Hypothesis: Bacterial induced inflammation disrupts the orderly progression of the stem cell hierarchy and has a role in the pathogenesis of breast cancer

BACKGROUND

The hierarchical model of stem cell genesis is based on the idea that the number of cell divisions between the zygote and fully differentiated epithelial cells is kept close to the minimum, which is log to the base 2 of the total number of cells produced in a human lifetime. The model assumes the orderly progression of stem cell divisions requires precise control at every stage in development. If the orderly progression is maintained then cancer will be rare. A prediction of the model is that if the orderly progression of the stem cell hierarchy is disturbed by trauma, ulceration or inflammation then cancer will occur.

HYPOTHESIS

Bacterial induced inflammation in breast ducts disturbs the stem cell hierarchy and is a cause of breast cancer.

EVIDENCE

Mammalian milk is not sterile. It contains a range of bacteria, derived endogenously by the entero-mammary circulation. The dominant flora consists of lactose fermenting bacteria. Pregnancy and breast feeding reduce the risk of subsequent breast cancer. The implication is that a lactose fermenting bacterial flora in breast ducts is protective. Malignant and benign breast tissue contains bacteria derived endogenously, but studies so far have not revealed a specific flora associated with malignancy. Periodontitis is associated with oral, oesophageal, colonic, pancreatic, prostatic and breast cancer. The pathogenic bacteria which cause periodontitis spread endogenously to cause inflammation at other epithelial sites. Meta-analysis of epidemiological studies shows that the consumption of yoghurt is associated with a reduction in the risk of breast cancer.

CONCLUSION

The hypothesis, although not proven, is supported by the available evidence. Lactose fermenting bacteria protect but pathogenic bacteria which induce inflammation raise the risk of breast cancer. The consumption of yoghurt also appears to be protective.

Plexin B2 and Semaphorin 4C Guide T Cell Recruitment and Function in the Germinal Center

Follicular T helper (T_FH) cells orchestrate the germinal center (GC) response locally. T_FH localization in GCs is controlled by chemo-guidance cues and antigen-specific adhesion. Here. we define an antigen-independent, contact-dependent, adhesive guidance system for T_FH cells. Unusual for amoeboid cell migration, the system is composed of transmembrane plexin B2 (PlxnB2) molecule, which is highly expressed by GC B cells, and its transmembrane binding partner semaphorin 4C (Sema4C), which is upregulated on T_FH cells. Sema4C on T_FH cells serves as a receptor to sense the GC-presented PlxnB2 cue and biases T_FH migration inwards at the GC edge to promote GC access. The absence of PlxnB2 from the GC or Sema4C from T_FH cells causes T_FH accumulation along the GC border, impairs T-B cell interactions in the GC, and is associated with defective plasma cell production and affinity maturation. Therefore, Sema4C and PlxnB2 regulate GC T_FH recruitment and function and optimize antibody responses.

B cell priming for extrafollicular antibody responses requires Bcl-6 expression by T cells

T follicular helper cells (Tfh cells) localize to follicles where they provide growth and selection signals to mutated germinal center (GC) B cells, thus promoting their differentiation into high affinity long-lived plasma cells and memory B cells. T-dependent B cell differentiation also occurs extrafollicularly, giving rise to unmutated plasma cells that are important for early protection against microbial infections. Bcl-6 expression in T cells has been shown to be essential for the formation of Tfh cells and GC B cells, but little is known about its requirement in physiological extrafollicular antibody responses. We use several mouse models in which extrafollicular plasma cells can be unequivocally distinguished from those of GC origin, combined with antigen-specific T and B cells, to show that the absence of T cell-expressed Bcl-6 significantly reduces T-dependent extrafollicular antibody responses. Bcl-6(+) T cells appear at the T-B border soon after T cell priming and before GC formation, and these cells express low amounts of PD-1. Their appearance precedes that of Bcl-6(+) PD-1(hi) T cells, which are found within the GC. IL-21 acts early to promote both follicular and extrafollicular antibody responses. In conclusion, Bcl-6(+) T cells are necessary at B cell priming to form extrafollicular antibody responses, and these pre-GC Tfh cells can be distinguished phenotypically from GC Tfh cells.

CD83 increases MHC II and CD86 on dendritic cells by opposing IL-10-driven MARCH1-mediated ubiquitination and degradation

Effective vaccine adjuvants must induce expression of major histocompatibility (MHC) class II proteins and the costimulatory molecule CD86 on dendritic cells (DCs). However, some adjuvants elicit production of cytokines resulting in adverse inflammatory consequences. Development of agents that selectively increase MHC class II and CD86 expression without triggering unwanted cytokine production requires a better understanding of the molecular mechanisms influencing the production and degradation of MHC class II and CD86 in DCs. Here, we investigate how CD83, an immunoglobulin protein expressed on the surface of mature DCs, promotes MHC class II and CD86 expression. Using mice with an N-ethyl-N-nitrosourea-induced mutation eliminating the transmembrane (TM) region of CD83, we found that the TM domain of CD83 enhances MHC class II and CD86 expression by blocking MHC class II association with the ubiquitin ligase MARCH1. The TM region of CD83 blocks interleukin 10-driven, MARCH1-dependent ubiquitination and degradation of MHC class II and CD86 in DCs. Exploiting this posttranslational pathway for boosting MHC class II and CD86 expression on DCs may provide an opportunity to enhance the immunogenicity of vaccines.

IL-21 acts directly on B cells to regulate Bcl-6 expression and germinal center responses

During T cell–dependent responses, B cells can either differentiate extrafollicularly into short-lived plasma cells or enter follicles to form germinal centers (GCs). Interactions with T follicular helper (Tfh) cells are required for GC formation and for selection of somatically mutated GC B cells. Interleukin (IL)-21 has been reported to play a role in Tfh cell formation and in B cell growth, survival, and isotype switching. To date, it is unclear whether the effect of IL-21 on GC formation is predominantly a consequence of this cytokine acting directly on the Tfh cells or if IL-21 directly influences GC B cells. We show that IL-21 acts in a B cell–intrinsic fashion to control GC B cell formation. Mixed bone marrow chimeras identified a significant B cell–autonomous effect of IL-21 receptor (R) signaling throughout all stages of the GC response. IL-21 deficiency profoundly impaired affinity maturation and reduced the proportion of IgG1⁺ GC B cells but did not affect formation of early memory B cells. IL-21R was required on GC B cells for maximal expression of Bcl-6. In contrast to the requirement for IL-21 in the follicular response to sheep red blood cells, a purely extrafollicular antibody response to Salmonella dominated by IgG2a was intact in the absence of IL-21.

