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*
Department of Internal Medicine, Washington University School of Medicine
at Barnes-Jewish Hospital, St. Louis, Missouri.
Department of Cell Biology and Physiology, Washington University School of
Medicine at Barnes-Jewish Hospital, St. Louis, Missouri.
Correspondence to Dr. Jeremiah Morrissey, Department of Medicine, Barnes-Jewish Hospital (North Campus), 216 South Kingshighway Blvd., St. Louis, MO 63110-1092. Phone: 314-454-7464; Fax: 314-454-5353; E-mail: morrisse{at}imgate.wustl.edu
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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receptor (TNFR)
genes were also studied; the induction of CD14 was blunted in TNFR 1-knockout
mice but not in TNFR2-knockout mice. Apoptosis of tubular cells in
lipopolysaccharide-resistant CH3/HeJ mice was significantly (P <
0.05) less than that in lipopolysaccharide-responsive CH3/HeN mice during UUO.
These results suggest that CD14 is acutely induced in tubular epithelial cells
in two mouse models of renal injury. This induction is regulated by tumor
necrosis factor-, through TNFR1. CD14 may participate in the apoptosis
of tubular epithelial cells on a more chronic basis by activating a pathway
that is absent or deficient in C3H/HeJ mice. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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(TNF-) receptor 1
(TNFR1) and Fas, have been identified as participants in apoptosis
(12), with CD14 being a recent
addition (13). To further
investigate the changes in gene expression associated with the pathogenesis of
fibrotic renal disease, we performed a gene-array analysis with a mouse model
of unilateral ureteral obstruction (UUO). We found that CD14 was among the
genes that were significantly upregulated after 1 d of UUO. Previous studies
suggested extramyeloid expression of CD14 in response to the administration of
lipopolysaccharide (LPS) to animals
(14). The increased induction
of CD14 in mice with UUO was not due to infection in this model of kidney
disease. These findings provided the foundation for the determination of
whether the induction of CD14 occurs as a pathophysiologic event in renal
disease. CD14 is a cell surface glycosylphosphatidylinositol (GPI)-linked protein that binds LPS that is already bound to extracellular LPS-binding protein (15). Additionally, CD14 can bind lipids, such as ceramide (16) and phosphoinositides (17), that have carbon, nitrogen, and oxygen molecular arrangements that are sterically similar to some domains of LPS (18). Transduction of the LPS signal across the plasma membrane occurs through activation of toll-like gene products (19, 20) with homology to the intracellular portion of the interleukin-1 receptor (19, 20). This pathway induces expression of inflammatory cytokines (15). GPI-anchored CD14 segregates this surface receptor into nonionic detergent-insoluble glycolipid microdomains within the plasma membrane (21). These glycolipid-rich microdomains contain heterotrimeric G-proteins and other signal transduction molecules, the activities of which are influenced by LPS through interactions with CD14 (21). These findings suggest that CD14 is involved in several pathways by which LPS, ceramide, or other lipids may affect cell function. This study was designed to characterize the mechanisms of activation of CD14 in kidney epithelial cells.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Animals were euthanized, under pentobarbital anesthesia, after 1 or 7 d of UUO or ischemia/reperfusion, as were the appropriate shamtreated animals. Kidneys were rapidly removed into ice, 1-mm coronal sections were placed in buffered formalin or the fixative Histochoice (Amresco, Solon, OH), and the remainder of each kidney was homogenized for preparation of total RNA (5, 22). Total RNA from individual mouse kidneys was separately analyzed by reverse transcription (RT)-PCR or pooled, as described below, for array analysis.
Gene-Array Analysis
Total RNA was pooled from three separate mouse kidneys for each condition,
i.e., RNA from three contralateral kidneys or three kidneys with
obstructed ureters from mice with UUO of 24-h duration. During these studies,
three separate pools of three kidneys (i.e., nine total mice) from
mice of the BALB/C strain were analyzed. Each total RNA pool was treated with
RNase-free DNase (Promega, Madison, WI). Portions of each pool were then
radiolabeled with [33P]dATP, using protocols and primers provided
by the manufacturer (Clontech, Palo Alto, CA). The radiolabeled cDNA was
hybridized to Atlas mouse cDNA expression arrays (7741-1; Clontech).
