Overexpression of innate immune response genes in a model of recessive polycystic kidney disease
2007; Elsevier BV; Volume: 73; Issue: 1 Linguagem: Inglês
10.1038/sj.ki.5002627
ISSN1523-1755
AutoresMichal Mrug, Ju Zhou, Yong Woo, Xiangqin Cui, Alexander J. Szalai, Jan Novák, Gary A. Churchill, Lisa M. Guay‐Woodford,
Tópico(s)Complement system in diseases
ResumoDefects in the primary cilium/basal body complex of renal tubular cells cause polycystic kidney disease (PKD). To uncover pathways associated with disease progression, we determined the kidney transcriptome of 10-day-old severely and mildly affected cpk mice, a model of recessive PKD. In the severe phenotype, the most highly expressed genes were those associated with the innate immune response including many macrophage markers, particularly those associated with a profibrotic alternative activation pathway. Additionally, gene expression of macrophage activators was dominated by the complement system factors including the central complement component 3. Additional studies confirmed increased complement component 3 protein levels in both cystic and non-cystic epithelia in the kidneys of cpk compared to wild-type mice. We also found elevated complement component 3 activation in two other mouse-recessive models and human-recessive PKD. Our results suggest that abnormal complement component 3 activation is a key element of progression in PKD. Defects in the primary cilium/basal body complex of renal tubular cells cause polycystic kidney disease (PKD). To uncover pathways associated with disease progression, we determined the kidney transcriptome of 10-day-old severely and mildly affected cpk mice, a model of recessive PKD. In the severe phenotype, the most highly expressed genes were those associated with the innate immune response including many macrophage markers, particularly those associated with a profibrotic alternative activation pathway. Additionally, gene expression of macrophage activators was dominated by the complement system factors including the central complement component 3. Additional studies confirmed increased complement component 3 protein levels in both cystic and non-cystic epithelia in the kidneys of cpk compared to wild-type mice. We also found elevated complement component 3 activation in two other mouse-recessive models and human-recessive PKD. Our results suggest that abnormal complement component 3 activation is a key element of progression in PKD. Polycystic kidney disease (PKD), a common genetic disorder affecting over 600 000 people in the United States and 12.5 million worldwide, is a major cause of end-stage renal disease in both children and adults.1.Gabow P. Autosomal dominant polycystic kidney disease.N Eng J Med. 1993; 329: 332-342Crossref PubMed Scopus (811) Google Scholar Autosomal-dominant PKD (ADPKD; MIM 173900; 173910) occurs in 1:400–1:1000 individuals and is caused by mutations in one of two genes, PKD1 or PKD2.2.The European Polycystic Kidney Disease Consortium The polycystic kidney disease 1 gene encodes a 14 kb transcript and lies within a duplicated region on chromosome 16.Cell. 1994; 77: 881-894Abstract Full Text PDF PubMed Scopus (705) Google Scholar, 3.The American PKD1 Consortium Analysis of the genomic sequence for the autosomal dominant polycystic kidney disease (PKD1) gene predicts the presence of a leucine-rich repeat.Hum Mol Genet. 1995; 4: 575-582Crossref PubMed Scopus (233) Google Scholar, 4.The International Polycystic Kidney Disease Consortium Polycystic kidney disease: the complete structure of the PKD1 gene and its protein.Cell. 1995; 8: 289-298Abstract Full Text PDF Scopus (603) Google Scholar, 5.Mochizuki T. Wu G. Hayashi T. et al.PKD2, a gene for polycystic kidney disease that encodes an integral membrane protein.Science. 1996; 272: 1339-1342Crossref PubMed Scopus (1103) Google Scholar Autosomal-recessive PKD (RPKD; MIM 263200) is less frequent (1:20 000 live births) and is caused by defects in a single gene, PKHD1.6.Onuchic L. Furu L. Nagasawa Y. et al.PKHD1, the polycystic kidney and hepatic disease 1 gene, encodes a novel large protein containing multiple IPT domains and PbH1 repeats.Am J Hum Genet. 