Expression of the rat renal PiT-2 phosphate transporter

BACKGROUND

NaPi-2a is the main sodium-dependent Pi (Na+-Pi) transporter in the apical membrane of the renal proximal tubule. Another group of Pi transporters, Glvr-1 (PiT-1) and Ram-1 (PiT-2), was identified. The PiT-2 cRNA induces Na+-dependent Pi uptake into Xenopus laevis oocytes. Prior studies have revealed the presence of the Pit-2 transporter in the kidney.

OBJECTIVES

Further characterization of the PiT-2 transporter in the kidney and assessment of its developmental regulation.

METHODS

Using primers specific for the PiT-2 mRNA and an antibody specific for the PiT-2 protein, we assessed the expression and developmental regulation of the renal PiT-2 mRNA and protein.

RESULTS

RT-PCR analysis revealed that a 182 bp product was evident in the total kidney (TK), cortex (C), and medulla (M). Northern blots demonstrated a PiT-2 mRNA of approximately 4 kb (expected size) in the TK, C, and M. PiT-2 mRNA expression was similar in all kidney regions. RT-PCR and Northern blot analysis revealed that the PiT-2 cDNA was highly abundant in OK and MDCK culture cells. RT-PCR and Northern blot analysis revealed expected products at all ages studied. Densitometry demonstrated similar levels of expression of PiT-2 mRNA in the kidneys of older versus younger animals, and persistent expression in elderly rats. The PiT-2 protein was present in the TK, C, and M, and in OK and MDCK cells. PiT-2 protein abundance was similar at all ages studied.

CONCLUSIONS

These studies further characterize the renal PiT-2 transporter and show that its expression is stable throughout development and ageing.

Mutations in DYT1: extension of the phenotypic and mutational spectrum

BACKGROUND

Most cases of early-onset primary torsion dystonia (PTD) are caused by the same three-base pair (bp) (GAG) deletion in the DYT1 gene. Exon rearrangements are a common mutation type in other genes and have not yet been tested for in DYT1. Several lines of evidence suggest a relationship of the DYT1 gene with Parkinson disease (PD).

OBJECTIVE

To investigate the frequency and type of DYT1 mutations and explore the associated phenotypes in a mixed movement disorders patient cohort and in controls.

METHODS

The authors screened 197 patients with dystonia (generalized: n = 5; focal/segmental: n = 126; myoclonus-dystonia: n = 34; neuroleptic-induced: n = 32), 435 with PD, and 42 with various other movement disorders, along with 812 healthy controls, for small deletions in exon 5 of DYT1 and tested for exon rearrangements by quantitative, duplex PCR in 51 GAG deletion-negative dystonia cases.

RESULTS

The GAG deletion was detected in five patients: three with early-onset PTD, one with generalized jerky or clonic dystonia, and one with generalized dystonia and additional features (developmental delay, pyramidal syndrome). A novel out-of-frame four-bp deletion (934_937delAGAG) in exon 5 of the DYT1 gene was found in a putatively healthy blood donor. No exon rearrangements were identified in DYT1.

CONCLUSIONS

In this mixed patient sample, the GAG deletion was rare and in two out of five cases associated with an unusual phenotype. In addition, a novel DYT1 truncating mutation of unknown clinical relevance was found in a putatively unaffected individual. DYT1 exon rearrangements, however, do not seem to be associated with PTD.

Down-regulation of aquaporin 3 in bronchiectatic airways in vivo

Bronchiectasis is characterized pathologically by permanent abnormal bronchial dilation, and clinically by chronic sputum production. Aquaporin 3 (AQP3), a recently described water channel that is also found in large airway cell membrane, could play a role in the pathogenesis and particularly that of bronchorrhea in bronchiectasis. However, little is known of its in vivo distribution and physiological role in human airways. We have, therefore, performed this quantitative immunohistochemistry study on endobronchial biopsies to evaluate the expression and clinical relevance of AQP3 in patients with idiopathic bronchiectasis (n = 25, 15 F, 64.3 +/- 11.5 years) and control subjects (n = 14, 5 F, 57.5 +/- 12.0 years). Quantitative image analysis was performed to evaluate the expression of AQP3 in the bronchial epithelial cells. Our results show that AQP3 was predominantly expressed in the basal cells of the epithelial layer in both groups. Expression of AQP3 was significantly reduced in the basal, but not columnar, epithelial cells in bronchiectasis compared with control airways (p = 0.02, 0.35). Only bronchiectatic patients with regular sputum production, but not their counterparts, had significant downregulation of epithelial AQP3 expression compared with control airways (p = 0.004, 0.24). Our findings suggest that AQP3 could have an important role in the pathogenesis of increased mucus production in bronchiectasis.

In vitro studies of aquaporins 1 and 3 expression in cultured human proximal tubular cells: upregulation by transferrin but not albumin

Dysregulated renal water handling is a cardinal feature of nephrotic syndrome that has been shown in animal models of experimental nephrosis to mediate renal aquaporin (AQP) expression. However, data on the effect of proteinuria on the proximal tubule, which is heavily vested with AQP1 and therefore may participate in water homeostasis, are limited. To investigate this, we exposed primary human proximal tubular epithelial cells (PTECs) to two key proteinuric components shown to perturb tubule function: human serum albumin and transferrin. Using reverse-transcriptase polymerase chain reaction and immunocytochemical techniques, PTECs in the quiescent state were found to express AQP3 in addition to AQP1 gene and protein, which was also validated in a human proximal tubule cell line, HK-2. Immunohistochemical staining localized AQP1 synthesis to the apical and basolateral membranes and AQP3 synthesis to the basolateral membrane of proximal tubule epithelium. Transferrin in doses reaching nephrotic range upregulated PTEC transcription and translation of both AQP1 and AQP3 in a time- and dose-dependent manner. After 24 hours of stimulation, transferrin led to a 2.4- and 2.2-fold increase in AQP1 and APQ3 messenger RNA expression, whereas protein synthesis surged by 40.7% +/- 2.48% and 24.2% +/- 0.9% compared with control, respectively. These effects were not observed with albumin challenge and were not caused by osmolality fluctuation with transferrin treatment. In summary, our novel finding of AQP3 in PTECs indicates a role for AQP3 in proximal tubule water reabsorption. The pathophysiological significance of heightened AQP1 and AQP3 expression in PTECs on protein challenge as occurs in the nephrotic state requires further investigation.

Novel mutation in the TOR1A (DYT1) gene in atypical early onset dystonia and polymorphisms in dystonia and early onset parkinsonism

Dystonia is a movement disorder involving sustained muscle contractions and abnormal posturing with a strong hereditary predisposition and without a distinct neuropathology. In this study the TOR1A (DYT1) gene was screened for mutations in cases of early onset dystonia and early onset parkinsonism (EOP), which frequently presents with dystonic symptoms. In a screen of 40 patients, we identified three variations, none of which occurred in EOP patients. Two infrequent intronic single base pair (bp) changes of unknown consequences were found in a dystonia patient and the mother of an EOP patient. An 18-bp deletion (Phe323_Tyr328del) in the TOR1A gene was found in a patient with early onset dystonia and myoclonic features. This deletion would remove 6 amino acids close to the carboxy terminus, including a putative phosphorylation site of torsinA. This 18-bp deletion is the first additional mutation, beyond the GAG-deletion (Glu302/303del), to be found in the TOR1A gene, and is associated with a distinct type of early onset dystonia.

Charge-dependent binding of polymeric IgA1 to human mesangial cells in IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is characterized by raised serum IgA1 and predominant mesangial IgA1 deposits of polymeric nature. The mechanism of polymeric IgA1 (pIgA1) deposition in the kidney mesangium is poorly understood in IgAN. It has been suggested that increased sialic acid content and anionic charge of the pIgA1 molecules may be operational in the IgA1 deposition in human mesangial cells (HMCs). The present study examined the binding of pIgA1 with different surface charges to HMCs. The binding characteristics of IgA1 to HMCs in the presence of polycation (poly-L-lysine) or polyanion (heparin) were also investigated.

METHODS

IgA1 was purified in sera from patients with IgAN and from healthy controls by jacalin affinity chromatography. IgA1 was further separated into pIgA1 and monomeric IgA1 (mIgA1) by fast protein liquid chromatography (FPLC). pIgA1 or mIgA1 with different net charges on their surface were resolved by ion exchange chromatography (IEC) with a Mono Q column. The binding characteristics of pIgA1 and mIgA1 to HMCs in the presence or absence of polycation or polyanion were examined by flow cytometry.

