[An immunocompromised patient with a histoplasmosis infection: a weakened patient's undisclosed trip]

A 69-year-old man with chronic lymphocytic leukemia presented with fever and a productive cough. He was diagnosed with a histoplasmosis infection, caused by the dimorphic fungus Histoplasma capsulatum, which is rare in the Netherlands but endemic in parts of the United States and South America. The patient was treated with high doses of itraconazole and gamma globulin infusions. This initially led to a clinical improvement, but eventually he developed a probable progressive histoplasmosis. The patient refused additional treatment and died. In immunocompromised patients, infections of the respiratory tract can be caused by a broad variety of agents. Knowledge of the patient's travel history is crucial to determine or exclude certain causal agents.

Inhibition of renal rho kinase attenuates ischemia/reperfusion-induced injury

The Rho kinase pathway plays an important role in dedifferentiation of epithelial cells and infiltration of inflammatory cells. For testing of the hypothesis that blockade of this cascade within the kidneys might be beneficial in the treatment of renal injury the Rho kinase inhibitor, Y27632 was coupled to lysozyme, a low molecular weight protein that is filtered through the glomerulus and is reabsorbed in proximal tubular cells. Pharmacokinetic studies with Y27632-lysozyme confirmed that the conjugate rapidly and extensively accumulated in the kidney. Treatment with Y27632-lysozyme substantially inhibited ischemia/reperfusion-induced tubular damage, indicated by reduced staining of the dedifferentiation markers kidney injury molecule 1 and vimentin, and increased E-cadherin relative to controls. Rho kinase activation was inhibited by Y27632-lysozyme within tubular cells and the interstitium. Y27632-lysozyme also inhibited inflammation and fibrogenesis, indicated by a reduction in gene expression of monocyte chemoattractant protein 1, procollagen Ialpha1, TGF-beta1, tissue inhibitor of metalloproteinase 1, and alpha-smooth muscle actin. Immunohistochemistry revealed reduced macrophage infiltration and decreased expression of alpha-smooth muscle actin, collagen I, collagen III, and fibronectin. In contrast, unconjugated Y27632 did not have these beneficial effects but instead caused systemic adverse effects, such as leukopenia. Neither treatment improved renal function in the bilateral ischemia/reperfusion model. In conclusion, the renally targeted Y27632-lysozyme conjugate strongly inhibits tubular damage, inflammation, and fibrogenesis induced by ischemia/reperfusion injury.

Neonatal dexamethasone administration causes progressive renal damage due to induction of an early inflammatory response

Glucocorticoids (GCs) are widely used to prevent chronic lung disease in immature newborns. Emerging evidence indicates that GC exposure in early life may interfere with kidney function and is associated with hypertension in later life. In this study, we have investigated the effect of neonatal dexamethasone (DEX) administration on renal function in rats. Male rats were treated with DEX in the first 3 days after birth, controls received saline (SAL). Severe renal damage associated with premature death was found at 50 wks upon DEX treatment, while renal function and morphology were normal in controls. A subsequent time-course study was performed from 2 days to 32 wks. Compared with controls, neonatal DEX administration led to significant and persistent growth retardation. Progressive proteinuria and increased systolic blood pressure were found from 8 wks onwards in DEX-treated animals. Renal α-SMA gene expression was elevated from wk 24 onwards and morphological fibrosis was noted at 32 wks of age following DEX treatment. Markedly increased renal gene expression of TNF-α and MCP-1 in DEX -treated rats was observed at day 7, probably contributing to the permanent increase in interstitial macrophage numbers that started at 14 days. Permanently elevated renal TGF-β gene expression was induced by DEX administration from 4 wks onwards. Our data indicate that neonatal DEX administration in rats leads to renal failure in later life, presumably due to an early inflammatory trigger that elicits a persistent pro-fibrotic process that eventually results in progressive renal deterioration.

Profiling of the renal kinome: a novel tool to identify protein kinases involved in angiotensin II-dependent hypertensive renal damage