2002; 70: 1305-1317Abstract Full Text Full Text PDF PubMed Scopus (359) Google Scholar,7.Ward C. Hogan M. Rossetti S. et al.The gene mutated in autosomal recessive polycystic kidney disease encodes a large, receptor-like protein.Nat Genet. 2002; 30: 259-269Crossref PubMed Scopus (550) Google Scholar The molecular basis of PKD is not well understood, but critical clues have been provided by immunolocalization studies, which demonstrated that multiple proteins encoded by PKD-associated genes colocalize to the primary cilia on the apical surface of renal epithelial cells. These include proteins encoded by all three human PKD genes (PKD1, PKD2, and PKHD1) as well as several protein products disrupted in animal models of PKD, for example, orpk, cpk, Inv, and Kif3a.8.Yoder B.K. Hou X. Guay-Woodford L.M. The polycystic kidney disease proteins, polycystin-1, polycystin-2, polaris, and cystin, are co-localized in renal cilia.J Am Soc Nephrol. 2002; 13: 2508-2516Crossref PubMed Scopus (688) Google Scholar, 9.Lin F. Hiesberger T. Cordes K. et al.Kidney-specific inactivation of the KIF3A subunit of kinesin-II inhibits renal ciliogenesis and produces polycystic kidney disease.Proc Natl Acad Sci USA. 2003; 100: 5286-5291Crossref PubMed Scopus (436) Google Scholar, 10.Morgan D. Eley L. Sayer J. et al.Expression analyses and interaction with the anaphase promoting complex protein Apc2 suggest a role for inversin in primary cilia and involvement in the cell cycle.Hum Mol Gen. 2002; 11: 3345-3350Crossref PubMed Scopus (122) Google Scholar Although the function of many PKD-associated proteins is not known, they are likely important for proper structure and/or function of the primary cilia.11.Taulman P. Haycraft C. Balkovetz D. Yoder B. Polaris, a protein involved in left–right axis patterning, localizes to basal bodies and cilia.Mol Biol Cell. 2001; 12: 589-599Crossref PubMed Scopus (252) Google Scholar, 12.Brown N. Murcia N. Delayed cystogenesis and increased ciliogenesis associated with the re-expression of polaris in Tg737 mutant mice.Kidney Int. 2003; 63: 1220-1229Abstract Full Text Full Text PDF PubMed Scopus (45) Google Scholar, 13.Hou X. Mrug M. Yoder B. et al.Cystin, a novel cilia-associated protein, is disrupted in the cpk mouse model of polycystic kidney disease.J Clin Invest. 2002; 109: 533-540Crossref PubMed Scopus (203) Google Scholar, 14.Woo D. Miao S. Pelayo J. Woolf A. Taxol inhibits progression of congenital polycystic kidney disease.Nature. 1994; 368: 750-753Crossref PubMed Scopus (126) Google Scholar For example, proteins encoded by PKD1 and PKD2 may act as mechanosensors or chemosensors on the cilia.15.Praetorius H. Spring K. Bending the MDCK cell primary cilium increases intracellular calcium.J Membr Biol. 2001; 184: 71-79Crossref PubMed Scopus (631) Google Scholar, 16.Praetorius H. Spring K. Removal of the MDCK cell primary cilium abolished flow sensing.J Membr Biol. 2003; 10: 1-9Google Scholar, 17.Koulen P. Cai Y. Geng L. et al.Polycystin-2 is an intracellular calcium release channel.Nat Cell Biol. 2002; 4: 191-197Crossref PubMed Scopus (534) Google Scholar Defects in the primary cilium/basal body complex of renal epithelial cells may trigger a myriad of secondary responses, for example, changes in solute transport, cell proliferation, apoptosis, extracellular matrix deposition, interstitial inflammation, and fibrosis (summarized in Yoder et al.18.Yoder B.K. Mulroy S. Eustace H. et al.Molecular pathogenesis of autosomal dominant polycystic kidney disease.Expert Rev Mol Med. 2006; 8: 1-22Crossref PubMed Scopus (45) Google Scholar). In addition, mutated PKD genes might trigger abnormalities in other (non-renal) cell types that may exacerbate PKD progression through pathways not directly related to the primary renal epithelial defect, for example, by increased vascular dysfunction and vessel fragility as demonstrated in mice homozygous for the mutant PKD1L allele.19.Kim K. Drummond I. Ibraghimov-Beskrovnaya O. et al.Polycystin 1 is required for the structural integrity of blood vessels.Proc Natl Acad Sci USA. 2000; 97: 1731-1736Crossref PubMed Scopus (255) Google