Monocyte/mesangial cell interactions in high-glucose co-cultures

BACKGROUND

Monocytes bind to human mesangial cells (HMC) in a co-culture model of leukocyte/ glomerular cell interactions. Since monocytic infiltration has been demonstrated in the early stages of diabetic glomerulopathy, we examined whether co-culture with myelomonocytes of the U937 cell line in media mimicking the diabetic microenvironment modulated phenotype, growth, and extracellular matrix production patterns of HMC.

METHODS

HMC monolayers grown for 5 days in 5.5 mmol/l (NG) or 30 mmol/l (HG) glucose media were examined 3, 24 and 48 h after addition of U937 cells by computer-assisted image analysis/fluorescence microscopy following fixation, staining for cell adhesion, and TUNEL/propidium iodide labelling for apoptosis. As matrix components may be relevant to both phenotype of cultured HMC and monocyte adhesion, reverse transcription-polymerase chain reaction, zymography, and ELISA were used to detect urokinase-plasminogen activator (uPa), collagen type IV (COL IV), transforming growth factor beta1 (TGF-beta1), matrix metalloproteinases (MMP), and relative inhibitors (tissue inhibitor of MMP (TIMP)) expression in co-cultures in NG/HG.

RESULTS

U937 adhesion at 1-3 h was increased in HG (from 54.9+/-6.6 to 87.1+/-5.8% U937/HMC). Control HMC proliferating in NG supplemented with 10% fetal bovine serum had an average cross-sectional area of 9993+/-505 micro(2) with 1.2+/-0.1 hillocks/high-power field, which increased to 13 651+/- 1114 micro(2) with 0.5+/-0.2 hillocks/high-power field in HG (P<0.05). TUNEL+HMC were nearly identical (4.9+/-1.7 vs 4.2+/-0.4% in HG, P=NS). Enhanced transcription and secretion of urokinase (uPA, +656%), COL IV (+137%), TGF-beta1 (+590%) were observed in co-cultures in HG. COL IV and TGF-beta1, but not uPA, were also increased in HMC alone, exposed to HG for 5 days. MMP-2/TIMP-2 ratio was decreased while MMP-1/TIMP-1 was increased in HG co-cultures. In both NG and HG, U937 adhesion reduced HMC number and hillocks at 24 h, with constant apoptosis. The effects of U937 were no longer detectable at 48 h, when apoptosis was 2.1+/-0.6 vs 4.0+/-0.4% in HG, and cell counts returned above basal, possibly due to a delayed proliferative response.

CONCLUSIONS

High glucose medium increases U937 cell adhesion to HMC. In turn, monocytes modulate number and spatial distribution of HMC, which are also markedly affected by ambient glucose levels. These interactions may be relevant to leukocyte infiltration, mesangial expansion, and glomerulosclerosis in diabetes.

Augmented membrane type 1 matrix metalloproteinase (MT1-MMP):MMP-2 messenger RNA ratio in gastric carcinomas with poor prognosis

The activation of zymogen and the amount of proteinase and its inhibition are important in determining the eventual activity of matrix-degrading enzymes involved in tumor aggressiveness. To evaluate a gene complement leading to matrix metalloproteinase 2 (MMP-2; Mr 72,000 gelatinase) activity, membrane type 1 MMP (MT1-MMP), urokinase-type plasminogen activator, MMP-2, and tissue inhibitor of metalloproteinase 2 transcriptional levels were measured in gastric carcinoma biopsies. Comparative tumor:normal tissue reverse transcription-PCR in a cohort of 25 patients revealed up to a 10-fold difference in the expression of MT1-MMP, a metalloproteinase that has been proposed as a membrane receptor activator of MMP-2; a 1-unit increment resulted in a 30% risk to survival. A 20% risk also resulted from a 1-unit increment in the MT1-MMP: MMP-2 ratio, which showed differences of up to 15-fold. Instead, the expression of urokinase-type plasminogen activator, which trips off a cascade ending in the activation of MMP-2, as well as the expression of MMP-2 itself and its inhibitor, tissue inhibitor of metalloproteinase 2, lacked correlation with patient follow-up. Zymography revealed MMP-2 activities that were often in conflict with the transcription results and also with follow-up. The results suggest the evaluation of MT1-MMP and/or MT1-MMP:MMP-2 transcription as a new preoperative molecular-level prognostic factor for gastric carcinoma.