RESULTS

In patients with IgAN, the absolute amount of mIgA1 and pIgA1 is significantly higher than that of healthy controls (P < 0. 001). There was significant increase in binding of pIgA1 from patients with IgAN to HMC and cell lysate. pIgA1 that interacted strongly with the ion exchanger also bound more to HMCs when compared with IgA1 interacted weakly with the ion exchanger (P < 0. 001). The anionic charged pIgA1 from patients was significantly higher than that of healthy controls (P < 0.001). Preincubation with poly-L-lysine increased the binding of pIgA1 to HMCs. The binding of pIgA1 to HMCs was decreased by preincubation with heparin.

CONCLUSIONS

The binding of IgA to HMCs is charge dependent. Polymeric IgA with the highest net negative charge binds more to HMCs. Preincubation with polyanion decreased the binding of polymeric IgA to HMCs. These results suggest an important role for anionic charge in IgA1 deposition onto the kidney mesangial cells.

Magnetic resonance imaging in primary bone tumors

MRI plays a major role in the evaluation and treatment planning of bone tumors. It should be used following plain films and before biopsy. The MR appearance of most tumors is nonspecific; however, the entire extent of the tumor and its relationship to adjacent structures can be determined at MRI providing a road map for the surgeon. The role of dynamic enhancement is evolving and has not yet been determined.

Changes of cytokine profiles during peritonitis in patients on continuous ambulatory peritoneal dialysis

Continuous ambulatory peritoneal dialysis (CAPD) has emerged as an important dialysis treatment modality worldwide. One of the major complications is bacterial peritonitis, which may result in subsequent technique failure because of loss of peritoneal clearance or peritoneal fibrosis. Bacterial peritonitis leads to the release of proinflammatory cytokines from resident and infiltrating cells in the peritoneal cavity. We studied 35 patients undergoing CAPD with acute bacterial peritonitis. All patients treated with antibiotics for 2 weeks after the clinical diagnosis of peritonitis had a good recovery. Peritoneal dialysate effluent (PDE) was collected on days 1, 3, 5, 10, 21, and 42 after the start of treatment. Cell populations were monitored by flow cytometry. PDE levels of interleukin-1beta (IL-1), IL-6, transforming growth factor-beta (TGF-beta), and basic fibroblast growth factor (FGF) were measured by enzyme-linked immunosorbent assay. Gene transcription of TGF-beta in macrophages from PDE was measured by quantitative polymerase chain reaction. Bacterial peritonitis was associated with a sharp increase in total cell and neutrophil counts (400-fold) in PDE up to 3 weeks after peritonitis despite clinical remission (P < 0.0001). There was an increased absolute number of macrophages during the first 3 weeks despite the reduced percentage of macrophages among total cells in PDE compared with noninfective PDE. There was a progressive increase in the percentage of mesothelial cells or dead cells in the total cell population in PDE over the entire 6-week period. PDE levels of IL-1, IL-6, TGF-beta, and FGF increased markedly on day 1 before their levels decreased gradually. PDE levels of these cytokines or growth factors were significantly greater than those in noninfective PDE (n = 76) throughout the study period (P < 0.01). Similarly, TGF-beta complementary DNA (cDNA) molecules per macrophage were significantly greater than those of macrophages in noninfective PDE throughout this period (P < 0.01). There was no significant correlation between PDE levels of TGF-beta and TGF-beta cDNA molecules per macrophage, suggesting that peritoneal macrophages are not the only source of TGF-beta in PDE. We conclude there is an active release of proinflammatory cytokines and sclerogenic growth factors through at least 6 weeks despite apparent clinical remission of peritonitis. The peritoneal cytokine networks after peritonitis may potentially affect the physiological properties of the peritoneal membrane.

Growth factors in continuous ambulatory peritoneal dialysis effluent. Their relation with peritoneal transport of small solutes

Recent studies reveal conflicting results on the change of solute transfer with time on continuous ambulatory peritoneal dialysis (CAPD) and recurrent peritonitis. Herein, we performed a cross-sectional study of 76 patients on CAPD to examine their peritoneal permeability by measuring the dialysate to serum ratio of creatinine (D/P) and the mass transfer area coefficients of creatinine (MTACCr) or glucose (MTACGlu). Transforming growth factor-beta1 (TGF-beta1), platelet-derived growth factor (PDGF), and epidermal growth factor (EGF) were measured in the dialysate by ELISA. TGF-beta1 mRNA in peritoneal macrophages were determined by a quantitative polymerase chain reaction. We failed to observe any correlation between the duration on dialysis and the peritoneal permeability in those patients with no previous peritonitis. Frequency of peritonitis episode did not affect the MTACCr, MTACGlu, or D/P. The MTACCr correlated well with MTACGlu (r = 0.78, p = 0. 001) and with D/P (r = 0.98, p < 0.0001). No inverse correlation was demonstrated between dialysate PDGF or EGF and the peritoneal permeability. A positive correlation was demonstrated between the dialysate TGF-beta1 and MTACCr, MTACGlu or D/P (r = 0.64, 0.54, and 0.64 respectively, p < 0.001). The dialysate TGF-beta1 levels in patients with low D/P (</=0.5) were only half of that in patients with normal or high D/P (p = 0.0002). The dialysate levels of TGF-beta1 did not correlate with PDGF or EGF. These findings raise the possibility that, other than diffusion across the peritoneal membrane from circulation, there could also be an intrinsic production of TGF-beta1 by peritoneal cells in these CAPD patients. Our findings raise the speculation that TGF-beta1 in dialysate from stable CAPD patients may exert an inhibitory action to fibroblast. Such action of TGF-beta1 could reduce the risk of peritoneal sclerosis and hence, maintains a satisfactory peritoneal permeability to small solutes.

Gene expression and synthesis of natriuretic peptides by cultured human glomerular cells

BACKGROUND

Atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide belong to a family of hormones that have natriuretic and vasodepressor activity and may play a pathophysiologic role in hypertension, heart failure and renal failure. Whereas immunoreactive human forms of these three natriuretic peptides are found in renal tubules, it is not clear whether they are derived from the systemic circulation or from local production.

OBJECTIVE

To examine the gene expression of natriuretic peptides in cultured human glomerular cells.

MATERIALS AND METHODS

We sought to determine the presence of messenger RNA encoding for these natriuretic peptides using polymerase chain reaction following reverse transcription. The polymerase chain reaction products were confirmed by direct sequencing. Atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide in cell-culture supernatants were measured by radioimmunoassays (with detection limits of 2.1, 2.1 and 0.21 pmol/l, respectively).

RESULTS

Atrial natriuretic peptide messenger RNA was not found in mesangial or glomerular epithelial cells (despite stimulation with tumor necrosis factor-alpha) except when the cells were cultured with a high concentration of fetal bovine serum (> 10%). Similarly, this peptide was not detected in supernatant unless the cells were cultured with fetal bovine serum at concentrations of > 10%. Brain natriuretic peptide messenger RNA was readily detected in cultured mesangial and glomerular epithelial cells with a lower concentration in the former. Brain natriuretic peptide was not found in the supernatant of resting mesangial cells but became detectable when incubated with tumor necrosis factor-alpha or fetal bovine serum. C-type natriuretic peptide messenger RNA was detected in mesangial and glomerular epithelial cells with a higher concentration in the latter. C-type natriuretic peptide was detected in the supernatant of resting glomerular epithelial cells and levels rose when incubated with increasing concentrations of tumor necrosis factor-alpha or fetal bovine serum. However, C-type natriuretic peptide was not detected in the supernatant of resting mesangial cells and remained undetectable following incubation with tumor necrosis factor-alpha or fetal bovine serum.

CONCLUSION

Our results suggest differences in the synthesis of natriuretic peptides between glomerular mesangial and epithelial cells.

Thickening of the diaphragm: a new computed tomography sign of diaphragm injury

Computed tomography examination is becoming a standard method of evaluating injury in blunt trauma. This report describes a previously unreported computed tomography sign of diaphragmatic injury. A retrospective review of imaging findings was performed on eight patients with surgically proven traumatic diaphragmatic rupture. Thickening of the diaphragm was present on computed tomography in six of eight patients with surgically proven diaphragm rupture. Two patients demonstrated previously established computed tomography signs of diaphragm rupture and two patients had no findings to suggest diaphragm injury. Diaphragm thickening is associated with diaphragm rupture and may be a useful diagnostic sign in the evaluation of patients with blunt trauma.

Increased sialylation of polymeric immunoglobulin A1: mechanism of selective glomerular deposition in immunoglobulin A nephropathy?

