Deafness in LIMP2-deficient mice due to early loss of the potassium channel KCNQ1/KCNE1 in marginal cells of the stria vascularis

Our previous studies revealed a critical role of the lysosomal membrane protein LIMP2 in the regulation of membrane transport processes in the endocytic pathway. Here we show that LIMP2-deficient mice display a progressive high-frequency hearing loss and decreased otoacoustic emissions as early as 4 weeks of age. In temporal overlap to hearing impairment, fluorescence immunohistochemical studies revealed that the potassium channel KCNQ1 and its β-subunit KCNE1 were almost completely lost in the luminal part of marginal cells in the stria vascularis, affecting first higher and later also lower frequency processing cochlear turns. Concomitant with this, the expression of megalin, a multiligand endocytic receptor, was reduced in luminal surfaces of marginal cells within the stria vascularis. KCNQ1/KCNE1 and megalin were also lost in the dark cells of the vestibular system. Although LIMP2 is normally expressed in all cells of the stria vascularis, in the organ of Corti and cochlear neurons, the lack of LIMP2 preferentially caused a loss of KCNQ1/KCNE1 and megalin, and structural changes were only seen months later, indicating that these proteins are highly sensitive to disturbances in the lysosomal pathway. The spatio-temporal correlation of the loss of KCNQ1/KCNE1 surface expression and loss of hearing thresholds supports the notion that the decline of functional KCNQ1/KCNE1 is likely to be the primary cause of the hearing loss. Our findings suggest an important role for LIMP2 in the control of the localization and the level of apically expressed membrane proteins such as KCNQ1, KCNE1 and megalin in the stria vascularis.     

Induction of active immunological hypo/non-responsiveness to C5 in adult C5-deficient DBA/2 mice.

A recently established, one-dimensional isoelectric focusing (IEF) method for distinguishing major histocompatibility complex (MHC) class II polymorphisms in an outbred species, cattle, has allowed us to analyse the involvement of the MHC in the recognition of antigen by bovine T cells. Bovine T-cell lines of Th cell phenotype (BoCD4+) specific for ovalbumin were generated from six individual high responder animals. These animals were bovine MHC (BoLA) class II typed using the IEF technique which detects bovine DR-like products. Four of the animals were shown to be heterozygous and two were homozygous for the IEF specificities. Six out of the 13 IEF specificities (EDF types) detected so far were represented by this group of animals. The cell lines were tested against a panel of IEF-typed antigen-presenting cells (APC) from unrelated donors. The lines only responded to antigen in proliferation assays when the APC shared at least one MHC class II EDF specificity with the BoCD4+ cell line. The responses did not correlate with BoLA class I specificities. However, lines from one of the animals were consistently generated to one of the two haplotypes only. This suggests that there are non-responder alleles to a multi-epitope antigen, present in the cattle population. The results demonstrate that IEF of bovine MHC class II products defines haplotypes of functional relevance, and may indeed be identifying the actual restriction elements involved in presentation of ovalbumin. These results have important implications for future vaccine design in an outbred species, particularly in terms of immune response gene effects and disease associations.     

Selective infection of CD4 effector memory T lymphocytes leads to preferential depletion of memory T lymphocytes in R5 HIV-1-infected humanized NOD/SCID/IL-2Rγ mice

To investigate the events leading to the depletion of CD4⁺ T lymphocytes during long-term infection of human immunodeficiency virus type 1 (HIV-1), we infected human CD34⁺ cells-transplanted NOD/SCID/IL-2Rγ^null mice with CXCR4-tropic and CCR5-tropic HIV-1. CXCR4-tropic HIV-1-infected mice were quickly depleted of CD4⁺ thymocytes and both CD45RA⁺ naïve and CD45RA⁻ memory CD4⁺ T lymphocytes, while CCR5-tropic HIV-1-infected mice were preferentially depleted of CD45RA⁻ memory CD4⁺ T lymphocytes. Staining of HIV-1 p24 antigen revealed that CCR5-tropic HIV-1 preferentially infected effector memory T lymphocytes (T_EM) rather than central memory T lymphocytes. In addition, the majority of p24⁺ cells in CCR5-tropic HIV-1-infected mice were activated and in cycling phase. Taken together, our findings indicate that productive infection mainly takes place in the activated T_EM in cycling phase and further suggest that the predominant infection in T_EM would lead to the depletion of memory CD4⁺ T lymphocytes in CCR5-tropic HIV-1-infected mice.     

