GRIFFONIA SIMPLICIFOLIA I-A4 STAINING OF MICE GLOMERULAR TUFTS AND ITS ALTERATION IN DIABETIC MICE

An isolectin from Griffonia simplicifolia (GS) seed—GSI-A₄—stained the outer aspect of glomerular tuft (GT) intensely in the kidneys of ICR, C57BL/6J, BALB/c and NSY mice. Loss of the GSI-A₄ staining was observed in the sclerotic areas of glomeruli in diabetic mice (NSY mice). This interesting staining will be useful for the analysis of the constitutions of GT in various experimental models of renal glomerular diseases in mice.     

Resistance to Secondary Amyloidosis in A/J Mice is Not Significantly Associated with Allelic Variants Linked to the Serum Amyloid A Gene Cluster

We have tested the hypothesis that structural allelic variants of serum amyloid A confer relative resistance to secondary amyloidosis in the A/J mouse. F₂ mice, previously generated from amyloid-resistant (A/J) and amyloid-susceptible (C57BL/6J) strains and categorized with respect to amyloid susceptibility, were genotyped by polymerase chain reaction (PCR) amplification of the polymorphic D7Nds5 microsatellite. This microsatellite is closely linked to the SAA gene cluster and can discriminate between D7Nds5 alleles of A/J and C57BL/6 J origin. The distribution of D7Nds5 genotypes in relation to splenic amyloid load did not deviate significantly from that expected of a random distribution, indicating that A/J amyloid resistance is not determined by variants at, or close to, D7Nds5 . Therefore, structural alleles in the tightly-linked SAA gene cluster do not confer amyloid resistance in this mouse model.     

apo-SAA1/apo-SAA2 Isotype Ratios during Casein- and Amyloid-Enhancing-Factor-Induced Secondary Amyloidosis in A/J and C57BL/6J Mice

A/J mice are resistant while C57BL/6J are susceptible to casein-induced secondary amyloidosis. One mechanism responsible for this phenotypic expression of resistance/susceptibility was shown to operate at the level of production of the 'amyloid-enhancing factor' (AEF). AEF and processing of the apo-SAA protein appear almost concomitantly during amyloidogenesis. In order to determine if AEF played a role in the processing of the apo-SAA protein, three major parameters (apo-SAA1/apo-SAA2 ratios, level of AEF, and fibril formation) were determined during casein-induced secondary amyloidosis. Kinetics of AEF production and serum levels of the two major apo-SAA isotypes were compared in A/J and C57BL/6J animals. Both strains showed equal relative amounts of the two isotypes after seven, 15 and 21 casein injections, irrespective of the fact that the A/J strain had no detectable level of AEF and no amyloid deposition; while C57BL/6J mice had a high AEF level and were amyloidotic after 15 and 21 injections. An increased apo-SAA1/apo-SAA2 ratio due to a decrease in apo-SAA2 was noted after 38 days of casein injections when both strains had extensive deposits of amyloid fibrils. Involvement of AEF as an effector molecule was determined by following the ratio of the two major serum apo-SAA isotypes and fibril formation during an accelerated protocol of amyloid induction in C57BL/6J animals. AEF had no direct effect on apo-SAA isotype ratios in the serum.     

Amyloid A protein amyloidosis induced in apolipoprotein-E-deficient mice.

Apolipoprotein E (apoE) is a constituent of lipoproteins other than low-density lipoprotein, and it principally acts in the transport and metabolism of plasma cholesterol and triglyceride. ApoE is a minor constituent of various kinds of amyloidoses and may play a role as a pathological chaperone for fibrillogenesis of amyloid fibril protein with the amyloid P component and proteoglycans. In this study, we examined the role of apoE in amyloidogenesis in vivo in apoE-deficient mutant mice with amyloid A protein (AA) amyloidosis induced by inflammatory stimulation. Amyloid deposition was seen in six of nine C57BL/6J control mice and in six of eight apoE-deficient mutant mice after the intraperitoneal and subcutaneous injections of the mixture of complete Freund's adjuvant and Mycobacterium butyricum. Moreover, amyloid deposition in apoE-deficient mice as well as C57BL/6J control mice started 48 or 72 hours after injection of amyloid-enhancing factor and silver nitrate, although the amount of amyloid deposit in C57BL/6J control mice was slightly larger than that in apoE-deficient mice. These amyloid deposits reacted with anti-mouse AA antibody were seen in the perifollicular area of the spleen. Immunoreactivity of apoE was seen irregularly in the amyloid deposits of C57BL/6J control mice but not in the amyloid deposit of apoE-deficient mice. From these results, we concluded that apoE is not always necessary for amyloid deposition and that the existence of apoE might slightly accelerate AA amyloid deposition in the earliest phase of AA amyloid deposition.     