Logic and extent of miRNA-mediated control of autoimmune gene expression

Over the past few decades, multiple mechanisms have emerged that operate to prune the lymphocyte repertoire of self-reactive specificities and maintain immunological tolerance. Multiple families of small noncoding RNAs known as microRNAs (miRNAs) target immune transcripts to fine-tune gene expression and turn on negative feedback loops. Both of these actions are crucial to limit co-stimulation, set precise cellular activation thresholds, curtail inflammation, control lymphocyte growth, and maintain regulatory T cell homeostasis and suppressive function. Analysis of predicted miRNA-mediated regulation of 72 lupus susceptibility genes in humans and mice reveals most contain numerous target sites for over 140 miRNAs conserved in mammals. MECP2, ROQUIN/RC3H1, BCL2, BIM, and PTEN contain over 50 miRNA target sites each, highlighting the need to control their final protein products with enormous precision to maintain the balance between immunity and tolerance. Overlap among targets of individual miRNAs is considerable, with each miRNA targeting a median of nine autoimmune genes. Three miRNAs--miR-181, miR-186, and miR-590-3p--together are predicted to target over 50% of all lupus genes. Also, a single miRNA cluster located at 14q32.31 containing 11 miRNAs is predicted to regulate 48 lupus susceptibility genes. Dysregulation of single or a few miRNAs or miRNA clusters can result from genetic variation, hormonal influences, or environmental triggers including EBV infection. In the light of this vast and promiscuous miRNA-mediated regulation of autoimmune genes it is anticipated that changes in miRNA levels or their target sequences will help explain susceptibility to complex autoimmune diseases.

Follicular helper T cells are required for systemic autoimmunity

Production of high-affinity pathogenic autoantibodies appears to be central to the pathogenesis of lupus. Because normal high-affinity antibodies arise from germinal centers (GCs), aberrant selection of GC B cells, caused by either failure of negative selection or enhanced positive selection by follicular helper T (T(FH)) cells, is a plausible explanation for these autoantibodies. Mice homozygous for the san allele of Roquin, which encodes a RING-type ubiquitin ligase, develop GCs in the absence of foreign antigen, excessive T(FH) cell numbers, and features of lupus. We postulated a positive selection defect in GCs to account for autoantibodies. We first demonstrate that autoimmunity in Roquin(san/san) (sanroque) mice is GC dependent: deletion of one allele of Bcl6 specifically reduces the number of GC cells, ameliorating pathology. We show that Roquin(san) acts autonomously to cause accumulation of T(FH) cells. Introduction of a null allele of the signaling lymphocyte activation molecule family adaptor Sap into the sanroque background resulted in a substantial and selective reduction in sanroque T(FH) cells, and abrogated formation of GCs, autoantibody formation, and renal pathology. In contrast, adoptive transfer of sanroque T(FH) cells led to spontaneous GC formation. These findings identify T(FH) dysfunction within GCs and aberrant positive selection as a pathway to systemic autoimmunity.

Suppressor of cytokine signaling 3 (SOCS3) limits damage-induced crypt hyper-proliferation and inflammation-associated tumorigenesis in the colon

Intestinal injury or chronic inflammation induce cytokines that promote crypt regeneration and mucosal repair. If excessive or prolonged, such mechanisms may increase colon cancer risk. Factors that terminate or limit cytokine action in intestinal epithelial cells (IEC) may protect against crypt hyperplasia and neoplasia. We hypothesized that suppressor of cytokine signaling-3 (SOCS3) is such a factor. Mice with Vilin-promoter/Cre-recombinase (VC)-mediated IEC-specific SOCS3 gene disruption (VC/HO), WT/HO littermates with floxed but intact SOCS3 genes and VC/WT mice were studied. Colon was examined after acute dextran sodium sulfate (DSS)-induced mucosal injury or after azoxymethane (AOM) and chronic DSS. Signaling pathways were examined in colon, cultured IEC or colon cancer cell lines. VC/HO mice showed no basal phenotype. After acute DSS, VC/HO exhibited enhanced crypt proliferation and crypt hyperplasia and reduced transforming growth factor (TGF) beta expression in colon. Inflammation and mucosal damage were similar across genotypes. Following AOM/DSS, VC/HO mice had increased size, number and load of colonic tumors and increased STAT3 and nuclear factor-kappa B (NF-kappaB) activation in colon. In vitro, SOCS3 overexpression reduced proliferation, IL-6-mediated STAT3 activation and tumor necrosis factor (TNF) alpha-mediated NF-kappaB activation. We conclude that cytokine induction of SOCS3 normally provides an intrinsic mechanism to limit injury-induced crypt hyperproliferation and inflammation-associated colon cancer by regulating both STAT3 and NF-kappaB pathways.

Identification of chromosome intervals from 129 and C57BL/6 mouse strains linked to the development of systemic lupus erythematosus

Systemic lupus erythematosus is an autoimmune disease in which complex interactions between genes and environmental factors determine the disease phenotype. We have shown that genes from the non-autoimmune strains 129 and C57BL/6 (B6), commonly used for generating gene-targeted animals, can induce a lupus-like disease. Here, we conducted a genome-wide scan analysis of a cohort of (129 x B6)F2 C1q-deficient mice to identify loci outside the C1qa locus contributing to the autoimmune phenotype described in these mice. The results were then confirmed in a larger dataset obtained by combining the data from the C1q-deficient mice with data from previously reported wild-type mice. Both analyses showed that a 129-derived interval on distal chromosome 1 is strongly linked to autoantibody production. The B6 genome contributed to anti-nuclear autoantibody production with an interval on chromosome 3. Two regions were linked to glomerulonephritis: a 129 interval on proximal chromosome 7 and a B6 interval on chromosome 13. These findings demonstrate that interacting loci between 129 and B6 mice can cause the expression of an autoimmune phenotype in gene-targeted animals in the absence of any disrupted gene. They also indicate that some susceptibility genes can be inherited from the genome of non-autoimmune parental strains.

