Gunnar H. Heine

Decline in estimated glomerular filtration rate and subsequent risk of end-stage renal disease and mortality

IMPORTANCE The established chronic kidney disease (CKD) progression end point of end-stage renal disease (ESRD) or a doubling of serum creatinine concentration (corresponding to a change in estimated glomerular filtration rate [GFR] of −57% or greater) is a late event. OBJECTIVE To characterize the association of decline in estimated GFR with subsequent progression to ESRD with implications for using lesser declines in estimated GFR as potential alternative end points for CKD progression. Because most people with CKD die before reaching ESRD, mortality risk also was investigated. DATA SOURCES AND STUDY SELECTION Individual meta-analysis of 1.7 million participants with 12,344 ESRD events and 223,944 deaths from 35 cohorts in the CKD Prognosis Consortium with a repeated measure of serum creatinine concentration over 1 to 3 years and outcome data. DATA EXTRACTION AND SYNTHESIS Transfer of individual participant data or standardized analysis of outputs for random-effects meta-analysis conducted between July 2012 and September 2013, with baseline estimated GFR values collected from 1975 through 2012. MAIN OUTCOMES AND MEASURES End-stage renal disease (initiation of dialysis or transplantation) or all-cause mortality risk related to percentage change in estimated GFR over 2 years, adjusted for potential confounders and first estimated GFR. RESULTS The adjusted hazard ratios (HRs) of ESRD and mortality were higher with larger estimated GFR decline. Among participants with baseline estimated GFR of less than 60 mL/min/1.73 m2, the adjusted HRs for ESRD were 32.1 (95% CI, 22.3-46.3) for changes of −57% in estimated GFR and 5.4 (95% CI, 4.5-6.4) for changes of −30%. However, changes of −30% or greater (6.9% [95% CI, 6.4%-7.4%] of the entire consortium) were more common than changes of −57% (0.79% [95% CI, 0.52%-1.06%]). This association was strong and consistent across the length of the baseline period (1 to 3 years), baseline estimated GFR, age, diabetes status, or albuminuria. Average adjusted 10-year risk of ESRD (in patients with a baseline estimated GFR of 35 mL/min/1.73 m2) was 99% (95% CI, 95%-100%) for estimated GFR change of −57%, was 83% (95% CI, 71%-93%) for estimated GFR change of −40%, and was 64% (95% CI, 52%-77%) for estimated GFR change of −30% vs 18% (95% CI, 15%-22%) for estimated GFR change of 0%. Corresponding mortality risks were 77% (95% CI, 71%-82%), 60% (95% CI, 56%-63%), and 50% (95% CI, 47%-52%) vs 32% (95% CI, 31%-33%), showing a similar but weaker pattern. CONCLUSIONS AND RELEVANCE Declines in estimated GFR smaller than a doubling of serum creatinine concentration occurred more commonly and were strongly and consistently associated with the risk of ESRD and mortality, supporting consideration of lesser declines in estimated GFR (such as a 30% reduction over 2 years) as an alternative end point for CKD progression.

SuperSAGE evidence for CD14++CD16+ monocytes as a third monocyte subset

Monocytes are a heterogeneous cell population with subset-specific functions and phenotypes. The differential expression of CD14 and CD16 distinguishes classical CD14(++)CD16(-), intermediate CD14(++)CD16(+), and nonclassical CD14(+)CD16(++) monocytes. Current knowledge on human monocyte heterogeneity is still incomplete: while it is increasingly acknowledged that CD14(++)CD16(+) monocytes are of outstanding significance in 2 global health issues, namely HIV-1 infection and atherosclerosis, CD14(++)CD16(+) monocytes remain the most poorly characterized subset so far. We therefore developed a method to purify the 3 monocyte subsets from human blood and analyzed their transcriptomes using SuperSAGE in combination with high-throughput sequencing. Analysis of 5 487 603 tags revealed unique identifiers of CD14(++)CD16(+) monocytes, delineating these cells from the 2 other monocyte subsets. Gene Ontology (GO) enrichment analysis suggests diverse immunologic functions, linking CD14(++)CD16(+) monocytes to Ag processing and presentation (eg, CD74, HLA-DR, IFI30, CTSB), to inflammation and monocyte activation (eg, TGFB1, AIF1, PTPN6), and to angiogenesis (eg, TIE2, CD105). In conclusion, we provide genetic evidence for a distinct role of CD14(++)CD16(+) monocytes in human immunity. After CD14(++)CD16(+) monocytes have earlier been discussed as a potential therapeutic target in inflammatory diseases, we are hopeful that our data will spur further research in the field of monocyte heterogeneity.

