Dendritic cells facilitate accumulation of IL-17 T cells in the kidney following acute renal obstruction

Abstract

Acute urinary obstruction causes interstitial inflammation with leukocyte accumulation and the secretion of soluble mediators. Here we show that unilateral ureteral ligation caused a progressive increase in renal F4/80(+) and F4/80(-) dendritic cells, monocytes, neutrophils and T-cells 24-72 h following obstruction. Depletion of dendritic cells by clodronate pretreatment showed these cells to be the most potent source of tumor necrosis factor and other pro-inflammatory mediators in the obstructed kidney. F4/80(+) dendritic cells and T-cells co-localized in the cortico-medullary junction and cortex of the obstructed kidney. Cytokine secretion patterns and surface phenotypes of T-cells from obstructed kidneys were found to include interferon-gamma-secreting CD4(+) and CD8(+) memory T-cells as well as interleukin 17 (IL-17)-secreting CD4(+) memory T-cells. Depletion of the intra-renal dendritic cells prior to ligation did not numerically reduce T-cells in obstructed kidneys but attenuated interferon-gamma and IL-17-competent T-cells. Our study shows that intra-renal dendritic cells are a previously unidentified early source of proinflammatory mediators after acute urinary obstruction and play a specific role in recruitment and activation of effector-memory T-cells including IL-17-secreting CD4(+) T-cells.

Figure 1. Progressive increase in multiple bone marrow-derived cell populations following acute renal obstruction

(a) Examples are shown of multicolor flow cytometry dot plots and gating used to analyze proportions of individual CD45⁺ cell populations within total cell suspensions from collagenase/DNase-digested kidneys. The examples shown are from an obstructed kidney 72 h following ureteral ligation. Staining definitions for the individual cell populations were F4/80⁺ DCs: CD45⁺/CD11c⁺/F4/80⁺/Ly6C⁻. F4/80⁻ DCs: CD45⁺/CD11c⁺/F4/80⁻/Ly6C⁻. Monocytes: CD45⁺/Ly6C⁺/CD11c⁻ (in separate experiments this population was also shown to be CD11b-hi). Neutrophils: CD45⁺/Ly6G⁺/CD11c⁻. CD4⁺ T cells: CD45⁺/CD3⁺/CD4⁺/CD8⁻. CD8⁺ T cells: CD45⁺/CD3⁺/CD8⁺/CD4⁻. (b) The proportions of total kidney cells with surface staining characteristics of F4/80⁺ DCs, F4/80⁻ DCs, monocytes, neutrophils, CD4⁺ T cells, and CD8⁺ T cells are shown graphically for obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys from groups of mice (n = 3) killed at 24 and 72 h after unilateral (left) ureteral ligation. Each cell population is expressed as mean±s.d. of the percent of total kidney cells expressing the designated staining characteristics by multicolor flow cytometry. ^†P<0.05 for Obstr. vs Ctrl. at the same time point. ^‡P<0.05 for 72 vs 24 h. The difference in F4/80⁺ DCs between control kidneys at 24 and 72 h has not been a reproducible finding.

Figure 2. Increased maturation marker expression by DCs in acutely obstructed kidneys

(a) Examples are shown of flow cytometry contour plots indicating MHC II (I-A^b) and CD86 (B7-2) surface staining of F4/80⁺ DCs (left) and F4/80⁻ DCs (right). For both DC populations, initial gating was performed on cells staining positive for CD45 and for the DC-specific marker CD11c. Dot plots are shown for cells derived from obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys at 24 and 72 h following unilateral (left) ureteral ligation. (b) Results are presented graphically for groups of three mice each killed at 24 and 72 h following unilateral ureteral ligation. Surface staining levels of MHC II and CD86 on F4/80⁺ DCs (left) and F4/80⁻ DCs (right) are expressed as mean±s.d. of the mean fluorescence intensity by flow cytometric analysis. ^†P<0.05 for Obstr. vs Ctrl. at the same time point. ^‡P<0.05 for 24 vs 72 h.

