Novel multi-probe RNase protection assay (RPA) sets for the detection of murine chemokine gene expression

Early ablation of Ccr2 in aggrecan-expressing cells following knee injury ameliorates joint damage and pain during post-traumatic osteoarthritis

OBJECTIVE

To investigate whether Ccr2 inactivation in aggrecan-expressing cells induced before post-traumatic OA (PTOA) onset or during progression, improves joint structures, synovial thickness and pain.

DESIGN

We induced a Ccr2 deletion in aggrecan-expressing cells (CCR2-AggKO) in skeletally mature mice using a tamoxifen-inducible Ccr2 inactivation. We stimulated PTOA changes (destabilization of medial meniscus, DMM) in CCR2-AggKO and CCR2+/+ mice, inducing recombination before DMM or 4 wks after DMM (early-vs late-inactivation). Joint damage was evaluated 2, 4, 8, 12 wks post-DMM using multiple scores: articular-cartilage structure (ACS), Safranin-O, histomorphometry, osteophyte size/maturity, subchondral bone thickness and synovial hyperplasia. Spontaneous (incapacitance meter) and evoked pain (von-Frey filaments) were assessed up to 20 wks.

RESULTS

Early aggrecan-Ccr2 inactivation in CCR2-AggKO mice (N=8) resulted in improved ACS score (8-12wk, P=0.002), AC area (4-12wk, P<0.05) and Saf-O score (2wks P=0.004, 4wks P=0.02, 8-12wks P=0.002) compared to CCR2+/+. Increased subchondral bone thickness was delayed only at 2 wks and exclusively following early recombination. Osteophyte size was not affected, but osteophyte maturation (cartilage-to-bone) was delayed (4wks P=0.04; 8 wks P=0.03). Although late aggrecan-Ccr2 deletion led to some cartilage improvement, most data did not reach statistical significance; osteophyte maturity was delayed at 12wks. Early aggrecan-Ccr2 deletion led to improved pain measures of weight bearing compared to CCR2+/+ mice (N = 9, 12wks diff 0.13 [0.01, 0.26], 16wks diff 0.15 [0.05, 0.26], 20wks diff 0.23 [0.14, 0.31]). Improved mechanosensitivity in evoked pain, although less noticeable, was detected.

CONCLUSIONS

We demonstrated that deletion of Ccr2 in aggrecan expressing cells reduces the initiation but not progression of OA.

Role of Chemokines in the Pathogenesis of Visceral Leishmaniasis

Abstract:

Visceral leishmaniasis (VL; also known as kala-azar), caused by the protozoan parasite Leishmania donovani is characterized by the inability of the host to generate an effective immune response. The manifestations of the disease depends on involvement of various immune components such as activation of macrophages, cell mediated immunity, secretion of cytokines and chemokines, etc. Macrophages are the final host cells for Leishmania parasites to multiply, and they are the key to a controlled or aggravated response that leads to clinical symptoms. The two most common macrophage phenotypes are M1 and M2. The pro-inflammatory microenvironment (mainly by IL-1β, IL-6, IL-12, IL-23, and TNF-α cytokines) and tissue injury driven by classically activated macrophages (M1-like) and wound healing driven by alternatively activated macrophages (M2-like) in an anti-inflammatory environment (mainly by IL-10, TGF-β, chemokine ligand (CCL)1, CCL2, CCL17, CCL18, and CCL22). Moreover, on polarized Th cells, chemokine receptors are expressed differently. Typically, CXCR3 and CCR5 are preferentially expressed on polarized Th1 cells, whereas CCR3, CCR4 and CCR8 have been associated with the Th2 phenotype. Further, the ability of the host to produce a cell-mediated immune response capable of regulating and/or eliminating the parasite is critical in the fight against the disease. Here, we review the interactions between parasites and chemokines and chemokines receptors in the pathogenesis of VL.

Safety levels of systemic IL-12 induced by cDNA expression as a cancer therapeutic

Aim: The aim of this work is to utilize a gene expression procedure to safely express systemic IL-12 and evaluate its effects in mouse tumor models. Materials & methods: Secondary lymphoid organs and tumors from EL4 and B16 tumor-bearing mice were analyzed by supervised and unsupervised methods. Results: IL-12 cDNA induced systemic IL-12 protein levels lower than the tolerated dose in patients. Control of tumor growth was observed in subcutaneous B16 and EL4 tumors. Systemic IL-12 expression induced a higher frequency of both total tumor-infiltrated CD45+ cells and proliferative IFN-γ+CD8+ T cells along with a lower frequency of CD4+FOXP3+ and CD11b+Gr-1+ cells. Conclusion: This approach characterizes the systemic effects of IL-12, helping to improve treatment of metastases or solid tumors.

