LAMPs and ABH histo-blood group antigens in granulation tissue

Endothelial cells are major participants in angiogenic processes accompanying wound repair. The functions of ABH histo-blood group antigens (HBGAs) and lysosome-associated membrane proteins LAMP-1 and LAMP-2 in endothelial cells of granulation tissue are currently unkown. Here we hypothesize that HBGAs and LAMPs enrich the phenotypic characteristics of endothelial cells and might be implicated in the plasticity of granulation tissue. Immunohistochemistry revealed permanent expression of HBGAs in the cytoplasm of endothelial cells of all sprouting capillaries regardless of the organ examined. A modulation in both the localization and the intensity of the signal for LAMPs was observed. Interestingly, LAMP-1 showed a more intensive staining compared to LAMP-2. LAMP-1 was found in the cytoplasm, as well as on plasma membranes of endothelial cells. We present the first comparative immunohistochemical study of the expression of HBGA and LAMPs in endothelial cells of granulation tissue. Novel evidence for modulating LAMP reactivity is reported. Our results suggest that both glycoconjugates might contribute to the process of neoangiogenesis and tissue remodeling in wound healing.     

Differential expression of LAMPs and ubiquitin in human thymus

Lysosome‐associated membrane proteins 1 and 2 (LAMP‐1 and LAMP‐2) are implicated in a variety of normal and pathological processes. LAMP‐2 is proposed to participate in chaperone‐mediated autophagy. Autophagy regulates T‐lymphocyte homeostasis by promoting both survival and proliferation. The biological importance of this process in the thymic gland and especially the involvement of LAMPs are far from being elucidated. The aim of the study was to examine the parallel expression of LAMPs and ubiquitin, a key molecule in autophagy, in normal human thymic glands and thymomas. The immunohistochemical expression of both markers was compared with that of cyclin D1 – an important regulator of cell cycle progression. Novel evidence for differential expression of LAMPs and ubiquitin is presented. Most Hassal's corpuscules in thymoma were negative for LAMPs, but positive in normal thymus. Both lymphocytes and epithelial cells in pathological thymus showed higher intensity for LAMP‐2 compared with LAMP‐1. In thymoma, ubiquitin was more intensively positive in these cell types compared with the normal thymus, suggesting activated autophagy in the course of this pathological state. A deregulation in cyclin D1 expression in thymoma is also reported. The functional importance of these molecules in autoghagy accompanying normal and pathological processes in the thymic gland is reviewed.     

Intracellular transport of acid β-glucosidase and lysosome-associated membrane proteins is affected in Gaucher's disease (G202R mutation)

Gaucher's disease (GD) is caused by an inherited deficiency of acid β-glucosidase with storage of glucosylceramides in the lysosomes of macrophages. This study identifies a G202R mutation in the acid β-glucosidase gene in an infant with severe neuronopathic (type 2) GD and only slightly reduced acid β-glucosidase activity. Western blot analysis, pulse chase experiments, and the thin frozen section immunogold method were used to analyse the implications of this mutation on the pathogenesis, clinical heterogeneity and diagnostic evaluation of GD. The results show that acid β-glucosidase persists in the patient's fibroblasts as a mannose-rich polypeptide in the endoplasmic reticulum and is not transported to the lysosomes. By contrast, high expression of the lysosome-associated membrane proteins LAMP-1 and LAMP-2, saposin C, and cathepsin D was observed in the patient's lysosomes. Immunogold labelling of the integral membrane proteins LAMP-1 and LAMP-2 increases significantly at the cell surface of Kupffer cells and fibroblasts as well as at the apical membrane of hepatocytes. In addition, LAMP-1 and LAMP-2 associate with the bilayer of stored glucosylceramide. It is concluded that defective intracellular transport of mutant acid β-glucosidase from the endoplasmic reticulum to lysosomes leads to a more severe clinical phenotype than the residual enzyme activity may indicate. Furthermore, the detection of LAMP in the tubular bundles of undigested glucosylceramides, as well as their increased concentration at the surfaces of the affected cells, suggests that these proteins play a role in the storage or removal of substrate in GD. Intracellular targeting of acid β-glucosidase and LAMP contributes to the broad phenotypic heterogeneity of GD. Copyright © 1999 John Wiley & Sons, Ltd.     

