Procalcitonin fails to differentiate inflammatory status or predict long-term outcomes in peritoneal dialysis-associated peritonitis

BACKGROUND

Peritonitis is the major complication in patients undergoing maintenance peritoneal dialysis (PD) and is associated with a significant risk of mortality. Previously, we have shown that patients treated for peritonitis and having prolonged elevation of C-reactive protein (CRP) are associated with higher mortality. The underlying cause for the chronic systemic inflammation remains unknown. We studied serum procalcitonin (PCT), which has been reported as an accurate marker for infection and inflammation, with respect to being a diagnostic and prognostic indicator of persistent chronic inflammation after peritonitis in patients with PD-related peritonitis.

METHODS

We conducted a prospective study on PD patients that developed PD-related peritonitis. Blood samples obtained at routine check-up before the onset of peritonitis were taken as baseline (D0). When patients developed PD-related peritonitis, serial blood samples were obtained on day 1 (D1), day 7 (D7), and day 42 (D42) for PCT, CRP, and other inflammatory markers. Patients were followed up for at least 2 years, during which outcomes of peritonitis and causes of death were recorded. Serum levels of CRP and PCT at day 42 were analyzed to assess for long-term prognosis.

RESULTS

35 patients [female 42.9%; mean age 63.8 +/- 13.1 years; 12 (34.3%) diabetics] were recruited. The onset of peritonitis was 3.61 +/- 3.56 years after PD initiation and median residual renal function at that time was 1.06 (range 0 - 6.1) mL/min. Median total white cell counts in PD effluent at days 1, 3, 7, and 42 were 3505/mm(3) (range 377 - 20 500/mm(3)), 297 (8 - 5880)/mm(3), 34 (0 - 5290)/mm(3), and 10 (0 - 115)/mm(3), respectively. Twelve (34.3%) and 14 (40%) PD effluents grew gram-positive and gram-negative micro-organisms respectively; others were culture negative. Median PCT was increased significantly at day 1 [2.00 (0.12 - 58.7) ng/mL, p < 0.001], day 7 [0.76 (0.13 - 15.25) ng/mL, p < 0.001], and day 42 [0.30 (0.13 - 0.79) ng/mL, p = 0.005] compared to baseline [0.20 (0.09 - 0.69) ng/mL]. Seven of 35 patients had false-negative results on day 1 (range 0.12 - 0.46) when PCT <0.5 ng/mL was used as the cutoff value for diagnosing peritonitis. For the long-term prognostic outcome, CRP at day 42 was significantly better than PCT in assessing overall prognosis (CRP: AUC 0.712, 95% CI 0.534 - 0.890 vs PCT: AUC 0.652, 95% CI 0.448 - 0.855). In Kaplan-Meier survival analysis, patients with elevated CRP (>3.0 mg/L) were associated with poorer long-term survival (p = 0.04) but elevated PCT at the 25th, 50th, or 75th percentiles failed to provide prognostic value.

CONCLUSIONS

PD patients after peritonitis may be associated with prolonged systemic inflammation. CRP was a better serum marker for monitoring inflammatory status and predicting long-term prognosis in our study. Although serum PCT is elevated in some patients at the time of peritonitis, its value in making a diagnosis and predicting long-term prognosis remains doubtful.

BMP-7 protects mesangial cells from injury by polymeric IgA

Bone morphogenetic protein-7 (BMP-7) is a potential therapeutic agent for acute and chronic renal diseases. Here we found that addition of polymeric IgA, isolated from patients with IgA nephropathy, increased the synthesis of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), transforming growth factor-beta (TGF-beta) and fibronectin in cultured human mesangial cells, effects blunted by BMP-7. When mesangial cells were cultured with both polymeric IgA and BMP-7 there was an increase in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-gamma). The activation of NF kappaB and TNF-alpha synthesis induced by polymeric IgA or TNF-alpha were downregulated by BMP-7 or rosiglitazone. BMP-7 inhibited TNF-alpha release from polymeric IgA-stimulated mesangial cells by activation of PPAR-gamma but suppressed TGF-beta release by mechanisms independent of PPAR-gamma. The expression of inhibitory Smad6 and 7 was increased whereas the expression of active Smad2 and 3 was reduced in these mesangial cells by BMP-7. Our study shows that BMP-7 ameliorates IgA nephropathy-derived polymeric IgA-induced TNF-alpha and TGF-beta synthesis in human mesangial cells through multiple mechanisms involving inhibitory Smads and PPAR-gamma.

