice receiving 400 mGy at 6 h before the challenging dose had a lower survival rate than the control group, but it was not observed when the conditioning 400-mGy irradiation was given 24 h beforehand. The conditioning doses of 100 and 200 mGy did not influence the survival of mice after the challenging dose. The mice receiving 50 mGy at 1 day, 3 days or 1 week before the challenging dose had a higher survival rate than the control, although this adaptive response was not observed when 50 mGy was given 6 h, 12 h, 3.5 weeks, or 5 weeks beforehand. When 50 mGy was given 2 weeks before the challenging dose, the adaptive response was observed in an experiment in which the mice were caged in our laboratory at the age of 5 weeks, whereas it was not observed in another experiment in which the mice were caged at 3 weeks. This study confirmed the presence of radioadaptive survival responses at the dose of 50 mGy given relatively shortly before the challenging dose.     

Iron regulation in C57BL/6 and DBA/2 mice subjected to iron overload

Many genes are likely involved in the control of iron metabolism in brain and in peripheral tissues, and genetically-defined murine strains present the opportunity to investigate genetic variations in iron metabolism. Weanling C57BL/6 (B6) and DBA/2 (D2) mice were divided into two treatment groups receiving distilled water with or without 5000 ppm ferric chloride ad libitum as their sole fluid source for 100 days. Iron overload increased liver, spleen and plasma iron levels in male and female B6 and female D2 mice. In D2 males, liver iron was increased relative to control, but spleen and plasma iron remained unaffected. Brain iron content was not different between control and iron-treated mice in ventral midbrain, caudate, pons or hippocampus, but D2 iron overloaded mice displayed lower iron levels in nucleus accumbens and prefrontal cortex. We conclude that genetic background influences the accumulation of excess iron in the periphery and iron regulation in the central nervous system.     

白藜芦醇对C57BL/6J小鼠脂代谢的影响

目的观察22.5mg/kg BW白藜芦醇对C57BL/6J小鼠血清和肝脏脂质的影响。方法 30只C57BL/6J雄性小鼠随机分为正常对照组、高脂组和高脂+白藜芦醇组,每组10只,正常对照组喂饲基础饲料,高脂组和高脂+白藜芦醇组喂饲高脂高胆固醇饲料。高脂+白藜芦醇组每日经灌胃给予22.5mg/kg BW白藜芦醇羧甲基纤维素钠溶液进行干预,正常对照组和高脂组均给予0.5%的羧甲基纤维素钠溶液灌胃。干预8周后测定小鼠血清TC、TG、HDL-C和LDL-C水平,肝脏TC和TG水平,并观察小鼠肝组织病理改变。结果高脂组和高脂+白藜芦醇组小鼠血清TC、LDL-C和HDL-C水平均高于正常对照组(P<0.05),高脂组血清TC和LDL-C水平还高于高脂+白藜芦醇组(P<0.05),但高脂组和高脂+白藜芦醇组小鼠血清TG水平均低于正常对照组(P<0.05)。高脂组小鼠肝脏TC水平高于高脂+白藜芦醇组和正常对照组(P<0.05)。结论 22.5mg/kg BW白藜芦醇可以降低喂饲高脂饲料的C57BL/6J小鼠体内胆固醇水平。     

登革病毒感染C57BL/6j小鼠动物模型建立

目的建立登革病毒2型(DEN-2)感染C57BL/6j小鼠模型,测定小鼠血液中的登革病毒含量。方法构建标准品质粒;用2种不同剂量(2×108copies/只;2×109copies/只)的DEN-2国际标准(NGC)株腹腔感染C57BL/6j小鼠;绝对定量荧光PCR法测定感染后小鼠外周全血病毒含量。结果C57BL/6j小鼠经腹腔感染病毒后,2×108copies/只感染组和2×109copies/只感染组测得第1,3,5 d的病毒含量分别为1.05×103.5～1.05×103.7,1.05×103.8～1.05×103.9,1.05×103.5～1.05×103.7;1.4×103.5～1.4×104.4,1.4×106.9～1.4×107.32,1.4×103.8～1.4×104.8copies/mL。结论成功建立登革病毒感染小鼠模型,外周血液中病毒含量呈峰状,于感染后第1 d病毒含量增加,第3 d达到高峰,第5 d呈下降趋势。     

Dietary fiber sources lower blood cholesterol in C57BL/6 mice.