Effects of experimental diabetes on the structure and ultrastructure of the coagulating gland of C57BL/6J and NOD mice

Diabetes mellitus can lead to reproductive disorders that in turn result in weakened fertility brought about by morphofunctional changes in the testes and accessory sex glands. However, doubts persist concerning the basic biology of the secretory epithelial cells and the stroma of the coagulating gland of diabetic mice. Thus, the objective of the present study was to analyze the histological and ultrastructural changes associated with stereology of the coagulating gland of mice with alloxan-induced diabetes, and of spontaneously diabetic mice. Sixteen mice of the C57BL/6J strain, and eight non-obese diabetic (NOD) mice were used. The animals were divided into three groups: 1) control (C), 2) alloxan diabetic (AD), and 3) NOD. Thirty days after the detection of diabetic status in group 2, all of the animals were killed and then perfused with Karnovsky's solution through the left cardiac ventricle. The coagulating gland was then removed and processed for morphometric study by light microscopy and electron microscopy. The results showed thickening of the stroma, atrophy of secretory epithelial cells, and disorganization of the organelles involved in the secretory process in both NOD and alloxan-induced mice. Thus, it may be concluded that the coagulating gland suffered drastic morphological changes, and consequently impaired glandular function, in the presence of diabetes mellitus type I in both NOD and AD mice.     

Experimental pneumococcal meningitis: impaired clearance of bacteria from the blood due to increased apoptosis in the spleen in Bcl-2-deficient mice

Necrotic and apoptotic neuronal cell death can be found in pneumococcal meningitis. We investigated the role of Bcl-2 as an antiapoptotic gene product in pneumococcal meningitis using Bcl-2 knockout (Bcl-2(-/-)) mice. By using a model of pneumococcal meningitis induced by intracerebral infection, Bcl-2-deficient mice and control littermates were assessed by clinical score and a tight rope test at 0, 12, 24, 32, and 36 h after infection. Then mice were sacrificed, the bacterial titers in blood, spleen, and cerebellar homogenates were determined, and the brain and spleen were evaluated histologically. The Bcl-2-deficient mice developed more severe clinical illness, and there were significant differences in the clinical score at 24, 32, and 36 h and in the tight rope test at 12 and 32 h. The bacterial titers in the blood were greater in Bcl-2-deficient mice than in the controls (7.46 +/- 1.93 log CFU/ml versus 5.16 +/- 0.96 log CFU/ml [mean +/- standard deviation]; P < 0.01). Neuronal damage was most prominent in the hippocampal formation, but there were no significant differences between groups. In situ tailing revealed only a few apoptotic neurons in the brain. In the spleen, however, there were significantly more apoptotic leukocytes in Bcl-2-deficient mice than in controls (5,148 +/- 3,406 leukocytes/mm2 versus 1,070 +/- 395 leukocytes/mm2; P < 0.005). Bcl-2 appears to counteract sepsis-induced apoptosis of splenic lymphocytes, thereby enhancing clearance of bacteria from the blood.     

HCV 5′ NCR和结构蛋白编码序列的拼接及在pLNSX中的克隆

目的:构建丙型肝炎病毒(HCV)5′末端非编码区(5′NCR)和结构蛋白编码基因序列逆转录病毒重组体,用于探索控制HCV感染的新途径和基因治疗。方法:对多株HCV核酸序列进行同源性比较设计引物,逆转录聚合酶链式反应(RT-PCR)扩增5′NCR、C、E1和E2/NS14个编码区共5个片段,分别克隆。以连接聚合酶链反应(PCR)将这5个片段拼接为一连续的长2547nt的片段,含HCV完整的5′NCR和全部的结构蛋白编码序列。将此序列插入pGEM-Zf(+)载体,与逆转病毒pLNSX载体中,转化大肠杆菌DH5a、转化菌落经酶切、PCR和Southern杂交鉴定。结果:通过RT-PCR和连接聚合酶链式反应(PCR)扩增出2547nt含HCV完整的5′NCR和全部的结构蛋白编码序列,将此序列与pGEM-Zf(+)重组得重组体pHC2547,与逆转录病毒载体pLNSX重组得pL-HC。结论:成功构建了HCV逆转病毒重组体,以利于HCV的胞内基因表达调控研究,更为探索HCV分子致病机制和转基因动物及基因治疗提供可靠的物质基础。     