Mice overexpressing latent TGF-beta1 are protected against renal fibrosis in obstructive kidney disease

Transforming growth factor (TGF)-beta1, once activated, binds to its receptors and mediates renal fibrosis via the downstream Smad signaling pathway. We reported here that mice overexpressing latent TGF-beta1 in keratinocytes were protected against renal fibrosis in a model of obstructive kidney disease. In normal mice, both transgenic (Tg) and wild-type (WT) mice had normal renal histology and function, despite a 10-fold increase in plasma latent TGF-beta1 in Tg mice. A severe renal fibrosis was developed in WT mice at 7 days after urinary obstruction. Unexpectedly, renal fibrosis was prevented in Tg mice, although levels of latent TGF-beta1 in both circulation and renal tissues remained high. Compared with the WT mice, quantitative real-time PCR showed that upregulation of renal alpha-smooth muscle actin (SMA), collagen I, and collagen III mRNA was inhibited in Tg mice (60-70% reduced, all P < 0.01). These were further confirmed by immunohistochemistry with a marked inhibition of tubulointerstitial accumulation of alpha-SMA+ fibroblasts, collagen I, and collagen III matrix in Tg mice (all P < 0.001). Further studies showed that inhibition of renal fibrosis in Tg mice was associated with a significant reduction in renal TGF-beta1 and CTGF (60% reduced, P < 0.05), an increase in renal Smad7, a suppression of TSP-1 (a critical factor for TGF-beta1 activation), and an inhibition of Smad2/3 activation (all P < 0.001). In conclusion, latent TGF-beta may play a protective role in renal fibrosis. Inhibition of renal TGF-beta1 expression and activation, thereby blocking the downstream TGF-beta signaling pathway, may be a critical mechanism by which latent TGF-beta1 protects against renal fibrosis.

Microscopic polyarteritis presenting with chest infections and acute appendicitis

We describe a 38-year-old male with antineutrophil cytoplasmic auto-antibody (ANCA) positive microscopic polyarteritis who presented with recurrent chest infections, lung haemorrhage, renal insufficiency and acute appendicitis. Appendectomy was followed by resolution of abdominal symptoms and the surgical specimen revealed vasculitis of the serosal vessels. A renal biopsy was performed because of impaired renal function and this revealed focal necrotising glomerulonephritis with absence of immune deposits. Chest infections were treated with antibiotics resulting in partial clinical response, but pulmonary symptoms relapsed and a complete resolution was achieved only after plasma exchange and the administration of cyclophosphamide. Our observation emphasises the protean manifestations of microscopic polyarteritis and the relationship between ANCA and disease activity.

Activation of podocytes by mesangial-derived TNF-alpha: glomerulo-podocytic communication in IgA nephropathy

We have previously documented that human mesangial cell (HMC)-derived TNF-alpha is an important mediator involved in the glomerulo-tubular communication in the development of interstitial damage in IgA nephropathy (IgAN). With the strategic position of podocytes, we further examined the role of mesangial cells in the activation of podocytes in IgAN. There was no binding of IgA from patients with IgAN to podocytes. Podocytes cultured with IgA from patients with IgAN did not induce the release of growth factors or cytokines. Furthermore, podocytes did not express mRNA of known IgA receptors. In contrast, IgA-conditioned medium (IgA-HMC medium) prepared by culturing HMC with IgA from patients with IgAN for 48 h significantly increased the gene expression and protein synthesis of TNF-alpha by podocytes with a 17-fold concentration above that of IgA-HMC medium. The upregulation of TNF-alpha expression by podocyte was only abolished by a neutralizing antibody against TNF-alpha but not by other antibodies. Exogenous TNF-alpha upregulated the synthesis of TNF-alpha by podocytes in an autocrine fashion. IgA-HMC medium prepared with IgA from patients with IgAN also significantly upregulated the expression of both TNF-alpha receptor 1 and 2 in podocytes. Our in vitro finding suggests podocytes may play a contributory role in the development of interstitial damage in IgAN by amplifying the activation of tubular epithelial cells with enhanced TNF-alpha synthesis after inflammatory changes of HMC.