Mice, humans and haplotypes—the hunt for disease genes in SLE

Defining the polymorphisms that contribute to the development of complex genetic disease traits is a challenging, although increasingly tractable problem. Historically, the technical difficulties in conducting association studies across the entire human genome are such that murine models have been used to generate candidate genes for analysis in human complex diseases, such as SLE. In this article we discuss the advantages and disadvantages of this approach and specifically address some assumptions made in the transition from studying one species to another, using lupus as an example. These issues include differences in genetic structure and genetic organisation which are a reflection on the population history. Clearly there are major differences in the histories of the human population and inbred laboratory strains of mice. Both human and murine genomes do exhibit structure at the genetic level. That is to say, they comprise haplotypes which are genomic regions that carry runs of polymorphisms that are not independently inherited. Haplotypes therefore reduce the number of combinations of the polymorphisms in the DNA in that region and facilitate the identification of disease susceptibility genes in both mice and humans. There are now novel means of generating candidate genes in SLE using mutagenesis (with ENU) in mice and identifying mice that generate antinuclear autoimmunity. In addition, murine models still provide a valuable means of exploring the functional consequences of genetic variation. However, advances in technology are such that human geneticists can now screen large fractions of the human genome for disease associations using microchip technologies that provide information on upwards of 100,000 different polymorphisms. These approaches are aimed at identifying haplotypes that carry disease susceptibility mutations and rely less on the generation of candidate genes.

Production of interleukin (IL)-10 and IL-12 by murine colonic dendritic cells in response to microbial stimuli

Intestinal dendritic cells (DC) are likely to regulate immunity to gut microflora, but little is known about their responses to bacterial antigens. Therefore, DC from normal murine colon were characterized and their cytokine responses to components of Gram-negative and/or Gram-positive bacteria assessed. Cells were obtained by digestion of colonic tissue and contained DC that were identified by flow cytometry as CD11c(+) major histocompatibility complex (MHC) class II(+) cells. Purified DC were obtained by immunomagnetic separation plus cell sorting. DC had the morphology of immature myeloid cells, were endocytically active, expressed low levels of co-stimulatory molecules and stimulated a weak allogeneic mixed leucocyte reaction. Analysis of flow cytometry data by a sensitive subtraction method allowed measurement of production of interleukin (IL)-12 and IL-10 by small numbers of gut DC by intracellular staining. Fewer than 5% of unstimulated DC produced either IL-10 or IL-12. IL-10 production was significantly up-regulated following stimulation with Bifidobacteria longum, but not after exposure to lipopolysaccharide (LPS) or Streptococcus faecium. In contrast, colonic DC produced IL-12 in response to both LPS and B.longum. Thus, colonic DC can produce both IL-12 and IL-10 following bacterial stimulation. Cell wall components from different bacteria stimulate distinct responses and may direct immune responses differentially in the gut.

Multiple loci are linked with anti-red blood cell antibody production in NZB mice -- comparison with other phenotypes implies complex modes of action

The New Zealand Black (NZB) mouse strain is a model of autoimmune haemolytic anaemia (AHA) and systemic lupus erythematosus (SLE), characterized by the production of anti-red blood cell (RBC) antibodies and anti-nuclear antibodies (ANA), respectively. A linkage analysis was carried out in an (NZB x BALB/c) F(2) cross in order to identify loci involved in the production of both anti-RBC IgM and IgG antibodies. These regions of linkage were compared with linkage data to ANA from the same cohort and other linkage analyses involving New Zealand mice. Four previously described NZB loci linked to anti-RBC antibodies were confirmed, and eight novel loci linked to this trait were also mapped: five of which were of NZB origin, and three derived from the non-autoimmune BALB/c background. A comparison between loci linked with anti-RBC antibodies and ANA demonstrated many that co-localize, suggesting the presence of genes that result in the general breaking of tolerance to self-antigen. Furthermore, the observation that some loci were associated only with the anti-RBC response suggests an antigen specific mechanism in addition to a general breaking of tolerance. A locus linked with anti-RBC antibodies and ANA on distal chromosome 7 in this cohort is orthologous to one on the q arm of human chromosome 11, a region linked to AHA and ANA in human SLE.

Spontaneous autoimmunity in 129 and C57BL/6 mice-implications for autoimmunity described in gene-targeted mice

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder in which complex genetic factors play an important role. Several strains of gene-targeted mice have been reported to develop SLE, implicating the null genes in the causation of disease. However, hybrid strains between 129 and C57BL/6 mice, widely used in the generation of gene-targeted mice, develop spontaneous autoimmunity. Furthermore, the genetic background markedly influences the autoimmune phenotype of SLE in gene-targeted mice. This suggests an important role in the expression of autoimmunity of as-yet-uncharacterised background genes originating from these parental mouse strains. Using genome-wide linkage analysis, we identified several susceptibility loci, derived from 129 and C57BL/6 mice, mapped in the lupus-prone hybrid (129 × C57BL/6) model. By creating a C57BL/6 congenic strain carrying a 129-derived Chromosome 1 segment, we found that this 129 interval was sufficient to mediate the loss of tolerance to nuclear antigens, which had previously been attributed to a disrupted gene. These results demonstrate important epistatic modifiers of autoimmunity in 129 and C57BL/6 mouse strains, widely used in gene targeting. These background gene influences may account for some, or even all, of the autoimmune traits described in some gene-targeted models of SLE.

Several strains of gene-targeted mice develop systemic lupus erythematosus (SLE). Analysis of these strains demonstrates that the genetic background profoundly influences the development of autoimmunity

New loci from New Zealand Black and New Zealand White mice on chromosomes 4 and 12 contribute to lupus-like disease in the context of BALB/c

New Zealand Black (NZB) and New Zealand White (NZW) mice are genetically predisposed to a lupus-like autoimmune syndrome. To further define the loci linked to disease traits in NZB and NZW mice in the context of the BALB/c genetic background, linkage analyses were conducted in two crosses: (NZW x BALB/c.H2(z))F(1) x NZB and (NZB x BALB/c)F(2). Novel loci linked to autoantibody production and glomerulonephritis, present in both NZB and NZW mice, were identified on proximal chromosomes 12 and 4. The chromosome 12 locus showed the strongest linkage to anti-nuclear Ab production. Additionally, a number of other novel loci linked to lupus traits derived from both the New Zealand and non-autoimmune BALB/c genomes were identified. Furthermore, we confirm the linkage of disease to a number of previously described lupus-associated loci, demonstrating that they are relatively background independent. These data provide a number of additional candidate gene regions in murine lupus, and highlight the powerful effect the non-autoimmune background strain has in influencing the genetic loci linked to disease.