Role of the C-C chemokine receptor-2 in a murine model of injury-induced osteoarthritis

OBJECTIVE

We previously found in our embryonic studies that proper regulation of the chemokine CCL12 through its sole receptor CCR2, is critical for joint and growth plate development. In the present study, we examined the role of CCR2 in injury-induced-osteoarthritis (OA).

METHOD

We used a murine model of injury-induced-OA (destabilization of medial meniscus, DMM), and systemically blocked CCR2 using a specific antagonist (RS504393) at different times during disease progression. We examined joint degeneration by assessing cartilage (cartilage loss, chondrocyte hypertrophy, MMP-13 expression) and bone lesions (bone sclerosis, osteophytes formation) with or without the CCR2 antagonist. We also performed pain behavioral studies by assessing the weight distribution between the normal and arthritic hind paws using the IITS incapacitance meter.

RESULTS

Testing early vs delayed administration of the CCR2 antagonist demonstrated differential effects on joint damage. We found that OA changes in articular cartilage and bone were ameliorated by pharmacological CCR2 blockade, if given early in OA development: specifically, pharmacological targeting of CCR2 during the first 4 weeks (wks) following injury, reduced OA cartilage and bone damage, with less effectiveness with later treatments. Importantly, our pain-related behavioral studies showed that blockade of CCR2 signaling during early, 1-4 wks post-surgery or moderate, 4-8 wks post-surgery, OA was sufficient to decrease pain measures, with sustained improvement at later stages, after treatment was stopped.

CONCLUSIONS

Our data highlight the potential efficacy of antagonizing CCR2 at early stages to slow the progression of post-injury OA and, in addition, improve pain symptoms.

Multiprobe ribonuclease protection assay for simultaneous measurement of mRNA expression

The multiprobe RNase protection assay enables investigators to monitor RNA expression of 8-12 genes with as little as 1 microg of total RNA. The commercial availability of numerous multi-gene template sets makes this assay practical for all basic research programs.

A ribonuclease protection assay-based approach for analysis of angiogenic gene expression in archival tissues

Archival, formalin-fixed and paraffin-embedded tissues routinely stored in pathology departments represent an invaluable resource for retrospective molecular biology studies for diagnostic and prognostic purposes. In such specimens extraction of transcriptionally competent RNA to be analyzed by conventional techniques, such as reverse transcription-polymerase chain reaction, is a challenging task. Therefore, we developed a novel methodological approach that allows successful detection and semiquantitative analysis of specific mRNAs obtained from archival formalin-fixed, paraffin-embedded specimens by ribonuclease protection assay. Specifically, we measured a panel of 7 angiogenic markers in selected archival tissues stored at room temperature and retrieved over a wide time span (10 y). The study series consisted in samples of benign and malignant melanocytic lesions. In our model, expression of FLT-1, the vascular-endothelial growth factor receptor-1, correlated with the expression of mRNAs encoding other tyrosine kinase receptors, such as TIE-1 and TIE-2, as well as with angiopoietin and with the protease-activated receptor-1 and vascular-endothelial growth factor itself. Relative to control (normal skin), in melanoma the expression of the selected angiogenic markers was significantly higher. In conclusion, our study provides evidence that ribonuclease protection assay on archival specimens would be highly valuable for retrospective studies, for diagnosis or prognosis.