CD14+CD16+ monocytes in coronary artery disease and their relationship to serum TNF-α levels

Monocytes play a central role in the inflammatory disease atherosclerosis. CD14+CD16+ monocytes are considered proinflammatory monocytes, as they have an increased capacity to produce proinflammatory cytokines, such as TNF-α, and are elevated in various inflammatory diseases.We hypothesized that patients with coronary artery disease (CAD) have increased levels of CD14+CD16+ monocytes, and that CD14+CD16+ monocytes are associated with inflammation markers. We investigated CD14+CD16+ monocytes in 247 patients with CAD and 61 control subjects using flow cytometry. In addition serum concentrations of TNF-α, IL-6, and Hs-CRP were assessed. Patients with CAD had higher levels of CD14+CD16+ monocytes than controls (13.6% versus 11.4%; p

Levels of virus-specific CD4 T cells correlate with cytomegalovirus control and predict virus-induced disease after renal transplantation.

Background. Immunosuppressive treatment in transplant patients frequently causes infectious complications with cytomegalovirus (CMV). The extent of CMV replication can be followed by a number of diagnostic methods. There is, however, no simple diagnostic tool to assess the quality of the cellular antiviral immune response of an individual patient. This would be of particular importance for therapy decisions, as patients with detectable virus load do not necessarily develop CMV-related disease. Using a rapid whole blood assay, the frequencies of CMV-reactive CD4 and CD8 T cells were followed after renal transplantation to characterize their relative contribution in the containment of CMV infection. Methods. T cells from transplant patients and healthy control persons were stimulated with CMV antigen in vitro. Based on specific cellular activation and induction of intracellular cytokines, the frequency of CMV-reactive CD4 and CD8 T cells was determined using flow cytometry. Viral load was quantified using the “hybrid-capture” assay. Results. The absence of CMV complications in long-term transplant recipients is reflected by stable virus-specific T-cell frequencies, which do not differ from healthy CMV-positive controls. In contrast, during the first months after transplantation, clinical symptoms are preceded by a decrease in CMV-reactive CD4 T-cell frequencies and an increase in CMV load. Conclusions. The individual immune response and CMV replication are critically balanced and can be characterized by assessing both viral load and antiviral T cells. Our experimental design allows the identification of patients with sufficient, insufficient, or absent T-cell activity and can serve as diagnostic tool to facilitate decisions on antiviral therapy.

FGF-23 and future cardiovascular events in patients with chronic kidney disease before initiation of dialysis treatment

BACKGROUND High levels of the phosphaturic hormone fibroblast growth factor 23 (FGF-23) predict mortality in haemodialysis patients. The prognostic relevance of increased plasma FGF-23 levels in patients with less advanced chronic kidney disease (CKD) who are not on dialysis therapy is presently unknown. METHODS We measured plasma c-terminal FGF-23 levels in 149 CKD patients not undergoing dialysis treatment. Patients were stratified by their baseline FGF-23 levels (>104 vs ≤ 104 rU/mL) and followed for a period of 4.8  ±  0.9 years. During the follow-up, the pre-specified combined clinical endpoint was the first occurrence of a cardiovascular event, e.g. myocardial infarction, coronary artery angioplasty/stenting/bypass surgery, stroke, carotid endarterectomy/stenting, non-traumatic lower extremity amputation, lower limb artery surgery/angioplasty/stenting or death. RESULTS At baseline, elevated FGF-23 levels >104 rU/mL were associated with more advanced CKD. Traditional cardiovascular risk factors and prevalent cardiovascular disease did not differ between CKD patients with high vs low FGF-23 levels. Fifty patients experienced a cardiovascular event during follow-up. Compared with CKD patients with FGF-23 ≤104 rU/mL, CKD patients with FGF-23 levels above the cut-off had worse event-free survival at univariate (log-rank test P  =  0.012) and multivariate analysis [hazard ratio 2.49 (95% CI 1.40-4.39); P = 0.002]. CONCLUSIONS Elevated FGF-23 plasma levels predict cardiovascular events in CKD patients not on dialysis therapy. This finding complements two recent cohort studies in which incident and prevalent haemodialysis patients with highest FGF-23 levels had worst survival. Lowering FGF-23 levels (e.g. by oral phosphate binder medication) could emerge as a promising new therapeutic option to reduce cardiovascular morbidity in CKD patients.

Monocyte heterogeneity in obesity and subclinical atherosclerosis.

AIMS Monocytes and monocyte-derived macrophages have been recognised as the cellular hallmark of atherosclerosis decades ago. Recently, they have also been shown to play a pivotal role in obesity. Monocytes display immunophenotypic heterogeneity with functionally distinct subpopulations. We initiated the I LIKE HOMe study to examine monocyte heterogeneity in obesity and subclinical atherosclerosis. METHODS AND RESULTS We assessed carotid intima media thickness (IMT), body mass index (BMI), and other cardiovascular risk factors in 622 healthy volunteers. Using flow-cytometry, we differentiated monocytes into CD14(++)CD16(-) and CD16(+) cells, which we further subdivided into CD14(++)CD16(+) and CD14((+))CD16(+) cells. Body mass index was significantly correlated with carotid IMT. High CD16(+) monocyte counts were significantly associated with both higher BMI and increased carotid IMT. Adjustment for CD16(+) monocyte counts weakened the correlation between BMI and carotid IMT, suggesting that the increase in CD16(+) monocyte numbers in obesity may partly explain the association between obesity and IMT. CONCLUSION Our results reveal a significant univariate association between CD16(+) monocytes and both obesity and subclinical atherosclerosis in low-risk individuals. They are in line with recent observations that CD16(+) monocytes show high endothelial affinity and a potent capacity to invade vascular lesions and to transform into pro-inflammatory cytokine producing macrophages.