A novel locus regulates both retroviral glycoprotein 70 and anti-glycoprotein 70 antibody production in New Zealand mice when crossed with BALB/c

Lupus-prone New Zealand Black and New Zealand White mice produce high serum levels of the endogenous retroviral envelope protein gp70 and develop an Ab response to this autoantigen as part of their autoimmune disease. Linkage analysis of two crosses involving New Zealand and BALB/c mice mapped these traits to a group of overlapping loci, including a novel locus on proximal chromosome 12. This locus was linked with serum gp70 and the autoimmune response against it. The linkage of serum gp70 levels to a previously described locus on distal chromosome 4 was also confirmed. Sequence analysis of a candidate gene on distal chromosome 4, Fv1, provided support that this gene may be associated with the control of serum gp70 levels in both New Zealand Black and New Zealand White mice. Linkage data and statistical analysis confirmed a close correlation between gp70 Ag and anti-gp70 Ab levels, and together gave support to the concept that a threshold level of gp70 is required for the production of anti-gp70 Abs. Serum levels of anti-gp70 Abs were closely correlated with the presence of renal disease, more so than anti-dsDNA Abs. Understanding the genetic basis of this complex autoantigen-autoantibody system will provide insight into the pathogenesis of lupus in mice, which may have implications for human disease.

A retrospective analysis of mycophenolic acid and cyclosporin concentrations with acute rejection in renal transplant recipients

OBJECTIVES

Although monitoring of cyclosporin (CsA) is standard clinical practice postrenal transplantation, mycophenolic acid (MPA) concentrations are not routinely measured. There is evidence that a relationship exists between MPA area under the concentration-time curve (AUC) and rejection. In this study, a retrospective analysis was undertaken of 27 adult renal transplant recipients.

METHODS

Patients received CsA and MPA therapy and had a four-point MPA AUC investigation. The relationship between MPA AUC performed in the first week after transplantation, as well as median trough cyclosporin concentrations, and clinical outcomes in the first month posttransplant were evaluated.

RESULTS

A total of 12 patients experienced biopsy proven rejection (44.4%) and 4 patients had gastrointestinal adverse events (14.8%). A statistically significant relationship was observed between the incidence of biopsy proven rejection and both MPA AUC (p = 0.02) and median trough CsA concentration (p = 0.008). No relationship between trough MPA concentration and rejection was observed (p = 0.21). Only 3 of 11 (27%) patients with an MPA AUC > 30 mg x h/L and a median trough CsA > 175 microg/L experienced acute rejection, compared with a 56% incidence of rejection for the remaining 16 patients. Patients who experienced adverse gastrointestinal events had significantly lower MPA AUC (p = 0.04), but median trough CsA concentrations were not significantly different (p = 0.24). Further, 3 of these 4 patients had rejection episodes.

CONCLUSIONS

In addition to standard CsA monitoring, we propose further investigation of the use of a 4-point sampling strategy to predict MPA AUC in the first week posttransplant, which may facilitate optimization of mycophenolate mofetil dose at a time when patients are most vulnerable to acute rejection.

Is obesity a favorable prognostic factor in peritoneal dialysis patients?

OBJECTIVE

To determine the influence of an elevated body mass index (BMI) on cardiovascular outcomes and survival in peritoneal dialysis (PD) patients.

DESIGN

Prospective, observational study of a prevalent PD cohort at a single center.

SETTING

Tertiary care institutional dialysis center.

PATIENTS

The study included all patients with a BMI of at least 20 who had been receiving PD for at least 1 month as of 31 January 1996 (n = 43). Patients were classified as overweight [BMI > 27.5; mean +/- standard error of mean (SEM): 32.1 +/- 1.1; n = 14] or normal weight (BMI 20-27.5; mean +/- SEM: 23.8 +/- 0.4; n = 29).

OUTCOME MEASURES

Patient survival and adverse cardiovascular events (myocardial infarction, congestive cardiac failure, cerebrovascular accident, and symptomatic peripheral vascular disease) were recorded over a 3-year period.

RESULTS

At baseline, no significant differences were seen between the groups in clinical, biochemical, nutritional, or echocardiographic parameters, except for a lower dietary protein intake (0.97 +/- 0.10 g/kg/day vs 1.44 +/- 0.10 g/kg/day, p = 0.004) and a higher proportion of well-nourished patients by subjective global assessment (100% vs 72%, p < 0.05) in the overweight group. After 3 years of follow-up, 29% of overweight patients and 69% of normal-weight patients had died (p < 0.05). Using a Cox proportional hazards model, a BMI greater than 27.5 was shown to be an independent positive predictor of patient survival, with an adjusted hazard ratio (HR) of 0.09 [95% confidence interval (CI): 0.01-0.85; p < 0.05]. However, being overweight did not significantly influence myocardial infarction-free survival (adjusted HR: 0.33; 95% CI: 0.07-1.48; p = 0.15) or combined adverse cardiovascular event-free survival (adjusted HR: 0.67; 95% CI: 0.23-1.93; p = 0.46).

CONCLUSIONS

Obesity conferred a significant survival advantage in our PD population. Obese patients should therefore not be discouraged from receiving PD purely on the basis of BMI. Moreover, maintaining a higher-than-average BMI to preserve "nutritional reserve" may help to reduce the mortality and morbidity rates associated with PD.

Novel surveillance and cure of a donor-transmitted lymphoma in a renal allograft recipient

BACKGROUND

In this report we describe a malignant lymphoma of donor origin inadvertently transplanted into two renal allograft recipients, despite standard comprehensive donor screening. The successful clearance of the tumor from both patients and a novel method of surveillance are detailed.

METHODS

Initial management consisted of withdrawal of immunosuppression to promote rejection of the allograft and the transplanted tumor in both patients, followed by graft removal. Peripheral blood microchimerism was assessed in both recipients using nested polymerase chain reaction to detect the DYZ3 gene on the Y chromosome (donor male, recipients female).