Interferon-gamma-dependent mechanisms of mycobacteria-induced pulmonary immunopathology: the role of angiostasis and CXCR3-targeted chemokines for granuloma necrosis

The mechanisms leading to granuloma caseation, a hallmark of tuberculosis (TB) in humans, are poorly understood. Lung histopathology of C57BL/6 (WT) mice 16 weeks after aerosol infection with Mycobacterium avium strain TMC724 is uniquely characterized by centrally necrotizing granulomas, strongly resembling human TB lesions. However, IFN-gamma-deficient (GKO) and IFN-gamma-receptor-deficient (GRKO) mice did not develop granuloma necrosis following M. avium infection. Comparison of differentially expressed genes in infected WT and GKO lungs by DNA microarray and RNase protection assays revealed that the angiostatic chemokines CXCL9-11 were significantly reduced in GKO mice. In contrast, angiogenic mediators such as angiopoietin and vascular endothelial growth factor, and angiogenic chemokines such as CXCL2, CCL3, and CCL4, remained unchanged or were expressed at higher levels than in infected WT mice, suggesting impaired neovascularization of the granuloma as a possible mechanism for caseation in WT mice. Granuloma vascularization was significantly decreased in central, but not peripheral, areas of granulomas of infected WT compared to GKO mice. In contrast to GRKO mice, WT mice showed signs of severe hypoxia in cells immediately surrounding the necrotic core of granulomas as measured immunohistochemically with a reagent detecting pimonidazole adducts. To test the hypothesis that CXCR3, the common receptor for the angiostatic chemokines CXCL9-11, is involved in granuloma caseation, histomorphology was assessed in M. avium-infected mice deficient for CXCR3 (CXCR3-KO). 16 weeks after infection, these mice developed caseating granulomas similar to WT mice. We conclude that IFN-gamma causes a dysbalance between angiostatic and angiogenic mediators and a concomitant reduction in granuloma vascularization, but that CXCR3-targeted chemokines are not sufficient to induce granuloma necrosis in a mouse model of mycobacteria-induced immunopathology.

Migration of mouse antibody-secreting hybridoma cells from blood to genital tract and its regulation by sex hormones are associated with the differential expression patterns of adhesion molecules and chemokines in the tract rather than in the antibody-secreting cells

To understand better the molecular mechanisms of differential migration of antibody-secreting cells (ASCs) into mouse genital tracts, and regulation by sex hormones, surface markers, hormone receptors and adhesion molecules in mouse SG2 and PA4 hybridoma cells, respectively, secreting IgG2b and polymeric IgA antibody were detected by flow cytometry or RT-PCR. Semi-quantitative RT-PCR was also used for measuring mRNA expression of adhesion molecules and chemokines (VCAM-1, ICAM-1, P-selectin, JAM-1 and CXCL12) in genital tracts of various adult mouse groups. The mRNAs of androgen receptor, estrogen receptor beta and CXCR4 were expressed in the ASCs. Sex hormones had no effect on expression of these molecules in ASCs. Except for VCAM-1, mRNA of all examined genes was expressed in normal mouse genital tracts. The mean of relative amounts of ICAM-1 and CXCL12 mRNA in all examined organs of females were higher (2.1- and 1.9-fold) than those in males. After orchiectomy or ovariectomy, the expression of ICAM-1, CXCL12 and P-selectin mRNA in the examined organs increased, except JAM-1 in male and CXCL12 in female. Sex hormone treatment recovered the changes to normal levels of mRNA expression in many examined genital tissues. In combination with our previous work, preferential migration of ASCs into female genital tract and regulation of migration by sex hormones are associated with expression patterns of adhesion molecules and chemokines in genital tract rather than in ASCs.

A method for the simultaneous analysis of mRNA levels of multiple cardiac ion channels with a multi-probe RNase protection assay

AIMS

Various pathological conditions can alter cardiac electrophysiological properties not only by physiological responses but also by modifying the gene expression of ion channels (electrical remodelling). To investigate the underlying mechanisms of the latter, electrophysiological alterations would require a simultaneous and comprehensive analysis of the mRNA level of the ion channel genes.

METHODS AND RESULTS

We designed 19 cardiac ion channel cDNA templates to analyse the corresponding mRNAs and classified them into three template sets. Those sets were a voltage-dependent K(+) channel series (rat erg, KvLQT1, Kv4.3, Kv4.2, Kv2.1, Kv1.5, Kv1.4, Kv1.2), an inwardly rectifying K(+) channel series (rat Kir6.2, SUR2A/B, Kir3.4, Kir3.1, Kir2.2, Kir2.1), and an inward cationic ion channel series (rat SCN5A, alpha1C, beta2, alpha2delta2 of cardiac L-type Ca(2+) channel and alpha1G). These cDNA templates were used to synthesize antisense digoxigenin-labelled RNA probes. An amount of the total RNA of 25 microg was adequate to analyse simultaneously the mRNA levels of the ion channel genes with the use of multi-probe RPA, and these three multi-probe template sets enabled us to evaluate the profile of the spatial and temporal transcripts of the cardiac ion channels.