Scholar Earlier, pathways involved in PKD pathogenesis were studied primarily in isolation. However, at least four recent reports have sought to provide more comprehensive evaluations of PKD-related transcriptional activity using high-throughput gene expression profiling. Two of these studies led to the identification of several tens of genes that were differentially expressed, but the data analysis did not suggest the activation of any integrated molecular pathway.20.Lee J.E. Park M.H. Park J.H. The gene expression profile of cyst epithelial cells in autosomal dominant polycystic kidney disease patients.J Biochem Mol Biol. 2004; 37: 612-617Crossref PubMed Google Scholar,21.Husson H. Manavalan P. Akmaev V.R. et al.New insights into ADPKD molecular pathways using combination of SAGE and microarray technologies.Genomics. 2004; 84: 497-510Crossref PubMed Scopus (42) Google Scholar A more recent study of end-stage ADPKD kidneys suggested that epithelial to fibroblast transition is the most prominent PKD-specific transcriptional abnormality.22.Schieren G. Rumberger B. Klein M. et al.Gene profiling of polycystic kidneys.Nephrol Dial Transplant. 2006; 21: 1816-1824Crossref PubMed Scopus (50) Google Scholar On the other hand, transcriptome profiling of kidneys form the Cy rat model of PKD indicated a prominent role for abnormalities in extracellular matrix metabolism, in particular those related to fibrosis and adhesion to the extracellular matrix.23.Riera M. Burtey S. Fontes M. Transcriptome analysis of a rat PKD model: importance of genes involved in extracellular matrix metabolism.Kidney Int. 2006; 69: 1558-1563Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar Taken together, these studies failed to identify a common set of genetic pathways involved in PKD progression. These differences may reflect different experimental designs and/or difference in the PKD model studied. Additional factors that could reduce the sensitivity of these gene expression profiles included a small number of studied tissues/individuals (for example, n=2)20.Lee J.E. Park M.H. Park J.H. The gene expression profile of cyst epithelial cells in autosomal dominant polycystic kidney disease patients.J Biochem Mol Biol. 2004; 37: 612-617Crossref PubMed Google Scholar as well as uncontrolled variability in a large number of genetic, environmental, age, tissue sampling, and processing factors that may influence gene expression. Compared to the human population, animal models are expected to provide more consistent gene expression profiling data because they permit use of experimental designs that reduce the effects of confounding genetic, environmental, and technical variables. Among RPKD models, the cpk mouse is one of the most extensively characterized.24.Preminger G. Koch W. Fried F. et al.Murine congenital polycystic kidney disease: a model for studying development of cystic disease.J Urol. 1982; 127: 556-560Abstract Full Text PDF PubMed Scopus (81) Google Scholar,25.Fry J. Koch W. Jennette J. et al.A genetically determined murine model of infantile polycystic kidney disease.J Urol. 1985; 134: 828-833Crossref PubMed Scopus (55) Google Scholar The cpk mutation (Cys1cpk), which arose spontaneously in the C57BL/6J-Pldnpa (B6) strain, involves a tandem deletion that leads to the truncation of a novel, cilia-associated protein called cystin.8.Yoder B.K. Hou X. Guay-Woodford L.M. The polycystic kidney disease proteins, polycystin-1, polycystin-2, polaris, and cystin, are co-localized in renal cilia.J Am Soc Nephrol. 2002; 13: 2508-2516Crossref PubMed Scopus (688) Google Scholar,13.Hou X. Mrug M. Yoder B. et al.Cystin, a novel cilia-associated protein, is disrupted in the cpk mouse model of polycystic kidney disease.J Clin Invest. 2002; 109: 533-540Crossref PubMed Scopus (203) Google Scholar The renal phenotype of the cpk mouse is characterized by massive cystic involvement of the collecting ducts, a pattern that strongly resembles human RPKD.26.Avner E. Studnicki F. Young M. et al.Congenital murine polycystic kidney disease. I. The ontogeny of tubular cyst formation.Pediatr Nephrol. 