Autoradiography of the membranes was used to detect gene expression.
mRNA Amplification
Total RNA (2 or 4 µg) was used to prepare cDNA, as described in previous
reports (5,
22). The amount of CD14 mRNA
was initially determined using primers spanning the one intron. The primers
were based on the GenBank accession number M34510 sequence and consisted of a
sense primer of 5'-CTCAAACTTTCAGAATCTACC-3' and an antisense
primer of 5'-GACTTGATAATATCACGCAACTG-3'. These primers correspond
to bases 148 to 169 and 498 to 520, respectively. In some studies, the primer
pairs were 5'-CCTCCGCAACGCGTCGCCGCGC-3' (sense) and
5'-GCTTCGCCTCGCCAGCCCTTTACGC-3' (antisense), corresponding to
bases 701 to 722 and 1125 to 1146, respectively.
The PCR procedure was performed as described previously (5, 22), using an initial denaturation step of 95°C for 5 min, followed by 35 cycles of 60°C annealing for 1 min, 72°C extension for 1 min, and 95°C denaturation for 1 min for the intron-spanning CD14 primers. The annealing temperature for the set of intronless CD14 primers was also 60°C for 1 min, for 28 cycles. The mRNA for ß-actin was amplified using primers based on the GenBank accession number V01217 sequence, i.e., 5'- GACGATATCGCCGCGCTCGCC-3' (sense) and 5'-GCCACGCTCCAGACGCAGGATG-3' (antisense), with annealing at 60°C for 1 min for 28 cycles. The mRNA for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was amplified using primers and protocols previously described by our laboratory (5, 22). The number of cycles used for amplification was adjusted to be in the linear range for relative quantitation, as determined in preliminary studies to optimize conditions for each mRNA.
PCR products were separated on buffered gels containing 2% agarose and ethidium bromide. The gels were illuminated with ultraviolet light and photographed with Polaroid 667 film. The negatives were scanned and digitized using a PhotoSmart system (Hewlett Packard, Palo Alto, CA), and the resultant.fpx files were imported into the Corel PhotoPaint 8 program (Corel, Ottawa, Ontario, Canada) for contrast enhancement. These files were converted to.cpt files and imported into the Corel Draw 8 program for presentation.
PCR products were sequenced directly by dideoxy chain termination, using a Thermo Sequence kit (Amersham Pharmacia Biotech, Piscataway, NJ). Additionally, PCR products were cloned into the PCR-II Topo vector (Invitrogen, Carlsbad, CA). The insert of the resultant clones was sequenced as described above.
The inserts of the cloned PCR products were individually amplified, and these products were subjected to restriction enzyme digestion, using the buffers and conditions recommended by the suppliers (Promega or New England Biolabs, Beverly, MA). Digests were separated on buffered gels containing 2% agarose.
Immunohistochemical Analyses
Kidney sections that had been fixed with Histochoice before being embedded
in paraffin were subsequently deparaffinized, rehydrated, and incubated with
1: 100 dilutions of a goat polyclonal antibody to CD14 (SC-6999; Santa Cruz
Biotechnology, Santa Cruz, CA). Non-immune goat serum served as a control. The
goat antibody was detected by incubation of the sections with 1:200 dilutions
of FITC-conjugated rabbit anti-goat antibody (F2016; Sigma Chemical Co., St.
Louis, MO).
Buffered formaldehyde-fixed sections were also embedded in paraffin. Sections were subsequently deparaffinized, rehydrated, and subjected to a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The commercially available TdT TUNEL-like in situ nonisotopic kit (Amersham Pharmacia Biotech) was used as described by the manufacturer, except for reductions in the volumes of reagents applied to the slides. The numbers of TUNEL-positive cells in five nonoverlapping fields (magnification, x200) of cortex in each kidney section were averaged to calculate the values for individual kidneys. The averages for six separate kidneys were then averaged to yield the mean ± SD. Statistical significance was determined using the t test.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Immunocytochemical Analysis of CD14
A factor that contributes to the increase in interstitial volume in renal
disease in general, and ureteral obstruction in particular, is the
infiltration of monocytes (5).