生殖支原体脂质相关膜蛋白经Toll样受体2激活NF-κB

目的 探讨生殖支原体(Mg)脂质相关膜蛋白(LAMPs)能否经Toll样受体2(TLR2)激活核转录因子κB(NF-κB).方法 提取MgLAMPs刺激THP-1细胞,ELISA检测NF-κBp65活化水平,RT-PCR检测THP-1细胞TLR2 mRNA的表达,随后ELISA检测TLR2中和抗体对LAMPs激活NF-κBp65的影响,最后用LAMPs刺激瞬时共转染pFLAG-TLR2、pNF-κB-luc、pRL-TK的293T细胞,双荧光素酶报告基因分析TLR2在LAMPs激活NF-κB中的作用.结果 LAMPs能诱导THP-1细胞激活NF-κBp65,并且与LAMPs浓度呈明显的剂量依赖性,当LAMPs为4.0μg/ml时NF-κBp65活化程度最高;LAMPs能上调THP-1细胞TLR2 mRNA的表达;TLR2中和抗体能使LAMPs激活NF-κBp65的活化程度降低60%;共转染pFLAG-TLR2浓度的增加,NF-κB的活化程度明显增加,并且与TLR2的转染量呈剂量依赖性.结论 Mg LAMPs能经TLR2激活NF-κB,TLR2介导的激活在LAMPs发挥致病性过程起着重要作用.     

Mycoplasma bovis-derived lipid-associated membrane proteins activate IL-1β production through the NF-κB pathway via toll-like receptor 2 and MyD88

Mycoplasma bovis causes pneumonia, otitis media, and arthritis in young calves, resulting in economic losses to the cattle industry worldwide. M. bovis pathogenesis results in part from excessive immune responses. Lipid-associated membrane proteins (LAMPs) can potently induce host innate immunity. However, interactions between M. bovis-derived LAMPs and Toll-like receptors (TLRs), or signaling pathways eliciting active inflammation and NF-κB activation, are incompletely understood. Here, we found that IL-1β expression was induced in embryonic bovine lung (EBL) cells stimulated with M. bovis-derived LAMPs. Subcellular-localization analysis revealed nuclear p65 translocation following EBL cell stimulation with M. bovis-derived LAMPs. An NF-κB inhibitor reversed M. bovis-derived LAMP-induced IL-1β expression. TLR2 and myeloid differentiation primary response gene 88 (MyD88) overexpression increased LAMP-dependent IL-1β induction. TLR2-neutralizing antibodies reduced IL-1β expression during LAMP stimulation. LAMPs also inhibited IL-1β expression following overexpression of a dominant-negative MyD88 protein. These results suggested that M. bovis-derived LAMPs activate IL-1β production through the NF-κB pathway via TLR2 and MyD88.     

Generalized lysosome-associated membrane protein-2 defect explains multisystem clinical involvement and allows leukocyte diagnostic screening in Danon disease

Danon disease, an X-linked dominant disorder, results from mutations in the lysosome-associated membrane protein-2 (LAMP2) gene and presents with hypertrophic cardiomyopathy, skeletal myopathy, and mental retardation. To investigate the effects of LAMP2 gene mutations on protein expression in different tissues, we screened LAMP2 gene mutations and LAMP-2 protein deficiency in the skeletal muscle of nine unrelated patients with hypertrophic cardiomyopathy and vacuolar myopathy. We identified three novel families (including one affected mother) with unreported LAMP2 gene null mutations and LAMP-2 protein deficiency in skeletal and myocardial muscle, leukocytes, and fibroblasts. LAMP-2 protein deficiency was detectable in various tissues, including leukocytes, explaining the multisystem clinical involvement. Skeletal muscle immunopathology showed that mutant protein was not localized in the Golgi complex, vacuolar membranes expressed sarcolemmal-specific proteins, and the degree of muscle fiber vacuolization correlated with clinical muscle involvement. In our female patient, muscle histopathology and LAMP-2 protein analysis was inconclusive, indicating that diagnosis in females requires mutation identification. The random X-chromosome inactivation found in muscle and leukocytes excluded the possibility that selective involvement of some tissues in females is due to skewed X-chromosome inactivation. Therefore, biochemical analysis of leukocytes might be used for screening in male patients, but genetic screening is required in females.     