Five sources of dietary fiber were compared for their effect on blood and liver cholesterol. The effects of soybean fiber, rice bran (full fat), oat bran, barley bran and mixed bran on total blood cholesterol concentrations and liver cholesterol concentrations were measured in beef-fed C57BL/6 male mice. Each diet contained cooked beef, beef tallow, corn starch and 7% dietary fiber from one of the five fiber sources. A control group consumed a fiber-free diet. Dietary cholesterol was provided by the beef and beef tallow only. The experimental diets were fed for 3 wk; blood and liver were collected when the mice were 18 wk old. The liver cholesterol concentration in the rice bran-fed group was the lowest of the six diet groups and was significantly different than concentrations in the oat bran-fed group and the barley bran-fed group (P less than 0.05). The oat bran, mixed bran, and barley bran did not significantly lower blood cholesterol in the mice. Both the soybean fiber and rice bran diet groups had significantly lower total blood cholesterol than did the fiber-free controls (P less than 0.05). The soybean fiber group also had significantly lower blood cholesterol than the mixed-bran group.     

Temperature dependence of ethanol depression in C57BL/6 and BALB/c mice

The relationship between environmental temperature, body temperature and brain sensitivity to ethanol was investigated in male C57BL/6S and BALB/cS mice. Age-matched, drug-naive mice of both strains were injected with 3.6 g/kg ethanol (20% w/v) and placed into a chamber kept at one of eight designated temperatures from 12 to 36 degrees C. Chamber temperature significantly affected wake-up rectal temperatures, sleep-times and wake-up brain ethanol concentrations in the intoxicated mice. Wake-up rectal temperatures were significantly, positively correlated with sleep-times and significantly, negatively correlated with wake-up brain ethanol concentrations in both strains. Linear regression analyses indicated that up to 47% of the variability in ethanol sensitivity of C57 mice and up to 31% of the variability in sensitivity of BALB mice could be accounted for by their wake-up rectal temperatures suggesting that the effects of ambient temperature on ethanol sensitivity were mediated, in part, by the resultant body temperatures. These results replicate and extend previous findings and demonstrate that temperature dependence of ethanol depression is not strain specific. The correlational and regression analyses provide additional evidence that brain sensitivity to ethanol depression varies with body temperature in accordance with membrane perturbation theories of anesthesia.     

Characterization of the ethanol-deprivation effect in substrains of C57BL/6 mice.

Ethanol craving plays a major role in relapse drinking behavior. Relapse and ethanol craving are an important focus for the treatment of alcoholism. The ethanol-deprivation effect (EDE) is a widely used animal model of alcohol craving. While the EDE is widely studied in rats, the molecular mechanisms underlying EDE are not clearly understood. The C57BL/6 inbred mouse strain is widely used for behavioral and molecular analyses of ethanol drinking but studies on the EDE have not been reported in this strain. In the present study, we characterized a simple behavioral protocol that rapidly and reliably induced EDE in C57BL/6 mice. Briefly, single-housed adult male C57BL/6NCrl and C57BL/6J mice were presented at the beginning of dark phase with two-bottle choice drinking containing either 10% wt/vol ethanol or tap water for 18 h/day, as well as food ad libitum. Following ethanol drinking for 4 days or 14 days, mice were deprived of ethanol for a period of 4 days. To study EDE, mice were reinstated with two bottles containing either ethanol (10% wt/vol) or water. Mice were exposed to single or multiple ethanol-deprivation cycles. Ethanol consumption (g/kg/18 h) and percent ethanol preference (% preference/18 hrs) was recorded for individual mice. C57BL/6NCrl mice consumed moderate amounts (4.78+/-0.63 g/kg) of ethanol but showed robust EDE after ethanol-drinking episodes (4 days or 14 days) as evidenced by increased ethanol consumption and ethanol preference following reinstatement of ethanol. While repeated ethanol deprivation in C57BL/6NCrl mice transiently increased ethanol consumption and ethanol preference, the magnitude of these behaviors was reduced as compared to the first deprivation cycle. In contrast, the C57BL/6J substrain consumed substantially higher levels (9.65+/-0.90 g/kg) of ethanol but did not show a clear EDE after single or multiple ethanol-deprivation cycles. In conclusion, we established a simple and reliable behavioral model to study EDE in C57BL/6NCrl mice. A reliable behavioral model to study EDE in inbred C57BL/6NCrl mice could greatly facilitate further studies on molecular mechanisms of ethanol craving behavior.     