The observed increase in CD14 levels within the kidney could be the result of
monocyte infiltration. Immunocytochemical localization of CD14 in coronal
sections of both contralateral unobstructed mouse kidneys and kidneys with
obstructed ureters, however, revealed that tubular epithelial cells exhibited
significant CD14 expression within and on the cell surface
(Figure 2). Expression of CD14
in the contralateral kidneys was sporadic in the cortex
(Figure 2A) but more uniform in
the medulla (Figure 2B). A
similar pattern was observed in both kidneys of sham-treated animals (data not
shown). In the kidneys with obstructed ureters, CD14 expression was more
prominent in the cortex (Figure
2C) and medulla (Figure
2D). The expression in the medulla in the contralateral kidneys
was in the thick ascending limb. Most tubule structures in the kidneys with
obstructed ureters were found to express CD14
(Figure 2). In general, the
tubules are more dilated in Figure
2C than in Figure
2B, indicating an obstructed ureter. This suggests that intrinsic
renal epithelial cells exhibit basal expression of CD14 and these cells can be
induced to overexpress CD14 in the mouse model of UUO. In additional
experiments (not shown), the increased expression of CD14 on renal epithelial
cells persisted for at least 5 to 7 d of UUO.
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Induction of CD14 mRNA
To further explore CD14 induction, we used RT-PCR. We routinely prepare
oligonucleotide primers that span gene introns and, when feasible, amplify the
3'-end of the prepared cDNA, to more accurately reflect gene expression.
For the CD14 gene, the one 97-bp intron within the coding region of the gene
separates the initiating methionine from the rest of the open reading frame
(GenBank accession numbers M34510 and X13987). PCR primers flanking the 97-bp
intron were used to amplify cDNA prepared by oligo(dT)-primed RT.
Figure 3 is representative of
several sets of mouse kidneys, comparing the CD14 mRNA contents for animals
that underwent sham operations and mice that were subjected to 1 d of UUO. As
was observed in the expression array, there was a significant increase in the
CD14 mRNA contents of the mouse kidneys with obstructed ureters, compared with
the unobstructed contralateral mouse kidneys
(Figure 3A). There was little
to no difference in the CD14 mRNA contents (266-bp band) observed for mouse
kidneys collected 1 d after sham operations
(Figure 3A). Surprisingly, in
each mouse kidney we observed a 363-bp product, which is coincidentally the
size expected for an unspliced gene transcript. Isolation of the 363-bp
product from agarose gels and digestion with a restriction enzyme
(CfoI, HaeIII, or PpuMI) yielded fragments
consistent with RT-PCR of an unspliced mRNA precursor. Furthermore, the
results of dideoxy chain termination sequencing of the 363-bp product were
consistent with the sequence of an exon-intron-exon product of CD14. This
sequence is discussed more extensively below. An additional PCR product at 340
bp was also present; it represents inadvertent initiation within the intron,
as deduced by restriction enzyme digestion. The oligo(dT)-primed cDNA was also
subjected to PCR using primers to GAPDH
(Figure 3B). This experiment
revealed that, whereas the CD14 mRNA contents varied with the source of
kidneys (UUO obstructed, UUO contralateral, sham-manipulated, or contralateral
to sham-manipulated), the amounts of GAPDH mRNA were constant.
|
Because the PCR primers were selected to span an intron and our results suggested that this intron was included within transcripts, we chose to validate our total RNA isolation procedure. To eliminate the possibility that genomic DNA routinely contaminated the total RNA preparations, the preparations were treated with RNase-free DNase (Promega) and reextracted with phenol-chloroform-isoamyl alcohol. The RTPCR procedure was then repeated. Figure 4 depicts an example of total RNA isolated from the contralateral kidney of a mouse after 1 d of UUO. One half of the sample was treated with RNase-free DNase, and both halves of the sample were extracted with phenol-chloroform-isoamyl alcohol and reprecipitated with ethanol. After RT-PCR, it was observed that DNase treatment did not significantly decrease the amount of the 363-bp band. This, together with the fact that the GAPDH primers for PCR span an intron and only the 535-bp intronless mRNA band was present in the gel for GAPDH, suggests that genomic DNA does not contaminate the total RNA preparation. Therefore, the fact that an intron-containing CD14 transcript was amplified by PCR indicates that a CD14 mRNA precursor is present in mouse kidneys.
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The original PCR primers for CD14 were selected to span the one intron and consequently amplify the 5'-end of the mRNA. As stated above, we usually prefer to select primers toward the 3'-end of the mRNA that span an intron, but this was not possible for the CD14 gene. Also, the nearly equal amounts of CD14 sequences for the putative mRNA precursors in the contralateral kidneys and putative precursor and mature mRNA in the kidneys with obstructed ureters are in contrast to the results in Figure 1. Because contamination of the total RNA preparations was not a problem (Figure 4), we amplified CD14 mRNA using primers for the 3'-end of the open reading frame. The same cDNA that were amplified with the original primers (Figure 2) were amplified with the 3'-end primers (Figure 5). This finding demonstrates that only the expected 446-bp product was amplified, and it indicates significant induction of CD14 mRNA contents in the kidneys with obstructed ureters. In additional experiments (not shown), CD14 mRNA levels were observed to be significantly increased in the kidneys with obstructed ureters through 5 to 7 d of UUO.