Immunoglobulin A nephropathy (IgAN) is characterized by raised serum IgA and predominant mesangial IgA deposits of polymeric nature. The abnormal glycosylation of the carbohydrate moieties in the hinge region of the IgA molecule has recently attracted much attention. In this study we investigated the galactosylation and sialylation of monomeric and polymeric IgA1 isolated from patients with IgAN. Total IgA1 in serum samples from patients with IgAN or from healthy controls was isolated with a jacalin-agarose column as jacalin-bound protein (JBP). Monomeric and polymeric IgA1 were distinctly separated by fast protein liquid chromatography. Lectin binding assays were designed to examine the sialylation and the expression of terminal galactose and N-acetyl galactosamine of the O-linked carbohydrate in the hinge region of the IgA molecule. Reduced terminal galactosylation was demonstrated in serum IgA and monomeric IgA1 isolated from patients with IgAN as compared with results in healthy control subjects. However, a reduction in terminal galactosylation was not found in polymeric IgA1 isolated from patients with IgAN. Instead, increased sialylation of IgA1 (alpha2-3 linked to galactose) was demonstrated in polymeric IgA1. This abnormality of IgA1 could bear considerable implication on the pathogenesis of IgAN, because the masking effect of sialic acid may hinder the clearance of polymeric IgA1 by the asialoglycoprotein receptor (ASGP-R) of the liver cells. An increase in the sialylated content would also render the polymeric IgA from patients with IgAN more anionic. These immunochemical properties may contribute to the selective glomerular deposition of polymeric IgA1 in IgAN.

Increased production of hyaluronan by peritoneal cells and its significance in patients on CAPD

Hyaluronan (HA) is a polysaccharide that forms a critical component of extracellular matrices. HA is present in high concentrations in tissues undergoing remodeling and morphogenesis, and it appears to have an important role in the early stages of wound healing. Here, we studied the level of HA in the peritoneal dialysate effluent (PDE) from 116 stable continuous ambulatory peritoneal dialysis (CAPD) patients. Longitudinal studies over a period of 6 weeks were performed in seven of these patients who developed peritonitis. The median HA level in PDE from these patients was 154.6 microg/L (range, 29.7 to 820.2 microg/L). Dialysate level of HA increased with age of the patients, but no such correlation was shown between HA level in PDE and duration of CAPD treatment or previous episodes of peritonitis. Patients with high or average peritoneal membrane transport of small solutes had a higher HA level in the PDE than those with a low peritoneal membrane transport (P = 0.046). A significant correlation was observed between PDE level of HA and interleukin-1beta (IL-1beta) or IL-6. The plasma level of HA in these patients was significantly greater than that of healthy controls (P < 0.0001), yet the plasma concentration of HA was only 85% that of the PDE concentration. In CAPD patients with peritonitis, there was a sharp increase in the PDE levels of HA, IL-1beta, and IL-6. These values decreased progressively with resolution of peritonitis. The changes in the PDE levels of HA closely followed those of IL-1beta or IL-6. In vitro [3H]-glucosamine incorporation studies suggest that the main bulk of HA is derived from synthesis by the peritoneal mesothelial cells, whereas the amount synthesized by macrophages is trivial. We conclude that elevated levels of HA found in the PDE of stable CAPD patients originate from increased synthesis by peritoneal mesothelial cells. This event may serve as a marker of regeneration and remodeling of the peritoneal lining.

Increased ascitic level of hyaluronan in liver cirrhosis

Hyaluronan (HA) is a polysaccharide that forms a critical component of extracellular matrixes. It is present in high concentrations in tissues undergoing remodeling and morphogenesis. Serum HA is elevated in patients with chronic liver disease, and this has been considered to be caused by impaired degradation by the liver endothelial cells. We studied the level of HA in the ascitic fluid and plasma from 27 patients with cirrhotic ascites. These values were compared with peritoneal dialysate effluent (PDE) and plasma from 33 patients with uremia who were undergoing continuous ambulatory peritoneal dialysis (CAPD). The median HA levels in ascitic fluid and plasma from our 26 patients with cirrhosis were significantly higher than corresponding PDE and plasma values from the 33 CAPD patients (p < 0.0001). The median peritoneal/plasma ratios of creatinine, albumin, and immunoglobulin G in either cirrhotic or CAPD patients were less than unity. In contrast, the median peritoneal/plasma ratios of HA in both groups of patients exceeded one with a higher peritoneal/plasma ratio of HA in patients with cirrhosis (p = 0.0035). A significant correlation was observed between the ascitic level of HA and interleukin-1beta, interleukin-6, or transforming growth factor-beta. Our in vitro cell culture studies revealed that HA is synthesized by both mesothelial cells and macrophages. We observed an additive effect in the synthesis of HA by mesothelial cells when the macrophage-conditioned medium was added to the RPMI culture medium. We conclude that a high level of HA is found in ascites from patients with cirrhosis. Our results strongly suggest that simultaneous increased synthesis of HA by the peritoneal cells and a reduction of degradation by liver endothelial cells occur in these patients with cirrhosis with ascites. This event of increased HA synthesis may be contributory to remodeling and regeneration of the peritoneal lining.

Gene transcription and synthesis of adrenomedullin by cultured human renal cells

Adrenomedullin (ADM) is a novel 52 amino acid peptide with a potent vasodilator effect. Gene expression of ADM is found in human kidney but the exact cell source in the kidney is uncertain. Its plasma level is raised in association with changes in sympathetic nervous activity and body fluid volume in hypertension and chronic renal failure. Herein, we examined the presence of mRNA encoding for ADM in cultured human glomerular cells. Adrenomedullin in cell culture supernatant was measured by a radio-immunoassay (with a detection level of 3.2 pmol/l). Adrenomedullin mRNA was found in cultured mesangial and glomerular epithelial cells as well as in vascular endothelial cells. Supernatant levels of ADM for cultured mesangial and glomerular epithelial cells were 21.2 and < 3.2 pmol/l respectively. Contrary to vascular smooth muscle cells, the gene expression for ADM in mesangial cells was up-regulated when incubated with increasing concentration of TNF-alpha or fetal bovine serum (FBS) but this effect was not observed with very high concentration. Parallel results were observed in adrenomedullin levels in supernatant from mesangial cell cultures. Forskolin, captopril, or TGF-beta had no effect on the transcription or synthesis of ADM in mesangial cells. The gene expression for ADM in glomerular epithelial cells was down-regulated when incubated with increasing concentration of TNF-alpha, forskolin or FBS. The ADM levels in all supernatant from resting glomerular epithelial cell cultures were < 3.2 pmol/l. Recent murine data show that ADM stimulates the release of cAMP but suppresses mitogenesis in cultured mesangial cells. Our results suggest ADM is synthesized by mesangial cells in an autocrine fashion and the peptide may potentially be involved in intra-renal blood pressure control.

Effect of anti-DNA autoantibodies on the gene expression of interleukin 8, transforming growth factor-beta, and nitric oxide synthase in cultured endothelial cells

Our study aims to determine whether anti-dsDNA exerts any effect on the gene expression of IL-8 or TGF-beta in cultured HUVEC. Both cytokines have angiogenic effect on endothelial cells. IgG was purified from 19 patients with SLE and from 19 healthy controls. Anti-dsDNA-depleted polyclonal IgG was also prepared from serum IgG of lupus patients by affinity chromatography with DNA cellulose column. Compared with either control IgG or anti-dsDNA-dep-IgG, HUVEC incubated with anti-dsDNA-containing-IgG expressed higher levels of IL-8 mRNA (p = 0.0001) and TGF-beta 1 mRNA (p = 0.0014). We demonstrated a significant increase in the percentage of cells with fragmented DNA in HUVEC incubated with anti-dsDNA-containing-IgG compared with those incubated with anti-dsDNA-dep-IgG, supporting the notion that anti-dsDNA may exert a direct apoptotic effect on cultured endothelial cells. Our study provides in vitro evidence that anti-dsDNA could play an important pathogenetic role in inducing inflammatory injury of vascular endothelium in SLE.

