Bleomycin induces pleural and subpleural fibrosis in the presence of carbon particles.

The pathological changes in idiopathic pulmonary fibrosis (IPF) typically start in subpleural lung regions, a feature that is currently not explained. IPF, as well as bleomycin-induced lung fibrosis, are more common in smokers. We hypothesised that carbon particles, which are major components of cigarette smoke that are transported to alveoli and pleural surface, might be involved in the development of subpleural fibrosis through interaction with pleural mesothelial cells. Carbon particles were administered to mice in combination with bleomycin through intratracheal and/or intrapleural injection and fibrosis was assessed using histomorphometry. Carbon administered to the chest cavity caused severe pleural fibrosis in the presence of bleomycin, whereas bleomycin alone had no fibrogenic effect. The pleural response was associated with progressive fibrosis in subpleural regions, similar to IPF in humans. Matrix accumulation within this area evolved through mesothelial-fibroblastoid transformation, where mesothelial cells acquire myofibroblast characteristics. In contrast, carbon did not exaggerate bleomycin-induced pulmonary fibrosis after combined intratracheal administration. This represents a novel approach to induce a robust experimental model of pleural fibrosis. It also suggests that carbon particles might be involved as a cofactor in the initiation and/or progression of (subpleural) pulmonary and pleural fibrosis. Mesothelial cells appear to be critical contributors to this fibrotic process.

Benefit of continuous renal replacement therapy in subgroups of acutely ill patients: a retrospective analysis.

AIMS: Acute renal failure in the intensive care setting is common and impacts on patient's outcome. Continuous hemodialysis or hemofiltration offers theoretical benefit for patients with acute renal failure, but the clinical benefit has not been demonstrated in randomized trials. ICU patients with acute renal failure are a heterogeneous population and we hypothesize that patients with increased illness severity would benefit from continuous renal replacement therapy. METHODS: From a comprehensive ICU database, we identified patients with acute renal failure exposed to continuous or intermittent renal replacement therapy. We a priori identified a subgroup of patients with multiple organ dysfunction syndrome, then used survival analysis to assess the effect of dialysis modality in the overall acute renal failure population and in the subgroup with increased illness severity. RESULTS: We identified 66 patients treated with intermittent and 36 patients treated with continuous renal replacement therapy. Patients with severe illness were preferentially selected for treatment with continuous dialysis (p = 0.01). Overall, there was no significant difference in survival between patients treated with intermittent or continuous dialysis. The relative risk of in-hospital mortality was significantly decreased in patients with multiple organ dysfunction syndrome (relative risk = 0.42+/-0.22, p = 0.027) treated with continuous therapy as compared with intermittent therapy. Among the survivors, continuous dialysis did not appear to hasten the return of renal function. CONCLUSIONS: This retrospective study suggests that continuous dialysis may be beneficial in a subgroup of ICU patients with multiple organ dysfunction syndrome or severe sepsis. Further randomized trials of dialysis modality should, if possible, concentrate on this population.

Cytokines and growth factors involved in peritoneal fibrosis of peritoneal dialysis patients.

Peritoneal fibrosis is initiated by exposure of peritoneal tissues to numerous harmful agents encountered during peritoneal dialysis. These agents interact with cells within the peritoneum to induce growth factors and cytokines that are important in the initiation, progression and maintenance of fibrosis. Some of the mediators implicated in the pathogenesis of peritoneal fibrosis include transforming growth factor (TGF) beta, connective tissue growth factor (CTGF), fibroblast growth factors (FGF), and platelet derived growth factor (PDGF).

The gene transfer of soluble VEGF type I receptor (Flt-1) attenuates peritoneal fibrosis formation in mice but not soluble TGF-beta type II receptor gene transfer.