VARIOUS EPITHELIAL AND NON-EPITHELIAL TUMORS SPONTANEOUSLY OCCURRING IN LONG-LIVED MICE OF A/St, CBA, C57BL/6 AND THEIR HYBRID MICE

Various kinds of epithelial and non-epithelial tumors, and tumor-like lesions spontaeously developed in long-lived mice of strains A/St, C57BL/6 and CBA, and of (C57BL/6 x CBA) F₁, hybrids, all of which had been fed in the 2nd Department of Pathology, Gifu University School of Medicine.
Some tumors were successfully transplanted into the same strain of mice. An interesting tumor line showing phagocytic activity and growing only in the liver even when inoculated subcutaneously, which was obtained from a reticulum cell neoplasm, Type A by Dunn, originated in the liver of a (C57BL/6 X CBA) F₁ hybrid male mouse.     

VH-Gene Family Dominance in Ageing Mice

The cellular composition and Vn-gene family repertoire were compared in different B-cell compartments from young adult (8–12 weeks) and old (18–24 months) C57BL/6 and BALB/c mice. Ageing mice were found to have a higher frequency of peripheral mature B cells utilizing genes from a single V_H-gene family. While in each individual old C57BL/6 mice cells expressing the V_H J558 gene family consistently were over-represented, a marked individual variation was observed in old BALB/c mice with increased frequency of either the V_h J558, Q52 or J606 families. Aged mice were found also to have a reduced number of bone-marrow pre-B cells and an augmented number of splenic Ig-secreting cells. These results suggest that old mice express less diversified antibody repertoires possibly as a consequence of reduced input from precursors and increased peripheral selection, which may be responsible for the progressive establishment of immunodeficiency.     

The kinin B1 receptor contributes to the cardioprotective effect of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in mice

Recent studies have shown that inhibition of angiotensin-converting enzyme (ACE) or angiotensin II receptors causes upregulation of the B₁ receptor (B₁R). Here we tested the hypothesis that activation of the B₁R partly contributes to the cardiac beneficial effect of ACE inhibitor (ACEi) and angiotensin II receptor blockers (ARB). B₁R knockout mice ( B₁R^−/− ) and C57Bl/6J (wild-type control animals, WT) were subjected to myocardial infarction (MI) by ligating the left anterior descending coronary artery. Three weeks after MI, each strain of mice was treated with vehicle, ACEi (ramipril, 2.5 mg kg⁻¹ day⁻¹ in drinking water) or ARB (valsartan, 40 mg kg⁻¹ day⁻¹ in drinking water) for 5 weeks. We found that: (1) compared with WT mice, B₁R^−/− mice that underwent sham surgery had slightly but significantly increased left ventricular (LV) diastolic dimension, LV mass and myocyte size, whereas systolic blood pressure, cardiac function and collagen deposition did not differ between strains; (2) MI leads to LV hypertrophy, chamber dilatation and dysfunction similarly in both WT and B₁R^−/− mice; and (3) ACEi and ARB improved cardiac function and remodelling in both strains; however, these benefits were significantly diminished in B₁R^−/− mice. Our data suggest that kinins, acting via the B₁R, participate in the cardioprotective effects of ACEi and ARB.     