Cyclooxygenase-2-deficient mice are resistant to 1-methyl-4-phenyl1, 2, 3, 6-tetrahydropyridine-induced damage of dopaminergic neurons in the substantia nigra

Cyclooxygenases (COX), key enzymes in prostanoid biosynthesis, may represent important therapeutic targets in various neurodegenerative diseases. In the present study, we explored the role of COX in Parkinson's disease (PD) by using 1-methyl-4-phenyl1, 2, 3, 6-tetrahydropyridine (MPTP) as a tool to create a rodent Parkinsonian model. MPTP (20 mg/kg, subcutaneously) was injected daily into COX-1- and COX-2-deficient mice and wild-type (WT) controls for five consecutive days. Immunocytochemical analysis of tissues collected 7 days after the final MPTP treatment showed that MPTP significantly decreased the number of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the substantia nigra pars compacta (SNc) of WT (40% decrease) and COX-1(-/-) (45% decrease) mutants. However, a much smaller loss of TH-ir neurons in COX-2(-/-) mutants (20% decrease) was observed. Furthermore, electrochemical analysis revealed a more than 70% decrease in the levels of dopamine and its metabolites (3,4-dihydroxyphenylacetic acid and homovanillic acid) in the striatum of the WT control COX-1(-/-) and COX-2(-/-) mutant mice. These results indicate that loss of COX-2 activity reduces MPTP-induced damage to the dopaminergic neurons of the SNc, but does not alter the levels of dopamine and its metabolites in the striatum. Interestingly, MPTP caused the same degree of loss of dopaminergic neurons in both COX-2(+/-) and COX-2(-/-) mice (20% loss). The results of this study indicate an important role of COX-2 in MPTP-induced neuronal degeneration and suggest the possibility that manipulation of the COX-2 could be an important target for therapeutic interventions in PD.     

The role of the B cells in the adoptive transfer of collagen-induced arthritis from DBA/1 (H-2q) to SCID (H−2d) mice

Collagen-induced arthritis (CIA) can be transferred from DBA/1 to SCID mice when native type II collagen (CII) is administered together with spleen cells, arthritis appearing some 14 days after cell transfer. In the present study, we demonstrate that both donor T- and B-lymphocyte populations play a role in this model, and that arthritis arises in SCID recipients of either murine or bovine native CII. Furthermore, the requirement for administration of soluble native CII can be replaced by subarthritogenic doses of serum from Wistar rats with CIA. In this case a fully developed arthritis appears as early as 2 days after cell transfer. However, protein G-purified IgG from CIA rat serum together with splenocytes from arthritic DBA/1 mice does not transfer arthritis. A key role of B cells in this model appears to be the production of a humoral arthritogenic factor since arthritis can be successfully transferred to SCID mice by CIA rat serum administered together with a B cell-depleted splenocyte population consisting of T cells and donor-histocompatible antigen-presenting cells. By contrast, transfer of disease cannot be achieved by co-administration of CIA rat serum and purified donor T cells, indicating that the presence of donor antigen-presenting cells is a requirement for adoptive transfer of arthritis. We propose that joint damage initiated by arthritogenic product(s) of the B cell lineage releases soluble antigens that are presented to T cells which perpetuate the disease. The finding that arthritis can be generated in SCID recipients of CIA rat serum together with splenocytes from non-arthritic DBA/1 mice immunized with denatured CII supports the hypothesis that T cells with specificity for denatured joint components perpetuate disease initiated by humoral factors.     