Expression study on D123 gene product: evidence for high positivity in testis

A novel 44-kDa gene product (D123) has been proposed as necessary for S-phase entry of the cell cycle: a point mutation resulted in a temperature-sensitive arrest in G1-phase. From human fibrosarcoma cDNA library, we have isolated an identical gene and studied its sequence and mRNA and protein expression. Compared with D123, three nucleotide differences within the human coding sequence, plus others, result in a change of two amino acids. A partial sequence similarity has been found with a yeast gene of unknown function. The protein has several potential phosphorylation sites, is highly hydrophilic, and may be highly structured in alpha-helix. The mRNA is abundantly expressed by a variety of normal and transformed cells and by all tissues examined, being most highly expressed in testis. Specific antibodies, raised against a rhD123 polypeptide, recognize a major 42- to 44-kDa molecule in crude extract of various human cell lines. Immunohistochemistry reveals that D123 protein is not homogeneously expressed: it is detected, often in granular vescicles, in the cytoplasm of some epithelial, stromal, and sperm cells and in varicosities lining nervous fibers, while it appears to be absent in nuclei, endothelial, and smooth muscle cells. The precise link between cytoplasmic occurrence of D123 and cell cycle progression still remains to be clarified.

Recombinant human TIMP-3 from Escherichia coli: synthesis, refolding, physico-chemical and functional insights

Matrix metalloproteinases are inhibited by a growing family of specific tissue inhibitors, TIMPs. The cDNA of the third member of the family, TIMP-3, was obtained by using a reverse transcription-polymerase chain reaction (RT-PCR) to amplify the corresponding mRNA from human placenta. Cloning and expression of the TIMP-3 were performed in Escherichia coli as a fusion protein with a 36 amino acid N-tail containing a His cluster. In the host vector system, rhTIMP-3 was stored intracellularly in its denatured, insoluble form in inclusion bodies. Slow dilution of denaturing and reducing agents, from rhTIMP-3 His bound to a metal affinity solid phase, was followed by partial acid removal of the N-tail, which leaves a residue of four amino acids. Circular dichroism, fluorescence and second-derivative UV spectroscopic analyses supported correct refolding of the recombinant and zymography showed inhibition of both MMP-2 and MMP-9 gelatinolytic activities. The role of the C-terminus, which has closer homology with TIMP-2 than TIMP-1, was also investigated: a C-truncated mutant, similarly cloned and expressed in E. coli, shows complete lack of inhibitory activity on MMP-9, still retaining some on MMP-2. The described protein engineering shows high yield of active inhibitor, unglycosylated as in the native form.

Effect of glucose and heparin on mesangial alpha 1(IV)COLL and MMP-2/TIMP-2 mRNA expression

Mesangial cells are responsible for the synthesis of mesangial matrix as well as its degradation, which is mediated by a number of proteolytic activities, including metalloproteinases (MMPs). Imbalanced matrix protein metabolism may be responsible for mesangial expansion and glomerulosclerosis in diabetic nephropathy. Heparin prevents this complication. In human and murine mesangial cell cultures, RT-PCR was able to detect mRNA expression for a number of molecules involved in the mesangial extracellular matrix turnover: type IV collagen [alpha 1(IV)COLL], MMP-1, MMP-2, MMP-3, MMP-9 and MMP-10, and the tissue inhibitors TIMP-1 and TIMP-2. The expression of mRNA for alpha 1(IV)COLL and MMP-2/TIMP-2 balance was studied in human cells in the presence of high glucose and heparin. mRNAs for all the studied molecules were expressed at different levels. Interestingly, a shift in the balance of alpha 1(IV)COLL, MMP-2 and TIMP-2 was observed in high glucose, which was partially reversed by heparin supplementation. The new equilibrium was mostly due to the down-regulation of type IV collagen expression, rather than further reduction of potential proteolysis. Our data, while extending the list of potential mediators of mesangial matrix catabolism, highlight a molecular mechanism by which the pathogenesis of diabetic nephropathy may be sustained, and at the same time suggest that heparin may have the potential to correct this abnormality.

Gelatinase A/TIMP-2 imbalance in lymph-node-positive breast carcinomas, as measured by RT-PCR