Binding of CD14 to Mycoplasma genitalium-Derived Lipid-Associated Membrane Proteins Upregulates TNF-α

Lipid-associated membrane proteins (LAMPs) are a mixture of mycoplasmal lipoproteins expressed on the surface, and they are the main structures for interaction with the host cells. The objective of this study was to explore the role of CD14 in immune recognition of Mycoplasma genitalium-derived LAMPs and investigate whether the binding of CD14 to LAMPs affects the inflammatory response. Enzyme-linked immunosorbent assay (ELISA), transient co-transfection, dual-luciferase reporter assay, specific inhibition assay, and competitive inhibition ELISA (CI-ELISA) were used. CD14 was involved in LAMP-stimulated production of tumor necrosis factor (TNF)-α by blocking CD14 antibody in THP-1 cells. Co-transfection experiments in HeLa cells provide evidence that CD14 facilitates LAMP-induced TNF-α release via toll-like receptor 2 (TLR2). In addition, LAMP-induced TNF-α release was increased by soluble CD14 but decreased by soluble TLR2. Lipid moieties of LAMPs pre-treated with lipoprotein lipase were responsible for TNF-α production. The binding of CD14 to LAMPs was supported by binding assay and CI-ELISA. Thus, we provide evidences that CD14 is not only able to recognize LAMPs but also its binding to LAMPs upregulates TNF-α release. These findings provide insight into the function of CD14 and the pathogenesis of mycoplasmal infections.     

Expressions of two adenomatous polyposis coli and E-cadherin proteins on human colorectal cancers

Mutations in the adenomatous polyposis coli (APC) gene contribute to the progression of colorectal tumorigenesis. Despite the importance, few studies regarding the localization of this protein on surgically resected human colorectal cancer specimens using immunohistochemistry have been reported so far because of the unavailability of the antibodies for this use. The goal of this study has been to provide the APC protein expression and to validate the APC molecular studies. We took advantage of an immunohistochemistry procedure of applying the unique detergent-mediated antigen retrieval technique to frozen sections and examined the expressions of one amino (N)-terminal (AC4) and one carboxy (C)-terminal APC antibody (HG2). Further, we compared the stainings of APC antibodies with those of the E-cadherin antibody using a quantitative image analysis. E-cadherin is a critical morphogenetic regulator during embryogenesis and recent evidence strongly suggests that downregulation of E-cadherin expression in cancers is associated with a high rate of invasion and metastasis. The analysis indicated statistically that normal epithelia showed stronger staining than cancer cells ( P<0.05). Further, in normal epithelia, the amino (N)-terminal APC antibody (AC4) showed a positive correlation with another carboxy (C)-terminal APC antibody (HG2). E-cadherin showed no positive correlation with other APCs in either the normal epithelia or cancer cells. This study verified reduced expressions of APCs and E-cadherin proteins in colorectal cancer cells. This suggests that the normal APC and E-cadherin protein expressions in benign epithelium are progressively and independently lost in the sporadic colorectal cancers.     