Figure 3. F4/80⁺ DCs are the predominant TNF-producing cell early following acute renal obstruction

(a) Examples of flow cytometric dot plots of cell suspensions from obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys stained intracellularly with a monoclonal antibody against TNF (TNF-AF488, upper plots) or with an isotype control antibody (rIgG1-AF488). Staining was carried out 24 h following unilateral (left) ureteral ligation. The percent of the total cells within the positive staining region are indicated. (b) Graphical results are shown for intracellular staining of cell suspensions from a total of four pairs of obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys. Staining was carried out 24 h following unilateral ureteral ligation. Results are expressed as mean±s.d. percent total kidney cells staining positive with anti-TNF (TNF⁺) or isotype control (rIgG1⁺) antibodies as measured by flow cytometry. ^†P<0.05 for anti-TNF vs isotype control. ^‡P<0.05 for Obstr. vs Ctrl. (c) Examples are shown of multicolor flow cytometric analysis of total kidney cells, TNF-negative (TNF⁻) and TNF-positive (TNF⁺) cells 24 h following ureteral ligation. Intracellular staining and gating for TNF⁺ and TNF⁻ cells was carried out as illustrated in (a). Staining of each population for CD45 is shown in the upper plots with the percentage of the cells contained within the positively stained region indicated. Staining of CD45⁺ cells from each population for CD11c and F4/80 is shown in the lower plots. The percentages of the cells that are CD11c⁺/F4/80⁺ (i.e. F4/80⁺ DCs) and CD11c⁺/F4/80⁻ (i.e. F4/80⁻ DCs) are indicated. (d) Results of qRT-PCR for mRNA-encoding TNF are shown for individual obstructed and nonobstructed (Ctrl.) kidneys (gray circles) and for the means of each group (black bars, n = 6) at 24 and 72 h after left UUL. RNA was prepared without prior tissue digestion or culture. Results are expressed as fold expression relative to that of the first of six nonobstructed 24 h kidneys. ^†P<0.05 for Obstr. vs Ctrl. (e) Results are shown of qRT-PCR for mRNA-encoding TNF in pooled CD11c-enriched cells and CD11c-depleted, CD45-enriched cells from obstructed and nonobstructed kidneys at 24 and 72 h after left UUL. RNA was prepared without overnight culture. Results are expressed as fold expression relative to that of the cell preparations from the nonobstructed 24 h kidneys.

Figure 4. T cells accumulate at the corticomedullary junction and cortex following acute urinary obstruction and colocalize with F4/80⁺ DCs

(a) Graphical results are shown for CD3⁺ T cells numbers in immunostained sections of nonobstructed (Ctrl.) and obstructed (Obstr.) kidneys at 24 and 72 h after left UUL (n = 4 of each). Results are expressed as mean±s.d. of the total CD3⁺ cells per high-power field in the medulla, corticomedullary junction, and cortex of each group. For each kidney, cells were counted and averaged from a total of 10 high-powered fields. ^†P<0.05 for Obstr. vs Ctrl.; ^‡P<0.05 for 72 vs 24 h. (b) Examples are shown of sequential sections of 72 h obstructed kidneys immunostained for CD3 (upper panels) and F4/80 (lower panels). Representative regions of the corticomedullary junction (left panels) and cortex (middle and right panels) containing clustered positively staining cells are indicated for each example by a dashed box.

Figure 5. Clodronate-containing liposomes selectively reduce F4/80⁺ DCs but do not prevent increased renal monocytes and T cells following acute renal obstruction

The proportions of total kidney cells with surface staining characteristics of F4/80⁺ DCs, F4/80⁻ DCs, monocytes, CD4⁺ T cells, and CD8⁺ T cells are shown graphically for obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys from groups of mice pretreated with either clodronate-containing (Clodr.) or inert (PBS) liposomes (n = 5 each) and killed 48 h after unilateral (left) ureteral ligation. Each cell population is expressed as mean±s.d. of the percent of total kidney cells expressing the designated staining characteristics by multicolor flow cytometry. ^‡P<0.05 for Clodr. vs PBS liposome groups. ^†P<0.05 for Obstr. vs Ctrl. kidneys (for examples of dot plots for each cell type see Supplementary Figure S3).