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CD14 Induction in Kidney Diseases
Because we observed that CD14 mRNA was induced in the kidney by UUO, we
decided to test whether this induction occurred with another form of renal
injury. It was found that 24-h kidney reperfusion after 40 min of ischemia
also induced CD14 mRNA formation, compared with the contralateral kidneys
(Figure 6). For sham-treated
mice, there was no change in the CD14 mRNA contents in the manipulated but not
ischemic kidneys. As was observed with the UUO model, the GAPDH mRNA contents
were indistinguishable between kidneys
(Figure 6).
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CD14 Induction in Other Mouse Strains
The original observation of CD14 induction in the kidney
(Figure 1) and the subsequent
characterization (Figures
2,3,4,5)
were performed in BALB/C mice. Our previous studies involving the rodent model
of UUO were performed using rats
(5,
23,24,25).
Because of the ability to alter the genetic characteristics of mice, we have
been shifting our studies to this species. The C3H/HeJ mouse strain exhibits
blunted responses to LPS, whereas mice of the C3H/HeN strain respond normally
to LPS (26,
27). We therefore subjected
mice of these LPS-tolerant and LPS-intolerant strains, along with C57BL/6
mice, to UUO. The latter mouse strain is a common background strain for
gene-knockout studies. In Figure
7, it can be observed that, regardless of the mouse strain, CD14
mRNA was induced after 1 d in the UUO model. In the BALB/C, CH3/ HeJ, and
CH3/HeN mice, there were significant amounts of the 363-bp CD14 mRNA
precursor. In the C57BL/6 mice, there were no significant amounts of precursor
(Figure 7). For this series of
different mouse strains, we amplified ß-actin mRNA rather than GAPDH
mRNA. The primers for ß-actin were selected from exons 2 and 4, which
span introns of 87 and 464 bp, respectively (GenBank accession number V01217).
There was no significant difference in the amounts of ß-actin mRNA
between the obstructed and unobstructed kidneys for each mouse strain
(Figure 7). Furthermore, the
size of the ß-actin PCR product was consistent with the 537-bp size
expected from the mRNA sequence. There is no evidence for a ß-actin
product containing both introns or either intron. This is additional support
for the uniqueness and specificity of identifying a CD14 mRNA precursor in the
mouse kidney.
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Differences in Intron Sequences Between Mouse Strains
We routinely sequence new PCR products as a means of unambiguously
establishing identity. Our sequence for the intron in the CD14 gene of BALB/C
mice was found to be consistent with a previously published sequence (GenBank
accession number X13987) and differed slightly from another published sequence
(GenBank accession number M34510) (Figure
8). Sequencing of the CD14 gene intron of C57BL/6 mice revealed a
deletion of bases 753 to 756 from the BALB/C mouse X13987 sequence. This was
confirmed by restriction enzyme digestion using AhdI, which cleaved
the BALB/C product but not the C57BL/6 product
(Figure 9). Whether the
presence or absence of these four bases within the intron influences the rate
of heterogeneous nuclear RNA splicing is not known. This could account for the
differences in the presence (BALB/C) or absence (C57BL/6) of demonstrable CD14
mRNA precursor in the two strains (Figure
7).
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TNF- Mediation of CD14 mRNA Induction
Previous reports suggested that extramyeloid induction of CD14 mRNA is
mediated by TNF- (28,
29). We previously observed
that TNF- is induced during UUO in mice
(22). To test for a probable
mechanism of CD14 induction, we subjected C57BL/6 mice and mice of this
background in which the TNFR1 and/or TNFR2 genes had been genetically knocked
out to UUO. As observed in Figure
7, there was a prominent induction of CD14 mRNA in the kidney, 1 d
after UUO, in the wild-type C57BL/6 mice
(Figure 10). There was no
change in CD14 mRNA levels in the TNFR1-knockout mice. The induction of CD14
mRNA in the TNFR2-knockout mice was similar to that observed for the C57BL/6
mice (Figure 10). There was
little precursor mRNA in the wild-type and TNFR2-knockout animals, whereas
precursor was evident in both kidneys of the TNFR1-knockout mice. This
suggests that CD14 mRNA induction attributable to UUO in the mouse kidney
occurs through a mechanism related to the TNFR1 gene product.