Regulation of protein kinase activities is crucial in both physiology and disease, but analysis is hampered by the multitude and complexity of kinase networks. We used novel peptide array chips containing 1,152 known kinase substrate sequences to profile different kinase activities in renal lysates from homozygous Ren2 rats, a model characterized by hypertension and angiotensin II (ANG II)-mediated renal fibrosis, compared with Sprague-Dawley (SD) control rats and Ren2 rats treated with an angiotensin-converting enzyme inhibitor (ACEi). Five-wk-old homozygous Ren2 rats were left untreated or treated with the ACEi ramipril (1 mg.kg(-1).day(-1)) for 4 wk; age-matched SD rats served as controls (n = 5 each). Peptide array chips were incubated with renal cortical lysates in the presence of radioactively labeled ATP. Radioactivity incorporated into the substrate motifs was measured to quantify kinase activity. A number of kinases with modulated activities, which might contribute to renal damage, were validated by Western blotting, immunoprecipitation, and immunohistochemistry. Relevant kinases identified by the peptide array and confirmed using conventional techniques included p38 MAP kinase and PDGF receptor-beta, which were increased in Ren2 and reversed by ACEi. Furthermore, insulin receptor signaling was reduced in Ren2 compared with control rats, and G protein-coupled receptor kinase (GRK) activity decreased in Ren2 + ACEi compared with untreated Ren2 rats. Array-based profiling of tissue kinase activities in ANG II-mediated renal damage provides a powerful tool for identification of relevant kinase pathways in vivo and may lead to novel strategies for therapy.

Mannose-6-phosphate/insulin-Like growth factor-II receptors may represent a target for the selective delivery of mycophenolic acid to fibrogenic cells

PURPOSE

The insulin-like growth factor axis plays an important role in fibrogenesis. However, little is known about mannose-6-phosphate/Insulin-like growth factor-II receptor (M6P/IGF-IIR) expression during fibrosis. When expressed preferentially on fibrogenic cells, this receptor may be used to selectively deliver drugs to these cells.

METHODS

We investigated M6P/IGF-IIR expression in livers of bile duct-ligated (BDL) rats and in renal vascular walls of renin transgenic TGR(mRen2)27 rats. Both models are characterized by fibrogenic processes. Furthermore, we studied whether drug delivery via M6P/IGF-II-receptor-mediated uptake is possible in fibroblasts.

RESULTS

M6P/IGF-IIR mRNA expression was investigated 3, 7 and 10 days after BDL. At all time-points hepatic M6P/IGF-IIR expression was significantly increased compared to healthy controls. Moreover, immunohistochemical staining revealed that alpha-sma-positive cells were M6P/IGF-IIR-positive. In kidneys of TGR(mRen2)27 rats, the number of M6P/IGF-IIR-positive arteries per microscopic field was increased 5.5 fold over healthy controls. To examine whether M6P/IGF-IIRs could be used as a port of entry for drugs, we coupled mycophenolic acid (MPA) to mannose-6-phosphate-modified human serum albumin (M6PHSA). M6PHSA-MPA inhibited 3T3-fibroblast proliferation dose-dependently, which was reversed by co-incubation with excess M6PHSA, but not by HSA.

CONCLUSIONS

M6P/IGF-IIRs are expressed by fibrogenic cells and may be used for receptor-mediated intracellular delivery of the antifibrogenic drug MPA.

Induction of kidney injury molecule-1 in homozygous Ren2 rats is attenuated by blockade of the renin-angiotensin system or p38 MAP kinase

Kidney injury molecule-1 (Kim-1) is associated with ischemic and proteinuric tubular injury; however, whether dysregulation of the renin-angiotensin system (RAS) can also induce Kim-1 is unknown. We studied Kim-1 expression in homozygous Ren2 rats, characterized by renal damage through excessive RAS activation. We also investigated whether antifibrotic treatment (RAS blockade or p38 MAP kinase inhibition) would affect Kim-1 expression. At 7 wk of age, homozygous Ren2 rats received a nonhypotensive dose of candesartan (0.05 mg x kg(-1) x day(-1) sc) or the p38 inhibitor SB-239063 (15 mg x kg(-1) x day(-1) sc) for 4 wk; untreated Ren2 and Sprague-Dawley (SD) rats served as controls. Kim-1 mRNA and protein expression were determined by quantitative PCR and immunohistochemistry, respectively, and related to markers of prefibrotic renal damage. Urinary Kim-1 was measured in 8-wk-old Ren2 and SD rats with and without angiotensin-converting enzyme inhibition (ramipril, 1 mg x kg(-1) x day(-1) in drinking water for 4 wk). Untreated Ren2 rats showed a >20-fold increase in renal Kim-1 mRNA (expressed as Kim-1-to-GAPDH ratio): 75.5 +/- 43.6 vs. 3.1 +/- 1.0 in SD rats (P < 0.01). Candesartan and SB-239063 strongly reduced Kim-1 mRNA: 3.1 +/- 1.5 (P < 0.01) and 9.8 +/- 4.2 (P < 0.05), respectively. Kim-1 protein expression in damaged tubules paralleled mRNA expression. Kim-1 expression correlated with renal osteopontin, alpha-smooth muscle actin, and collagen III expression and with tubulointerstitial fibrosis. Damaged tubular segments expressing activated p38 also expressed Kim-1. Urinary Kim-1 was increased in Ren2 vs. SD (458 +/- 70 vs. 27 +/- 2 pg/ml, P < 0.01) rats and abolished in Ren2 rats treated with ramipril (33 +/- 5 pg/ml, P < 0.01). Kim-1 is associated with development of RAS-mediated renal damage. Antifibrotic treatment through RAS blockade or p38 MAP kinase inhibition reduced Kim-1 in the homozygous Ren2 model.