Rhodococcus lung abscess complicating kidney transplantation: successful management by combination antibiotic therapy

In this report, a renal transplant recipient with Rhodococcus lung abscess is described. A high clinical suspicion and appropriate combination antibiotic therapy obviated the need for surgical intervention and was associated with a good clinical outcome. The optimal regimen of combination antibiotic therapy is discussed.

Synthesis of TNF-alpha by mesangial cells cultured with polymeric anionic IgA--role of MAPK and NF-kappaB

BACKGROUND

Deposition of polymeric IgA1 (pIgA) in kidney mesangium is the hallmark of IgA nephropathy (IgAN). Current consensus is that a fraction of IgA1 molecules in the circulation of IgAN patients exhibit aberrant structures or properties that may lead to their deposition. Our previous findings suggest that the anionic property of IgA1 may play a role in mesangial IgA1 deposition in patients with IgAN. In the present study, the functional consequences of the binding of anionic polymeric IgA1 to human mesangial cells (HMCs) were investigated.

METHODS

Anionic polymeric IgA1 from IgAN patients and healthy subjects was isolated by sequential jacalin affinity chromatography, size exclusion chromatography using size exclusion and MonoQ ion exchange chromatography. HMCs were cultured with purified anionic polymeric IgA1 and the release of tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) was examined by enzyme-linked immunosorbent assay. The signalling pathways involved in anionic pIgA-mediated HMC activation were examined by immunoblotting. Standard electrophoretic mobility shift assay (EMSA) was used to further examine whether the transcriptional factor NF-kappaB is associated in the signalling process. To define the mechanism of TNF-alpha and IL-6 production, HMCs were cultured with anionic pIgA in the presence or absence of p42/p44 mitogen-activated protein kinase (MAPK) inhibitor (PD98059), NF-kappaB inhibitor pyrrolidine dithiocarbamate (PDTC) or NF-kappaB blocking permeable peptides.

RESULTS

Compared with less anionic pIgA or monomeric IgA1 (mIgA), anionic pIgA from patient with IgAN significantly increased cell proliferation (P<0.05) when cultured with HMC. These anionic pIgA significantly increased the synthesis of TNF-alpha (P<0.05) and IL-6 (P<0.05) in a dose and time-dependent manner. Furthermore, the increased synthesis of IL-6 and TNF-alpha by anionic pIgA in HMC was significantly diminished (P<0.01) in the presence of NF-kappaB inhibitor pyrrolidine dithiocarbamate and NF-kappaB blocking permeable peptides SN50 (P<0.01). The increased synthesis of IL-6 by anionic pIgA in HMC was reduced by inhibitor to NF-kappaB or p42/p44 MAPK and was abolished by the simultaneous presence of inhibitors to p42/p44 MAPK and NF-kappaB. The up-regulation of TNF-alpha was partially suppressed by inhibitor to NF-kappaB but not PD98059.

CONCLUSION

Our results suggest that polymeric anionic IgA1 could activate HMC and increase the synthesis of TNF-alpha and IL-6. While both the p42/p44 MAPK and NF-kappaB pathways are essential in regulating the anionic pIgA-induced synthesis of IL-6, TNF-alpha synthesis mediated by anionic pIgA is partly dependent on NF-kappaB.