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Tubule Cell Apoptosis
In renal disease and especially during obstructive nephropathy, tubule
cells are removed by apoptosis
(8,9,10).
CD14 has recently been implicated as a participant in apoptosis involving
macrophages (13). The possible
contribution of CD14 to apoptosis was determined using LPS-responsive C3H/HeN
and LPS-nonresponsive C3H/HeJ mice. After 7 d of UUO, the animals were
euthanized, and microscopic sections of each kidney were examined for
apoptosis using the TUNEL assay. Figure
11 is a representative photomicrograph of kidney sections obtained
from C3H/HeN (Figure 11A) and
C3H/HeJ (Figure 11B) mice.
Apoptotic TUNEL-positive cells appear as dark nuclei. When values for several
fields within each kidney section were averaged and these individual averages
were then averaged for six different mice, a significant decrease in the
number of cortical tubular epithelial cells was observed. The LPS-responsive
mouse kidney sections contained 19.4 ± 2.6 TUNEL-positive cells,
compared with 14.7 ± 2.1 TUNEL-positive cells (P < 0.004)
in LPS-unresponsive mice. This indicates that at 7 d of UUO there is less
apoptosis of tubule cells occurring in the kidneys of mice that are
genetically deficient in their responses to LPS.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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(29). Our results demonstrate
that epithelial cells of the kidney exhibit low but constitutive expression of
CD14 and this expression is significantly upregulated during UUO and
ischemia/reperfusion, on an acute basis. Furthermore, in the UUO model, CD14
upregulation appears to be mediated by TNF- through TNFR1.
In this study, we also provide evidence for heterogeneous nuclear RNA
processing to mature mRNA as a limiting step in CD14 expression in normal
kidneys or the contralateral unobstructed kidneys in the BALB/C mouse model of
UUO. After UUO, more CD14 precursor appears to be processed to CD14 mRNA. In
C57BL/6 mice, there was vigorous induction of CD14 mRNA in the UUO model, with
little evidence of a precursor. In the TNFR1-knockout mice with a C57BL/6
background, there was blunted induction, with evidence of a CD14 precursor.
The fact that this product contained unspliced CD14 exon-intron-exon sequences
was confirmed by sequencing. Interestingly, the intron sequence of BALB/C mice
differed from that of C57BL/6 mice, which could account for the different
rates of processing observed for these two mouse strains. In TNFR1-knockout
mice, in the absence of the tonic TNF- influence, precursor processing
again becomes a limiting step, as evidenced by the presence of precursor.
Whether this truly represents a precursor-product relationship or indicates
diversion of potential precursor to a catabolic pathway in normal
(sham-operated) or contralateral kidneys remains to be determined.
The existence of the CD14 mRNA precursor was detected with PCR primers that span the one intron of the open reading frame of the gene, using 35 cycles of amplification. This revealed that nearly equal amounts of mRNA precursor were present in the kidneys, regardless of treatment. When PCR primers corresponding to the middle of the CD14 protein sequence were used for 28 amplifications, significant induction of CD14 mRNA was observed in the injured kidneys, compared with the contralateral kidneys. The amount of mRNA precursor is therefore very small, compared with the amount of induced mRNA.
CD14 is a GPI-anchored protein that normally binds to LPS (15). Recently, CD14 was found to bind to ceramide (16) or to inositol phospholipids (17). During renal disease in general, it is unlikely that LPS is generated. Recent studies, however, indicated that ceramide levels are increased in several forms of acute renal failure (30,31,32,33). CD14 is described as a "pattern recognition receptor" (34) that binds molecules that sterically mimic LPS, such as ceramide (16, 18). Local increases in ceramide or inositol phosphate levels may be detected by CD14 located on renal epithelial cells, thus contributing to some aspects of renal disease. Another mechanism by which CD14-associated signal transduction may affect cell function is through glycolipid microdomains containing heterotrimeric G-proteins and associated effector proteins (21).