Intracellular Delivery of the p38 Mitogen-Activated Protein Kinase Inhibitor SB202190 [4-(4-Fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole] in Renal Tubular Cells: A Novel Strategy to Treat Renal Fibrosis

During renal injury, activation of p38 mitogen-activated protein kinase (MAPK) in proximal tubular cells plays an important role in the inflammatory events that eventually lead to renal fibrosis. We hypothesized that local inhibition of p38 within these cells may be an interesting approach for the treatment of renal fibrosis. To effectuate this, we developed a renal-specific conjugate of the p38 inhibitor SB202190 [4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole] and the carrier lysozyme. First, we demonstrated that SB202190 inhibited the expression of albumin-induced proinflammatory (monocyte chemoattractant protein-1) and transforming growth factor (TGF)-beta1-induced profibrotic (procollagen-Ialpha1) genes over 50% in renal tubular cells (normal rat kidney-52E). Next, we conjugated SB202190 via a carbamate linkage to lysozyme. However, this conjugate rapidly released the drug upon incubation in serum. Therefore, we applied a new platinum(II)-based linker approach, the so-called universal linkage system (ULS), which forms a coordinative bond with SB202190. The SB202190-ULS-lysozyme remained stable in serum but released the drug in kidney homogenates. SB202190-ULS-lysozyme accumulated efficiently in renal tubular cells and provided a local drug reservoir during a period of 3 days after a single intravenous injection. Treatment with SB202190-ULS-lysozyme inhibited TGF-beta1-induced gene expression for procollagen-Ialpha1 by 64% in HK-2 cells. Lastly, we evaluated the efficacy of a single dose of the conjugate in the unilateral renal ischemia-reperfusion rat model. A reduction of intrarenal p38 phosphorylation and alpha-smooth muscle actin protein expression was observed 4 days after the ischemia-reperfusion injury. In conclusion, we have developed a novel strategy for local delivery of the p38 MAPK inhibitor SB202190, which may be of use in the treatment of renal fibrosis.

Specific MAP-kinase blockade protects against renal damage in homozygous TGR(mRen2)27 rats

Angiotensin II (AngII) plays an important role in renal damage by acting on hemodynamics, cell-growth, proliferation, and fibrosis, mainly by effects on the AngII type 1 (AT(1)) receptor. The AT(1) receptor activates several intracellular signaling molecules such as mitogen-activated protein kinases extracellular signal-regulated kinase (ERK) and p38, but their role in AngII-mediated renal damage is not well characterized. We therefore investigated whether pharmacologic blockade of ERK and p38 could prevent renal damage in high-renin homozygous transgenic rats (Ren2), with the effects of an AT(1) receptor antagonist (AT(1)-RA) as a reference. Seven-week-old homozygous Ren2 rats were treated with low-dose AT(1)-RA candesartan, ERK inhibitor tyrphostin, or p38 inhibitor SB239063 for 4 weeks. Untreated Ren2 and SD rats served as controls. Blood pressure was measured at 7 and 11 weeks. At 11 weeks, plasma renin activity (PRA) and serum aldosterone were determined, and the animals were killed. Kidney sections were scored for glomerular and interstitial smooth muscle actin and glomerular desmin expression as early markers for renal damage. Mesangial matrix expansion was determined as a marker for structural damage. PRA and aldosterone levels were elevated in untreated Ren2 rats in comparison to SD controls. AT(1)-RA further increased PRA but decreased aldosterone. All parameters of renal damage were elevated in untreated Ren2 rats. Blood pressure was not elevated at week 7 in Ren2 and not affected by either treatment. Mild signs of hypertensive damage were found in untreated Ren2 rats. All interventions significantly diminished damage to glomerular epithelium and interstitium. In addition, AT(1) receptor and p38 blockade reduced mesangial matrix expansion. In homozygous Ren2 rats, renal damage was ameliorated by a nonhypotensive dose of an AT(1)-RA and, similarly, by blockade of ERK or p38. This suggests that ERK and p38 are involved in AngII-mediated renal damage.