Peritoneal fibrosis formation is a consequence of inflammation/injury and a significant medical problem to be solved. The effects of soluble VEGF receptor type I (sFlt-1) gene transfer on experimental peritoneal fibrosis were examined and compared with soluble transforming growth factor-beta (TGF-beta) receptor type II (sTGF beta RII) gene transfer. Male C57BL/6 mice were injected with 1.5 x 10(8) plaque-forming unit of adenovirus encoding active TGF-beta (AdTGF beta) intraperitoneally. Some mice had been treated with sTGF betaRII or sFlt-1 plasmid injection into skeletal muscle with electroporation 4 days before virus administration. Mice were euthanized at day 14 after virus administration. AdTGF beta induced significant elevation of serum active TGF-beta, caused significant inflammatory response [weight loss, elevation of serum amyloid-P (SAP) and IL-12, increased expression of monocyte chemoattractant protein-1 (MCP-1) mRNA], and induced marked thickening of the peritoneum and collagen deposition. Gene transfer of sFlt-1 reduced the collagen deposition approximately 81% in mesenteric tissue. Treatment with sFlt-1 decreased ICAM-1 and MCP-1 mRNA expression significantly. Significant negative correlation between serum sFlt-1 and placental growth factor level was observed, whereas there was no significant negative correlation between sFlt-1 and VEGF. On the other hand, sTGF beta RII treatment enhanced the AdTGF beta-induced inflammation (significant elevation of SAP, TNF-alpha, and IL-12 levels and upregulation of ICAM-1 and MCP-1 mRNA expressions) and failed to prevent collagen deposition. These observations indicate that sFlt-1 gene transfer might be of therapeutic benefit in peritoneal fibrosis.

Randomized study of temporary hemodialysis catheters.

Temporary catheters are still essential for acute dialysis access but their performance has not been compared in randomized trials. We conducted a randomized trial of our standard catheter and a newly designed catheter. The primary outcome was maximized blood flow over the entire use of the catheter. Seventy-six patients provided maximum blood flows. The new catheter provided an average blood flow of 349 ml/min and the standard catheter provided flows of 320 ml/mm (p=0.09). Lumen reversal occurred in 56.8% of dialysis sessions with the standard catheter compared to 27.4% with the new catheter (p<0.001). Left-sided internal jugular catheters and catheters inserted in females provided 103 ml/min and 36 ml/min less blood flow, respectively, compared to right sided catheters and catheters placed in males. Approximately 20% of catheters were removed for poor blood flow. Left sided catheters and catheters in females were more likely to need removal for malfunction but catheter design did not influence removal rates.

Budesonide enhances repeated gene transfer and expression in the lung with adenoviral vectors.

The immune response with generation of neutralizing antiviral antibodies is an obstacle to effective repeated adenoviral gene transfer. Different immunosuppressive drugs facilitate repeat administration of adenovectors, but the clinical utility is uncertain because of systemic side effects. We investigated the use of topical corticosteroid in improving gene expression after repeated injection of adenovectors into mouse lungs. Using a vector expressing murine interleukin-6 (mIL-6) as a marker cytokine for gene expression, we show that budesonide given around exposure to adenovirus to the lung significantly maintained high levels of expressed transgene protein in bronchoalveolar lavage fluid (BALF) after as many as four consecutive injections of virus at two weekly intervals (p = 0.02 versus saline). Differences between treatment groups were most obvious 4 and 6 wk after the initial exposure to adenovirus (equivalent to three and four total exposures). In Week 4, transgene mIL-6 concentration was 2,327 +/- 955 pg/ml in budesonide compared with 336 +/- 246 pg/ml in saline-treated mice (p = 0.001). However, budesonide did not significantly protect transgene expression beyond Week 8 (four prior exposures). The improved transgene expression in budesonide-treated compared with saline-treated animals was associated with a reduction, but not prevention of neutralizing antiviral antibodies (BALF p < 0.001, serum p = 0.04). We conclude that budesonide can be valuable in gene therapy of the lung where repeated transient gene transfer is necessary.

Transient expression of IL-1beta induces acute lung injury and chronic repair leading to pulmonary fibrosis.

IL-1beta is one of a family of proinflammatory cytokines thought to be involved in many acute and chronic diseases. Although it is considered to participate in wound repair, no major role has been attributed to IL-1beta in tissue fibrosis. We used adenoviral gene transfer to transiently overexpress IL-1beta in rat lungs after intratracheal administration. The high expression of IL-1beta in the first week after injection was accompanied by local increase of the proinflammatory cytokines IL-6 and TNF-alpha and a vigorous acute inflammatory tissue response with evidence of tissue injury. The profibrotic cytokines PDGF and TGF-beta1 were increased in lung fluid samples 1 week after peak expression of IL-1beta. Although PDGF returned to baseline in the third week, TGF-beta1 showed increased concentrations in bronchoalveolar lavage fluid for up to 60 days. This was associated with severe progressive tissue fibrosis in the lung, as shown by the presence of myofibroblasts, fibroblast foci, and significant extracellular accumulations of collagen and fibronectin. These data directly demonstrate how acute tissue injury in the lung, initiated by a highly proinflammatory cytokine, IL-1beta, converts to progressive fibrotic changes. IL-1beta should be considered a valid target for therapeutic intervention in diseases associated with fibrosis and tissue remodeling.