Compartmentalization of pro-inflammatory cytokines in tuberculous pleurisy

Increased levels of interleukin-6 (IL-6) and IL-8 are found in various immunologically mediated inflammatory disorders. Concentrations of IL-6, IL-8 and the soluble form of the IL-6 receptor (sIL-6R) were determined in serum and effusion fluid of 25 patients with tuberculous pleurisy utilizing enzyme linked immunosorbent assays (EIA). Serum IL-6 levels were only slightly increased in patients with tuberculous pleurisy in comparison to controls (11.1 +/- 2.1 vs 7.3 +/- 1.0 pg ml-1). IL-8 could not be detected in the serum of tuberculosis patients, but it was detected in the serum of healthy controls (8.0 +/- 1.5 pg ml-1). In comparison to serum, IL-6 and IL-8 were found in high concentrations in pleural effusions (IL-6: 932 +/- 70 vs 11.1 +/- 2.1 pg ml-1, P < 0.0001; IL-8: 450 +/- 85 vs 0 +/- 0 pg ml-1). In contrast, sIL-6R concentrations were much higher in serum compared to pleural effusion levels [30,477 +/- 1905 vs 9881 +/- 1177 pg ml-1, P < 0.0001 (mean +/- SEM)]. The authors conclude that elevated levels of IL-6 and IL-8 in pleural effusions are compartmentalized at the site of active disease. The low levels of sIL-6R in the presence of high levels of IL-6 in pleural effusions, and the high levels of sIL-6R in the presence of low levels of IL-6 in serum suggest that the expression or shedding of sIL-6R may be downregulated in the presence of excessive amounts of IL-6.

Gene expression of the renin-angiotensin system in human kidney

BACKGROUND

Immunocytochemical studies have revealed that all components of the renin-angiotensin system are widely distributed in human tissues yet the information on the gene expression of the renin-angiotensin system in various types of cell remains scarce.

OBJECTIVE

We explored the presence of a local renin-angiotensin system in human kidney.

METHODS

We sought to determine the presence of messenger RNA (mRNA) encoding for renin, angiotensinogen, and angiotensin converting enzyme (ACE) in cultured human glomerular cells and human umbilical vein endothelial cells using a two-step polymerase chain reaction. The gene expression of the renin-angiotensin system in normal human kidney and in diseased kidney was studied by in-situ hybridization using synthetic oligonucleotides.

RESULTS

By using a two-step polymerase chain reaction, renin, angiotensinogen, and ACE mRNA were found in cultured mesangial and epithelial cells but only ACE mRNA was present in human umbilical vein endothelial cells. Renin mRNA was detected in juxtaglomerular granular cells and also in glomerular and tubular epithelia in normal kidney by in-situ hybridization. A similar tubular, but not mesangial, distribution was found with angiotensinogen and ACE mRNA. In contrast, stronger signals for renin, angiotensinogen and ACE mRNA were detected in mesangial and epithelial cells of kidney tissues from hypertensive patients and from patients with renal pathology characterized by mesangial proliferation (immunoglobulin A nephropathy, diabetes mellitus, or lupus nephritis).

CONCLUSIONS

That gene expression of the renin-angiotensin system occurs in resident glomerular cells supports the hypothesis that there is a local renin-angiotensin system in human kidney. Our findings support the previous speculation that the renin-angiotensin system could be a local factor involved in the progression of chronic renal failure and consequent development of hypertension.

Dialysate cell population and cancer antigen 125 in stable continuous ambulatory peritoneal dialysis patients: their relationship with transport parameters

We investigated the total cell count and cell population of the overnight peritoneal dialysis effluent (PDE) by flow cytometry in 76 stable continuous ambulatory peritoneal dialysis (CAPD) patients. The mean percentage of mesothelial cells and macrophages was 4.4% and 57%, respectively. A higher percentage of dead cells among the mesothelial cells compared with other cell populations in the PDE was observed. Peritoneal transport properties were studied in every patient by determining the dialysate to plasma ratio of creatinine concentration (D/P) at the fourth hour of the peritoneal equilibration test, and the mass transfer area coefficient of creatinine (MTACCr) or glucose. Cancer antigen 125 (CA125), suggested as a bulk marker for the mesothelial mass in stable peritoneal dialysis patients, was determined in the PDE. No correlation was demonstrated between CA125 and the number of mesothelial cells, lymphocytes, or macrophages in the PDE. A significant correlation was observed between CA125 and different parameters of peritoneal transport (D/P and MTACCr). On the contrary, neither the history of peritonitis nor the duration of CAPD appeared to affect the CA125 concentration in the PDE. The lack of correlation between CA125 in the PDE and the duration of CAPD may be related to the early loss of peritoneal transport properties as a result of the use of hypertonic dialysate in the majority of our patients with small-volume CAPD (3 x 2 L daily exchange). Our findings suggest that CA125 may not necessarily correlate well with the number of mesothelial cells in PDE. In patients with vanishing of the mesothelial layer, the measurement of CA125 (as a bulk marker for the mesothelial mass in the peritoneum) may reflect the change of peritoneal transport properties.

Family support for the elderly in China: issues and challenges

With the introduction of economic reforms, families in China are challenged by a variety of family-related problems. Demographic and social changes are affecting both the capacity and willingness of the family to provide care for the elderly. The Chinese Government is aware of the importance of the family in the welfare of its citizens, and has promulgated a series of laws and regulations prescribing family obligations. Yet formal services supporting families are extremely underdeveloped, and it is urgent that the government formulate an effective policy to facilitate, support, and maximize family care.

Common occurrence of an antiidiotypic antibody that recognizes T14+ anti-DNA antibodies in patients with systemic lupus erythematosus

OBJECTIVE

To investigate whether antibodies to a T14 anti-DNA antibody can be found in patients with systemic lupus erythematosus (SLE).

METHODS

Seventy-six serum samples (37 from patients with SLE) were randomly selected from among sera submitted for routine antinuclear antibody testing. Short, overlapping peptides based on the partial VH (variable region of the heavy chain) sequence of the T14 antibody were synthesized on multipins and screened for reactivity with SLE sera. In addition, selected peptides from T14 and related proteins were synthesized in bulk and screened for reactivity with both SLE and control sera. A monoclonal antibody was generated to determine the prevalence of the T14 idiotype (T14+ Id) in the different study populations.

RESULTS

Antibodies were detected by a peptide based on the third complementarity-determining region (CDR3) of the T14 protein in 15 (41%) of 37 patients with SLE or 15 (54%) of 28 who had anti-DNA antibodies, in 3 (9%) of 34 patients without anti-DNA antibodies (9 of whom had SLE), and in 6 (10%) of 57 healthy controls. In SLE sera, the antiidiotypic (anti-Id) responses (IgM and IgG) correlated well with the anti-DNA responses (IgG), and both responses correlated well with the T14+ Id activity in SLE sera. Control peptides based on the 18/2 (16/6+ Id) and S107 proteins detected low antibody activities in SLE sera, attributable to cross-reactivity with the T14 peptide. A peptide based on an unrelated human antibody was not reactive with these sera.

CONCLUSION

Anti-Id antibodies directed to T14 VHCDR3 were found commonly in the sera of patients with SLE, and they appeared to be induced by the anti-DNA antibodies present in the sera. Based on these findings, these secondary antibodies may be pathogenic in SLE.

Upregulation of adhesion molecule expression on endothelial cells by anti-DNA autoantibodies in systemic lupus erythematosus

The mechanism of vasculopathy in systemic lupus erythematosus (SLE) remains unclear and the evidence for a direct pathogenic role of anti-double-stranded DNA antibodies (anti-dsDNA) is not strong. Our study aims to determine whether anti-dsDNA exerts any effect on the expression of adhesion molecules on endothelial cells. IgG was purified from 17 patients with SLE (median anti-dsDNA titer, 404 IU/ml) and from 9 healthy controls (median titer 16 IU/ml). Anti-dsDNA-depleted polyclonal IgG (anti-dsDNA-dep-IgG) (median anti-dsDNA titer 17 IU/ml) was prepared from sera of these patients with SLE by affinity chromatography with DNA cellulose column. Expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin on human umbilical vein endothelial cells (HUVEC) cultured with either control IgG or anti-dsDNA were compared by flow cytometry. The levels of adhesion molecules in the supernatant of cultured HUVEC were assessed by sandwich ELISA. Compared with either control IgG or anti-dsDNA-dep-IgG, HUVEC incubated with anti-dsDNA expressed a significantly higher mean fluorescence intensity of ICAM-1 and in VCAM-1 and a higher supernatant concentration of ICAM-1 and VCAM-1 but not E-selectin. At the same time, ICAM-1 mRNA was also raised with increased neutrophil adherence in HUVEC incubated with anti-dsDNA. Pretreatment of HUVEC with native DNA or histone before incubation with anti-dsDNA did not increase the expression of adhesion molecules. Our study provides in vitro evidence that anti-dsDNA could play an important pathogenic role in inducing inflammatory injury of vascular endothelium in SLE.