Carbonic anhydrase gene expression in CA II-deficient (Car2−/−) and CA IX-deficient (Car9−/−) mice

Using real-time PCR and immunohistochemistry, we have examined the expression of carbonic anhydrase isozymes (CA) I, II, III, IV, IX, XII, XIII and XIV in the brain, kidney, stomach and colon of the wild-type, CA II-deficient ( Car2^−/− ), and CA IX deficient ( Car9^−/− ) mice. The expression of Car4, Car12, Car13 and Car14 mRNAs did not show any significant deviations between the three groups of mice, whereas both groups of CA deficient mice showed decreased expression levels of Car1 in the colon and Car3 in the kidney. The Car2 mRNA level was greatly reduced but not completely abolished in all four tissues from the Car2^−/− mice in which no CA II protein was expressed. Sequencing the Car2 cDNA isolated from C57BL6 Car2^−/− mice revealed two nucleotide differences from the wild-type C57BL6 mice. One is a silent polymorphism found in Car2 mRNA from wild-type DBA mice, which is the strain that provided the original mutagenized chromosome. The second change is a mutation that causes prematurely terminated translation at codon 155 (Gln155X). Car9 mRNA and CA IX protein expression levels were up-regulated about 2.5- and 3.6-fold, respectively, in the stomach of the Car2^−/− mice. These results suggest that the loss of function of cytosolic CA II in the stomach of Car2^−/− mice leads to up-regulation of an extracellular CA, namely CA IX, which is expressed on the cell surface of the gastric epithelium.     

Degradation of Serum Amyloid A in Amyloid-Susceptible and Amyloid-Resistant Mouse Strains

Degradation of serum amyloid A (apoSAA) by resident peritoneal cells (RPCS) and conditioned medium (CDM), prepared with RPCS, from amyloid-susceptible CBA/J mice, amyloid-resistant CE/J mice and their amyloid-resistant CBA/J × CE/J F₁ progeny was investigated in vitro . Serum amyloid A was derived from murine acute phase (AP) plasma and associated with high density lipoprotein (HDL). Degradation of apoSAA by RPCS and CDM from CBA/J mice was complete while degradation by RPCS and CDM from CE/J mice did not occur. Degradation of apoSAA by RPCS and CDM from CBA/J × CE/J F₁ hybrid mice was indistinguishable from that by RPCS and CDM from the CBA/J parent. Intermediate fragments were not detected with either RPCS or CDM from CBA/J mice or CBA/J × CE/J F₁ hybrid mice. Degradation of apoSAA was inhibited by phenylmethanylsulfonyl fluoride (PMSF) indicating that the enzyme, secreted into the fluid phase, was a serine esterase. Unlike apoSAA, HDL-associated apoA-1 remained intact. It was thus concluded that while selective degradation of HDL-associated apoSAA (apoSAA-HDL) by RPCS from the CBA/J and CE/J mice was significantly different, the genetic study did not support the hypothesis that there was direct linkage between impaired degradation of apoSAA-HDL in the CE/J mouse strain and protection against amyloid fibril formation. As amyloid resistance in CBA/J × CE/J F₁ hybrid mice is not attributable to failure to express the amyloidogenic isoform apoSAA₂, the study supports the original hypothesis that amyloid resistance may be linked to expression of apoSAA_cej     

Immunobiological Studies on Experimental Visceral Leishmaniasis. V. The I-ABm12 Mutation Specifies Resistance to Infection

The I-A^Bm12 mutation of the I-Aβ subunit converted Leishmania donovani -susceptible C57BL/6 (B6) mice into the relatively resistant B6C-H-2 Bm12 (Bm12) strain. The relative resistance was reflected not only in the reduced splenic and hepatic parasite burden in Bm12 (compared with B6) but also by the ability of Bm12 mice to mount a T-cell proliferative response to parasite antigens. Assay of antileishmanial antibody (immunoglobulin G (IgG)_2a and IgG₁) in the sera of infected mice showed that in Bm12 mice the predominant isotype was IgG_2a, rather than IgG₁, whereas a similar level of both isotypes were found in B6 mice. From the serum immunoglobulin isotype titre it appeared that the antileishmanial T-cell response was biased towards a T helper (Th) 1 response in Bm12 mice whereas it was a mixed Th1 and Th2 response in B6 mice. These observations provide credence to the notion that polymorphism in class II major histocompatibility complex (MHC) molecules is responsible for the difference in the disease phenotype.     