Proteoglycans decorin and biglycan differentially modulate TGF-beta-mediated fibrotic responses in the lung.

Transforming growth factor (TGF)-beta is a key cytokine in the pathogenesis of pulmonary fibrosis, and pharmacological interference with TGF-beta can ameliorate the fibrotic tissue response. The small proteoglycans decorin and biglycan are able to bind and inhibit TGF-beta activity in vitro. Although decorin has anti-TGF-beta properties in vivo, little is known about the physiological role of biglycan in vivo. Adenoviral gene transfer was used to overexpress active TGF-beta, decorin, and biglycan in cell culture and in murine lungs. Both proteoglycans were able to interfere with TGF-beta bioactivity in vitro in a dose-dependant manner. In vivo, overexpression of TGF-beta resulted in marked lung fibrosis, which was significantly reduced by concomitant overexpression of decorin. Biglycan, however, had no significant effect on lung fibrosis induced by TGF-beta. The data suggest that differences in tissue distribution are responsible for the different effects on TGF-beta bioactivity in vivo, indicating that decorin, but not biglycan, has potential therapeutic value in fibrotic disorders of the lung.

Transient transgene expression of decorin in the lung reduces the fibrotic response to bleomycin.

Pulmonary fibrosis is a chronic progressive disease with no effective therapy. Transforming growth factor beta (TGF-beta) is thought to be a key profibrotic mediator and blocking its activity is therefore one of the targets of new treatment strategies for fibrosis. Decorin is an endogenous proteoglycan and one of the known inhibitors of TGF-beta. The short half-life of peptide-based therapeutics makes gene transfer a promising approach to achieve prolonged protein levels in the lung. Replication-deficient adenovirus was used to deliver decorin transgene (AdDec) to the airways by a single intranasal injection in a murine bleomycin model of lung fibrosis. The ability of vector-derived decorin to inhibit TGF-beta was examined in a bioassay and its effect on bleomycin-induced pulmonary fibrosis was determined by histomorphology and lung hydroxyproline. In vitro, supernatant from cells infected with AdDec abrogated the bioactivity of TGF-beta in a dose-dependent manner whereas control virus (AdDL70) had no effect. In vivo, treatment of bleomycin-injected mice with AdDec substantially reduced the fibrogenic response compared with control virus (hydroxyproline: bleomycin/AdDec, 1.96 microg/mg; bleomycin/AdDL70, 3.05 microg/mg; p = 0.0005). These results suggest that a single administration of AdDec was able to generate a local pulmonary environment that effectively blocked the fibrogenic response to bleomycin by inhibition of TGF-beta.

Interstitial nephritis in patients with inflammatory bowel disease treated with mesalamine.

Mesalamines are slow-release formulations of 5-aminosalicylic acid (5-ASA) and are effective as primary treatment and maintenance therapy in inflammatory bowel disease. Interstitial nephritis is a recognized side effect. We report two cases of biopsy-confirmed interstitial nephritis in patients being treated with 5-ASA. Both had a trial of steroid therapy. One patient had partial recovery of renal function but the other patient was in chronic renal failure and likely was approaching the need for dialysis. Interstitial nephritis is an under-recognized complication of 5-ASA therapy. Early identification and withdrawal of this drug can lead to a partial or complete reversal of renal dysfunction.

A chronic inflammatory infusion model of peritoneal dialysis in rats.

