Matthew D. Jose

Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: new developments and revised recommendations

The publication of the Australasian Creatinine Consensus Working Groups position statements in 2005 and 2007 resulted in automatic reporting of estimated glomerular filtration rate (eGFR) with requests for serum creatinine concentration in adults, facilitated the unification of units of measurement for creatinine and eGFR, and promoted the standardisation of assays. New advancements and continuing debate led the Australasian Creatinine Consensus Working Group to reconvene in 2010. The working group recommends that the method of calculating eGFR should be changed to the Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) formula, and that all laboratories should report eGFR values as a precise figure to at least 90 mL/min/1.73 m2. Age‐related decision points for eGFR in adults are not recommended, as although an eGFR < 60 mL/min/1.73 m2 is very common in older people, it is nevertheless predictive of significantly increased risks of adverse clinical outcomes, and should not be considered a normal part of ageing. If using eGFR for drug dosing, body size should be considered, in addition to referring to the approved product information. For drugs with a narrow therapeutic index, therapeutic drug monitoring or a valid marker of drug effect should be used to individualise dosing. The CKD‐EPI formula has been validated as a tool to estimate GFR in some populations of non‐European ancestry living in Western countries. Pending publication of validation studies, the working group also recommends that Australasian laboratories continue to automatically report eGFR in Aboriginal and Torres Strait Islander peoples. The working group concluded that routine calculation of eGFR is not recommended in children and youth, or in pregnant women. Serum creatinine concentration (preferably using an enzymatic assay for paediatric patients) should remain as the standard test for kidney function in these populations.

The role of macrophages in allograft rejection.

Macrophage accumulation has long been recognized as a feature of allograft rejection, yet the role of macrophages in rejection remains underappreciated. Macrophages contribute to both the innate and acquired arms of the alloimmune response and thus may be involved in all aspects of acute and chronic allograft rejection. Recent advances in macrophage biology have allowed a better understanding of the mechanisms of macrophage accumulation, their state of activation and the pleuripotent roles they play in allograft rejection. Therapeutic attention to macrophages, in addition to T lymphocytes, may lead to improved outcomes in organ transplantation.

Macrophages act as effectors of tissue damage in acute renal allograft rejection

Background. Macrophages constitute 38% to 60% of infiltrating cells during acute renal allograft rejection. Their contribution to tissue damage during acute rejection was examined by depleting macrophages in a rat model. Methods. Lewis rats underwent bilateral nephrectomy and then received a Dark Agouti renal allograft and liposomal-clodronate, control phosphate-buffered saline liposomes, or saline intravenously (n=7 per group) on days 1 and 3 postsurgery. Grafts were harvested on day 5. Results. Liposomal-clodronate treatment resulted in a 70% reduction in blood ED1+ monocytes and 60% reduction in intragraft ED1+ macrophages (both P <0.01). Half of all remaining interstitial ED1+ cells were undergoing apoptosis (terminal deoxynucleotide transferase-mediated dUTP nick-end labeling+/ED1+), and thus functional depletion of more than 75% of macrophages was achieved. Histologic and functional parameters of acute rejection were attenuated: interstitial infiltrate, tubulitis, and glomerulitis (P <0.01); tubular cell apoptosis (P <0.001); tubular cell proliferation (P <0.001); and serum creatinine (P <0.01). Production of inducible nitric oxide synthase by infiltrating cells and urinary nitric oxide excretion was reduced by 90% (P <0.001). In contrast, no reduction in the number of other leukocytes was seen (CD3+, CD4+, CD8+, and natural killer cells). Activation of lymphocytes (CD25+) and production of lymphocyte effector molecules (granzyme B) were unaltered. Conclusion. This study demonstrates that macrophages contribute to tissue damage during acute rejection.

Review article: Luminex technology for HLA antibody detection in organ transplantation.