AN ELECTRON MICROSCOPIC STUDY ON DIGESTIVE TRACT AMYLOIDOSIS IN FERRIC NITRILOTRIACETATE (Fe-NTA)-INDUCED "F1 AMYLOIDOSIS" MICE

The histological distribution and ultrastructural findings were investigated in 52 amyloid-positive cases obtained from 80 F, mice (32 males and 48 females) receiving 126 to 502 daily intraperitoneal injections of ferric nitrilotriacetic acid (Fe-NTA) resulting from reciprocal crossing of 20 parental mice receiving daily intraperitoneal injections of Fe-NTA for 5 months. Of 52 amyloidotic F₁ mice 49 (94%) developed a moderate degree of amyloid deposits in the gastrointestinal tract. Moderate amounts of amyloid deposits were sporadically discernible in the lamina propria of the stomach pars glandularis, the duodenal mucosa, and to a lesser extent in that of the rectal mucosa. Electron microscopic observation revealed that macrophages adjacent to amyloid mass were radiating outward abundant bundles of non-branching amyloid fibrils from the cytoplasmic invaginations. In the cytoplasm of the macrophages there were occasionally acid phosphatase-positive lysosomes including amyloid fibrils measuring approximately 100 Å in width. Moreover, it is discussed whether fibroblasts or fibroblast-like interstitial cells are involved in amyloid formation.     

Expression of mouse apolipoprotein SAA1.1 in CE/J mice: isoform-specific effects on amyloidogenesis

Amyloid A (AA) amyloid deposition in mice is dependent upon isoform-specific effects of the serum amyloid A (SAA) protein. In type A mice, SAA1.1 and SAA2.1 are the major apolipoprotein-SAA isoforms found on high-density lipoproteins. During inflammation, both isoforms are increased 1000-fold, but only SAA1.1 is selectively deposited into amyloid fibrils. Previous studies showed that the CE/J mouse strain is resistant to amyloid induction. This resistance is not due to a deficiency in SAA synthesis, but is probably related to the unusual SAA isoform present. The CE/J mouse has a single acute-phase SAA protein (SAA2.2), which is a composite of the SAA1.1 and SAA2.1, with an amino terminus similar to the nonamyloidogenic SAA2.1. Recently, genetic experiments suggested that the SAA2.2 isoform might provide protection from amyloid deposition. To determine the amyloidogenic potential of the CE/J mouse, we generated SAA adenoviral vectors to express the various isoforms in vitro and in vivo. Purified recombinant SAA proteins demonstrated that SAA1.1 was fibrillogenic in vitro, whereas SAA2.2 was unable to form fibrils. Incubation of increasing concentrations of the nonamyloidogenic SAA2.2 protein with the amyloidogenic SAA1.1 did not inhibit the fibrillogenic nature of SAA1.1, or alter its ability to form extensive fibrils. Injection of the mouse SAA1.1 or SAA2.2 adenoviral vectors into mice resulted in isoform-specific expression of the SAA proteins. Amyloid induction after viral expression of the SAA1.1 protein resulted in the deposition of amyloid fibrils in the CE/J mouse, whereas SAA2.2 expression had no effect. Similar expression of the SAA2.2 protein in C57BL/6 mice did not alter amyloid deposition. These data demonstrate that the failure of the CE/J mouse to deposit amyloid is due to the structural inability of the SAA2.2 to form amyloid fibrils. This mouse provides a unique system to test the amyloidogenic potential of altered SAA proteins and to determine the important structural features of the protein.     