The matrix metalloproteinase/tissue inhibitor of matrix metalloproteinase profile in colorectal polyp cancers

Aims:  The matrix metalloproteinase (MMP)/tissue inhibitor of metalloproteinase (TIMP) system has a major role in tumour invasion and metastasis. Roles in pathways involved in early tumour development are also being identified for this system, and the aim of this study was to define the expression profile of the major MMPs and TIMPs in colorectal polyp cancers.
Methods and results:  The expression and cellular localization of individual MMPs and TIMPs was determined in colorectal polyp cancers by immunohistochemistry. All the MMPs and TIMPs showed immunoreactivity in carcinomatous epithelium. MMP1 ( P  < 0.001), MMP2 ( P  = 0.003), MMP3 ( P  = 0.004), TIMP1 ( P  = 0.01) and TIMP2 ( P  < 0.001) showed significant increases in immunoreactivity in carcinomatous epithelium compared with adenomatous epithelium. MMP7 showed immunoreactivity in carcinomatous epithelium, but showed no immunoreactivity in either normal epithelium or adenomatous epithelium. MMP and TIMP expression was limited in normal epithelium to MMP1, MMP2 and TIMP3.
Conclusions:  This study defines the expression profile of MMPs and TIMPs in colorectal polyp cancers and shows that the increased expression of MMPs and TIMPs occurs at an early stage of colorectal neoplasia. It provides evidence to support the hypothesis that these molecules have a key involvement in the early stages of tumour development.     

Keratins in colorectal epithelial function and disease

Keratins are the largest subgroup of intermediate filament proteins, which are an important constituent of the cellular cytoskeleton. The principally expressed keratins (K) of the intestinal epithelium are K8, K18 and K19. The specific keratin profile of a particular epithelium provides it with strength and integrity. In the colon, keratins have been shown to regulate electrolyte transport, likely by targeting ion transporters to their correct location in the colonocytes. Keratins are highly dynamic and are subject to post-translational modifications including phosphorylation, acetylation and glycosylation. These affect the filament dynamics and hence solubility of keratins and may contribute to protection against degradation. Keratin null mice (K8(-/-) ) develop colitis, and abnormal keratin mutations have been shown to be associated with inflammatory bowel disease (IBD). Abnormal expression of K7 and K20 has been noted in colitis-associated dysplasia and cancers. In sporadic colorectal cancers (CRCs) may be useful in predicting tumour prognosis; a low K20 expression is noted in CRCs with high microsatellite instability; and keratins have been noted as dysregulated in peri-adenomatous fields. Caspase-cleaved fragment of K18 (M30) in the serum of patients with CRC has been used as a marker of cancer load and to assess response to therapy. These data suggest an emerging importance of keratins in maintaining normal function of the gastrointestinal epithelium as well as being a marker of various colorectal diseases. This review will primarily focus on the biology of these proteins, physiological functions and alterations in IBD and CRCs.     

LAMP-2-deficient human B cells exhibit altered MHC class II presentation of exogenous antigens

Major histocompatibility complex (MHC) class II molecules present antigenic peptides derived from engulfed exogenous proteins to CD4⁺ T cells. Exogenous antigens are processed in mature endosomes and lysosomes where acidic proteases reside and peptide‐binding to class II alleles is favoured. Hence, maintenance of the microenvironment within these organelles is probably central to efficient MHC class II‐mediated antigen presentation. Lysosome‐associated membrane proteins such as LAMP‐2 reside in mature endosomes and lysosomes, yet their role in exogenous antigen presentation pathways remains untested. In this study, human B cells lacking LAMP‐2 were examined for changes in MHC class II‐restricted antigen presentation. MHC class II presentation of exogenous antigen and peptides to CD4⁺ T cells was impaired in the LAMP‐2‐deficient B cells. Peptide‐binding to MHC class II on LAMP‐2‐deficient B cells was reduced at physiological pH compared with wild‐type cells. However, peptide‐binding and class II‐restricted antigen presentation were restored by incubation of LAMP‐2‐negative B cells at acidic pH, suggesting that efficient loading of exogenous epitopes by MHC class II molecules is dependent upon LAMP‐2 expression in B cells. Interestingly, class II presentation of an epitope derived from an endogenous transmembrane protein was detected using LAMP‐2‐deficient B cells. Consequently, LAMP‐2 may control the repertoire of peptides displayed by MHC class II molecules on B cells and influence the balance between endogenous and exogenous antigen presentation.     