RESULTS

Although microchimerism was detected on day 6 after transplantation and day 1 after explantation, repeat peripheral blood examination at 1, 3, and 6 months after explantation demonstrated no microchimerism. Both patients remain well at 12 months and have been relisted for transplantation.

CONCLUSION

Despite inadvertent transplantation of a previously undiagnosed malignancy of donor origin, the recipients' immune response was able to eliminate donor tumor cells after the withdrawal of immunosuppression. Repeated surveillance of peripheral blood from both recipients, using a novel application of the technique of nested polymerase chain reaction to amplify donor DNA, demonstrated no persistence of donor cells, supporting effective eradication of the donor malignancy.

A comparison of the effects of dialysis and renal transplantation on the survival of older uremic patients

BACKGROUND

Patients over age 60 constitute half of all new patients accepted into the renal replacement therapy programs in Australia. However, the optimal treatment of their end-stage renal disease remains controversial. The aim of the present study was to compare survival for dialysis and renal transplantation in older patients who were rigorously screened and considered eligible for transplantation.

METHODS

The study cohort consisted of 174 consecutive patients over 60 who were accepted on to the Queensland cadaveric renal transplant waiting list between January 1, 1993 and December 31, 1997. Follow-up was terminated on October 1, 1998. Data were analyzed on an intention-to-transplant basis using a Cox regression model with time-varying explanatory variables. An alternative survival analysis was also performed, in which patients no longer considered suitable for transplantation were censored at the time of their removal from the waiting list.

RESULTS

There were 67 patients receiving a renal transplant, whereas the other 107 continued to undergo dialysis. These two groups were well matched at baseline with respect to age, gender, body mass index, renal disease etiology, comorbid illnesses, and dialysis duration and modality. The overall mortality rate was 0.096 per patient-year (0.131 for dialysis and 0.029 for transplant, P<0.001). Respective 1-, 3- and 5-year survivals were 92%, 62%, and 27% for the dialysis group and 98%, 95%, and 90% (P<0.01) for the transplant group. Patients in the transplant group had an adjusted hazard ratio 0.16 times that of the dialysis group (95% confidence interval 0.06-0.42). If patients were censored at the time of their withdrawal from the transplant waiting list, the adjusted hazard ratio was 0.24 (95% confidence interval 0.09-0.69).

CONCLUSIONS

Renal transplantation seems to confer a substantial survival advantage over dialysis in patients with end-stage renal failure who are rigorously screened and considered suitable for renal transplantation.

The kinetics of mycophenolic acid and its glucuronide metabolite in adult kidney transplant recipients

BACKGROUND

Mycophenolic acid kinetics have been reported to vary after renal transplantation, and mycophenolic acid area under the concentration-time curve (AUC) is the best predictor of suppression of graft rejection.

METHODS

To determine whether mycophenolic acid kinetics vary after renal transplantation and to examine the potential role of enterohepatic recirculation, we investigated the kinetics of mycophenolic acid and mycophenolic acid glucuronide on days 2, 5, and 28 after transplantation in 10 kidney transplant recipients (male/female ratio, 1.5; mean age, 41.7 +/- 5.0 years) given 1 g mycophenolate mofetil twice a day. To facilitate therapeutic drug monitoring, we examined a limited sampling strategy for estimating 12-hour mycophenolic acid [AUC(0-12)].

RESULTS

The mean +/- SE AUC(0-12) for mycophenolic acid on day 28 was 38.5 +/- 1.6 mg x h/L, with a secondary peak 4 to 8 hours after dosing that was attributable to enterohepatic recirculation. Marked variability was shown in the kinetic profile of mycophenolic acid among patients across the three sampling days. Mycophenolic acid AUC(0-12) was positively predicted by both serum creatinine (P = .01) and serum albumin (P = .03) but not by time after transplantation, body weight, or trough concentration. Limited sampling (at 0, 1, 3, and 6 hours) accounted for 84.1% of the variability in the mycophenolic acid AUC(0-12) data and predicted the AUC(0-12) closely (r2 = 0.954) when evaluated in 10 different kidney transplant recipients.

CONCLUSIONS

Mycophenolic acid AUC(0-12) is predicted by serum albumin and creatinine after kidney transplantation, and the AUC(0-12) may be determined during the early posttransplant period while the patient remains hospitalized with use of a limited sampling strategy to facilitate therapeutic drug monitoring.

Serum leptin correlates with fat mass but not dietary energy intake in continuous ambulatory peritoneal dialysis patients

OBJECTIVES

In view of previous studies demonstrating hyperleptinemia in uremic and hemodialysis patients, the aims of the present study were to determine whether serum leptin levels are elevated in peritoneal dialysis (PD) patients, to establish whether leptin is significantly removed by PD, and to elucidate the relationship of plasma leptin to body composition, dietary intake, nutritional indices, and dialysis adequacy.

DESIGN

Cross-sectional analysis of PD patients and matched healthy controls.

SETTING

Tertiary-care institutional dialysis center.

PARTICIPANTS

The study included 49 PD patients [35 women and 14 men; median age 63 years, interquartile range (IQR) 49.5-68.5 yr; body mass index (BMI) 25.5 +/- 0.8] and 27 controls (11 men and 16 women; median age 42 years, IQR 34.8-51; BMI 27.2 +/- 0.9). For evaluation of leptin clearance, 8 patients receiving nocturnal intermittent PD were also evaluated.

MAIN OUTCOME MEASURES

The primary outcome measure was plasma leptin concentration. Dialysate leptin concentration was also measured in 7 patients.