Interleukin-5 messenger RNA expression in peripheral blood CD4+ cells in asthma

BACKGROUND

IL-5 has been implicated in the pathogenesis of asthma through its regulatory role on eosinophil survival, proliferation, and effector function.

OBJECTIVE

The study was designed to investigate the relationships between IL-5 messenger RNA expression in circulating CD4+ cells and serum concentrations of eosinophil cationic protein (ECP), a marker of eosinophil activation, and disease activity in asthma.

METHODS

IL-5 gene expression was assessed semiquantitatively in ex vivo stimulated CD4+ cells by reverse transcription-polymerase chain reaction and serum ECP concentration measured from venous blood samples collected from patients with acute severe asthma before the commencement of systemic steroid therapy (day 1) and on day 7 and from patients with stable asthma and healthy volunteers.

RESULTS

IL-5 gene expression was significantly higher in patients with acute asthma before steroid treatment than in those with stable disease and healthy subjects (p < 0.0001). Similar results were obtained with serum ECP levels: levels in patients with acute asthma were highest (20.30 +/- 5.31 micrograms/L), followed by levels in patients with stable asthma (2.76 +/- 0.65 micrograms/L) and levels in normal control subjects (1.37 +/- 0.06 micrograms/L; p < 0.01 for all comparisons). Significant falls in both IL-5 expression and serum ECP level were seen on day 7 (p < 0.001) and coincided with a significant improvement in peak expiratory flow (p < 0.0001). Significant correlations were observed between IL-5 expression and ECP level (rho = 0.39, p < 0.01), IL-5 expression and peak expiratory flow (rho = -0.55, p < 0.0002), and peak expiratory flow and ECP level (rho = -0.32, p < 0.04).

CONCLUSION

Our data therefore support an important regulatory role of IL-5 on eosinophil function in human asthma in vivo.

Serologic study of immunoglobulin A-fibronectin aggregates in immunoglobulin A nephropathy

The immunoglobulin A (IgA)-fibronectin aggregates, detected by enzyme-linked immunosorbent assay using either antifibronectin or collagen I as binding protein, were previously found to be raised in the circulation of patients with IgA nephropathy (IgAN). It has been suggested that IgA-fibronectin aggregates are involved in the pathogenesis and that the plasma IgA-fibronectin level may even be of diagnostic value in IgAN. Nevertheless, a recent report has questioned the specificity of these assays as plasma IgA may interact with immobilized IgG and these assays detect not only IgA-fibronectin, but also total plasma IgA. These doubts render the interpretation of raised IgA-fibronectin aggregates in IgAN impossible. We isolated total IgA, in plasma by jacalin-agarose. Monomeric and polymeric IgA1 were distinctly separated by fast protein liquid chromatography. When the fast protein liquid chromatography fractions were analyzed for IgA-fibronectin using the antifibronectin capture assay, increased optical density values were predominantly observed in polymeric IgA but not in monomeric IgA. Similar findings were found when the fast protein liquid chromatography fractions were studied using a novel gelatin-anti-IgA assay that avoided nonspecific interaction between plasma IgA and immobilized IgG used as the capture antibody in antifibronectin capture assay. Using our gelatin-anti-IgA assay, we failed to demonstrate a diagnostic increase in IgA-fibronectin aggregates in polymeric IgA from patients with IgAN compared with controls. Our finding of circulating IgA-fibronectin aggregates in patients with IgAN comparable to those of healthy controls did not support the notion that these aggregates may have a pathogenetic role or diagnostic value in IgAN.

Anti-DNA autoantibodies stimulate the release of interleukin-1 and interleukin-6 from endothelial cells

The pathogenetic mechanism of vasculitis in systemic lupus erythematosus (SLE) remains a subject of debate. Evidence for a direct pathogenetic role of anti-double-stranded DNA antibodies (anti-dsDNA) is not strong. Supernatant concentrations of interleukin-1 beta and interleukin-6, and mRNAs encoding for interleukin-1 alpha and interleukin-1 receptor-1 were determined in cultured human umbilical vein endothelial cells (HUVEC), incubated with control IgG (n = 18), anti-dsDNA (n = 18), or IgG from the same lupus patient depleted of anti-dsDNA by affinity chromatography (anti-dsDNA-dep-IgG). Compared with control IgG, there was a significant increase of supernatant interleukin-1 beta and interleukin-1 alpha mRNA in endothelial cells incubated with anti-dsDNA. The supernatant interleukin-1 beta and interleukin-6, and mRNAs encoding for interleukin-1 alpha and interleukin-1 receptor-1, were significantly elevated in endothelial cells incubated with anti-dsDNA, compared with those incubated with anti-dsDNA-dep-IgG. Pretreating HUVEC with native DNA before incubating with anti-dsDNA did not result in an additive effect. These in vitro studies suggest that anti-dsDNA plays an important pathogenetic role in inducing inflammatory injury of vascular endothelium in SLE.

Increased binding of polymeric lambda-IgA to cultured human mesangial cells in IgA nephropathy

IgA nephropathy (IgAN) is characterized by raised plasma lambda-IgA1 and mesangial polymeric lambda-IgA1 deposits. It remains uncertain whether the predominant glomerular lambda-IgA1 deposits represent a selective uptake of polymeric IgA or a non-specific uptake due to elevated circulating lambda-IgA1 levels in response to an unidentified antigen. In this study, we explored whether there is an increased binding of monomeric IgA1 (mIgA1) or polymeric IgA1 (pIgA1) from patients with IgAN to cultured human mesangial cells (HMC). Total IgA1 in plasma from patients or healthy controls was isolated by jacalin-agarose column as jacalin-bound proteins (JBP). Monomeric IgA1 and pIgA1 were distinctly separated by FPLC. HMC were incubated with IgA preparations and IgA bound to HMC was determined by flow cytometry analysis using standard curves constructed by known concentrations of kappa-IgA1 or lambda-IgA1. In order to avoid any increased binding of IgA to HMC due to elevated kappa- or lambda-IgA concentrations in JBP samples from patients, JBP samples from patients or controls were appropriately diluted to achieve comparable levels of total IgA1. No differences in the total mIgA1 or pIgA1 concentration, percentage of mIgA1 or pIgA1, or the kappa/lambda ratio of mIgA1 or pIgA1 were found between adjusted JBP samples from patients or healthy controls. We found a sharp rise in percentage of pIgA1 among IgA1 bound to HMC (70%), despite the fact that only 3% of the IgA1 in the adjusted JBP samples were polymeric, suggesting that pIgA1 had a higher affinity to HMC than mIgA1. Furthermore, the kappa/lambda ratios of pIgA1 bound to HMC were significantly lower than the kappa/lambda ratios of pIgA1 in adjusted JBP only with IgAN patients but not healthy controls (P = 0.0026). Our data suggest a preferential mesangial binding of polymeric lambda-IgA1 from patients with IgAN. These polymeric lambda-IgA immune complexes are likely to be "pathogenic" and are important in the pathogenesis of IgAN.

Increased release of von Willebrand factor antigen from endothelial cells by anti-DNA autoantibodies

OBJECTIVE

To determine whether antibodies to double stranded DNA (anti-dsDNA) have a pathogenic role in systemic lupus erythematosus (SLE).

METHODS

IgG was purified from 17 patients with SLE (median anti-dsDNA titre 1212 IU/ml) and nine healthy controls (median titre 40 IU/ml). Anti-dsDNA depleted polyclonal IgG (median anti-dsDNA titre 17 IU/ml) was also prepared from sera of the 17 patients by affinity chromatography on a DNA cellulose column. Binding to antiendothelial cell antibodies (AECA) and expression of von Willebrand factor (VWF) antigen by cultured human umbilical vein endothelial cells (HUVECs) were studied by flow cytometry.

RESULTS

The percentage of HUVECs binding to AECA or expressing VWF was greater for cells incubated with IgG from patients with SLE than for cells incubated with control IgG, though values did not reach statistical significance; nevertheless, HUVECs incubated with IgG from patients expressed a greater mean fluorescence intensity with AECA (p = 0.0001) and greater VWF expression (p = 0.019). Both the fluorescence intensity and percentage of HUVECs binding to AECA or expressing VWF were significantly greater in HUVEC incubated with IgG containing anti-dsDNA than in those incubated with anti-dsDNA depleted IgG. The concentration of VWF in the supernatant was significantly increased in HUVECs incubated with IgG containing anti-dsDNA compared with control IgG or anti-dsDNA depleted IgG. Pretreatment of HUVECs with native DNA before incubation with IgG from lupus patients did not increase binding to AECA, or expression or release of VWF.