Monocyte subpopulations and cardiovascular risk in chronic kidney disease

Chronic microinflammation and its cellular hallmark, monocyte activation, contribute substantially to the tremendous burden of cardiovascular disease (CVD) in patients with chronic kidney diseases (CKD). Monocyte heterogeneity is widely acknowledged. Cell-surface expression of CD14 and CD16 defines three functionally and phenotypically distinct subsets of monocytes: classical (CD14++CD16−) monocytes, intermediate (CD14++CD16+) monocytes, and nonclassical (CD14+CD16++) monocytes. A growing body of circumstantial evidence suggests that intermediate monocytes, in particular, contribute to the development of atherosclerosis in the general population as well as in patients with CKD. Intermediate monocytes express a unique pattern of chemokine receptors that have been implicated in atherogenesis. Moreover, this subset of monocytes is predisposed to secrete proinflammatory cytokines. Findings from epidemiological studies indicate that numbers of intermediate monocytes increase with worsening renal function, and that high cell counts predict adverse outcomes in patients undergoing dialysis as well as in patients at early stages of CKD. Based on laboratory and clinical data, intermediate monocytes are a promising therapeutic target for CVD in patients with CKD.

Plasma Klotho is not related to kidney function and does not predict adverse outcome in patients with chronic kidney disease

A decreased expression of the fibroblast growth factor (FGF)-23 coreceptor Klotho was postulated as an early alteration in chronic kidney disease mineral and bone disorder, resulting in a compensatory increase in plasma FGF-23 levels. Klotho exists in both membrane-bound and secreted (sKlotho) forms, the latter of which may exert vasculoprotective effects. Here we analyzed plasma sKlotho levels in a large cohort of 312 patients with stage 2-4 chronic kidney disease, and assessed plasma levels of FGF-23, sKlotho, parathyroid hormone, and urinary fractional phosphate excretion. Patients were prospectively followed for an average of 2.2 years for the occurrence of death or initiation of renal replacement therapy. The levels of sKlotho were significantly associated with age, but not with the glomerular filtration rate or other parameters of calcium-phosphate metabolism. Moreover, while patients with high FGF-23 levels faced worst outcome even after adjustment for confounders, we found no prognostic impact of sKlotho. Thus, plasma levels of sKlotho were not related to kidney function and did not predict adverse outcome in patients with chronic kidney disease. Future studies are needed to understand how tissue expression, urinary excretion, and plasma levels of Klotho diverge in progressive chronic kidney disease.

Clinical relevance of FGF-23 in chronic kidney disease

Fibroblast growth factor (FGF)-23 is a recently discovered regulator of calcium-phosphate metabolism. Whereas other known FGFs mainly act in a paracrine manner, FGF-23 has significant systemic effects. Together with its cofactor Klotho, FGF-23 enhances renal phosphate excretion in order to maintain serum phosphate levels within the normal range. In patients with chronic kidney disease (CKD), FGF-23 levels rise in parallel with declining renal function long before a significant increase in serum phosphate concentration can be detected. However, in cross-sectional studies increased FGF-23 levels in patients with CKD were found to be associated not only with therapy-resistant secondary hyperparathyroidism but were also independently related to myocardial hypertrophy and endothelial dysfunction after adjustment for traditional markers of calcium-phosphate metabolism. Finally, in prospective studies high serum FGF-23 concentrations predicted faster disease progression in CKD patients not on dialysis, and increased mortality in patients receiving maintenance hemodialysis. FGF-23 may therefore prove to be an important therapeutic target in the management of CKD.

Monocyte heterogeneity in human cardiovascular disease

Atherosclerosis has been characterized as an inflammatory process, in which monocytes and monocyte-derived macrophages are of paramount importance. Contrasting with their established role in atherosclerosis, monocytes have not unanimously been found to predict cardiovascular events in large epidemiological studies. However, in these studies human monocyte heterogeneity has been largely overlooked so far. Three human monocyte subsets can be distinguished: classical CD14(++)CD16(-), intermediate CD14(++)CD16(+) and nonclassical CD14(+)CD16(++) monocytes. Of note, correct enumeration of subset counts requires appropriate staining and gating strategies that encompass a pan-monocytic marker (e.g. HLA-DR or CD86). In experimental studies on murine atherogenesis a monocyte subset-specific contribution to atherosclerosis has been established. However, major interspecies differences in atherogenesis itself, as well as in the immune system (including monocyte subset phenotype and distribution) preclude a direct extrapolation to human pathology. Experimental and pilot clinical studies point to a prominent involvement of intermediate CD14(++)CD16(+) monocytes in human atherosclerosis. Future clinical studies should analyze monocyte heterogeneity in cardiovascular disease. If a specific contribution of intermediate monocytes should be confirmed, immunomodulation of this monocyte subset could represent a future therapeutic target in atherosclerosis.