Smad7 transgene attenuates peritoneal fibrosis in uremic rats treated with peritoneal dialysis

Transforming growth factor beta (TGF-beta) plays a critical role in the pathogenesis of the peritoneal fibrosis that complicates long-term peritoneal dialysis (PD). We studied the TGF-beta/Smad signaling pathway in peritoneal fibrosis induced in uremic rats treated with PD and explored the therapeutic potential of Smad7 to prevent fibrogenesis. After subtotal nephrectomy, uremic rats were treated with peritoneal dialysis using 4.25% dextrose-containing fluid. The peritoneum of uremic rats treated with PD demonstrated fibrosis, increased TGF-beta expression, increased Smad2/3 activation, decreased Smad7 expression, and increased expression of fibrogenic and angiogenic factors. In addition, peritoneal function was impaired and its structure was altered, including a thickened submesothelial layer. In rats transfected with a Smad7 transgene using an ultrasound-microbubble-mediated system, peritoneal fibrosis was attenuated, peritoneal function was improved, and Smad2/3 activation was inhibited. We suggest that administration of Smad7 inhibits peritoneal fibrogenesis in uremic rats treated with PD by correcting the imbalance between downregulated Smad7 and activated Smad2/3. Blockade of the TGF-beta/Smad signaling pathway may represent a novel therapeutic approach to prevent peritoneal fibrosis in patients treated with PD.

Risks and outcomes of peritonitis after flexible colonoscopy in CAPD patients

OBJECTIVE

The ISPD 2005 guidelines for peritonitis recommend antibiotic prophylaxis for patients undergoing colonoscopy with polypectomy while on continuous ambulatory peritoneal dialysis (CAPD) but there is little literature to support this recommendation. This study aimed to look into the risks and outcomes of peritonitis after colonoscopy in CAPD patients.

PATIENTS AND METHODS

All records of flexible colonoscopy performed on our CAPD patients from January 1994 to January 2006 were retrieved. Demographic and clinical data, use of antibiotics before colonoscopy, endoscopic findings, procedure performed, and peritonitis data were analyzed.

RESULTS

77 CAPD patients underwent 97 colonoscopies. No peritonitis developed in the 18 cases where antibiotics were given before colonoscopy. Among those without antibiotic prophylaxis, 4 episodes of peritonitis occurred within 24 hours after the procedure and 1 occurred 5 days later. All responded to intraperitoneal antibiotics. Colonic biopsy and polypectomy were not associated with more peritonitis (2 in 41 with biopsy vs 3 in 38 without biopsy, p = 0.67; 1 in 30 with polypectomy vs 4 in 49 without polypectomy, p = 0.64).

CONCLUSION

The risk of peritonitis after colonoscopy without antibiotic prophylaxis was 6.3%. All peritonitis episodes responded to intraperitoneal antibiotics. Colonic biopsy or polypectomy did not appear to increase the risk of peritonitis. Although statistically not significant when compared with patients without antibiotic prophylaxis, we observed no peritonitis after colonoscopy in patients that were given antibiotics for prophylactic purposes or for other reasons. The efficacy of prophylactic antibiotics would be better defined by large randomized trials.

Membranous nephropathy: when and how to treat

The treatment of idiopathic membranous nephropathy is heavily debated because of wide variation in outcome. A rational treatment strategy is needed to appropriately administer conservative treatment to the low-risk group but immunosuppressive therapy to those with medium or high risk of renal deterioration. Currently, combinations of steroids with alkylating agents are best studied. Newer forms of immunosuppressive treatment are currently under study.

Growth Hormone Treatment during Hemodialysis in a Randomized Trial Improves Nutrition, Quality of Life, and Cardiovascular Risk

Nutritional markers, such as lean body mass (LBM) and serum albumin, predict outcome in dialysis patients, in whom protein-energy malnutrition is associated with increased morbidity and mortality. The metabolic effects of human growth hormone (hGH) may improve the nutritional and cardiovascular health of these patients and consequently reduce morbidity and mortality. The aim of this study was to establish clinical proof of concept of hGH treatment for the improvement of the nutritional status in adult patients who are on maintenance hemodialysis. A total of 139 adult patients who were on maintenance hemodialysis and had serum albumin levels < or =40 g/L were randomly assigned to 6 mo of treatment with placebo or 20, 35, or 50 microg/kg per d hGH. Change in LBM and serum albumin (primary outcomes), health-related quality of life, and secondary efficacy and safety parameters were monitored. The study showed that hGH treatment increased LBM significantly at all dosage levels (2.5 kg [95% confidence interval 1.8 to 3.1] versus -0.4 kg [95% confidence interval -1.4 to 0.6]; P < 0.001 for pooled hGH groups versus placebo). Serum albumin tended to increase (P = 0.076), serum transferrin (P = 0.001) and serum HDL (P < 0.038) increased, and plasma homocysteine was reduced (P = 0.029). TNF-alpha also tended to decrease with treatment (P = 0.134). An improvement in the Role Physical SF-36 quality-of-life subscale was observed (P = 0.042). There were no differences in clinically relevant adverse events between groups. In conclusion, hGH therapy safely improves LBM, other markers of mortality and morbidity, and health-related quality of life in adult patients who are on maintenance hemodialysis. A long-term study is warranted to investigate whether these treatment benefits result in reduced mortality and morbidity.