涎腺腺样囊性癌中Cyclin D1、MMP-7和PRB2/p130表达及意义

目的探讨Cyclin D1、MMP-7和PRB2/p130蛋白在涎腺腺样囊性癌组织中的表达及与涎腺腺样囊性癌生物学行为的关系。方法应用免疫组化SP法检测46例涎腺腺样囊性癌和30例正常涎腺组织中Cyclin D1、MMP-7和PRB2/p130蛋白的表达。结果 Cyclin D1、MMP-7和PRB2/p130在涎腺腺样囊性癌中的阳性率分别为71.74%、67.39%、63.04%;Cyclin D1和PRB2/p130蛋白在涎腺腺样囊性癌中的表达与病理类型有关(P<0.05),MMP-7在涎腺腺样囊性癌中的表达与病理类型无关(P>0.05);Cyclin D1、MMP-7和PRB2/p130蛋白在涎腺腺样囊性癌复发组中的阳性率与无复发组相比,差异有显著性(P<0.05);Cyclin D1与PRB2/p130在涎腺腺样囊性癌中的表达呈负相关,与MMP-7表达呈正相关。结论 Cyclin D1、MMP-7和PRB2/p130蛋白的异常表达在涎腺腺样囊性癌发生、发展和复发中起重要作用,联合检测多个指标可能对患者预后的判断有指导意义。     

Effects of sex and age on the susceptibility of C57BL/6J mice to infection with <Emphasis Type="Italic">Brachylaima cribbi</Emphasis> and the course of infection in NOD SCID mice

The C57BL/6J strain of Mus musculus is susceptible to the terrestrial trematode Brachylaima cribbi. The duration of infection in these mice is generally 9-12 weeks with a peak excretion of eggs at 4 weeks post-infection (wpi). The effects of age and sex on the course of infection were investigated by comparing infections in male and female mice aged 8 or 28 weeks at the time of infection. There were no significant differences in the susceptibility of the adolescent mice of either sex or older male mice. However, older, mature female mice were significantly more resistant to B. cribbi infection than older mature males and adolescent females with reduced worm burden, fecundity and egg fertility. In comparison with young males, all three parameters were again reduced but this was only significant statistically for reduced egg fertility. It is likely that mature female sex hormones influence resistance to B. cribbi infection. The susceptibility of immunodeficient NOD SCID mice was evaluated and compared with C57BL/6J mice. NOD SCID mice were susceptible to B. cribbi infection with the infection persisting with a relatively unchanged worm burden for the life of the mouse with the longest surviving mice being 31 wpi. The life-span of B. cribbi is therefore at least 31 weeks. There were no significant differences in egg excretion, worm burden or fecundity among NOD SCID mice at 4, 8 or 18 wpi. As the infection progressed in NOD SCID mice, the location of worms in the small intestine moved from the anterior third in the early stages of the infection to the mid- to posterior intestine in the later stages. Comparison of the infection in NOD SCID mice with C57BL/6J mice indicates that the expulsion of worms in the latter is mediated by an immune response.     

Contribution of the ABC transporters Bcrp1 and Mdr1a/1b to the side population phenotype in mammary gland and bone marrow of mice

The ability of cells to export Hoechst 33342 can be used to identify a subpopulation of cells (side population [SP]) with characteristics of stem cells in many tissues. The ATP-binding cassette transporters Bcrp1 (Abcg2) and Mdr1a/1b (Abcb1a/1b) have been implicated as being responsible for this phenotype. To further explore the involvement of these transporters in the SP phenotype, we have generated Bcrp1/Mdr1a/1b triple knockout mice and studied the effect of their absence on the SP in bone marrow and mammary gland. Whereas in bone marrow Bcrp1 was almost exclusively responsible for the SP, both transporters contributed to the SP phenotype in the mammary gland, where their combined absence resulted in a nearly complete loss of SP. Interestingly, bone marrow of Mdr1a/1b-/- mice frequently displayed an elevated SP, which was reversible by the Bcrp1 inhibitor Ko143, suggesting that Bcrp1 can compensate for the loss of Mdr1a/1b in bone marrow.     