Over-production of gelatinase A (MMP-2) or under-production of its inhibitor (TIMP-2) may result in the matrix degradation crucial for metastasis, and early evaluation of their expression in primary tumor would offer important prognostic informations. RT-PCR amplicons of MMP-2 and TIMP-2 mRNA from tissue biopsies of 13 breast carcinomas and one fibrocystic mastopathy were quantitated. In comparison with their normal-tissue counterparts, their expression trends were not uniform: in some cases MMP-2 increased in the tumor without changes in TIMP-2, in others TIMP-2 expression also increased, although to a lesser extent than MMP-2; only in 2 cases was it slightly lower in the tumor tissue. Nevertheless, clearer insights were gained from the comparison of the ratio (R) between MMP-2tumor/normal and TIMP-2tumor/normal: as in the fibrocystic mastopathy, the R in carcinomas without lymph-node involvement (LN-) was usually lower than I in most cases. In contrast, in 5 out of 6 patients with lymph-node metastasis (LN+), the ratio ranged between 2 and 4. While the R magnitude was not related to the frequency of positive lymph nodes out of the total analyzed, nor to relapse status at follow-up (all relapse-free), the clear-cut difference between the LN- and LN+ groups was statistically significant. Results suggest that evaluation of MMP-2/TIMP-2 mRNA balance may constitute an early prognostic approach, which may also be more reliable concerning cancer aggressiveness as compared with the MMP-2 alone, and that boosting TIMP-2 expression may be a therapeutic strategy to prevent metastasis.

Gelatinase A (MMP-2) and its mRNA detected in both neoplastic and stromal cells of tumors with different invasive and metastatic properties

Simultaneous presence of gelatinase A (MMP-2) and MMP-2 messenger RNA (mRNA) in 30 malignant tumors with various degrees of differentiation and biological behavior was evaluated by immunohistochemistry and in situ hybridization. The series consisted of 10 gastric carcinomas, 10 colorectal carcinomas, five squamous skin carcinomas, and five basal cell skin tumors. MMP-2 was detected in all cases. MMP-2 mRNA was expressed in the stromal cells in all cases and was more marked in the less-differentiated gastric and colonic carcinomas; it was also detected in the neoplastic cells of poorly differentiated tumors, particularly in those of the signet-ring cell type, both in the colon and stomach. The study confirmed that stromal cells have a specific role in tumor invasion and suggests a direct relationship between neoplastic epithelium and stromal cells in the most aggressive varieties.

Reverse transcription-polymerase chain reaction phenotyping of metalloproteinases and inhibitors involved in tumor matrix invasion

The matrix metalloproteinase enzymes have been implicated in tumor invasion and metastasis by a series of correlative immunohistochemical studies. In addition, direct evidence for the role of these enzymes in this pathologic process comes from studies using specific metalloproteinase inhibitors to block tumor invasion and metastasis formation, both in vitro and in vivo. Synthetic oligonucleotide primers for four metalloproteinases (MMP-1, MMP-2, MMP-9, MMP-10) and their tissue inhibitors (TIMP-1, TIMP-2) were selected, synthesized, and optimized in the reverse transcriptase-polymerase chain reaction (RT-PCR) to study the qualitative profile of these enzymes and inhibitors in cultured human tumor cells and tumor tissues. These primers are specific and generate unique amplification products for each appropriate enzyme and inhibitor. Slight enhancement in the amplification of cDNA products was achieved by adding dimethylsulfoxide to the reaction mixture, but commercial enhancement reagents were ineffective. Using this RT-PCR method, cDNA amplification was successful with RNA from as few as 20 cultured tumor cells. The RT-PCR analysis was done on three invasive human colon adenocarcinomas and their paired adjacent normal mucosa. The results show MMP-1 and MMP-2 products in all three tumors, and MMP-2 detected in one of the three normal mucosa samples; TIMP-2 expression was present in two of three patients and awaits quantitative assessment of RT-PCR products.

Release of granulocyte-macrophage colony-stimulating factor by alveolar macrophages in the lung of HIV-1-infected patients. A mechanism accounting for macrophage and neutrophil accumulation

In this paper, the release of granulocyte-macrophage colony-stimulating factor (GM-CSF) in the lung of patients with HIV-1 infection was evaluated. This cytokine has well recognized effects on granulocyte and macrophage growth and differentiation and plays some role in the mechanisms leading to the accumulation of alveolar macrophages (AM) in patients with interstitial lung disease. Detectable levels of GM-CSF (up to 10 pg/ml) were demonstrated in unconcentrated bronchoalveolar lavage fluid retrieved from HIV-1-seropositive patients, thus suggesting that the GM-CSF is released in vivo in the lung during HIV-1 infection. A statistically significant correlation was demonstrated between the bronchoalveolar lavage concentrations of GM-CSF and the absolute numbers of AM and lung neutrophils. Cell-free supernatants obtained from unstimulated 24-h cultured AM isolated from HIV-1-infected patients contained discrete amounts of GM-CSF, as demonstrated by an immunoenzymatic assay. AM lost the capability of releasing GM-CSF after 72 h of culture, thus suggesting that the production of GM-CSF is not constitutive in AM. After exposition of AM with LPS, the release of GM-CSF and the expression of its mRNA significantly increased with respect to the baseline values; interestingly, the amount of GM-CSF released by LPS-stimulated AM was more than 10-fold higher in HIV-1-infected patients than in healthy subjects. As demonstrated by flow cytometry analysis, more than 70% of freshly isolated AM efficiently bound phycoerythrin-GM-CSF, thus indicating that they express the receptor for GM-CSF. Determination of AM in G1, S, and G2+M by flow cytometry showed that, after 48 h of culture with GM-CSF, 5.5 to 7% of AM entered the proliferative phase of the cell cycle. Taken together, these findings suggest that AM might represent an important source of GM-CSF production in HIV-1 infection. In particular, the hypothesis is formulated that pulmonary opportunists might trigger AM to synthesize GM-CSF in situ. The local overproduction of this cytokine is likely to play a role in the pathogenic events leading to the local proliferation of AM and recruitment of neutrophils in AIDS-associated interstitial lung disease.