Figure 6. Renal DCs are required for maximal secretion of multiple proinflammatory mediators by bone marrow-derived cell populations within the acutely obstructed kidney

Graphical results are shown for multiple ELISAs of supernatants from overnight cultures of equal numbers of total kidney cells and CD45-depleted kidney cells derived from the obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys of two groups of mice subjected 24 h previously to unilateral (left) ureteral ligation. The groups (n = 4 each) consisted of mice pretreated with either clodronate-containing (Clodr.) or inert (PBS) liposomes. All results are expressed as mean±s.d. concentration (pg/ml) of the proinflammatory mediator concentration in supernatants from each group of kidney cell cultures. ELISAs were carried out for TNF, IL-6, RANTES (CCL5), MCP-1 (CCL2), MIP-2 (CXCL2), and IP-10 (CXCL10). ^†P<0.05 for Clodr. vs PBS liposome groups. ^‡P<0.05 for Obstr. vs Ctrl. kidneys.

Figure 7. The presence of IFNγ- and IL-17-competent T cells in acutely obstructed kidneys is reduced by depletion of intrarenal DCs

Graphical results are shown for ELISAs of culture supernatants of cell suspensions from obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys of groups of mice that were pretreated with inert (PBS) liposomes or clodronate-containing (Clodr.) liposomes (n = 3 of each). Cells suspensions were prepared 24 h following unilateral (left) ureteral ligation and plated in equal numbers for each condition in the absence (unstimulated) or presence (2C11 0.1 μg/ml) of a low amount of soluble anti-CD3 T-cell stimulatory antibody. Results, expressed as mean±s.d. of the concentration (pg/ml) of either IL-2, IFNγ, or IL-17 for each condition, are shown for total kidney cell suspensions (left graphs, unsorted kidney cells) and for CD4-enriched kidney cells (right graphs). ^†P<0.05 for 2C11 vs equivalent condition unstimulated. ^‡P<0.05 for PBS vs equivalent condition for Clodr. ^¶P<0.05 for Obstr. vs equivalent Ctrl. kidney.

Figure 8. IL-17- and IFNγ-producing CD4⁺ T-cell populations are increased in the kidney 72 h following acute urinary obstruction in the presence of DCs

(a) Graphical results are shown for ELISAs of culture supernatants of cell suspensions from obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys of groups of mice that were pretreated with inert (PBS) liposomes or clodronate-containing (Clodr.) liposomes (n = 3 of each). Cell suspensions were prepared 72 h following unilateral (left) ureteral ligation and plated in equal numbers for each condition in the absence (unstimulated) or presence (2C11 0.1 μg/ml) of a low dose of soluble anti-CD3 T-cell stimulatory antibody. Results, expressed as mean±s.d. of the concentration (pg/ml) of either IFNγ or IL-17 for each condition, are shown for total kidney cell suspensions (left graphs, unsorted kidney cells) and for CD4-enriched kidney cells (right graphs). ^†P<0.05 for 2C11 vs equivalent condition unstimulated. ^‡P<0.05 for PBS vs equivalent condition for Clodr. ^¶P<0.05 for Obstr. vs equivalent Ctrl. kidney. (b) Graphical results are shown for qRT-PCR assays of mRNA-encoding IFNγ (left graph) and IL-17 (right graph) in samples prepared from CD4-enriched cells of nonobstructed (Ctrl.) and obstructed kidneys of otherwise untreated mice at 24 and 72 h following left UUL. Cell samples were neither stimulated nor placed in culture before RNA extraction. Results are expressed as fold expression compared to the 24 h control sample with the numerical value for each column indicated above it.

Figure 9. IFNγ and IL-17-competent T cells constitute separate cell populations within obstructed kidneys and are associated with early increased expression of DC-derived activating cytokines