RESULTS

Serum leptin levels were significantly higher (p < 0.01) in patients (males: median 11 ng/mL, IQR 9-19 ng/mL; females: 53 ng/mL, 19.5-128 ng/mL) compared with controls (males: 5.5 ng/mL, 4-9.5 ng/mL; females: 12 ng/mL, 9.8-17.3 ng/mL). Leptin levels in both groups correlated positively with BMI (r = 0.64 and 0.60, respectively; p < 0.0001) and with percentage body fat determined by dual-energy x-ray absorptiometry (r = 0.86 and 0.82, respectively; p < 0.01). Dialysis patients exhibited a greater increase in serum leptin for any given increase in BMI. No significant correlation was observed between leptin concentration and residual renal function, dialysis adequacy (Kt/V), dietary protein or caloric intake, or serum levels of albumin, prealbumin, C-reactive protein, glucose, and insulin-like growth factor-I. Although leptin was detectable in peritoneal dialysate after a 6-hour dwell (median 4.2 ng/mL, IQR 1.1-8.5 ng/mL, n = 8), serum leptin levels were not appreciably lowered following intermittent PD via an automated cycler (63.9 +/- 19.3 ng/mL vs 57.6 +/- 20.5 ng/mL, p = NS, n = 8).

CONCLUSIONS

Serum leptin levels are elevated in PD patients and are not appreciably cleared by PD. Although hyperleptinemia correlates poorly with dialysis adequacy and protein intake, a strong and significant relationship was maintained between serum leptin and fat mass. Serum leptin could therefore serve as a useful clinical marker of body fat content in PD patients.

Sclerosing peritonitis: the experience in Australia

BACKGROUND

Sclerosing peritonitis (SP) is a rare but serious complication of peritoneal dialysis (PD). Small-bowel obstruction (SBO) due to encapsulation, dense adhesions, or mural fibrous is characteristic, often associated with peritonitis. The aim of the study was to determine the incidence, clinical features, effect of duration of dialysis, and other possible aetiological factors in severe SP.

METHODS

All dialysis units in Australia were surveyed for possible cases up to 1994. Patients were included if there was either surgical or radiological evidence of sclerosing encapsulating peritonitis or SBO with tanned or thickened peritoneum in the absence of other causes of SBO.

RESULTS

Fifty-four patients were analysed. The duration of continuous PD was mean 52 +/- 30 months, median 48 months and range 8-127 months. Nineteen cases were diagnosed between 1980 and 1989 and 35 between 1990 and 1994, giving mean annual incidences 1.9 and 4.2 per 1000 PD periods respectively. The overall prevalence was 0.7%, which increased progressively with the duration of PD being 1.9, 6.4, 10.8, and 19.4% for patients on dialysis for > 2, 5, 6 and 8 years respectively. Sclerosing encapsulating peritonitis was diagnosed in 87% of cases, SBO in 92%, and haemoperitoneum in 8%. Peritoneal calcification was present in seven cases, all of which had been on PD > 7 years. Peritonitis was associated with 38% of cases with fungal infection in 7%. Treatment with immunosuppression in five patients appeared to result in a favourable outcome in three. The mortality rate was 56%.

CONCLUSION

Severe sclerosing peritonitis is a serious complication of peritoneal dialysis and there is a time dependent increase on CAPD.

The role of DEXA bone densitometry in evaluating renal osteodystrophy in continuous ambulatory peritoneal dialysis patients

OBJECTIVE

The aims of this study were to assess the clinical utility of total and regional bone densitometry in a large continuous ambulatory peritoneal dialysis (CAPD) population and to determine the clinical, biochemical, and radiographic variables that best identified osteopenic CAPD patients.

DESIGN AND PATIENTS

A cross-sectional study was performed on 45 CAPD patients (19 males, 26 females), comprising the total CAPD population at the Princess Alexandra Hospital.

MAIN OUTCOME MEASURES

Total body (TB), anteroposterior lumbar spine (APL), femoral neck (FN), Ward's triangle (WT), and skull bone mineral densities (BMDs) were measured using dual-energy x-ray absorptiometry (DEXA) and then correlated with clinical, biochemical, and radiographic indices of uremic osteodystrophy.

RESULTS

BMDs were not significantly different from age- and sex-matched reference population data. Considerable regional variation of BMD Z scores were noted between FN (-0.11 +/- 0.23), WT (-0.11 +/- 0.22), and APL (1.22 +/- 0.04) (p = 0.003). APLZ scores were significantly reduced in patients with a previous history of fracture (-1.36 +/- 1.07 vs 0.89 +/- 0.31), bone pain (-0.72 +/- 1.08 vs 1.01 +/- 0.31), or steroid treatment (-0.62 +/- 0.39 vs 1.16 +/- 0.35). Increased BMD Z scores for APL (1.82 +/- 0.57 vs 0.38 +/- 0.29, p < 0.05), FN (0.32 +/- 0.36 vs -0.38 +/- 0.29, p = 0.014), and WT (0.45 +/- 0.38 vs -0.45 +/- 0.26, p < 0.05) were found in patients with radiographic hyperparathyroid bone disease. Both APL BMD Z scores and skull BMDs were weakly correlated with PTH (r = -0.33, p < 0.05 and r = -0.33, p < 0.05, respectively) and with CAPD duration (r = 0.30, p < 0.05 and r = -0.30, p < 0.05). Generally, however, total body and regional BMDs were poorly related to age, renal disease type, dialysis duration, renal failure duration, serum aluminum, calcium, phosphate, alkaline phosphatase, osteocalcin, and parathyroid hormone.

CONCLUSIONS

We conclude that the prevalence of osteopenia is not increased in CAPD patients. Clinical and biochemical parameters do not reliably predict BMD measurements, but prior steroids and bone symptoms are major risk factors for important bone loss. Although DEXA can reliably detect osteopenia in different skeletal regions, its usefulness in detecting osteodystrophy is limited by the confounding effects of superimposed hyperparathyroid osteosclerosis, which increases BMD.

A randomized trial comparing 1.25 mmol/l calcium dialysate to 1.75 mmol/l calcium dialysate in CAPD patients

BACKGROUND

Effective control of hyperparathyroidism and renal osteodystrophy in CAPD patients requires a combination of calcitriol and calcium carbonate (CaCO3), but is frequently limited by hypercalcaemia. Reducing dialysate calcium (Ca) concentration may overcome this problem, but had not been examined in a controlled trial.

METHODS

45 stable CAPD patients were randomly assigned in a prospective double-blind trial to either a study group (1.25 mmol/l Ca dialysate) or a control group (1.75 mmol/l Ca dialysate) for 12 months. Clinical, biochemical and radiological parameters of secondary hyperparathyroidism were followed.