CONCLUSION

The newly developed ion channel multi-probe RPA templates provide an aid in the comprehensive analysis of the electrical remodelling of the heart.

The membrane-bound chemokine CXCL16 expressed on follicle-associated epithelium and M cells mediates lympho-epithelial interaction in GALT

The recently identified CXCL16 has dual functions as a transmembrane adhesion molecule and a soluble chemokine. In this study we found that CXCL16 mRNA and protein were expressed constitutively on the follicle-associated epithelium covering Peyer's patches (PPs), isolated lymphoid follicles, and cecal patches, but minimally on the villous epithelium in the murine gastrointestinal tract. The CXCL16 receptor CXCR6/Bonzo was constitutively expressed on subpopulations of CD4+ and CD8+ T cells isolated from PPs. The expression of CXCR6/Bonzo on the PP T cells was up-regulated after stimulation with anti-CD3 and anti-CD28 mAbs. The activated PP T cells showed chemotactic migration in response to the soluble N-terminal chemokine domain of CXCL16. Furthermore, the activated PP T cells selectively adhered to cells expressing murine CXCL16. To determine the physiological role of CXCL16 in GALT, we first carefully analyzed T cell distribution in PPs. T cells localized not only in the interfollicular region but also at a lesser frequency in the subepithelial dome (SED) and in the germinal center of lymphoid follicles. Consistently, the majority of the adoptive transferred activated T cells migrated into the SED and the interfollicular region. However, the neutralization of CXCL16 specifically reduced the migration of the adoptive, transferred, activated T cells into the SED of PPs. These data suggest that CXCL16 expressed on the follicle-associated epithelium plays an important role in the recruitment and retention of activated T cells in the SED and should, at least partially, be responsible for lymphocyte compartmentalization in GALT.

Phenotypic profiling of engineered mouse melanomas with manipulated histamine production identifies histamine H2 receptor and rho-C as histamine-regulated melanoma progression markers

In the present study, the impact of acquired neoplastic L-histidine decarboxylase (HDC) expression, and its direct consequence, the release of histamine in the tumor environment, was assessed on melanoma tumor progression. B16-F10 mouse melanoma cells were manipulated via stable transfection, and nine novel transgenic variants were generated in triplicates, constitutively expressing the full-length sense mouse HDC mRNA, a mock control, and an antisense HDC RNA segment, respectively. Establishing both primary skin tumors and lung metastases in C57BL/6 mice, the nine variants with different histamine-releasing capacities were subjected to a comprehensive comparative progression profiling in vivo. Our analyses showed trends of markedly accelerated tumor growth (P < 0.001), and moderately increased metastatic colony-forming potential (P = 0.010) along with rising levels of local histamine production. Using RNase protection assay for screening of the melanoma progression profile, and Western blotting for subsequent result validation, we looked for molecular progression markers affected by melanoma histamine secretion. Investigation of 21 functionally clustered markers associated with tumor proliferation, angiogenesis, invasivity, metastasis formation, local or systemic immunomodulation, and histamine signaling revealed positive correlations between histamine production, tumor histamine H2 receptor and rho-C expression (P < 0.001, P = 0.002, respectively). These observations confirm the involvement of histamine in the molecular machinery of melanoma progression.

Correlation of tumor- and stromal-derived MT1-MMP expression with progression of human ovarian tumors in SCID mice

OBJECTIVE

Human ovarian carcinoma samples were orthotopically implanted into SCID mice to investigate the contribution of matrix metalloproteases (MMPs) to the spread of ovarian tumors.

METHODS

Mice were inoculated with patient tumor samples, and developed ovarian tumors over a 16-week period with metastasis occurring in some mice. Species-specific quantitative RT-PCR was used to identify the source of tumor-associated MMPs.