Mediators of inflammation and fibrosis

During peritoneal dialysis, peritoneal cells are repeatedly exposed to a non-physiologic hypertonic environment with high glucose content and low pH. Current sterile dialysis solutions cause inflammation in the submesothelial compact zone, leading to fibrosis, angiogenesis, and, eventually, ultrafiltration failure. Although the normal interstitium separates the peritoneal microvasculature from the dialysis fluid and makes transperitoneal transport less efficient, changes in the submesothelial compact zone can result in progressive increases in solute transfer and ultrafiltration diminution. This peritoneal dysfunction will further be amplified with the development of an epithelial-to-mesenchymal transition of mesothelial cells and dissipation of the osmotic driving force through the increased area and solute transport that accompany neoangiogenesis of the submesothelial microvasculature. The alteration of the peritoneal membrane can be further aggravated by peritonitis, advanced glycation end-products, and glucose degradation products. Furthermore, new data are emerging to support a proinflammatory role for peritoneal adipocytes.

Tuberculous and fungal peritonitis in patients undergoing continuous ambulatory peritoneal dialysis

Tuberculous and fungal infections are two relatively uncommon but important causes of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). The clinical features, diagnosis, and management of these two special forms of CAPD-related peritonitis are highlighted in this article.

An animal study of the effects on p16 and PCNA expression of repeated treatment with high-energy laser and intense pulsed light exposure

BACKGROUND AND OBJECTIVE

Non-ablative skin rejuvenation treatments that involve the use of laser/light sources together with cooling devices have gained much popularity in recent years due to the lack of down time that is associated with them. One important but neglected issue is long-term safety. Does the repeated use of non-ablative skin rejuvenation lead to photoaging? Are we creating another sun-bed phenomenon? Recently, we performed an in vitro study to examine the effect of sub-lethal QS 755 nm lasers on the expression of p16INK4a on melanoma cell lines, and found that sub-lethal laser damage could increase DNA damage, which led to an increase in p16 expression. Our objective was to assess the cutaneous effect of repeated exposure to high-energy lasers and intense pulsed light sources on male Institute of Cancer Research (ICR) mice.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-eight male ICR mice were divided into four groups. Other than the control group, all groups received either laser (585 nm pulsed dye laser or 1,320 nm Nd:YAG laser) or intense pulsed light (IPL) treatment. All four groups were anesthetized with a mixture of Hypnorm/Dormicum before treatment. The animals were irradiated twice a week for 6 months. Signs of toxicity such as mortality and weight loss were checked once a week. Skin tumor formation was evidenced by lesions of greater than 1 mm in diameter that persisted for 2 weeks. At the end of the 6 months, the expression of proliferating cell nuclear antigen (PCNA) and p16 in the mouse skin was determined by immunohistochemical staining and immunoblotting using specific monoclonal antibodies for mouse PCNA and p16. The results were expressed as mean +/- standard error of the mean (SEM). Statistical difference was assessed by multiple ANOVA. A P-value of <0.05 was considered to be significant.

RESULTS

At the end of the 6 months, none of the animals had developed any signs of toxicity such as mortality or weight lost. There was no evidence of tumor formation. There were significant elevations of p16 and PCNA in all treated groups as compared to the control group (ANOVA P < 0.05). This particularly applied to the group that was treated with the 1,320 nm Nd:YAG laser.

CONCLUSION

The repeated use of high-energy laser and intense pulsed light source did not cause any toxicity in mice. The changes in p16 and PCNA imply that further studies are necessary to consider the implications of repeated exposure to longer wavelength radiation in human skin.