The effects of intracellular Ca2+ on cardiac K+ channel expression and activity: novel insights from genetically altered mice

We tested the hypothesis that chronic changes in intracellular Ca²⁺ (Ca²⁺_i) can result in changes in ion channel expression; this represents a novel mechanism of crosstalk between changes in Ca²⁺ cycling proteins and the cardiac action potential (AP) profile. We used a transgenic mouse with cardiac-specific overexpression of sarcoplasmic reticulum Ca²⁺ ATPase (SERCA) isoform 1a (SERCA1a OE) with a significant alteration of SERCA protein levels without cardiac hypertrophy or failure. Here, we report significant changes in the expression of a transient outward K⁺ current ( I _to,f), a slowly inactivating K⁺ current ( I _K,slow) and the steady state current ( I _SS) in the transgenic mice with resultant prolongation in cardiac action potential duration (APD) compared with the wild-type littermates. In addition, there was a significant prolongation of the QT interval on surface electrocardiograms in SERCA1a OE mice. The electrophysiological changes, which correlated with changes in Ca²⁺_i, were further corroborated by measuring the levels of ion channel protein expression. To recapitulate the in vivo experiments, the effects of changes in Ca²⁺_i on ion channel expression were further tested in cultured adult and neonatal mouse cardiac myocytes. We conclude that a primary defect in Ca²⁺ handling proteins without cardiac hypertrophy or failure may produce profound changes in K⁺ channel expression and activity as well as cardiac AP.     

Central CRF, urocortins and stress increase colonic transit via CRF1 receptors while activation of CRF2 receptors delays gastric transit in mice

Recently characterized selective agonists and developed antagonists for the corticotropin releasing factor (CRF) receptors are new tools to investigate stress-related functional changes. The influence of mammalian CRF and related peptides injected intracerebroventricularly ( i.c.v. ) on gastric and colonic motility, and the CRF receptor subtypes involved and their role in colonic response to stress were studied in conscious mice. The CRF₁/CRF₂ agonists rat urocortin 1 (rUcn 1) and rat/human CRF (r/h CRF), the preferential CRF₁ agonist ovine CRF (oCRF), and the CRF₂ agonist mouse (m) Ucn 2, injected i.c.v. inhibited gastric emptying and stimulated distal colonic motor function (bead transit and defecation) while oCRF_9–33OH (devoid of CRF receptor affinity) showed neither effects. mUcn 2 injected peripherally had no colonic effect. The selective CRF₂ antagonist astressin₂-B ( i.c.v. ), at a 20 : 1 antagonist: agonist ratio, blocked i.c.v. r/hCRF and rUcn 1 induced inhibition of gastric transit and reduced that of mUcn 2, while the CRF₁ antagonist NBI-35965 had no effect. By contrast, the colonic motor stimulation induced by i.c.v. r/hCRF and rUcn 1 and 1h restraint stress were antagonized only by NBI-35965 while stimulation induced by mUcn 2 was equally blocked by both antagonists. None of the CRF antagonists injected i.c.v. alone influenced gut transit. These data establish in mice that brain CRF₁ receptors mediate the stimulation of colonic transit induced by central CRF, urocortins (1 and 2) and restraint stress, while CRF₂ receptors mediate the inhibitory actions of these peptides on gastric transit.     

Anti-Parental-Strain Lymphocyte Responsiveness of F1 Hybrid-Strain Lymphocytes

The interactions between immunocompetent parental-strain tells and the F₁ hybrid rat into which these cells have been injected were studied. This involved examination of the behavior of both parental- and host-strain cells. Host lymphocytes reactive against parental-strain lymphocytes appeared in the thoracic duct lymph within 12 h of the intravenous injection of parental thoracic duct lymphocytes or thymus cells. The activity of these F₁ hybrid-strain lymphocytes was directed preferentially against parental-strain lymphocytes with anti-F₁ hybrid potential. This subpopulation of parental cells was absent from the thoracic duct but was well represented in the spleen, this enrichment being masked by a reversible F₁ hybrid anti-parental-strain lymphocyte response. If the anti-parental-strain lymphocyte activity of F₁ hybrid cells was interrupted by the destruction of host-strain cells with antiserum, parental-strain lymphocytes in the tissues of F₁ hybrid rats could be reactivated. By this procedure it was possible to passage graft-versus-host reactions initiated by parental-strain lymphocytes through several F₁ hybrid rats, thereby implying that anti-parental lymphocyte activity is of importance in limiting the serial passage of these reactions. Some of the anti-parental lymphocyte activity observed on the part of F₁ hybrid-strain cells was probably mediated by anti-idiotypic antibodies, but other phenomena, especially selective migration of both donor and host lymphocyte subpopulations, are of major importance in the interaction between parental-strain lymphocytes and an F₁ hybrid host.     