Since its inception in the early 1960s, the serologically based complement‐dependent cytotoxicity (CDC) assay has been the cornerstone technique for the detection of human leucocyte antigen (HLA) antibodies, not only in pre‐transplant renal patients, but also in other forms of organ transplantation. Recently, solid phase assays have been developed and introduced for this purpose, and in particular the Flow‐based bead assays such as the Luminex system. This latter assay has proved to be far more sensitive than the CDC assay and has revealed pre‐sensitization in potential transplant recipients not detected by other methods of HLA antibody detection. However, the clinical implications of this increased sensitivity have not been convincingly demonstrated until recently. This technology for HLA antibody detection permits the evaluation of the clinical importance of antibodies directed at, for example, HLA‐DPB1 and HLA‐DQA1, which has not been possible to date. There are Luminex issues, however, requiring resolution such as the ability to distinguish between complement fixing and non‐complement fixing antibodies and determination of their relative clinical significance. Luminex technology will permit a re‐evaluation of the role of HLA antibodies in both early and late antibody‐mediated rejection.

Blockade of Macrophage Colony-Stimulating Factor Reduces Macrophage Proliferation and Accumulation in Renal Allograft Rejection

Macrophage accumulation within an acutely rejecting allograft occurs by recruitment and local proliferation. To determine the importance of M‐CSF in driving macrophage proliferation during acute rejection, we blocked the M‐CSF receptor, c‐fms, in a mouse model of acute renal allograft rejection. C57BL/6 mouse kidneys (allografts, n = 20) or BALB/c kidneys (isografts, n = 5) were transplanted into BALB/c mice. Anti‐c‐fms antibody (AFS98) or control Ig (50 mg/kg/day, i.p.) was given daily to allografts from days 0–5. All mice were killed day 6 postoperatively. Expression of the M‐CSF receptor, c‐fms, was restricted to infiltrating CD68+ macrophages. Blockade of c‐fms reduced proliferating (CD68+/BrdU+) macrophages by 82% (1.1 v 6.2%, p < 0.001), interstitial CD68+ macrophage accumulation by 53% (595 v 1270/mm2, p < 0.001), and glomerular CD68+ macrophage accumulation by 71% (0.73 V 2.48 CD68+ cells per glomerulus, p < 0.001). Parameters of T‐cell involvement (intragraft CD4+, CD8+ and CD25+ lymphocyte numbers) were not affected. The severity of tubulointerstitial rejection was reduced in the treatment group as shown by decreased tubulitis and tubular cell proliferation. Macrophage proliferation during acute allograft rejection is dependent on the interaction of M‐CSF with its receptor c‐fms. This pathway plays a significant and specific role in the accumulation of macrophages within a rejecting renal allograft.

Macrophage colony-stimulating factor expression and macrophage accumulation in renal allograft rejection

BACKGROUND Studies of infiltrating cells from acutely rejecting renal allografts show that a high proportion of these cells are macrophages, and early macrophage infiltration is a poor prognostic sign for transplant survival. Macrophage colony-stimulating factor (M-CSF), produced by tubular and mesangial cells, has been associated with macrophage infiltration and proliferation in experimental and human kidney diseases. We investigated the expression of M-CSF in a model of acute rejection. METHODS Lewis rats underwent bilateral nephrectomies and received an orthotopic Dark Agouti allograft or Lewis isograft. Animals received cyclosporine (10 mg/kg/day) from day 0 to day 3 and were killed at days 4, 8, or 14 after transplantation. Macrophages (ED1+) and T cells (W3-13+) were identified by immunohistochemistry, and M-CSF expression was identified by Northern blotting and in situ hybridization. RESULTS Isografts had normal renal function without histological evidence of rejection. Allografts exhibited a moderate infiltrate at day 4 but progressed to severe rejection at day 14, with elevated serum creatinine level and severe tubulointerstitial damage. Macrophages and T cells were present in equal proportion in the infiltrate at day 4. At day 14, the number of macrophages increased fivefold (2580/mm2), although T cells were unchanged (380/mm2). Proliferating macrophages (ED1+, BrdU+) increased from day 4 (4%) to day 14 (10%). M-CSF mRNA expression was strongly up-regulated in allografts compared with isografts and normal rat. In situ hybridization demonstrated M-CSF expression by resident and infiltrating cells. Renal tubular expression was minimally increased at day 4 but strongly up-regulated at day 14 (more than 50% of tubules positive), particularly in areas of tubular damage. Tubular M-CSF expression colocalized with areas of intense macrophage infiltration and proliferation. Serial sections with double labeling demonstrated that T cells were the dominant source of M-CSF at day 4, yet later in the rejection (day 14) the predominant sites of production were both renal tubular cells and interstitial macrophages. CONCLUSIONS Renal production of M-CSF by graft-infiltrating (macrophages and T lymphocytes) and resident (tubular) cells was up-regulated during acute rejection. M-CSF promotes macrophage recruitment and proliferation and may thereby play a pathogenic role in acute rejection. The kinetics of M-CSF production during acute rejection suggest that local macrophage proliferation may be initiated by T cells and perpetuated by both renal tubular and autocrine release.