CONCLUSIONS

Our study provides in vitro evidence that antibodies to DNA have a pathogenic role in the induction of inflammatory injury of the vascular endothelium in SLE.

The mechanism of ion conduction by valinomycin: analysis of charge pulse responses

Even though valinomycin has been employed and studied extensively for over 30 years, the attempts to explain its mechanism have not been entirely successful. The basic carrier model uses four rate constants that describe association of an ion and carrier, transfer of the complex across the membrane, dissociation of the complex, and transfer of the free carrier back across the membrane. If the basic model is correct all of these constants are independent of ion concentration. In previous work with rubidium the rate constants for transfer of free carrier, transfer of complexes, and dissociation were independent of the concentration, but the rate constant for association varied markedly. No satisfactory explanation for these observations was proposed. In this study current relaxations after charge pulses have been analyzed using digital data acquisition, a Bayesian algorithm, and inspection of linear plots of residuals. In agreement with previous results the relaxations for sufficiently high rubidium or potassium concentrations contain three exponential components, but the rate constants for association and dissociation decrease to similar extents as ion concentration increases. A simple extension of the carrier model to allow a more realistic description of association and dissociation is in good agreement with the rate constants fitted in the present study but not those for low ion concentrations found in previous work. At high ion concentrations the rate-limiting step in association appears to be a change in the conformation of the free carrier preceding the bimolecular association reaction. Transfer of neutral, free valinomycin between the surfaces is slower than the transfer of the charged ion-valinomycin complexes. Transfer of the complex may be hastened by deformation of the membrane, or transfer of the free carrier may be slowed by a need for conformation changes.

Biliary IgA secretion in obstructive jaundice: the effects of endoscopic drainage

BACKGROUND

Immunoglobulin A is the predominant immunoglobulin in the bile. Data on the effects of biliary obstruction on IgA secretion are few.

METHODS

The serum and bile IgA levels in patients with common duct stones (n = 27) or with malignant obstructive jaundice (n = 20) were collected by insertion of nasobiliary catheters. Single samples of common duct bile from patients with gallstones (n = 24) were collected as controls. Bile samples collected were measured for total IgA, secretory IgA, and free secretory component levels by sandwich enzyme-linked immunosorbent assays.

RESULTS

Bile total IgA, secretory IgA, and free secretory component in the common duct stones group (82.7 +/- 11.4 microgram/ml, 18.4 +/- 1.7 microgram/ml, 0.74 +/- 0.15 microgram/ml) and the malignant obstructive jaundice group (81.6 +/- 10.7 microgram/ml, 18.2 +/- 2.4 microgram/ml, 0.57 +2- 0.12 microgram/ml) were found to be significantly lower than those of the control gallstone patients (104.8 +/- 3.4 microgram/ml, 33.2 +/- 2.9 microgram/ml, 1.03 +/- 0.12 microgram/ml) (P < 0.05). Serum secretory IgA levels in the common duct stones (26.53 +/- 1.75 microgram/ml) and malignant obstructive jaundice groups (26.03 +/- 3.48 microgram/ml) were significantly higher than the gallstone group (18.45 +/- 4.56 microgram/ml). The bile-to-serum concentration ratio of total IgA, secretory IgA, and free secretory component levels rose significantly within 48 hours after relief of obstruction.

CONCLUSIONS

Biliary obstruction secondary to both calculus or malignancy of the hepatobiliary system causes suppression of bile IgA secretion and elevated serum level of secretory IgA. Bile secretory IgA secretion recovers with endoscopic drainage of the obstructed system.

Identification and characterization of human serum alpha2-HS glycoprotein as a jacalin-bound protein

We recently adopted immobilized jacalin as an affinity adsorbent to purify human serum IgA for laboratory study. In the course of our investigation, we detected a serum protein that co-eluted with IgA from jacalin-agarose affinity column. It constituted in significant quantity (24.0 +/- 0.9%, n = 30) of total jacalin-bound protein (JBP) and the yield was equivalent to 0.4 +/- 0.1 mg per ml serum. The molecular mass of this protein was 55 kDa with electromobility in the alpha 2 region as demonstrated by SDS-PAGE and immunoelectrophoresis. N-terminal microsequencing of this 55 kDa protein revealed that it is human alpha 2-HS glycoprotein (alpha 2HSG). The molecular interaction of alpha 2HSG with jacalin was characterized by competitive ELISA: human serum IgA, human colostrum secretory IgA (sIgA), and monosaccharides including D-galactose and melibiose exhibited strong inhibitory effect on its binding to jacalin. Accordingly, we propose that human alpha 2HSG binds in a similar manner as that of the bovine fetuin to jacalin. In addition, alpha 2HSG displays similar binding property to jacalin from different geographic area (India and Malaysia) and from different laboratory preparations (Sigma, Pierce and 'homemade' jacalin).

Elevated interleukin-2 receptor level in patients with active pulmonary tuberculosis and the changes following anti-tuberculosis chemotherapy

Soluble interleukin-2 receptor (sIL-2R) is a marker of T-lymphocyte activation. We have undertaken a study to examine the serum sIL-2R levels in patients with pulmonary tuberculosis (TB) and the changes following anti-TB chemotherapy. Forty four patients with pulmonary TB or tuberculous pleural effusion were recruited. Serum was collected from the patients before and at 1, 2, 4 and 6 months after initiation of anti-TB chemotherapy. Serum sIL-2R level was measured by an enzyme immunoassay. The mean sIL-2R level before treatment was 1,452 +/- 103 (SEM) U.ml-1, which was significantly higher than that of healthy control subjects (374 +/- 30 U.ml-1). There was no significant change in the sIL-2R level at 1 month, but there was a gradual reduction from the second month onwards. At the sixth month the mean sIL-2R level was 1080 +/- 81 U.ml-1, which was significantly lower than that before treatment. However, despite clinical improvement, the sIL-2R levels at the sixth month were still significantly higher than those of control subjects. We conclude that sIL-2R levels were elevated in patients with pulmonary TB and there was a gradual reduction following anti-TB chemotherapy. However, the sIL-2R levels were still higher than control subjects at completion of treatment, suggesting a delayed resolution of the inflammation in patients with pulmonary TB.

Heat-aggregated IgA prepared from patients with IgA nephropathy increases priming of human neutrophils to produce inositol triphosphate following FMet-Leu-Phe stimulation in vitro

It is envisaged that circulating IgA complexes play a primary role in the glomerular injury of IgA nephropathy, the most common glomerulonephritis worldwide. In this study, we examined the pathophysiological effects of IgA and IgG isolated from IgA-nephritic patients on the signal transduction of human neutrophils. Heat-aggregated forms and monomers of IgA and IgG were prepared from sera of 11 IgA-nephritic patients and 11 healthy controls. Signal transduction was studied by measuring the inositol triphosphate (IP3) production in neutrophils incubated with the immunoglobulin preparations. Different forms of IgA or IgG from IgA-nephritic patients failed to induce a significant increase in IP3 production directly as compared with control IgA or IgG. However, neutrophils preincubated with heat-aggregated IgA (HAA) from IgA-nephritic patients demonstrated a significant rise in IP3 production upon subsequent stimulation by a chemotactic peptide, FMet-Leu-Phe (FMLP); a similar finding was not observed with heat-aggregated IgG. HAA pretreatment of neutrophils increased FMLP-induced IP3 production in a dose-dependent manner. The raised IP3 production was not due to increased FMLP receptors, as HAA preincubation of neutrophils did not increase the binding of tritiated FMLP. The increased IP3 production upon FMLP stimulation in HAA-primed neutrophils was completely abolished by pertussis toxin in a dose-dependent manner. These findings tend to refute a direct stimulatory effect of HAA on phospholipase C, but, instead, may suggest that HAA prepared from IgA-nephritic patients upregulates the activation of G proteins in the plasma membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

CD4-positive cells from patients with IgA nephropathy demonstrate increased mRNA of cytokines that induce the IgA switch and differentiation

IgA nephropathy (IgAN) is characterized by raised serum IgA1 and mesangial IgA1 deposits. We have previously shown increased T-cell activation in IgAN. Recently, transforming growth factor-beta (TGF-beta) has been shown to induce IgA isotype switch at a clonal level and interleukin 5 (IL5) promotes differentiation into IgA-bearing B cells. In the present study we have examined the TGF-beta and IL5 mRNA expression by mitogen-activated CD4-positive T cells from patients with IgAN (n = 25), patients with other primary nephritides (CGN) (n = 24), and healthy control subjects (n = 25). The cytokine genes were analysed by reverse transcription (RT)-polymerase chain reaction (PCR) and were semi-quantitated by normalizing the differences occurring during RT and PCR using a housekeeping gene, beta-actin. CD4-positive T cells from IgA nephritic patients expressed a higher level of IL5 mRNA than healthy controls (P < 0.01) and patients with CGN (P < 0.005). CD4-positive T cells from IgA nephritic patients expressed a higher level of TGF-beta mRNA than healthy controls (P < 0.01) but no difference was demonstrated on comparison with CGN patients. Elevated TGF-beta mRNA expression in patients with CGN probably reflects its other important function as a 'sclerogenic' factor involved in the glomerulosclerosis found in these nephritides. Our data suggest that there is increased expression of cytokine genes which induce the IgA isotype switch and differentiation; these immunological abnormalities may be important in the pathogenesis of IgAN.