Tuberculous lymphadenitis in patients undergoing continuous ambulatory peritoneal dialysis

The aim of this study was to review the clinical features of tuberculous (TB) lymphadenitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Nine cases of TB lymphadenitis were diagnosed among 910 patients over a period of 10 years. There were five men and four women with a mean age of 51 +/- 15.5 years. The TB lymphadenitis involved the cervical lymph nodes in six patients, supraclavicular lymph nodes in two patients and mediastinal lymph nodes in one patient. Six patients presented with clinically enlarged lymph nodes of whom four also had fever. Three other patients were incidentally found to have enlarged lymph nodes on routine chest X-ray or ultrasound examination of the neck. Diagnosis of TB lymphadenitis was made by demonstrating caseating granulomata with or without positive acid-fast bacilli on excisional lymph node biopsy. All patients were cured with standard anti-tuberculosis drugs for 12 months. No recurrence of the TB lymphadenitis was observed after a mean follow-up of 59 +/- 30 months. We conclude that TB lymphadenitis is not uncommon among patients on CAPD. A high index of suspicion is needed for early diagnosis of this condition. Prompt initiation of anti-tuberculosis treatment is associated with good prognosis.

Pilot study of pegylated interferon-alpha 2a in dialysis patients with chronic hepatitis C virus infection

AIM

Pegylated interferon (PEG-IFN) combined with ribavirin is recommended for the treatment of chronic hepatitis C virus (HCV) infection in patients without renal failure. The optimal treatment of hepatitis C in dialysis patients remains to be established. A high incidence of adverse effects has been observed with conventional interferon and PEG-IFN alpha-2b in dialysis patients.

METHODS

We conducted a prospective study to investigate the tolerability and efficacy of PEG-IFN alpha-2a (135 microg weekly for 48 weeks) in six dialysis patients with chronic HCV infection.

RESULTS

Two patients completed 48 weeks of treatment. Treatment was stopped in three patients (beyond 24 weeks) when they developed unrelated complications, and stopped in one patient due to failure of viral clearance. None required treatment discontinuation due to adverse effects, and PEG-IFN alpha-2a was subjectively well tolerated. Marrow suppression with mild anaemia, leucopenia, or thrombocytopenia remained common. Two patients (infected with genotypes 3a and 1b, respectively) had sustained virological response.

CONCLUSIONS

Results from this pilot study showed that PEG-IFN alpha-2a appeared relatively well tolerated in dialysis patients with chronic HCV infection, and about one-third of patients could achieve sustained virological response.

Delaying initiation of dialysis till symptomatic uraemia--is it too late?

BACKGROUND

The optimal timing of initiating renal replacement therapy in patients with chronic renal failure remains uncertain. The primary objective of our study is to determine whether delaying dialysis initiation as a result of patients' choice may have any impact on survival in subjects with end-stage renal disease.

METHODS

We prospectively studied the clinical outcome during the first year of all consecutive patients (n=233) deemed suitable for peritoneal dialysis (PD) after pre-dialysis counselling over a 2-year period from 2002 to 2004. All patients who were offered dialysis were included in the analysis from the day of initial counselling regardless of whether or not they were eventually established on PD.

RESULTS

There were 151 'elective starters' (50.3% male, mean+/-SD age=57.7+/-13.9 years, 39.7% diabetic) who were electively initiated on dialysis when glomerular filtration rate reached 10 ml/min/1.73 m2 or below. The remaining 82 subjects (53.7% male, mean+/-SD age=58.4+/-11.3 years, 46.3% diabetic, P=0.33 vs elective starters) declined dialysis initially (initial refusers). On follow-up, 45 (55%) initial refusers developed a uraemic emergency and agreed to undergo dialysis, and 39 (48%) were eventually established on maintenance PD (late starters). Kaplan-Meier analysis of 1-year survival showed a significantly higher rate of all-cause (18.3% vs 6.6%, P=0.004, log-rank test) and cardiovascular (9.8% vs 2.6%, P=0.014) mortality among the initial refusers.