(a) Examples of 3D flow cytometric dot plots are shown for kidney cell suspensions prepared from obstructed and nonobstructed (control) kidneys of normal adult mice 72 h following unilateral (left) ureteral ligation. Cell suspensions were cultured overnight with Golgi export inhibitor in the absence (unstimulated) or presence (anti-CD3) of soluble T-cell stimulatory antibody and then were surface stained for CD45 and CD4 and intracellularly stained for IFNγ and IL-17. Dot plots are gated on CD45⁺ cells. Separate IFNγ and IL-17⁺ populations that are predominantly (but not exclusively) CD4⁺ are evident in the cell sample from obstructed kidney following anti-CD3 stimulation (right upper dot plot). (b) Results of qRT-PCR for mRNA-encoding the cytokine-specific chains for IL-12 (p35) and IL-23 (p19) are shown for individual obstructed and nonobstructed (Ctrl.) kidneys (gray circles, n = 6 of each) and for the means of each group (black bars) at 24 after left UUL. RNA was prepared without prior tissue digestion or culture. Results are expressed as fold expression relative to that of the first of six nonobstructed 24 h kidneys. ^†P<0.05 for Obstr. vs Ctrl. Insert: results are shown of qRT-PCR for mRNA-encoding IL-12 p35 and IL-23 p30 in pooled CD11c-enriched cells from obstructed kidneys at 24 and 72 h after left UUL. RNA was prepared without overnight culture. Results are expressed as fold expression relative to that of the cell preparations from the nonobstructed kidneys.

Figure 10. IL-17-competent, CD4⁺ T cells within acutely obstructed kidneys have the phenotype of activated, memory T cells

Flow cytometric analysis is shown for CD4⁺ and CD4⁻ T cells present among a CD45-enriched cell suspension prepared by magnetic bead separation from a pooled digest of three mouse kidneys 72 h after ureteral ligation. The cell suspension was cultured overnight in the presence of 1.0 μg/ml anti-CD3ε stimulatory antibody. A Golgi export inhibitor was added for the final 4 h of culture. Aliquots of cells for each condition were surface stained for CD4 and for a panel of additional T-cell surface markers then intracellularly stained with antibodies against IL-17 (anti-IL-17) and IFNγ (anti-IFNγ). The gating region for CD4⁺ cells is illustrated in the upper left dot plots. The proportion of cells that were positive for intracellular IL-17 staining is shown for CD4⁺ and CD4⁻ populations in the upper right dot plots. The remaining dot plots, gated on either CD4⁺ or CD4⁻ populations, demonstrate intracellular staining for IL-17 (y axis) and surface staining with PE-coupled antibodies against various T-cell markers or intracellular staining for IFNγ (x axis). Numerical values of the median fluorescence intensity or the percentage positive for each PE-labeled surface marker are shown for IL-17⁺ and IL-17⁻ cells. In the case of IFNγ staining (lower right), the proportions of cells that are IL-17⁺/IFNγ⁻, IL-17⁺/IFNγ⁺, and IL-17⁻/IFNγ⁺ are indicated (a similar analysis of IFNγ⁺ cells among the CD4⁺ and CD4⁻ populations is presented in Supplementary Figure S5).

Figure 11. Reduction of F4/80⁺ DCs is associated with reduced proportion of CD44^hi T cells within kidney cell suspensions at 72 h after acute urinary obstruction

Graphical results are shown for surface staining of cell suspensions prepared from obstructed (Obstr.) and nonobstructed (Ctrl.) kidneys 72 h following unilateral (left) ureteral ligation. Groups of mice were pretreated with inert liposomes (PBS, n = 4) and clodronate-containing liposomes (Clodr., n = 4). (a) The proportions of the total kidney cells suspensions that stained for surface marker combinations indicative of F4/80⁺ DCs (CD45⁺/CD11c⁺/Ly6C⁻/F4/80⁺), F4/80⁻ DCs (CD45⁺/CD11c⁺/Ly6C⁻/F4/80⁻), and monocytes (CD45⁺/CD11c⁻/Ly6C⁺/F4/80⁻) are shown as mean±s.d. for each condition. (b) The proportions of the total kidney cells suspensions that stained for surface marker combinations indicative of total T cells (CD45⁺/CD3⁺), CD4⁺ T cells (CD45⁺/CD3⁺/CD4⁺), and CD8⁺ T cells (CD45⁺/CD3⁺/CD8⁺) are shown as mean±s.d. for each condition. (c) The proportions of total T cells, CD4⁺ T cells, and CD8⁺ T cells that stained highly for CD44 are shown as mean±s.d. for each condition. (d) The mean fluorescence intensities for CD44 surface staining of total T cells, CD4⁺ T cells, and CD8⁺ T cells are shown as mean±s.d. for each condition. ^†P<0.05 for Obstr. vs equivalent condition Ctrl. ^‡P<0.05 for PBS vs equivalent condition for Clodr.