Increased mRNA encoding for transforming factor-beta in CD4+ cells from patients with IgA nephropathy

IgA nephropathy (IgAN) is a mesangial proliferative glomerulonephritis characterized by predominant mesangial IgA deposits. Recently, transforming growth factor-beta (TGF-beta) is shown to exert widespread effects on extracellular matrix by enhancing its accumulation. In an experimental model of acute mesangial glomerulonephritis TGF-beta appeared to be involved in the process of glomerulosclerosis, and treatment with antagonists of TGF-beta prevented the development of glomerulosclerosis. We examined the TGF-beta mRNA expression by mitogen activated CD4+ T cells from 31 patients with IgAN, 25 healthy controls and 10 patients with minimal change nephropathy (MCN) or focal glomerulonephritis (FGN) who were comparable in age and sex. The cytokine gene was analyzed with reverse transcription followed by polymerase chain reaction and was semiquantitated by normalizing the differences occurring during reverse transcription and polymerase chain reaction using a housekeeping gene, beta-actin. CD4+ T cells from IgA nephritic patients expressed a higher level of TGF-beta mRNA than that of healthy controls or that of MCN/FGN [TGF-beta/actin ratio 1.11 (median), range 0.24 to 3.87 vs. 0.88, range 0.2 to 3.83, P = 0.0157 and 0.36 range 0.09 to 1.6, P = 0.006]. When the biopsies were classified into three grades according to the severity of glomerular and interstitial pathology, there were highly significant differences between the TGF-beta mRNA in CD4+ T cells from the three groups of IgA nephritic patients (grade 1, 0.52, range 0.24 to 0.79; grade 2, 1.2, range 0.5 to 3.33; grade 3, 2.17, range 1.45 to 3.87].(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-neutrophil cytoplasmic antibodies (ANCA) and inflammatory bowel diseases in Chinese

Inflammatory bowel diseases are uncommon in the Chinese, but the incidence is rising. Their differentiation from infective colitis is often not clear-cut and diagnosing inflammatory bowel diseases can be difficult in Asia. We have studied Chinese patients with ulcerative colitis (N = 19) and Crohn's disease (N = 12) for anti-neutrophil cytoplasmic antibodies (ANCA) by indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assays (ELISA). Patients with enteric fever (N = 29) and irritable bowel syndrome (N = 24) were recruited as controls. Seventy-three percent of ulcerative colitis patients exhibited either p-ANCA (31%) or c-ANCA (42%) by IIF. Twenty-five percent of Crohn's disease patients were found to be p-ANCA positive. However, these ANCA were nonreactive to anti-alpha granule, antiproteinase 3, antimyeloperoxidase, or antilactoferrin. All positive patients had extensive colitis. Sera collected from patients suffering from enteric fever and irritable bowel syndrome were negative for ANCA by IIF and ELISA. We concluded that the detection of ANCA is helpful in diagnosing inflammatory bowel diseases. Further attempts to characterize these autoantibodies are needed.

Effect of anti-neutrophil cytoplasm autoantibodies on the intracellular calcium concentration of human neutrophils

BACKGROUND

The discovery of circulating autoantibodies to neutrophil cytoplasm antigens (ANCA) has implicated autoimmune mechanisms in the pathogenesis of systemic vasculitis although it is uncertain whether these play a primary role or arise secondary to neutrophil injury.

EXPERIMENTAL DESIGN

We examined the pathophysiologic effect of ANCA on intracellular cytosolic-free calcium concentration (Ca2+)i in neutrophils by preincubating cells with ANCA-positive IgG or F(ab')2 preparations followed by stimulation with calcium ionophore (A23187). The mechanism by which ANCA may affect (Ca2+)i was studied by analyzing the production of platelet-activating factor (PAF), an intracellular messenger which is the mediator through which A23187 acts.

RESULTS

ANCA-positive F(ab')2 induced a small but insignificant increase in (Ca2+)i. Preincubation of neutrophils with ANCA-positive IgG or F(ab')2 reduced the calcium mobilization induced by subsequent stimulation with A23187 compared with experiments performed with antibody preparations from ANCA-negative disease or healthy controls. The suppression of A23187-induced calcium mobilization was dose-dependent and correlated with the serum ANCA levels at clinical presentation. ANCA did not bind PAF but reduced the binding of PAF to neutrophils, suggesting that ANCA may prevent the expression of PAF receptor on activated neutrophils. The preincubation of neutrophils with increasing concentrations of F(ab')2 preparation resulted in reduced membrane and supernatant concentrations of PAF, an effect that was more prominent with ANCA-positive F(ab')2.

CONCLUSIONS

Our data suggest ANCA may potentially mediate a pathophysiologic effect on neutrophils through interference with the signal transduction pathways utilized in neutrophils' activation. One of the possible mechanisms underlying the suppressive effect of ANCA on A23187-induced calcium mobilization may be mediated through the reduction of PAF synthesis.

Use of antineutrophil cytoplasmic autoantibodies in diagnosing vasculitis in a Chinese patient population

Antineutrophil cytoplasmic autoantibodies (ANCA) have been used as markers of systemic vasculitides, including microscopic polyarteritis (MPA) and Wegener's granulomatosis. The diagnostic potential of ANCA assays together with antibodies against the neutrophil enzymes myeloperoxidase (MPO) and proteinase 3 for detecting a systemic vasculitis was tested in a Chinese patient population. 672 sera were received for ANCA assay, and ANCA detected by indirect immunofluorescence was positive in 73 sera from 42 patients. Of the 42 patients, 3 had cytoplasmic ANCA, while 39 had a perinuclear pattern. There was no patient with Wegener's granulomatosis. Two cytoplasmic ANCA positive patients suffered from ulcerative colitis. Another cytoplasmic ANCA positive patient was a carrier of human immunodeficiency virus. Of the 39 perinuclear ANCA positive patients, 10 had MPA. Eight of them were tested for anti-MPO antibody, and all were positive. Other immune disorders that were perinuclear ANCA positive included: 13 patients with systemic lupus erythematosus, 3 with mixed connective tissue disease, 1 with Goodpasture's syndrome, 2 with inflammatory bowel disease, and 2 patients with IgA nephropathy. Anti-MPO antibody was not specific for MPA, and 7 out of the 13 patients with systemic lupus erythematosus were anti-MPO antibody positive. Our study suggests that ANCA and anti-MPO antibody are not specific for MPA in a Chinese population. They would alert the clinician of the possibility of vasculitis, but a clinicopathological correlation is essential in making the diagnosis.

Correction of anemia using self-administered daily subcutaneous erythropoietin in uremic patients on continuous ambulatory peritoneal dialysis

We studied the effects of self-administered, daily, low-dose, subcutaneous (SC) erythropoietin (EPO) therapy in 15 uremic patients on continuous ambulatory peritoneal dialysis (CAPD) for 16 weeks to assess its efficacy and safety. The patients had baseline hemoglobin (Hb) levels of < 8 g/dl and were started on 10 u/kg/day of beta-EPO. The dosage of EPO was adjusted every 4 weeks according to hematological response. The patients learned to inject into their thighs themselves. Hb increased significantly from 6.6 +/- 0.2 g/dl (mean +/- SEM) at week 0 to 9.0 +/- 0.3 at week 8 and 10.0 +/- 0.4 at week 16 (p < 0.0001). Hematocrit (Hct) increased significantly from 0.20 +/- 0.01 at week 0 to 0.27 +/- 0.01 at week 8 and 0.29 +/- 0.001 at week 16 (p < 0.0001). The mean EPO dose was 10 u/kg/day at week 0 and 10.5 +/- 0.4 at week 8 and 10.3 +/- 0.5 at week 16. After minor adjustments in antihypertensive therapy had been made no significant differences in mean arterial blood pressure were noted. Six of 15 patients required increased dosage of antihypertensive drugs. All patients were given oral iron supplements. There was a significant decrease in percentage of transferrin saturation and 10 patients required additional intravenous iron supplements. There was no significant difference in the serum levels of creatinine, albumin, potassium, phosphate and urate with EPO treatment. There were no local complications at the sites of injection and the injections themselves were quite painless.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum concentration of soluble interleukin 2 receptors in asthma. Correlation with disease activity