1987; 2: 210-218Crossref Scopus (29) Google Scholar In the liver, ductal plate malformation gives rise to a biliary dysgenesis phenotype that closely resembles congenital hepatic fibrosis observed in human RPKD. Other commonly used RPKD models include bpk and orpk mice. The bpk mutation (Bicc1bpk), involving the insertion of 2-bp into exon 22 of the gene encoding bicaudal C (Bicc1), arose spontaneously in the BALB/c strain,27.Cogswell C. Price S. Hou X. et al.Positional cloning of jcpk/bpk locus of the mouse.Mamm Genome. 2003; 14: 242-249Crossref PubMed Scopus (65) Google Scholar and its renal and biliary phenotypes closely resemble the cpk and human RPKD abnormalities.28.Nauta J. Ozawa Y. Sweeney W. et al.Renal and biliary abnormalities in a new murine model of autosomal recessive polycystic kidney disease.Pediatr Nephrol. 1993; 7: 163-172Crossref PubMed Scopus (96) Google Scholar The orpk mouse has a more complex phenotype with renal cysts appearing initially in proximal tubular segment and later (at 2–3 weeks of age) in collecting ducts.29.Richards W. Sweeney W. BK B.Y. et al.Epidermal growth factor receptor activity mediates renal cyst formation in polycystic kidney disease.J Clin Invest. 1998; 101: 935-939Crossref PubMed Scopus (172) Google Scholar The orpk mutation (Ift88Tg737Rpw), generated by insertional mutagenesis in FVB/N oocytes, disrupts expression of polaris, a primary cilia associated protein.30.Moyer J. Lee-Tischler M. Kwon H.-Y. et al.Candidate gene associated with a mutation causing recessive polycystic kidney disease in mice.Science. 1994; 264: 1329-1333Crossref PubMed Scopus (303) Google Scholar We have recently described several quantitative trait loci that modulate RPKD-related phenotypes in a (B6-cpk/+ × CAST)F1 intercross.31.Mrug M. Li R. Cui X. et al.Kinesin family member 12 is a candidate polycystic kidney disease modifier in the cpk mouse.J Am Soc Nephrol. 2005; 16: 905-916Crossref PubMed Scopus (44) Google Scholar One of the strategies to prioritize positional quantitative trait loci gene candidates was gene expression profiling of mildly and severely affected kidneys from this cross. In this study, we present a comprehensive evaluation of whole-genome expression profiling of these cpk kidneys, and based on the data, we have generated hypotheses about the biological processes that distinguish disease progression in mildly vs severely affected RPKD kidneys. We examined the gene expression profiles of seven most mildly and seven most severely affected cystic kidneys selected from the F2 cohort of affected cpk mice (n=461). These mice were generated in (B6-cpk/+ × CAST)F1 intercrosses. The severity of their phenotypes were defined by kidney length, weight, and volume.31.Mrug M. Li R. Cui X. et al.Kinesin family member 12 is a candidate polycystic kidney disease modifier in the cpk mouse.J Am Soc Nephrol. 2005; 16: 905-916Crossref PubMed Scopus (44) Google Scholar Transcriptional profiles of these extreme kidney phenotypes were obtained with 14 Affymetrix 430 2.0 arrays. Among ∼40 000 transcripts represented on each array, the differential expression of ∼2700 was statistically significant (P 2-fold (the most prominently overexpressed genes). Expression of about half of these 100 transcripts was increased in severely affected cpk kidneys, whereas the remaining transcripts had decreased expression. Large-scale validation of the Affymetrix 430 2.0 data was obtained by repeating the analyses with Affymetrix U74Av2 arrays. Strong correlation between the 430 2.0 and U74Av2 data sets (r=0.72 for all transcripts, r=0.90 for differentially expressed genes with P<0.05 after adjusting for multiple testing) provided technical validation of the 430 2.0 data (Figure 1). Biological relevance of the array data also suggests its validity. For example, severely affected kidneys consistently underexpressed genes that are known to be expressed at higher levels in normal kidneys vs other normal tissues.32.Zhang W. Morris Q.D. Chang R. et al.The functional landscape of mouse gene expression.J Biol. 2004; 3: 21Crossref PubMed Scopus (241) Google Scholar These genes are associated with major metabolic pathways, in particular with the generation of precursor metabolites and energy (for example, ATP biosynthesis, fatty acid oxidation, oxidative phosphorylation, carboxylic acid metabolism, amino-acid metabolism, sulfur metabolism, aromatic compound metabolism, and steroid metabolism). The observed gene downregulation is consistent with the reduction of functional renal parenchyma in advanced PKD (summarized in Madsen and Tisher33.Madsen K. Tisher C. Anatomy of the kidney.in: Brenner B. Brenner and Rector’s the Kidney. 