RESULTS

Twenty-three patients did not complete the study due to death (9), transplantation (7) or conversion to haemodialysis (7). Eleven patients in each group completed the study. Mean serum Ca, phosphate, ionized Ca, aluminium, alkaline phosphatase (AP), and bone mineral density (BMD) Z-scores did not differ significantly at any time within or between the two groups. Severe hypercalcaemia was more common in the control group (11 vs. 2, P = 0.027). Mean serum intact parathyroid hormone (PTH) and osteocalcin (OCN) initially rose in the study group relative to controls at 3 months (40 +/- 7 vs 12 +/- 3 pmol/l, P = 0.004, and 33 +/- 5 vs 15 +/- 2 micrograms/l, P = 0.002 respectively), but were not sustained. Median weekly dosages of calcitriol and daily dosages of CaCO3 increased significantly in the study group (O microgram to 1 microgram P = 0.014 and 1260 mg to 2520 mg P = 0.002 respectively), but not in the control group. Supplementary aluminium hydroxide (A1, (OH)3) was required for phosphate control in both study (n = 5) and control patients (n = 4).

CONCLUSIONS

Lowering dialysate calcium concentration reduced the frequency of severe hypercalcaemia and allowed prescription of larger quantities of calcitriol and CaCO3. However, in this study it offered no advantage in terms of A1(OH)3 requirement, while bone mass density did and may have initially exacerbated secondary hyperparathyroidism not change.

Recovery of gastrointestinal function after renal transplantation in a patient with sclerosing peritonitis secondary to continuous ambulatory peritoneal dialysis

We describe the rapid and dramatic improvement in gastrointestinal function that occurred after successful renal transplantation in a women with severe sclerosing peritonitis secondary to continuous ambulatory peritoneal dialysis (CAPD). We postulate that the antiinflammatory effect of the immunosuppressive agents was the most important factor leading to the patient's recovery.

Effect of OKT3 in steroid-resistant renal transplant rejection

Between January 1, 1982, and November 1, 1986, 169 cadaver renal graft transplantations were performed at this hospital with CsA as induction therapy. OKT3 was not available in this period. Of these grafts, 15.9% were lost within 6 months, 10.7% from acute rejection (AR). Between November 1, 1986, and October 1, 1992, 483 cadaver renal graft transplantation were performed. Induction therapy included CsA and OKT3 was available. Of these grafts, 8.7% were lost inside 6 months, 3.1% from AR. Of these last 483 grafts, 113 received 125 courses of OKT3. Ten courses were prophylactic, and 115 courses in 103 patients were for rejection resistant to steroid therapy (biopsy proven in all but 2 cases. Ninety-three percent of rejection episodes treated with OKT3 responded, at least initially. Graft survival in OKT3-treated patients was 81%, 77%, and 76% at 6 months, 1 year, and 2 years, respectively. In contrast, graft survival in steroid-resistant rejection during the first period (without OKT3) was 59%, 57%, and 57% at these intervals. There were 8 infective deaths within 6 months in the 113 OKT3-treated patients, compared with 2 in the 343 who did not receive OKT3 (P < 0.001). There were 7 viral deaths in the OKT3 group compared with none in those not receiving OKT3 (P < 0.001). Prophylaxis with oral acyclovir and cotrimoxazole was instituted in October 1990 in OKT3-treated patients and ganciclovir use was increased. Since this change, no further viral deaths have occurred. OKT3 is a very effective antirejection agent, but its use is associated with an increased mortality from viral infections. With appropriate prophylaxis and treatment, however, this mortality can be reduced.

Onset of dialysis encephalopathy in cyclosporine-treated renal allograft recipients

Three patients who developed typical features of dialysis encephalopathy following renal transplantation are presented. No patient had evidence of overt neurological dysfunction pretransplantation. All patients were taking cyclosporine at the time of onset of neurological disease. Two patients died as a result of their neurological condition. The third patient made a satisfactory recovery. Factors responsible for the onset of dialysis encephalopathy in the renal posttransplantation period are discussed. We propose that cyclosporine may have been an important precipitating factor of the neurological syndrome of these patients.

Selection of ESRD treatment: an international study

Using the method of paired comparisons, we surveyed nephrologists in three different socioeconomic regions, North Carolina, Southern California, and Australia-New Zealand, to determine their preferences among the major end-stage renal disease (ESRD) treatment modalities. For comparison, we also determined how patients were assigned to the treatment modalities, based on registry data in the regions. Preferences were determined in for six standard ESRD treatment modalities--living related donor (LRD), four-antigen match, LRD two-antigen match, and cadaver (CAD) transplantation; and home peritoneal dialysis (HPD), home hemodialysis (HHD), and facility hemodialysis (FHD)--and for three categories of patients--patients with diabetes, patients over age 60, and patients in general. There was overall agreement in the ranking of treatments by the nephrologists from all three regions for each of the three patient categories; however, significant differences were noted between regions in preferences for certain modalities. Comparison within and between regions revealed striking disparities between preferences and practice. Analysis of these findings provides important insights into the process of ESRD treatment selection and identifies issues that merit further consideration.

Cyclosporin A in the treatment of childhood glomerulonephritis

Seven children with steroid resistant nephrotic syndrome (focal segmental sclerosis in six, mesangial proliferation in one) were treated with Cyclosporin A for 12 weeks. Five of these children were also resistant to cyclophosphamide. All patients had normal renal function. Cyclosporin was started at 8 mg/kg/day then increased until a trough blood level of 100-300 ng/ml (HPLC) was achieved. Three of the seven patients achieved complete remission, and the other four had a significant reduction in their proteinuria (p less than 0.05). In the three patients who achieved complete remission, relapse of proteinuria occurred within six weeks of ceasing Cyclosporin. All patients experienced some impairment in renal function with mean creatinine clearance decreasing from 129 +/- 19 to 91 +/- 13 ml/min/1.73m2 (p less than 0.05). One child was subsequently treated with Cyclosporin for 12 months. He remains in remission with a repeat renal biopsy showing no evidence of nephrotoxicity. One other child with steroid sensitive minimal change nephrotic syndrome who had severe steroid toxicity was treated with a lower dose (5 mg/kg/day) for 12 months. She remained in remission off steroids, but relapsed 16 weeks after Cyclosporin was ceased. A renal biopsy after 12 months showed no nephrotoxicity. Cyclosporin should be considered in steroid resistant nephrotic syndrome, and in children with minimal change disease who show signs of steroid toxicity and short remission period after cyclophosphamide. Serial renal biopsies are recommended with prolonged therapy.