We evaluated whether serum soluble interleukin 2 receptor (sIL-2R), a marker of T lymphocyte activation in vivo, could be useful to monitor disease activity in asthma. Venous blood was collected from 26 patients with acute severe asthma prior to the commencement of systemic corticosteroid therapy (day 1), 15 with stable disease, and 13 normal control subjects. Serum sIL-2R level was significantly higher in acute asthma (462.7 +/- 36.1 U/ml; mean +/- SEM) than stable disease (328.5 +/- 30.4 U/ml, p = 0.013) which in turn, was significantly raised when compared with control subjects (239.0 +/- 22.9 U/ml; p = 0.0003 vs acute; p = 0.036 vs stable). Nevertheless, sIL-2R concentrations in 11 patients with acute and 11 with stable disease did not exceed the upper limit of normal, ie, mean +.2 SD of the value in control subjects = 404.4 U/ml. Repeated measurements of sIL-2R in 24 acute asthmatics on day 3 revealed no significant fall (464.6 +/- 37.2 U/ml, NS), although the reduction in sIL-2R was significantly correlated with the corresponding improvement in peak expiratory flow (r = -0.52, p = 0.005). Following resolution of the acute attack, further measurements performed in 11 of these subjects on day 28 showed a significant fall in sIL-2R (p = 0.016). Our data showed that although serum sIL-2R was raised in asthma and, to a certain extent, might reflect disease activity, the considerable overlap of values between asthma of differing severity and normal control subjects precludes its clinical use as an index of asthma severity.

Heat-aggregated IgA prepared from patients with IgA nephropathy increases calcium mobilization and superoxide production of human neutrophils in vitro

IgA nephropathy, characterized by predominant mesangial IgA deposition, is the commonest glomerulonephritis worldwide. It is envisaged that circulating IgA plays a primary role in the glomerular injury of IgA nephropathy. In this study, we examined the pathophysiologic effect of IgA and IgG isolated from IgA nephritic patients on the signal transduction and oxidative metabolism of human neutrophils. Heat-aggregated forms, monomers, and F(ab')2 fragments of IgA and IgG were prepared from sera of 11 IgA nephritic patients and 11 healthy controls. Signal transduction was studied by measuring calcium mobilization and oxidative metabolism by measuring superoxide production. Different forms of IgA and IgG from patients with IgA nephropathy did not induce a significant increase in calcium mobilization directly. Nonetheless, neutrophils preincubated with heat-aggregated IgA or IgG from IgA nephritic patients demonstrated a significant rise in calcium mobilization upon subsequent stimulation by a chemotactic peptide, FMet-Leu-Phe (FMLP). Heat-aggregated IgA or IgG pretreatment of neutrophils increased FMLP-induced calcium mobilization in a dose-dependent manner. Aggregated IgA or IgG prepared by heat aggregation from IgA nephritic patients induced a significantly greater superoxide production from neutrophils than immunoglobulins from healthy controls. Similarly, heat-aggregated IgA and IgG induced superoxide production in a dose-dependent manner. Our data suggest that heat-aggregated forms of IgA and IgG exert an upregulatory effect on signal transduction and oxidative metabolism in human neutrophils. These findings indirectly support the view that neutrophils could be activated in IgA nephropathy and may potentially be participating in the inflammatory process of glomerular and interstitial injury.

Pulmonary embolism from a popliteal vein aneurysm

This is the first report of a venous aneurysm detected by radionuclide venography. Aneurysms of the popliteal vein are very rare. Described here is a case of a saccular popliteal venous aneurysm that presented as dyspnea secondary to pulmonary embolism. In this case, there was recurrent PE despite anticoagulant therapy. Almost all such aneurysms are associated with PE, about half of which are recurrent. This report demonstrates another useful aspect of obtaining a simultaneous radionuclide venogram when performing a perfusion lung scan with Tc-99m MAA.

Characterization of cytokine gene expression in CD4+ and CD8+ T cells after activation with phorbol myristate acetate and phytohaemagglutinin

Cytokines are important mediators involved in the development of effector cells and in the regulation of immune responses. The gene expression of these mediators in T cell subset has yet to be fully elucidated. Using sensitive reverse transcription-polymerase chain reaction (RT-PCR), the kinetics of cytokine gene expression in human CD4+ and CD8+ T cells were examined. CD4+ T cells were more readily activated by phorbol myristate acetate (PMA) and phytohaemagglutinin (PHA) than CD8+ T cells in terms of the IL-2 receptor (IL-2R) mRNA expression. Quantitative differences in cytokine gene expression between CD4+ and CD8+ T cells were confirmed and higher levels of cytokine mRNAs were induced in CD4+ than in CD8+ T cells. Early induction of IL-2 mRNA was observed in both T cell subsets. The demonstration of different kinetics of cytokine gene expression illustrates one of the examples of the complexity of immunoregulation. The differential response of cytokine gene expression in different T cell subsets should be taken into consideration when clinical studies in cytokine production by peripheral blood mononuclear cells are interpreted.

Genomic analysis using a yeast artificial chromosome library with mouse DNA inserts

A yeast artificial chromosome library with mouse genomic DNA inserts has been constructed. The library encompasses a 2.5-fold coverage of the mouse genome, with an average insert size of 250 kilobases. The screening strategy uses the polymerase chain reaction on pooled DNAs prepared from individually stored clones. The usefulness of the library for chromosome walking was illustrated by constructing a 600-kilobase-long contig of DNA surrounding Hba-ps4, a DNA marker that is tightly linked to the fused (Fu) locus on chromosome 17.

Effects of alpha-interferon and prednisone on serum-soluble interleukin-2 receptor (sIL-2R) in chronic hepatitis B infection

The level of serum-soluble interleukin-2 receptor (sIL-2R) was measured in 32 patients to investigate the effect of prednisone and alpha-interferon therapy on chronic hepatitis B virus infection. All the patients were seropositive for hepatitis B surface antigen and hepatitis B e antigen, with histological evidence of chronic persistent or chronic active hepatitis. Twenty-six patients received oral prednisone, followed by subcutaneous recombinant alpha-interferon, and six patients received multivitamin tablets and served as controls. After 4 wk of prednisone in reducing dosage, serum sIL-2R fell significantly from 673.6 +/- 52.9 U/ml to 584.8 +/- 39.4 U/ml (mean +/- SE, p less than 0.05). It rose to 733.4 +/- 45.7 U/ml (p less than 0.05) on the 4th wk of interferon, but returned to pretreatment level at completion of interferon. There was a significant correlation between serum sIL-2R and alanine aminotransferase levels (r = 0.36, p less than 0.001). The level of serum sIL-2R before treatment and its response to prednisone and interferon were not useful in predicting seroconversion of hepatitis B e antigen and anti-hepatitis B e.

Cytokine production by peripheral blood mononuclear cells in IgA nephropathy

The regulation of cytokine production and T cell proliferation by other cytokines is mandatory in mediating inflammatory responses but the full understanding is far from complete. We have previously reported increased production of IL-2 and IL-2 receptors (IL-2R) in IgA nephropathy. The present study was undertaken to examine other cytokine production during T cell activation in IgA nephropathy. Peripheral blood mononuclear cells (PBMC) from 17 IgA nephritic patients and 14 controls were cultured with phytohaemagglutinin and phorbol myristate acetate for 48 h for maximal cytokine production. IL-2Rs and IL-4 receptors (IL-4Rs) expressed on cultured PBMC were studied by a radioimmunoassay using monoclonal antibodies against these receptors. Although the total cellular IL-2R expression and percentages of T helper and T suppressor cells did not differ between the patients and controls, there was a significant increase in activated T helper cells expressing IL-2R in patients with IgA nephropathy. The total cellular IL-4R expression was elevated in IgA nephritic patients (P less than 0.005). IL-2 production by PBMC was raised in IgA nephritic patients compared with controls (P less than 0.05) but no difference in IL-4 or IL-6 production was observed. The interferon-gamma production by PBMC was significantly increased in patients with IgA nephropathy (P less than 0.025). No correlation was observed between individual cytokine levels. Our data suggest there are selective increases in cytokine production in IgA nephropathy.