7th edn. Vol. 1. Elsevier Inc., Philadelphia2004: 4-72Google Scholar). On the other hand, expression of several genes that were previously found to be overexpressed in PKD kidneys, for example, Aqp2, Avpr2, Clu, Col1, Egfr, Fn1, Fos, Hmox1, Jun, and Myc, was increased in severely vs mildly affected cpk kidneys. In addition, we found overexpression of markers associated with RPKD-related vs RPKD-unrelated renal epithelial cell types, using a list of nephron segment-specific markers (summarized in Madsen and Tisher33.Madsen K. Tisher C. Anatomy of the kidney.in: Brenner B. Brenner and Rector’s the Kidney. 7th edn. Vol. 1. Elsevier Inc., Philadelphia2004: 4-72Google Scholar) validated by serial analysis of gene expression.34.Chabardes-Garonne D. Mejean A. Aude J.C. et al.A panoramic view of gene expression in the human kidney.Proc Natl Acad Sci USA. 2003; 100: 13710-13715Crossref PubMed Scopus (135) Google Scholar Consistent with previous studies of cpk mice that described replacement of renal parenchyma by cysts derived from principal cells of collecting ducts,35.Ricker J. Gattone V. Calvet J. Rankin C. Development of autosomal recessive polycystic kidney disease in BALB/c-cpk/cpk mice.J Am Soc Nephrol. 2000; 11: 1837-1847PubMed Google Scholar our array analyses demonstrated that the expression of the principal cell markers examined was increased in severely affected cpk kidneys. In comparison, the expression of markers associated with other nephron segments was decreased (13 markers) or unchanged (seven markers) (see Table 1).Table 1Expression of principal cell markers is increased in severely affected cpk kidneysSegmentSubsegmentCellsMarkerGeneExpressionFold changeGlomerulusEndothelial cellsVEGF-RFlt1(VEGFR1)——Visceral epithelial cellsVEGFVegfaDecreased1.3CD2APCd2ap——Heymann antigen (megalin)Lrpap1Decressed1.5Heymann antigen (Lrp2)Lrp2——collagen type 4Col4——Mesangial cellsangiotensin-R, type 1Agtr1Decreased1.4Macula densaBSC-1,Na+,K+,2Cl-cotransporter bumetanide sensitiveSlc12a1Decreased1.6Proximal tubulePars convolutaHeymann antigen (Lrp2)Lrp2——maltaseMgam——cubilinCubnDecreased1.9L-alpha-OH-acid oxidaseHao2——D-AA oxidaseDao1Decreased1.4Distal tubuleThick ascending limbROMKKcnj1Decreased1.4BSC-1,Na+,K+,2Cl-cotransporter bumetanide sensitiveSlc12a1Decreased1.6Ca++ sensing receptorCasrDecreased1.2parathyroid hormone receptorPthr1Decreased2.2Distal convolutedTSC, Na/Cl cotransporter thiazide sensitiveSlc12a3Decreased2.011-beta-OH-steroid dehydrogenase 2Hsd11b2——CalbindinCalb1——FXYD domain containing ion transport regulator 2Fxyd2Decreased1.3transient receptor potential cation channelTrpm6——Connecting segmentkallikrein (renal/pancreas/salivary -KLK1)Klk6Decreased2.6calbindinCalb1——TSC, Na/Cl cotransporter thiazide sensitiveSlc12a3Decreased2.0Collecting ductCorticalIntercalated cells (35–40%)vacuolar H+ ATPaseAtp6v1b1Decreased1.5AE-4, anion exchangerSlc4a9——Principal cells (60–75%)ENAC, sodium channel amiloride sensitiveScnn1bIncreased1.6vasopressin receptorAvpr2Increased1.3aquaporin 2Aqp2Increased1.9Outer medullaryPrincipal cells (60–75%)ENAC, sodium channel amiloride sensitive, alpha unitScnn1aIncreased1.6ENAC, sodium channel amiloride sensitive, beta unitScnn1bIncreased1.6aquaporin 2Aqp2Increased1.9 Open table in a new tab We performed functional annotation of differentially expressed genes in severely vs mildly affected cpk kidneys using the Expression Analysis Systematic Explorer and additional tools from the Database for Annotation, Visualization and Integrated Discovery (version 2.1). Using these tools, we performed functional annotation analyses that allowed identification of enriched biological themes within a