Effects of strontium-90 plus external irradiation in C57BL/6J mice

421 C57BL/6J female mice were subdivided into 11 groups. Five of these groups were given 300 rad total body irradiation from a 137Cs source at an age of 65 days. One day later, these irradiated mice were treated intraperitoneally with varying amounts of 90Sr (0, 0.032, 0.10, 0.32, and 1.0 mu Ci/g of body weight). Five groups of mice that had not been irradiated were treated on the same day with the same doses of 90Sr as given the five irradiated groups, and a sixth unirradiated group was treated with 2 mu Ci/g body weight. Each mouse treated with 90Sr and still alive was monitored between 249 and 303 days later in a total body well scintillation detector; mice with counts that differed by more than approximately 50% from the mean for their group were eliminated. A total of 402 mice were accepted for the experiment; these mice were followed to the end of their life span and then autopsied. Mice treated with the highest doses of 90Sr (1.0 and 2.0 mu Ci/g) experienced significantly elevated number of deaths from infections relative to the control group; these deaths occurred relatively early after 90Sr injection, and were particularly severe in the group of mice that had received 300 rad of external irradiation in addition to 1.0 mu Ci90Sr/g. There was no evidence of synergism between 90Sr injection and 300 rad external irradiation for production of bone tumors. Tumors of the type that occur spontaneously in C57BL/6J mice appeared to be more frequent in 90Sr-treated mice and in externally irradiated mice than in controls, but the numbers of excess tumors in these groups were not statistically significant (P less than 0.09).     

Gender differences in the effects of ethanol on C57BL/6 mice.

The influence of gender on the stimulatory and depressant effects of ethanol was examined in C57BL/6 (C57) mice. In Experiment 1, locomotor activity was assessed in young (2-month-old) male and female mice injected intraperitoneally (IP) with stimulatory (1.5 g/kg) or depressant (2.5 g/kg) doses of ethanol. Both the stimulatory and the depressive effects of ethanol were greater in young male than female C57 mice, and the gender difference was unrelated to blood ethanol concentration (BEC). In Experiment 2, older (9-month-old) male and female mice were given ethanol (2.5 g/kg) either by IP injection or gavage to determine if the gender differences in BEC and ethanol effects observed in the first experiment depended upon the route of ethanol administration. In this experiment, ethanol reduced locomotor activity more in males than females whether given by gavage or IP injection, and the males had higher BECs than females at the time of testing. Thus, the differences in the behavioral effects of ethanol appeared to be related to BEC. The greater depressive effect of ethanol on older male mice in this experiment is consistent with an earlier report of prolonged ethanol-hypnosis in older male C57 mice. Therefore, differences in BEC could account for the gender differences in the behavioral effects of ethanol on older but not young mice. The gender difference in BEC of mice obtained in the present and earlier reports is opposite to that reported for humans.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vaccination evokes gender-dependent protection against tularemia infection in C57BL/6Tac mice