Identical VHD and DJH Junctions in Monoclonal Antibodies Derived in Response to Dextran B512 Could be the Result of Developmental Selection

We describe here the CDR3s of a collection of monoclonal antibodies (MoAb) with specificity for the carbohydrate dextran B512 produced in the mouse strain C57BL/6. In spite of the postulated mechanisms for variability in this region, a high proportion of these monoclonals displayed identical V_HD (24/30) and DJ_H (21/30) junctions and 21 of them were identical in the whole CDR3. These 21 independently generated identical CDR3s could be ordered in eight groups indicating that not a particular CDR3, but instead the mechanism for generating identical junctions was preserved. Two of the CDR3s in this study were found to be identical to the CDR3 of the monoclonal B1-8 produced in C57BL/6 in response to proteins bearing the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP). This and other parameters support the notion that the generation of identical junctions could be independent of antigenic selection. We also report here the association between J_H usage and amino acid (aa) residues at the V_HD and DJ_H junctions. Since these MoAb were generated in response to dextran B512, immunoglobulin conformation has to be compatible with antigen binding. Nevertheless, no aa residue of CDR3 could be directly related to antigen binding. We postulate therefore, that the observed selection of CDR3s could be directed to the production of variable regions with protein configuration most suitable with immunoglobulin folding and may occur prior to antigenic selection. Selection for junctional residues in relation to J_H usage and the generation of identical CDR3s are probably different events. Possible genetic mechanisms operating for CDR3 construction and/or selection by cellular ligands are discussed.     

Unresponsiveness of CD4+ T Cells from a Non-Responder Strain to HgCl2 is Not Due to CD8+-Mediated Immunosuppression: an Analysis of the Very Early Activation Antigen CD69

Injections of HgCl₂ lead to autoimmune manifestations in genetically predisposed rats and mice. In this study, the authors examined the responsiveness of T subsets from different mouse strains to HgCl₂ by tracing their expression of the very early activation antigen CD69. The authors found increased expression of the CD69 antigen on CD4⁺ T cells from the responder A.SW and BALB/c mice, but not on CD4⁺ T cells from the non-responder DBA/2 mice, indicating an activation of T helper cells in the responder strains. However, the CD69 antigen was induced on CD8⁺ T cells from all strains irrespective whether they were susceptible or resistant to mercury-induced autoimmunity. Since CD8⁺ T cells have been described as mediating immunosuppression and as being responsible for the resistance to autoimmune induction by mercury, the authors tested whether CD8⁺ T cells inhibited the activation of CD4⁺ T cells by HgCl₂ in the non-responder strains. However, there was no evidence for a suppressive role of CD8⁺ T cells from the DBA/2 mice in the response to HgCl₂. The findings indicate that T helper cells play a central role in the immunological effects of HgCl₂ and unresponsiveness of T helper cells in the nonresponder strains is not due to CD8⁺-mediated immunosuppression.     

The molecular basis and biological significance of VH replacement

Summary:  First observed in mouse pre-B-cell lines and then in knock-in mice carrying self-reactive IgH transgenes, V _H replacement has now been shown to contribute to the primary B-cell repertoire in humans. Through recombination-activating gene (RAG)-mediated recombination between a cryptic recombination signal sequence (RSS) present in almost all V _H genes and the flanking 23 base pair RSS of an upstream V _H gene, V _H replacement renews the entire V _H -coding region, while leaving behind a short stretch of nucleotides as a V _H replacement footprint. In addition to extending the CDR3 region, the V _H replacement footprints preferentially contribute charged amino acids. V _H replacement rearrangement in immature B cells may either eliminate a self-reactive B-cell receptor or contribute to the generation of self-reactive antibodies. V _H replacement may also rescue non-productive or dysfunctional V _H DJ _H rearrangement in pro-B and pre-B cells. Conversely, V _H replacement of a productive immunoglobulin H gene may generate non-productive V _H replacement to disrupt or temporarily reverse the B-cell differentiation process. V _H replacement can thus play a complex role in the generation of the primary B-cell repertoire.     