gene data set, particularly Gene Ontology (GO) terms for biological processes. These analyses revealed that severely affected kidneys underexpressed those metabolic genes that represent a hallmark of the normal kidney transcriptome,32.Zhang W. Morris Q.D. Chang R. et al.The functional landscape of mouse gene expression.J Biol. 2004; 3: 21Crossref PubMed Scopus (241) Google Scholar as described above. In contrast, severely affected cpk kidneys overexpressed genes associated with biological processes related to development, cell adhesion, chemotaxis, response to external stimulus (that is, wounding), and immune response (Table 2). Similar results were obtained when associations with GO terms and relationship of the GO terms within the data set were visualized using the VisuaL Annotation Display (Figure 2a). However, these functional annotations are based on presence (or absence) of specific genes in the analyzed data set and are not influenced by fold changes in differential gene expression. To identify biological processes related to most highly overexpressed genes, we repeated all analyses with a subset of genes whose expression was changed more than twofold between severely and mildly affected cpk kidney transcriptomes. These analyses revealed that the most prominently (greater than twofold) overexpressed genes were associated with immune response, in particular with the acute-phase response and complement activation (Table 2 and Figure 2b) that form the core of the humoral component of innate immunity.Table 2Biological processes up-regulated in severely affected cpk kidneysGene ontologyTermCount%P-valueAll genes with significantly increased expression; P 2-fold increase in expression (63 DAVID IDs) GO:0006955Immune response1523.811.77E-08 GO:0009613Response to pest, pathogen, or parasite1320.634.16E-08 GO:0051707Response to other organism1320.636.04E-08 GO:0006952Defense response1523.813.07E-07 GO:0009607Response to biotic stimulus1523.814.36E-07 GO:0006817Phosphate transport69.521.02E-06 GO:0006950Response to stress1422.222.09E-6 GO:0006959Humoral immune response711.115.00E-06 GO:0016064Humoral defense mechanism (sensu Vertebrata)57.941.91E-05 GO:0015698Inorganic anion transport69.523.75E-05 GO:0006958Complement activation, classical pathway46.354.00E-05 GO:0006953Acute-phase response46.353.99E-5 GO:0050874Organismal physiological process1930.168.34E-05 GO:0006820Anion transport69.528.34E-05 GO:0006956Complement activation46.350.0002 GO:0045087Innate immune response46.350.0003 GO:0006954Inflammatory response57.940.0007 GO:0009605Response to external stimulus711.110.0027 GO:0009611Response to wounding69.520.0050 GO:0006960Antibacterial humoral response (sensu Protostomia)23.170.0052DAVID, Database for Annotation, Visualization and Integrated Discovery. Open table in a new tab DAVID, Database for Annotation, Visualization and Integrated Discovery. To further investigate biological processes associated with severe cpk renal phenotype, we used a complementary in silico approach and queried the suite of databases maintained at NCBI (for example, PubMed and Gene) for biological functions of individual overexpressed genes. These analyses identified immune response as the most common association for genes overexpressed in severely affected cpk kidneys and confirmed the results generated with the Database for Annotation, Visualization and Integrated Discovery and VisuaL Annotation Display tools. These in silico analyses also revealed that innate immune system markers dominated among genes with the highest (2.5- to 4.7-fold) overexpression (Table 3). Among the most highly overexpressed transcripts, 1.5- to 4.7-fold (on average 2.7-fold), was a subset of genes encoding acute-phase reactants; in addition to 10 genes shown in Table 3, acute-phase reactant encoding genes included α1-antichymotrypsin (Serpina3n), α2-antiplasmin (Serpinf1), hemoxygenase 1 (Hmox1), C1-inhibitor (Serping1), and lipopolysaccharide-binding protein (Lpb). In addition, the in silico analysis revealed that many of the overexpressed genes are markers of macrophages (Table 4), the cellular component of innate immunity. Some of these markers, including Arg1, Ccl17, Ccr5, F13a, Fcer1g, Mrc1, Il4ra, Il10ra, Il13ra1, and Saa3, are associated with alternatively activated (M2) macrophage phenotype (reviewed in Gordon36.Gordon S. Alternative activation of macrophages.Nat Rev Immunol. 