Release of granulocyte-macrophage colony-stimulating factor by alveolar macrophages in the lung of HIV-1-infected patients. A mechanism accounting for macrophage and neutrophil accumulation

In this paper, the release of granulocyte-macrophage colony-stimulating factor (GM-CSF) in the lung of patients with HIV-1 infection was evaluated. This cytokine has well recognized effects on granulocyte and macrophage growth and differentiation and plays some role in the mechanisms leading to the accumulation of alveolar macrophages (AM) in patients with interstitial lung disease. Detectable levels of GM-CSF (up to 10 pg/ml) were demonstrated in unconcentrated bronchoalveolar lavage fluid retrieved from HIV-1-seropositive patients, thus suggesting that the GM-CSF is released in vivo in the lung during HIV-1 infection. A statistically significant correlation was demonstrated between the bronchoalveolar lavage concentrations of GM-CSF and the absolute numbers of AM and lung neutrophils. Cell-free supernatants obtained from unstimulated 24-h cultured AM isolated from HIV-1-infected patients contained discrete amounts of GM-CSF, as demonstrated by an immunoenzymatic assay. AM lost the capability of releasing GM-CSF after 72 h of culture, thus suggesting that the production of GM-CSF is not constitutive in AM. After exposition of AM with LPS, the release of GM-CSF and the expression of its mRNA significantly increased with respect to the baseline values; interestingly, the amount of GM-CSF released by LPS-stimulated AM was more than 10-fold higher in HIV-1-infected patients than in healthy subjects. As demonstrated by flow cytometry analysis, more than 70% of freshly isolated AM efficiently bound phycoerythrin-GM-CSF, thus indicating that they express the receptor for GM-CSF. Determination of AM in G1, S, and G2+M by flow cytometry showed that, after 48 h of culture with GM-CSF, 5.5 to 7% of AM entered the proliferative phase of the cell cycle. Taken together, these findings suggest that AM might represent an important source of GM-CSF production in HIV-1 infection. In particular, the hypothesis is formulated that pulmonary opportunists might trigger AM to synthesize GM-CSF in situ. The local overproduction of this cytokine is likely to play a role in the pathogenic events leading to the local proliferation of AM and recruitment of neutrophils in AIDS-associated interstitial lung disease.

Spontaneous production of interleukin-6 by alveolar macrophages from human immunodeficiency virus type 1-infected patients

To test the hypothesis that the lung represents a source of interleukin (IL)-6 in human immunodeficiency virus type 1 (HIV-1)-positive subjects, alveolar macrophages (AM) obtained from the bronchoalveolar lavage (BAL) fluid of 10 HIV-1-positive patients were investigated for the expression of IL-6 mRNA and the ability to release IL-6. The presence of IL-6 in BAL fluid was also investigated. It has been demonstrated that freshly recovered AM from HIV-1-positive patients show a strong IL-6 mRNA signal. The message for IL-6 increases following culture with LPS. Supernatants obtained from AM cultured in medium alone contain high amounts of IL-6; the values are three to four times higher following culture with LPS. IL-6 has also been detected in the BAL fluid from 5 of 8 HIV-1-positive patients. Results of immunoblotting analysis were consistent with those given above. These findings suggest that the lung represents a source of IL-6 production in HIV-1-infected subjects with lung disorders.

[Collagenase IV and laminin receptors in cultured trophoblast cells]

Human trophoblast cells were obtained from a term placenta and cultured through several stages. Using specific antibodies marked using an avidin biotin system and given the characteristic "invasiveness" of placental tissue, the Authors investigated the possible presence of those markers which have been found to be correlated with invasive and metastatic tumour cells. The positivity shown by cultured trophoblast cells towards laminin receptors and collagenase IV may have important implications which might explain the strange formation and maintenance of the human uteroplacental circulation in which embryonal tissue is in direct contact with maternal blood.