Francisella tularensis (Ft) is a Category A biothreat agent for which there currently is no FDA-approved vaccine. Thus, there is a substantial effort underway to develop an effective tularemia vaccine. While it is well established that gender can significantly impact susceptibility to primary infection, the impact of gender on vaccine efficacy is not well established. Thus, development of a successful vaccine against tularemia will require an understanding of the impact gender has on vaccine-induced protection against this organism. In this study, a role for gender in vaccine-induced protection following Ft challenge is identified for the first time. In the present study, mucosal vaccination with inactivated Ft (iFt) LVS elicited gender-based protection in C57BL/6Tac mice against respiratory challenge with Ft LVS. Specifically, vaccinated male mice were more susceptible to subsequent Ft LVS challenge. This increased susceptibility in male mice correlated with increased bacterial burden, increased tissue inflammation, and increased proinflammatory cytokine production late in post-challenge infection. In contrast, improved survival of iFt-vaccinated female mice correlated with reduced bacterial burden and enhanced levels of Ft-specific Abs in serum and broncho-alveolar lavage (BAL) fluid post-challenge. Furthermore, vaccination with a live attenuated vaccine consisting of an Ft LVS superoxide dismutase (SodB) mutant, which has proven efficacious against the highly virulent Ft SchuS4 strain, demonstrated similar gender bias in protection post-Ft SchuS4 challenge. Of particular significance is the fact that these are the first studies to demonstrate that gender differences impact disease outcome in the case of lethal respiratory tularemia following mucosal vaccination. In addition, these studies further emphasize the fact that gender differences must be a serious consideration in any future tularemia vaccine development studies.     

Caloric restriction in C57BL/6J mice mimics therapeutic fasting in humans

Background  

Caloric restriction (CR) has long been recognized as a dietary therapy that improves health and increases longevity. Little is known about the persistent effects of CR on plasma biomarkers (glucose, ketone bodies, and lipids) following re-feeding in mice. It is also unclear how these biomarker changes in calorically restricted mice relate to those observed previously in calorically restricted humans.     

Novel tocotrienols of rice bran inhibit atherosclerotic lesions in C57BL/6 ApoE-deficient mice

We are studying novel tocotrienols, which have a number of activities that might interfere with the formation of atherosclerotic plaques, including hypocholesterolemic, antioxidant, anti-inflammatory and antiproliferation effects. This study compared the effects of alpha-tocopherol, the tocotrienol-rich fraction (TRF(25)) and didesmethyl tocotrienol (d-P(25)-T3) of rice bran on the pathogenesis of atherosclerotic lesions in C57BL/6 apolipoprotein (apo)E-deficient (-/-) mice. These mice are an excellent model because they become hyperlipidemic even when they consume a low fat diet and they develop complex atherosclerotic lesions similar to those of humans. These compounds were also tested in wild-type C57BL/6 apoE (+/+) and (+/-) mice fed low or high fat diets. When a high fat diet was supplemented with alpha-tocopherol, TRF(25) or d-P(25)-T3 and fed to mice (+/+) for 24 wk, atherosclerotic lesion size was reduced 23% (P = 0.33), 36% (P = 0.14) and 57% (P < 0.02), respectively, and in mice (+/-) fed for 18 wk, lesions were reduced by 19% (P = 0.15), 28% (P < 0.01) and 33% (P < 0.005), respectively, compared with mice fed a control diet. A low fat diet did not cause atherosclerotic lesions in these mice. The low fat diet supplemented with TRF(25) or d-P(25)-T3 fed to apoE-deficient (-/-) mice for 14 wk decreased atherosclerotic lesion size by 42% (P < 0.04) and 47% (P < 0.01), respectively, whereas alpha-tocopherol supplementation resulted in only an 11% (P = 0.62) reduction. These results demonstrate the superior efficacy of tocotrienols compared with alpha-tocopherol. Although tocotrienols decreased serum triglycerides, total and LDL cholesterol levels, the decreases in atherosclerotic lesions seem to be due to the other activities. Serum tocol concentrations in various groups are also described. This is the first report of a significant reduction in the atherosclerotic lesion size in all three genotypes of apoE mice fed a novel tocotrienol (d-P(25)-T3) of rice bran. Dietary tocotrienol supplements may provide a unique approach to promoting cardiovascular health.     