2003; 3: 23-35Crossref PubMed Scopus (4379) Google Scholar) that facilitates wound healing and fibrosis. Immunocompetence of these putative macrophages is indicated by the overexpression of genes encoding CD64 and CD32 (Fcgr1 and Fcgr2b), CD14, TLR-4, complement receptor 3 (CR3; CD11b/CD18), and CD123, an interleukin (IL)-3 growth factor receptor. Their functional activation is suggested by the overexpression of Abca1 and Slpi, and the phagocytic activity by the overexpression of Acta2, Actc1, Actg2, Pxn. The expression of a gene encoding the receptor for major macrophage activator interferon-γ (Ifngr2) was increased, but there was no change in the expression of interferon-γ ligand (Ifng). Finally, the overexpression of multiple monocyte/macrophage chemoattractants, for example, monocyte chemoattractant protein-2, -3, and -5 (MCP-2, MCP-3, and MCP-5; Ccl8, Ccl7, and Ccl12) is consistent with an accelerated active recruitment of the monocyte/macrophage-like cells to the severely affected cpk kidneys.Table 3Most significantly overexpressed genes in severely affected cpk kidneys (by fold change)GeneChangeFunctionProposed PKD pathogenesis componentHp4.7Antioxidant; acute-phase reactant; neovascularization mediatorImmune response, stress/ischemia/trauma, vascular dysfunctionC33.9Inflammatory mediator; regeneration mediator; acute-phase reactantImmune response, stress/ischemia/traumaArg13.4Arginine hydrolase; activated macrophage marker; acute-phase reactantImmune responseActg23.3Smooth muscle cells; neovascularizationVascular dysfunctionLcn22.9Iron transporter; acute renal failure marker; acute-phase reactantStress/ischemia/trauma, immune responseSaa32.9Acute-phase reactant; secreted by macrophagesImmune responseCtss2.8Macrophage elastaseImmune responseSprr2f2.8Epithelial expression?Lrg12.7Granulocytic differentiation markerImmune responseE430024C06Rik2.7??Ccl62.7Monocyte chemotactic factorImmune responseLzp-s2.6Antimicrobial agent; produced by macrophages; acute-phase reactantImmune responseNiban2.6‘Protector against cell death under stress’Stress/ischemia/traumaIl18r12.6Cytokine receptor; macrophage, NK and T-cell markerImmune response1200016E24Rik2.6??Cd1632.6Macrophage Fe scavenger receptor; acute-phase reactantImmune responseSocs32.6Blocks Jak/STAT pathway; predominantly expressed in Th cellsImmune responseSerpine12.5Complement inhibitor; acute-phase reactantImmune responseC1qb2.5Macrophage produced/macrophage activatorImmune responseTimp12.5Degradation of extracellular matrix; granulocyte activatorImmune responseCd142.5Predominant expression: monocyte/macrophage; acute-phase reactantImmune responseF13a2.5Coagulation factor; predominant expression: monocyte/macrophageImmune responseJak/STAT, Janus kinase/signal transducers and activators of transcription; PKD, polycystic kidney disease.All listed genes had P<0.001. Open table in a new tab Table 4Macrophage-associated markers overexpressed in severely affected cpk kidneysCell type/process markersGeneFold changeProteinMonocyte/leukocyte/lymphocyteCcr22.1monocyte chemoattractant protein (Mcp) 1 receptorPtprc1.4CD45 antigenMonocyte/lymphocyteCcr11.2Mcp-3 and RANTES receptorMonocyte/megakaryocyteCxcl71.4chemokine (C-X-C motif) ligand 7 (Pbp)Monocyte and granulocyteCsf2rb11.8colony stimul. factor 2 (GM-CSF) receptor, beta 1Csf2rb21.8colony stimul. factor 2 (GM-CSF) receptor, beta 2Il3r1.3interleukin 3 receptor, alpha chainIl6r1.3interleukin 6 receptor, alphaTrem21.3triggering receptor expressed on myeloid cells 2Monocyte and macrophageCD142.5CD14 antigen (LPS/apoptotic cell receptor)CD681.6CD68 antigenCD1632.6CD163 antigenIfngr21.2interferon gamma receptor 2Csf1r1.4colony stimulating factor 1 (macrophage) receptorMacrophageMmd1.3monocyte to macrophage differentiationMpeg11.4macrophage expressed gene 1Msr21.5macrophage scavenger receptor 2Macrophage
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