The ketoconazole-cyclosporin interaction in an elderly renal transplant patient

Administration of ketoconazole to an elderly renal transplant patient who was taking cyclosporin resulted in markedly increased whole blood cyclosporin concentrations and evidence of both renal and hepatic dysfunction.

Algal peritonitis complicating continuous ambulatory peritoneal dialysis

A 41-year-old woman on continuous ambulatory peritoneal dialysis (CAPD) presented with algal peritonitis. Prototheca wickerhamii was isolated from multiple dialysate effluent cultures. Despite treatment with amphotericin B, catheter removal was required. An attempt to reinsert a Tenckhoff catheter 3 months later was unsuccessful because of dense intraperitoneal adhesions. Prototheca sp are a rare cause of human disease, this being the first reported case of algal peritonitis complicating CAPD.

Abdominal hernias complicating continuous ambulatory peritoneal dialysis

Twenty-five percent of all CAPD patients reviewed in this study developed abdominal hernias. Eleven hernias (32.4%) occurred at the catheter insertion site, 17.6% were inguinal, 26.5% were epigastric and umbilical and 23.5% occurred at the site of previous abdominal incisions. The risk of developing a hernia was significantly greater in patients over 40 years of age, women of parity greater than 3, patients who had had undergone more than 3 laparotomies and those with a previous hernia repair. Three hernias became incarcerated, one with intestinal strangulation. Early surgical repair is advisable to avoid these complications.

A prospective randomized trial of low-dose versus high-dose steroids in cadaveric renal transplantation

Low-dose steroid regimens, in combination with azathioprine, have become increasingly common for immunosuppression of renal transplant recipients. The change from conventional high-dose steroid regimens was prompted by the results of several prospective trials that showed similar graft survivals with high-dose and low-dose steroids, but a lower incidence of steroid-induced complications in low-dose-steroid--treated patients. However, the number of patients entered into the trials was small, and consequently there remained a possibility that a clinically relevant difference in graft survival could have remained undetected. A multi-center prospective trial was performed to compare graft survival with high-dose (91 patients) and low-dose (98 patients) oral steroids in combination with azathioprine. There was significantly worse graft survival in the low-dose group. The difference was largely due to a poor graft survival in patients receiving low-dose steroids and azathioprine less than 1.75 mg/kg/day. Graft survivals were similar in the high-dose and low-dose steroid patients who received azathioprine doses of greater than 1.75 mg/kg/day. The results indicate that the combination of low doses of both steroids and azathioprine provides inadequate immunosuppression in renal transplantation, although higher doses of azathioprine allow the use of low-dose steroids without significantly more graft losses than with high-dose steroids.

Severe tubulo-interstitial disease in a renal allograft due to cytomegalovirus infection

A 34 year old female developed impaired function of her renal allograft 21 months post-transplant. This was associated with lethargy, pyrexia, tenosynovitis, pancytopenia and a colonic ulcer. Severe tubulo-interstitial changes with intranuclear inclusion bodies and intracytoplasmic herpes type viral particles were seen on renal biopsy. There was no evidence of rejection. Cytomegalovirus was cultured from the urine and there was a rise in CMV antibody titer. These findings suggested the renal impairment was due to a direct cytopathic effect of the CMV. Despite treatment with transfer factor and adenine arabinoside, there was progressive loss of graft function.

Experience with continuous ambulatory peritoneal dialysis

Thirty-one patients were trained for continuous ambulatory peritoneal dialysis (CAPD) over a 34-month period. Their mean age (42 +/- 14 years) did not differ from that of the total dialysis population. The training was conducted primarily on an outpatient basis by one registered nurse. The duration of treatment ranged from two to 34 months (median, 8.0 months). The technique failed in seven patients, in four because of peritonitis and in three because of catheter complications. Nine patients received renal transplants and one died while on CAPD. Dialysis was very effective with good biochemical control and excellent control of hypertension. Haemoglobin concentrations rose in 28 of the 31 patients (mean at 12 months, 2.0 g/L in 12 patients). Rehabilitation was comparable to that of home haemodialysis patients and superior to that of patients on hospital haemodialysis. The incidence of peritonitis decreased over the study period because of better patient selection, improved technology, and increased experience.

Failure to demonstrate renal uptake of labelled platelets in chronic glomerulonephritis

1. Renal localization of autologous 111In-labelled platelets was studied in patients with chronic glomerulonephritis. External imaging was performed with a gamma-camera fitted with a medium energy collimator and the images were collected by a computer. 2. Images of 111In-labelled platelet distribution showed that there was a marked contribution to the radioactivity within each renal silhouette from adjacent spleen or liver. It was not possible to demonstrate renal accumulation of 111In-labelled platelets. 3. The application of 111In-labelled platelets to the study of intrarenal platelet consumption in chronic glomerulonephritis is limited by the sensitivity of current techniques and the scatter from adjacent splenic and hepatic radioactivity.

HLA in systemic lupus erythematosus: influence on severity

Forty-four patients with systemic lupus erythematosus (SLE) were classified as mild or more severe on the basis of renal biopsy changes and the degree of proteinuria. The HLA phenotype A2 plus B7 was associated with the mild cases, while A1 plus B8 was associated with more severe disease. These findings suggest that immunogenetic factors are important in determining the severity of SLE and that combinations of HLA-A and -B locus antigens may be significant in HLA disease associations.

The treatment of paracetamol overdose with charcoal haemoperfusion and cysteamine

A 53-year-old female was admitted to hospital one hour after taking an overdose of 60 g of paracetamol and 960 mg of codeine. Two hours after ingestion of the drug, the plasma concentration of paracetamol was 3040 mumol/l. In view of the enormous, and potentially fatal, plasma concentration of the drug, charcoal haemoperfusion was undertaken as well as cysteamine therapy. Charcoal haemoperfusion and cysteamine therapy led to the rapid removal of the paracetamol from the body and consequently prevented the development of severe hepatic necrosis. It is suggested that charcoal haemoperfusion as well as cysteamine has a role in the management of severe overdosage with paracetamol. This is the first report on the use of charcoal haemoperfusion for acute poisoning in Australia.