Distribution of sialosyl Tn and Tn antigens within normal and malignant colorectal epithelium

Expression of the core blood group structures sialosyl Tn (STn) and Tn is regarded as a colorectal cancer-specific change reflecting truncated synthesis of the oligosaccharide component of goblet cell mucin. The distribution of STn and Tn in normal and malignant epithelium has been studied in detail by a combination of mucin-, lectin-, and immunohistochemistry with and without pretreatment with potassium hydroxide (KOH), neuraminidase, and KOH–neuraminidase. When O-acetylated sialic acid (neuraminidase-resistant) is converted by saponification to non-O-acetylated sialic acid (neuraminidase-sensitive), normal colorectal goblet cells (mainly of the lower two-thirds of crypts) are immunoreactive with the monoclonal antibody TKH2 (specific for STn). This immunoreactivity is abolished by the interposition of neuraminidase, but goblet cells then become immunoreactive with Hb-Tn1 (specific for Tn). While colorectal cancer mucin expresses STn, expression of Tn is not seen in either goblet cell mucin or extracellular material showing the morphological and histochemical characteristics of secretory mucin. Tn expression in cancers is mainly limited to the Golgi zone and in a proportion of cases to cytoplasm and apical membrane (glycocalyx) of columnar cells and inspissated material within lumina. The material reacting with Hb-Tn1 may be upregulated, membrane-associated MUC1 glycoprotein rather than MUC2 or MUC4 goblet cell mucin. The presence of STn and cryptic Tn within normal colorectal goblet cells and the absence of Tn expression within colorectal cancer secretory mucin contradicts the generally accepted concept of cancer-specific incomplete glycoprotein synthesis within these neoplasms.     

结肠癌组织中STC1的表达及其与肿瘤微环境的关系

目的:探讨斯钙素1(STC1)在结肠癌组织中的表达,分析STC1与结肠癌预后的相关性,并探讨其与结肠癌肿瘤微环境的联系。方法:用UALCAN数据库(http://ualcan.path.uab.edu/index.html)和Oncomine数据库(https://www. oncomine.org)分析STC1在正常结肠组织及结肠癌组织中的表达水平;RT-qPCR及Western blot检测结肠癌及其癌旁组织中STC1的表达;使用OncoLnc(http://www.oncolnc.org/)分析工具评估STC1表达水平与结肠癌临床预后的相关性。氯化钴缺氧和脂多糖诱导处理结肠癌HT-29细胞,RT-qPCR和Western blot检测细胞STC1的表达水平变化;运用TIMER分析工具(https://cistrome.shinyapps.io/timer/),分析STC1与缺氧诱导因子1α(HIF1α)及免疫调节的相关性。结果:STC1在结肠癌组织中的表达水平显著高于正常结肠组织,并且STC1的高表达与结肠癌的分期和不良预后呈正相关关系(P0.01)。在结肠癌HT-29细胞中,缺氧能够显著诱导STC1表达,STC1的表达水平与HIF1α的水平存在正相关关系;炎症模拟条件下,STC1的表达水平显著升高,STC1与炎症分子的表达和肿瘤组织中免疫细胞的浸润水平存在密切关系。结论:STC1在结肠癌组织中高表达,是结肠癌不良预后的一个重要的分子标志物,并且STC1与结肠癌肿瘤微环境,特别是与结肠癌的缺氧及免疫调节存在密切关系。     

结直肠肿瘤P53蛋白表达与肿瘤临床病理学特征及预后的关系

应用免疫组织化学方法观察７２例结直肠、１１例腺瘤、３０例癌旁粘主１５例正常粘膜Ｐ５３蛋白表达及其与肿瘤临床病理学特征和预后的关系。结果显示：结直肠癌Ｐ５３蛋白阳性率为５０％，腺瘤的阳性率为１８．１８％（Ｐ＜０．０５），阳性细胞主要分布在腺瘤的增生区或不典型增生区；正常粘膜、癌粘膜Ｐ５３蛋白均阴性。Ｐ５３蛋白阳性的结直肠癌多呈浸润性生长方式，且以浸润至浆膜外者居多，患者片存率较Ｐ５３蛋白阴性者（Ｐ＜