Correlation of serum metalloproteinase levels with lung cancer metastasis and response to therapy

Cancer cells elaborate metalloproteinases which may play a role in invasion and metastasis. The serum level of the M(r) 72,000 type IV collagenase (MMP-2) was measured in 87 lung cancer patients. Stage IV cancer levels were significantly elevated (P less than 0.0001) compared to normal sera. A significant difference (P less than 0.01) was found between enzyme levels in the presence versus the absence of distant metastasis. For 29 patients treated with combination chemotherapy, a positive relationship was noted between response failure and elevated enzyme levels. Serum metalloproteinase levels may provide information relevant to prognosis as well as treatment decisions.

Degradation of immobilized soluble elastin by tumor cells in culture: quantitation by ELISA

A new, sensitive assay based on the enzyme-linked immunosorbent assay has been developed for measuring elastolytic activity produced by invasive and/or metastatic tumor cells in culture. Elastin peptides, obtained by treating the insoluble protein with either oxalic acid, KOH, or chymotrypsin, are adsorbed onto the surface of cell culture microtiter plastic wells, and incubated with dilution of standard proteinases or viable normal or tumor cells. The total amount of immobilized elastin peptides is revealed by the mean of specific antibodies, and detected by a microplate reader, while dose- and time-dependent reduction of bound antibodies after incubation with proteases or cells is taken as a measure of elastin degradation. Adsorbed elastin has been found to be available as a substrate for purified enzymes, as well as for living melanoma cells (A2058 and B16-BL6), c-Ha-ras transformed rat embryo fibroblasts, and human pulmonary macrophages, as demonstrated by the release into the culture medium of lower molecular weight digestion products. No degradation was achieved by BALB/3T3 and rat embryo control fibroblasts, and no inhibition was produced by the presence of fetal calf serum which, on the contrary, potentiated the degradation by active cells. This new method, revealing degradation of only a few nanograms of soluble elastin peptides, can be used for studying the importance in tissue invasion and metastasis of elastolytic proteinases produced by cells in culture.

Genetic polymorphism of C3 in the Veneto population, Italy

The distribution of C3 phenotypes in the population of Veneto was investigated by electrophoresis on agarose gel. In our sample (n = 810) the three common phenotypes C3 SS, C3 FF and C3 FS and a further phenotype, C3 S-VF, were observed. The following gene frequencies could be calculated: C3S = 0.8068, C3F = 0.1926 and C3V = 0.0006. These frequencies have been compared with those found in other populations. The analysis of 21 mother-child pairs was in agreement with an autosomal codominant inheritance.

Hormonal and basement membrane markers for immunoidentification of cultured human trophoblast cells

Improvement of human chorionic villi cells in vitro culture has been obtained by supplementing the medium with 30% human fetal cord serum, instead of fetal calf serum. Expression of human chorionic gonadotropin, estrogen and progesterone receptors, laminin, laminin receptors, and type IV collagen has been studied on first subculture passages (4-7 weeks) by immunoperoxidase method. A minority of the cultured cells were positive for estrogen receptors, the majority were positive for progesterone receptors, while all cells were negative for human chorionic gonadotropin. Cultured cells showed variable positive immunostaining for basement membrane markers like laminin, and type IV collagen, and for laminin receptors. Detection of both progesterone receptors and laminin, or type IV collagen, excluded fibroblast contamination and could then be useful for quick identification of cultured trophoblast cells.

Rapid method for cultured trophoblast cells identification

The addition of human foetal cord serum to the culture medium improves the in vitro growth of human chorionic villi cells. The expression of HCG, laminin, laminin receptor, and type IV collagen has been studied on first passage (4-7 weeks) cultured villi cells by the immunoperoxidase method. No cells were positive for HCG, while various patterns of basement membrane markers were always detectable. The presence of laminin and collagen type IV excludes fibroblast contamination and can be used for a rapid trophoblast cells identification.

Properdin factor B(Bf) polymorphism in the population of Veneto, Italy

The distribution of Bf phenotypes in the population of Veneto was investigated by agarose gel electrophoresis and immunofixation. In our sample (n = 592), the seven common phenotypes F, S, F-S, S-S0.7, S-F1, F-S0.7, F-F1 were observed and the following gene frequencies calculated: Bf*S = 0.7399; Bf*F = 0.2280; Bf*F1 = 0.0177; Bf*S0.7 = 0.0144. These gene frequencies are compared to those found in other populations. Analysis of 21 mother-child pairs was in agreement with an autosomal codominant inheritance.