RESULTS

Membrane-type (MT)1-MMP mRNA was significantly increased in high-grade tumors, tumors with evidence of serosal involvement, and tumors in which distant metastases were detected. The increase in MT1-MMP expression was predominantly from the human tumor cells, with a minor contribution from the mouse ovarian stroma. Neither human nor mouse MT2-MMP were correlated with tumor progression and MT3-MMP levels were negligible. While tumor cells did not produce significant amounts of MMP-2 or MMP-9, the presence of tumor was associated with increased levels of MMP-2 expression by mouse ovarian stroma. Stromal-derived MT1-MMP was greater in large tumors and was associated with stromal MMP-2 expression but neither was significantly linked with metastasis.

CONCLUSIONS

These studies indicate that tumor-derived MT1-MMP, more so than other gelatinolytic MMPs, is strongly linked to aggressive tumor behavior. This orthotopic model of human ovarian carcinoma is appropriate for studying ovarian tumor progression, and will be valuable in the further investigation of the metastatic process.

Chemokine gene expression in toll-like receptor-competent and -deficient mice infected with Leishmania major

We studied the expression of a subset of chemokines, including RANTES/CCL5, MIP-1alpha/CCL3, IP-10/CXCL10, and MCP-1/CCL2, in Toll-like receptor (TLR)-competent and -deficient mice after infection with Leishmania major. Chemokine expression at the site of infection (the footpad), in the draining lymph nodes and in the spleens of infected animals was determined by using two different methods of analysis. The results indicate that L. major infection causes overall upregulation of RANTES/CCL5, MIP-1alpha/CCL3, IP-10/CXCL10, and MCP-1/CCL2 in the footpads and lymph nodes, while expression of these chemokines is constitutive in the spleens of TLR4-competent mice (C57BL/10ScSn) and TLR4-deficient mice (C57BL10/ScN). Different patterns of expression were detected depending on the time postinfection, but there was little variation in the expression of these four chemokines in the presence or absence of TLR4.

Expression of lipopolysaccharide-associated receptors in different human intestinal epithelial cells

AIM: To investigate the expression of lipopolysaccharide (LPS)-associated receptors-CD14, Toll-like receptor 4 (TLR4) and MD-2 in human intestinal epithelial cells (IECs) and to discuss the molecular mechanism by which IECs tolerated to LPS.

METHODS: The expression of CD14, TLR4 and MD-2 mRNA of human normal intestinal epithelial cells (HNIEC) and human intestinal epithelial cell line (HIC) was detected by RNase protection assay (RPA). The expression of CD14, TLR4 and MD-2 proteins on normal human small intestinal and colonic epithelial cells was detected by immunohis-tochemistry, and THP1 cells were used as positive control.

RESULTS: HNIEC expressed very low CD14, TLR4 and MD-2 mRNA and HICs did not express them. Neither normal human small intestinal nor colonic epithelial cells expressed TLR4, CD14 and MD2 proteins.

CONCLUSION: Low or loss of expression of TLR4, CD14 and MD-2 on IECs may be an important molecular mechanism by which IECs tolerate to lipopolysaccharide, and this will be helpful to understand the pathogenesis of inflammatory bowel disease.

Differential production of macrophage inflammatory protein 1gamma (MIP-1gamma), lymphotactin, and MIP-2 by CD4(+) Th subsets polarized in vitro and in vivo

Due to differential expression of chemokine receptors, the Th1 and Th2 subsets of CD4(+) T cells differ in their migratory responses to chemokines. These differences in the migration patterns are likely to play a role in the initiation and regulation of Th1 and Th2 immune responses, inflammatory processes, and T-cell-mediated pathology. In the present study we evaluated the role of activated Th cells as producers of chemokines. Three different sources of murine Th cells were used, i.e., long-term-cultured Th1 and Th2 cell clones, Th1 and Th2 cells differentiated from naïve CD4(+) spleen and lymph node cells in vitro, and Th1 and Th2 subsets polarized in vivo using a murine experimental Leishmania major infection model. Following stimulation with anti-CD3, macrophage inflammatory protein 1gamma (MIP-1gamma) and lymphotactin were produced selectively by Th1 cells but not by Th2 cells. In contrast, only Th2 cells produced MIP-2. The possible biological relevance of these data was substantiated by the finding that in vivo-polarized Th1 cells, but not Th2 cells, produced MIP-1gamma and lymphotactin while in vivo-polarized Th2 cells secreted MIP-2. The above data demonstrate that Th1 and Th2 cells differ in their ability to produce chemokines, suggesting that Th1 and Th2 subsets differentially contribute to recruitment of cells into inflammatory foci.