Cyclic AMP-dependent Cl− secretion induced by thromboxane A2 in isolated human colon

Increased release of thromboxane A₂ (TXA₂) has been shown to be involved in inflammatory bowel diseases. In the present study, we have investigated the effect of a stable TXA₂ analogue (STA₂) on the electrical parameters in isolated human colonic mucosa. In the human mucosa set between Ussing chambers, STA₂ stimulated Cl⁻ secretion in a concentration-dependent manner with an EC₅₀ of 0.06 μ m . The STA₂-induced Cl⁻ secretion was significantly inhibited by ONO-3708 (10 μ m ), a specific TXA₂ receptor antagonist. The effect of STA₂ (0.3 μ m ) was independent of the colonic segment from which the tissue was obtained, from caecum to rectum. Chromanol 293B, an inhibitor of the cAMP-dependent KvLQT1 channel, attenuated the STA₂-induced Cl⁻ secretion in the human colonic mucosa (IC₅₀ value 1.18 μ m ). We found that KvLQT1 mRNA and protein were expressed in all the tested segments of the human colon. The STA₂-induced Cl⁻ secretion was significantly inhibited by 8-bromo-2'-monobutyryladenosine-3',5'-cyclic monophosphorothioate (50 μ m ), a membrane-permeant cAMP antagonist. STA₂ (0.3 μ m ) significantly increased the intracellular cAMP levels and the short-circuit current via TXA₂ receptor in a human colonic cell line. These results suggest that the TXA₂-induced Cl⁻ secretion in the colon is mediated via the cAMP pathway in addition to the Ca²⁺–calmodulin pathway which was previously reported.     

炎症反应通过上调CD36表达促进小鼠肾脏损伤

目的:探讨慢性炎症对小鼠肾脏CD36表达的影响及其在小鼠肾脏损伤中的作用。方法:将8周龄雄性C57BL/6J小鼠和CD36基因敲除(CD36KO)小鼠随机分为C57BL/6J生理盐水注射组、C57BL/6J酪蛋白注射组和CD36KO酪蛋白注射组,每组8只。高脂喂养处理14周后,收集小鼠血清、24 h尿液和肾组织样本。ELISA试剂盒检测血清中肿瘤坏死因子α(TNF-α)含量,全自动生化仪测定血、尿肾功能指标,HE染色和Masson染色分析肾脏病理改变,real-time PCR和Western blot检测肾脏组织中CD36及炎症/趋化因子(MCP-1、IL-6和TNF-α)m RNA和蛋白的表达,试剂盒测定组织内过氧化氢含量,免疫组化染色测定肾组织Nrf2和TGF-β1的蛋白表达。结果:与生理盐水注射组相比,酪蛋白注射能增强C57BL/6J小鼠血清TNF-α含量和肾组织中TNF-α的蛋白表达(P 0. 05),提示酪蛋白注射能成功诱导小鼠全身和肾脏局部的慢性炎症。同时酪蛋白注射显著促进了小鼠肾组织的CD36和TGF-β1蛋白表达,引起肾小球硬化、蛋白尿和血清肌酐含量显著增加,组织过氧化氢含量明显增加,Nrf2含量和抗氧化能力明显降低(P 0. 05)。而酪蛋白处理的CD36基因敲除小鼠肾组织病理学改变不明显,血、尿肾功能指标和尿量较酪蛋白处理的C57BL/6J小鼠明显降低,且肾组织过氧化氢含量低于酪蛋白处理的C57BL/6J小鼠(P 0. 05)。结论:炎症应激通过促进小鼠肾组织CD36表达,促进氧化应激,导致小鼠肾损伤。