Early experience and the consumption of alcohol by adult C57BL/6J mice

Two types of early experience were examined for their effect on voluntary alcohol consumption by adult C57BL/6J mice: the experiences associated with belonging to a particular litter, and the experience of early postweaning choice between water and a 10% alcohol solution. Males from identified litters were individually caged from arrival at three weeks of age and given a choice between 10% alcohol and water when eight weeks old. Another group without notation of litter was given alcohol-water choice upon arrival at three weeks of age. Alcohol intake was examined by three measures: daily licks of 10% alcohol, alcohol selection (percent alcohol drinking), and volume of alcohol drunk daily. Belonging to a particular litter did affect body weight and growth, but had no effect on adult consumption of alcohol. Postweaning exposure to alcohol choice, however, produced a small but significant and prolonged increase in alcohol consumption by adults. Furthermore, a developmental trend was found in mice offered alcohol choice at an early age: alcohol preference developed as postweaning growth slowed.     

Dietary glucosinolates inhibit splenic inflammation in high fat/cholesterol diet-fed C57BL/6 mice

BACKGROUND/OBJECTIVESObesity is associated with chronic inflammation. The spleen is the largest organ of the lymphatic system and has an important role in immunity. Obesity-induced inflammatory responses are triggered by Toll-like receptor (TLR)-myeloid differentiation primary response 88 (MyD88) pathway signaling. Phenethyl isothiocyanate (PEITC) and 3,3′-diindolylmethane (DIM), major dietary glucosinolates present in cruciferous vegetables, have been reported to produce anti-inflammatory effects on various diseases. However, the effects of PEITC and DIM on the obesity-induced inflammatory response in the spleen are unclear. The purpose of this study was to examine the anti-inflammatory effects of PEITC and DIM on the spleen and their mechanism in high fat/cholesterol diet (HFCD)-fed C57BL/6 mice.MATERIALS/METHODSWe established an animal model of HFCD-induced obesity using C57BL/6 mice. The mice were divided into six groups: normal diet with AIN-93G diet (CON), high fat diet (60% calories from fat) with 1% cholesterol (HFCD), HFCD with PEITC 30 mg/kg/day or 75 mg/kg/day (HFCD+P30, HFCD+P75), and HFCD with DIM 1.5 mg/kg/day or 7.5 mg/kg/day (HFCD+D1.5, HFCD+D7.5). Enzyme-linked immunosorbent assay was used to evaluate pro-inflammatory cytokine secretion. Western blot and quantitative polymerase chain reaction were used to analyze protein and mRNA levels of nuclear factor kappa B (NF-κB) p65, interleukin 6 (IL-6), cyclooxygenase 2 (COX-2), TLR2, TLR4, and MyD88 in spleen tissue.RESULTSSerum IL-6 levels were significantly higher in the HFCD group than in groups fed a HFCD with PEITC or DIM. Levels of NF-κB p65 protein and TLR2/4, MyD88, NF-κB p65, IL-6, and COX-2 mRNA were significantly higher in the HFCD group than in the CON group and were reduced by the PEITC and DIM supplements.CONCLUSIONSPEITC- and DIM-supplemented diets improved splenic inflammation by modulating the TLR2/4-MyD88 pathway in HFCD-fed mice. We suggest that dietary glucosinolates may at least partially improve obesity-induced inflammation of the spleen.     

Profiling of cellular immune responses to Mycoplasma pulmonis infection in C57BL/6 and DBA/2 mice

Mycoplasma infections cause respiratory tract damages and atypical pneumonia, resulting in serious problems in humans and animals worldwide. It is well known that laboratory inbred mouse strains show various susceptibility to Mycoplasma pulmonis (M. pulmonis) infection, which causes murine respiratory mycoplasmosis. In this study, we aimed to demonstrate the difference in cellular immune responses between resistant strain, C57BL/6NCrSlc (B6) and susceptible strain, DBA/2CrSlc (D2) after challenging M. pulmonis infection. D2 mice showed higher amount of bacterial proliferation in lung, higher pulmonary infiltration of immune cells such as neutrophils, macrophages, and lymphocytes, and higher levels of interleukin (IL)-1β, IL-6, IL-17A, and tumor necrosis factor-α in bronchoalveolar lavage fluid than did B6 mice. The results of this study suggest that D2 mice are more susceptible than B6 mice to M. pulmonis infection due to a hyper-immune inflammatory response.