Excess cone cell proliferation due to lack of a functional NR2E3 causes retinal dysplasia and degeneration in rd7/rd7 mice

The rd7 mouse is a model for hereditary retinal degeneration characterized clinically by retinal spotting throughout the fundus and late onset retinal degeneration, and histologically by retinal dysplasia manifesting as folds and whorls in the photoreceptor layer. This study demonstrates that the rd7 phenotype results from a splicing error created by a genomic deletion of an intron and part of an exon. Hematoxylin/eosin staining of rd7 tissue shows that the whorls in the outer nuclear layer of the retina do not appear during embryonic development but manifest by postnatal day 12.5 (P12.5). Furthermore, in situ hybridization data indicates that the Nr2e3 message is first present at barely discernable levels at embryonic day 18.5, becomes abundant by P2.5, and reaches maximal adult levels by P10.5. Results from these experiments indicate that Nr2e3 message is expressed prior to the development of S-cones. This data coincides with studies in humans showing that mutations in Nr2e3 result in a unique type of retinal degeneration known as enhanced S-cone syndrome, where patients have a 30-fold increase in S-cone sensitivity compared to normal. Immunohistochemical staining of cone cells demonstrates that rd7 retinas have an increased number of cone cells compared to wild-type retinas. Thus, Nr2e3 may function by regulating genes involved in cone cell proliferation, and mutations in this gene lead to retinal dysplasia and degeneration by disrupting normal photoreceptor cell topography as well as cell-cell interactions.     

Hypersusceptibility of A/J mice to tuberculosis is in part due to a deficiency of the fifth complement component (C5)

Mycobacterium tuberculosis (MTB) causes tuberculosis in man, which occurs as an acute, chronic or dormant disease reactivating over several years. The mechanisms of persistence and reactivation are not well understood and there is a need for animal models. Moderate-dose, aerosol infection killed A/J mice earlier than partially resistant C57Bl/6 mice, whereas a low-dose, aerosol-induced chronic infection exacerbated earlier in A/J mice. A/J mice lethally infected with MTB but drug cured of disease underwent reactivation of tuberculosis at least 100 days before similarly infected C57Bl/6 mice. Because A/J mice were C5 deficient, congenic B10 mice sufficient and deficient for C5 were infected intravenously with MTB to define the role of C5. C5-deficient mice again showed enhanced growth of MTB in the lungs. MTB-infected macrophages from C5-deficient mice showed enhanced growth of MTB coinciding with a reduced secretion of both cytokines (TNF-alpha, IL-1beta, IL-6, IL-12) and chemokines (KC, MIP-2 and MIP-1alpha) in A/J and TNF-alpha and chemokines in C5-deficient mice. Because C5-deficient macrophages could be activated from extraneous C5 and TNF-alpha we suggest that both play a role in the macrophage-mediated killing as well as containment mechanisms in tuberculosis.     

Skewing of the Th1/Th2 responses in mice due to variation in the level of expression of an antigen in a recombinant BCG system

In spite of rapid developments in the study of mycobacteria during the last two decades, tuberculosis (TB) has maintained its status as the leading killer among all infectious diseases. Extensive evidence exists to support a central role for a T-helper type 1 (Th1) immune response for protection against TB in mice and humans. Bacille Calmette-Guerin (BCG), the only vaccine against TB, although not perfect in its ability to protect against the adult form of TB, is a strong inducer of Th1 responses and is being increasingly used as a delivery vehicle for the presentation of foreign antigens to the immune system. It has been proposed that expression of immunodominant antigens or cytokine genes in BCG can enhance the ability of BCG to induce a Th1 immune response. Since dose of the antigen is considered as one of the parameters that influence the Th cell responses, the level of expression of the candidate antigen should influence the final Th response against the recombinant BCG (rBCG). In the present study, the effect of over-expression of a candidate antigen Antigen 85B (Ag 85B) in a rBCG system, on the Th-priming ability of BCG has been investigated in the murine model. BALB/c mice were immunized with three different rBCG constructs expressing Ag 85B to various levels. Induction of Th1/Th2 responses was analyzed by measuring levels of interferon-gamma (Th1) and interleukin-10 (Th2) in antigen-stimulated splenocyte cultures and by quantifying the antigen-specific IgG2a (Th1) and IgG1 (Th2) antibody responses. By varying the level of expression of Ag 85B, specific immune responses against Ag 85B were observed to range from mixed Th1/Th2 to Th1. However, the BCG-specific immune responses in case of all rBCG-immunized animals remained predominantly Th1.     