CONCLUSION

Patients who refuse timely start of dialysis have worse overall outcome at one year after the offer of dialysis, compared with elective starters.

Hyperleptinaemia and chronic inflammation after peritonitis predicts poor nutritional status and mortality in patients on peritoneal dialysis

BACKGROUND

The serum leptin level is elevated in patients undergoing peritoneal dialysis (PD) and associated with a loss of lean body mass. The nutritional status of PD patients may further be worsened following peritonitis. We investigated the association between hyperleptinaemia, inflammation and malnourishment in PD-related peritonitis.

METHODS

We conducted a prospective study on PD patients who developed peritonitis. Blood samples were obtained as baseline (D0) before the onset of peritonitis, and once peritonitis developed, leptin, adiponectin (ADPN) and other inflammatory markers were collected, on day 1 (D1), day 7 (D7) and day 42 (D42) of peritonitis. Patients were followed-up for any censor event or 1 year after peritonitis.

RESULTS

Forty-two patients with a mean age of 62.9+/-13.2 years were recruited. Fourteen (33.3%) were diabetic. The serum leptin levels increased significantly from baseline to day 1 and 7, but fell back to the premorbid state at day 42. In contrast, the ADPN level decreased from a baseline value of 15.60+/-10.4 microg/ml to 13.01+/-8.1 microg/ml on day 1 (P=0.01) but rose to 14.39+/-8.9 microg/ml on day 7 (P=0.28) and 13.87+/-7.9 microg/ml on day 42 (P=0.21). High-sensitivity C-reactive protein (hs-CRP) increased significantly from baseline to day 1, 7 and even at day 42. The lean body mass (LBM) and nutritional markers decreased significantly after peritonitis. For patients with high hs-CRP (>3.0 mg/l) at day 42, there was a higher mortality rate than for those with lower hs-CRP (<3.0 mg/l, P=0.02), even if they were in clinical remission of peritonitis.

CONCLUSIONS

Our study confirmed an increase in serum leptin during acute peritonitis and a prolonged course of systemic inflammation after apparent clinical remission of peritonitis. These factors related to the persistent chronic inflammation may contribute to the development of malnourishment and poor survival rate.

Interaction between proximal tubular epithelial cells and infiltrating monocytes/T cells in the proteinuric state

We hypothesize an interaction between T cells/monocytes and the tubules in the development of tubulointerstitial injury in chronic proteinuric nephropathy. We established in vitro co-culture systems of proximal tubular epithelial cells (PTEC) and T cells/monocytes to study the contribution of soluble factors and cell-to-cell contact in the development of tubulointerstitial injury. The release of monocyte chemoattractant protein-1 (MCP1 or CCL2), Regulated upon Activation, normal T cell Expressed and Secreted (RANTES or CCL5), soluble intracellular adhesion molecules-1 (sICAM-1), or interleukin-6 (IL-6) was increased in PTEC following apical exposure to human serum albumin (HSA). The release of CCL2, CCL5, or sICAM-1 from PTEC was enhanced by contact of monocytes/T cells on the basolateral surface. Tumor necrosis factor-alpha (TNF-alpha) and IL-1beta are important soluble factors as suggested by the blocking effect of antibodies (Abs) against TNF-alpha or IL-1beta but not against other cytokines. The percentage of CD4+ T cells expressing both chemokine receptors, CCR2 and CCR5, was increased after culturing with supernatant from the apical or basolateral surface of PTEC following apical exposure to HSA. However, only CCR2 was upregulated in CD8+ T cells, whereas CCR5 expression was increased in monocytes. The chemotaxis of CD4+ or CD8+ T cells to supernatant from PTEC upon apical exposure to HSA was reduced with neutralizing Abs against CCL5 and/or CCL2, whereas the chemotaxis of monocytes was only reduced by anti-CCL5 but not by anti-CCL2. In summary, chemokines released by HSA-activated PTEC are amplified by monocytes/T cells. Mediators released by HSA-activated PTEC can differentially modulate the expression of chemokine receptors in monocytes/T cells and hence, alter their chemotaxis towards activated PTEC. These interactions are pivotal in the development of tubulointerstitial injury.