OBJECTIVES: Peritoneal membrane changes are related to daily exposure to non physiologic dialysate and recurrent acute inflammation. We modified a daily infusion and inflammation model and evaluated it for fibrotic and angiogenic features. The feasibility of adenovirus-mediated gene transfer in the model was also assessed. METHODS: Peritoneal catheters were implanted in rats. Over a period of 4 weeks, the animals received a daily infusion of Dianeal 4.25% (Baxter Healthcare Corporation, Deerfield, IL, U.S.A.) with an initial three doses of lipopolysaccharide (LPS) or physiologic saline. Peritoneal fluid was assayed for transforming growth factor beta (TGFbeta) and vascular endothelial growth factor (VEGF). Animals were humanely killed at week 5. Net ultrafiltration was then measured, and tissue samples were immunostained for factor VIII. Mesenteric tissue was assayed for hydroxyproline content. Adenovirus-mediated gene transfer of beta-galactosidase was assayed by intraperitoneal administration of the virus, 4 days before the end of the experiment. RESULTS: Animals treated with either Dianeal or physiologic saline showed peritoneal membrane thickening and increased vascularity. Fibrosis was demonstrated by increased hydroxyproline concentration. Ultrafiltration was impaired. We found increased concentrations of VEGF and TGFbeta in the peritoneal fluid of animals treated with LPS and daily infusion. Adenovirus-mediated gene transfer to the peritoneal membrane was demonstrated in the model. CONCLUSIONS: Exposure to LPS and daily Dianeal or physiologic saline leads to peritoneal fibrosis and neoangiogenesis. Vascularization and glucose transport correlate with ultrafiltration failure. The present animal model mimics changes seen in humans on peritoneal dialysis and may be valuable for evaluating short-term interventions to prevent membrane damage.

Peritoneal membrane transport and hypoalbuminemia: cause or effect?

OBJECTIVE: Peritoneal membrane transport has been associated with serum albumin and clinical outcome. We examined the relationship between serum albumin and peritoneal membrane transport status before and after the initiation of peritoneal dialysis. SETTING: Patients were followed at a tertiary-care regional nephrology program at St. Joseph's Hospital, McMaster University, Hamilton, Ontario, Canada. METHODS: Incident peritoneal dialysis patients between 1 January 1995 and 31 May 1998 were eligible if there was a peritoneal equilibration test within 180 days of starting dialysis, and a serum albumin value measured within 90 days prior to, and 20 to 70 days after initiating dialysis. MAIN OUTCOME MEASURES: Serum albumin, before and after the initiation of dialysis, and the presence of proteinuric renal disease were compared with the peritoneal equilibration test results. RESULTS: Among 67 identified patients, there were 7 high, 27 high-average, 26 low-average, and 7 low transporters and the mean serum albumin values before dialysis were 35.1, 37.4, 37.8, and 40.4 g/L, respectively (p < 0.001). Serum albumin values prior to the initiation of dialysis correlated significantly with the 4-hour D/P creatinine ratio (r = -0.251, p = 0.040). After initiation of dialysis, the correlation was stronger (r= -0.447, p< 0.001). Serum albumin prior to initiation of dialysis was lower for those with proteinuric than nonproteinuric renal disease (36.4 g/L vs 38.8 g/L, p = 0.04). The trend to lower serum albumin in high transporters was seen in patients with both proteinuric and nonproteinuric renal disease. CONCLUSION: The association between higher peritoneal membrane transport and lower serum albumin is present before initiation of dialysis in both proteinuric and nonproteinuric renal disease. The poor outcomes associated with low serum albumin and higher peritoneal membrane transport might be explained by other underlying factors. The contribution of inflammation, malnutrition, and fluid overload requires further study.

Diagnosis of thyroid disease in hospitalized patients: a systematic review.

BACKGROUND: The optimal approach for the diagnosis of hypothyroidism and hyperthyroidism in hospitalized patients is controversial. OBJECTIVES: To estimate the prevalence of undiagnosed thyroid disease among inpatients, review the usefulness of clinical signs and symptoms, and elucidate the characteristics of the sensitive thyrotropin (thyroid-stimulating hormone) (sTSH) test in this population. METHODS: We undertook a systematic review of the literature by conducting a MEDLINE search covering January 1966 through December 1996. Searching was conducted in duplicate and independently. Specific inclusion and exclusion criteria were predetermined. RESULTS: Prevalence of thyroid disease among inpatients is approximately 1% to 2% and is similar to the outpatient population. Absence of clinical features of thyroid disease lowers the pretest likelihood and makes screening even less useful. Presence of clinical features, especially those specific for thyroid disease (eg, goiter), may increase the pretest likelihood and increase the yield of testing. Acute illness reduces the specificity of second-generation sTSH tests for thyroid disease. The positive likelihood ratio associated with an abnormal sTSH test result in ill inpatients is about 10 compared with about 100 in outpatients. CONCLUSION: In unselected general medical, geriatric, or psychiatric inpatient populations, sTSH testing provides a low yield of true-positive and many false-positive results.