Recovery from EAE is associated with decreased survival of encephalitogenic T cells in the CNS of B7-1/B7-2-deficient mice

Adoptive transfer experiments using C57BL/6 mice lacking B7-1 and B7-2 as recipients of wt (wt) encephalitogenic T cells demonstrate a key role for B7 costimulation during the effector phase of experimental autoimmune encephalomyelitis (EAE). Following transfer of encephalitogenic T cells, B7-1/B7-2-deficient (-/-) recipients develop a transient and mild disease as compared to wt recipients. To understand the mechanism by which B7-1/B7-2 may influence the effector phase of EAE, we analyzed T cells, pro-inflammatory cytokines and chemokines within the CNS of wt and B7-1/B7-2-/- recipients at different times after adoptive transfer of activated myelin specific T cells. There was a marked decline in T cells and inflammatory mediators in the CNS of B7-1/B7-2-/- recipients by day 30 post transfer. B7-1/B7-2-/- mice developed more TUNEL+ apoptotic cells in the parenchyma and greater ratios of TUNEL+ cells/parenchymal foci than wt mice resulting in virtual disappearance of parenchymal foci. Therefore, without B7-1 and B7-2 costimulation in the target organ, there is increased T cell apoptosis and attenuation of inflammation. These results indicate that B7-1 and B7-2 provide critical costimulatory signals for sustaining survival of pathogenic T cells within the central nervous system parenchyma during the effector phase of EAE and suggest novel treatment approaches in the effector phase of autoimmune diseases.     

Activation of the 2-5OAS/RNase L pathway in CVB1 or HAV/18f infected FRhK-4 cells does not require induction of OAS1 or OAS2 expression

The latent, constitutively expressed protein RNase L is activated in coxsackievirus and HAV strain 18f infected FRhK-4 cells. Endogenous oligoadenylate synthetase (OAS) from uninfected and virus infected cell extracts synthesizes active forms of the triphosphorylated 2-5A oligomer (the only known activator of RNase L) in vitro and endogenous 2-5A is detected in infected cell extracts. However, only the largest OAS isoform, OAS3, is readily detected throughout the time course of infection. While IFNβ treatment results in an increase in the level of all three OAS isoforms in FRhK-4 cells, IFNβ pretreatment does not affect the temporal onset or enhancement of RNase L activity nor inhibit virus replication. Our results indicate that CVB1 and HAV/18f activate the 2-5OAS/RNase L pathway in FRhK-4 cells during permissive infection through endogenous levels of OAS, but contrary to that reported for some picornaviruses, CVB1 and HAV/18f replication is insensitive to this activated antiviral pathway.     

Transgenic expression of full-length 2',5'-oligoadenylate synthetase 1b confers to BALB/c mice resistance against West Nile virus-induced encephalitis

Susceptibility of inbred strains to infection with West Nile virus (WNV) has been genetically associated with an arginine-to-a nonsense codon substitution at position 253 (R253X) in the predicted sequence of the murine 2′,5′-oligoadenylate synthetase 1B (OAS1B) protein. We introduced by transgenesis the Oas1b cDNA from MBT/Pas mice carrying the R253 codon (Oas1b^MBT) into BALB/c mice homozygous for the X253 allele (Oas1b^BALB/c). Overexpression of Oas1b^MBT mRNA in the brain of transgenic mice prior and in the time course of infection provided protection against the neuroinvasive WNV strain IS-98-ST1. A 200-fold induction of Oas1b^MBT mRNA in the brain of congenic BALB/c mice homozygous for a MBT/Pas segment encompassing the Oas1b gene was also efficient in reducing both viral growth and mortality, whereas a 200-fold induction of Oas1b^BALB/c mRNA was unable to prevent virally-induced encephalitis, confirming the critical role of the R253X mutation on Oas1b activity in live mice.