Retention of knowledge and perceived relevance of basic sciences in an integrated case-based learning (CBL) curriculum

BackgroundKnowledge and understanding of basic biomedical sciences remain essential to medical practice, particularly when faced with the continual advancement of diagnostic and therapeutic modalities. Evidence suggests, however, that retention tends to atrophy across the span of an average medical course and into the early postgraduate years, as preoccupation with clinical medicine predominates. We postulated that perceived relevance demonstrated through applicability to clinical situations may assist in retention of basic science knowledge.MethodsTo test this hypothesis in our own medical student cohort, we administered a paper-based 50 MCQ assessment to a sample of students from Years 2 through 5. Covariates pertaining to demographics, prior educational experience, and the perceived clinical relevance of each question were also collected.ResultsA total of 232 students (Years 2–5, response rate 50%) undertook the assessment task. This sample had comparable demographic and performance characteristics to the whole medical school cohort. In general, discipline-specific and overall scores were better for students in the latter years of the course compared to those in Year 2; male students and domestic students tended to perform better than their respective counterparts in certain disciplines. In the clinical years, perceived clinical relevance was significantly and positively correlated with item performance.ConclusionsThis study suggests that perceived clinical relevance is a contributing factor to the retention of basic science knowledge and behoves curriculum planners to make clinical relevance a more explicit component of applied science teaching throughout the medical course.

Remote indigenous peritoneal dialysis patients have higher risk of peritonitis, technique failure, all-cause and peritonitis-related mortality

BACKGROUND The number of indigenous patients with end-stage kidney disease (ESKD) is increasing in Australia, reflecting a similar trend in other countries. Because many indigenous patients live in remote areas, peritoneal dialysis (PD) is often preferred. Compared to non-indigenous PD patients, indigenous patients have increased complication rates but the effect of residential locations on outcomes remains unclear. The aim of this study is to examine the association between race and PD outcomes stratified by location. METHODS Using the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry, all adult ESKD patients commencing PD in Australia between 1995 and 2008 were included. Patients were stratified as non-indigenous or indigenous race and were grouped according to their residential location, the latter stratified into metropolitan, regional and remote areas. Outcomes evaluated included peritonitis, technique failure, peritonitis-related and all-cause mortality. RESULTS Regional and/or remote PD patients generally have a greater risk peritonitis-related complications and/or mortality compared to metropolitan patients. However, remote indigenous PD patients had the greatest risk of all PD-related complications, including all-cause and peritonitis-related mortality. CONCLUSIONS This registry analysis demonstrates that non-metropolitan PD patients, especially remote indigenous patients, have higher complication rates, suggesting that environmental factors are important in determining PD outcomes.

Dose adjustment guidelines for medications in patients with renal impairment: how consistent are drug information sources?

It is known that patients with renal disease are often administered inappropriate dosages of drugs. A lack of quantitative data in the available drug information sources and inconsistency in dosing information may augment the problem of dosing error.

Calcineurin inhibitors in renal transplantation: adverse effects

Date written: August 2005