Apoptosis in the kidney can be mediated by several pathways, including TNFR1 and Fas systems (12). Recently, CD14 has been associated with apoptosis as a macrophage surface molecule involved in cell tethering (13). Tubular epithelial cells have antigen-presenting properties reminiscent of those of "professional" antigen-presenting cells, such as macrophages (35,36,37). We found that LPS-resistant mice (C3H/HeJ) exhibited modest but significant decreases in the numbers of apoptotic cells, compared with LPS-responsive (C3H/HeN) mice, at 7 d of UUO. This apparent blunting of apoptosis in the LPS-nonresponsive mice may be coincidental, and any linkage to CD14 requires more rigorous study.
We observed acute (1-d) induction of CD14 mRNA and protein in kidneys with obstructed ureters, which persisted for at least 5 to 7 d. It is possible that the presence of CD14 at 6 to 7 d contributed, in part, to cellular apoptosis measured at 7 d. This finding does not mean that the TNFR1 or Fas systems are ineffectual; it indicates only that other novel but redundant pathways for apoptosis exist in the kidney. Because there is an inflammatory cell infiltrate in the UUO model (5, 10), it is also possible for the CD14 on epithelial cells to participate in macrophage-mediated events that involve inflammatory signals. It is not currently known what proportion of TNFR1-mediated apoptosis is attributable to a CD14-mediated pathway. Interestingly, the severity of graft-versus-host disease is significantly less if the donor cells are derived from LPS-nonresponsive mice (38). This finding suggests that quantifiable cellular changes are determined by the LPS-responsiveness of genetically predisposed mice and indicates that some downstream component of CD14-dependent ligand binding is associated with renal tubule cell apoptosis and subsequent tubule atrophy in disease. The generation of ceramide, leading to increased DNA damage in cultured renal epithelial cells, was recently established (39). It is therefore possible that ceramide, acting through CD14 as a receptor, influences apoptosis. It should be remembered that, although C3H/HeJ and C3H/HeN mice displayed equal CD14 induction in the obstructed kidneys (Figure 7), the LPS-responsive gene is located downstream of CD14 (19, 20)
The CD14 gene is located on human chromosome 5 at site q23-q31, which encodes several growth factors and growth factor receptors (40, 41). In mice, this region of chromosome 5 is split between chromosome 11, which contains growth factors, and chromosome 18, which contains growth factor receptors (41). The murine CD14 gene is located on chromosome 18, thus forming a syntenic group with growth factor receptors, including the platelet-derived growth factor receptor (40, 41). This linkage of the CD14 gene with the genes for growth factor receptors is interesting but remains undefined.
Immunocytochemical staining for CD14 in sections of mouse kidney revealed a nouniform pattern of CD14 expression within and on cortical tubular epithelial cells, with sporadic staining of mesangial cells within glomeruli. It should be pointed out that mesangial cells in culture display increasing percentages of CD14-staining cells with increasing passage number (42). An established rat kidney epithelial cell line (NRK52E) responds to LPS (43). Furthermore, murine proximal tubular epithelial cells in culture respond to LPS to upregulate inducible nitric oxide synthase (44). The expression of CD14 mRNA in several renal cell lines and microdissected kidney tubules (45) was very recently described. The modest expression within proximal convoluted tubules and the abundant expression within inner medullary collecting duct tubules (45) are consistent with our immunohistochemical results (Figure 2). These findings suggest that intrinsic renal cells have the capacity to express CD14, which cannot be attributed to myeloid cell contamination. This expression of CD14 is upregulated on an acute basis in renal disease in vivo and may contribute, in part, to the eventual apoptosis of tubular epithelial cells, through a cell pathway downstream of CD14 binding to ligand.
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Acknowledgments |
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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B: Regulation
of renal fibrosis during ureteral obstruction. Semin
Nephrol 18:603
-611, 1998[Medline]
B. J Leukocyte Biol57
: 174-179,1995[Abstract]
in
induction of murine CD14 gene expression by lipopolysaccharide.
Infect Immun 65:4822
-4831, 1997[Abstract]
production to lipopolysaccharide
stimulation by donor cells predicts the severity of experimental acute
graft-versus-host disease. J Clin Invest102
: 1882-1891,1998[Medline]
B in normal rat kidney epithelial
(NRK52E) cells is mediated via a redox-insensitive, calcium-dependent pathway.
Toxicol Appl Pharmacol 154:219
-227, 1999[Medline]
(IFN ) receptor-deficient mice: IFN -dependent
up-regulation of MHC class II in renal tubules. Kidney
Int 48:1721
-1727, 1995[Medline]
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