Up-regulation of cytokines in glomerulonephritis associated with murine malaria infection.

Malaria infections often cause glomerulonephritis (GN), and multiple factors have been implicated in the pathogenesis of glomerular injury. The role of cytokines in malaria associated glomerulonephritis has not been clearly defined. To study the importance of cytokines in malarial nephritis, we investigated the expression of tumour necrosis factor-alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), IL-6, IL-10 and granulocyte macrophage-colony stimulating factor (GM-CSF) in kidneys acutely infected with murine malaria parasite Plasmodium berghei ANKA in C57BL/6 J mice. Groups of six mice sacrificed on days 5, 8-10, 15, and 20 postinfection, and normal controls were used for cytokine analysis. Elevated levels of messenger RNA (mRNA) specific for these cytokines in infected kidneys after day 5 postinfection were demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Kidney sections stained with specific antibodies against TNF-alpha, IL-1alpha, IL-6, IL-10 and GM-CSF by immunohistochemistry showed that the staining for these cytokines on the glomeruli was positive from day 10 postinfection, and increased progressively, mainly in the infiltrating macrophages and the glomerular mesangium. Strong correlation was found between the expression of TNF-alpha with IL-6, and IL-1alpha with IL-6. The expression of TNF-alpha, IL-1alpha, IL-6, and IL-10 also strongly correlated with the severity of proteinuria. Our findings show that there is up-regulation of cytokines in the pathogenesis of glomerulonephritis associated with murine malaria infection.

Upregulation of major histocompatibility complex (MHC) antigen in nephritis associated with murine malaria infection.

The importance of immune complexes in the pathogenesis of malarial nephritis is well established. The expression was studied of major histocompatibility complex (MHC) class I and class II antigens and the infiltration of inflammatory cells, with their possible roles in cellular immune reactions in the pathogenesis of nephritis in a murine malaria model. Thirty-six kidney sections obtained on days 5, 8-10, 15, and 20 from C57BL/6J mice acutely infected with Plasmodium berghei and uninfected control mice were stained with specific antibodies for cellular immune markers by immunohistochemistry. From day 10 post-infection, markedly enhanced expression of both MHC class I and class II (Ia) antigens was observed in the kidneys. In the glomeruli, the expression was in the mesangium and along the capillaries. MHC class II was strongly expressed in the proximal tubules. Enhanced expression of MHC class I and class II was found in the endothelium of blood vessels, especially the peritubular capillaries. In addition, immune cells positive for CD4+ and CD8a+ markers, and class I and class II antigens were present around small arteries, or in focal areas of the interstitium. There were strong correlations between MHC class I expression in the glomeruli; MHC class II expression in the glomeruli/proximal tubules; and CD4+, CD8a+ infiltrates in the tubulointerstitium; with the severity of renal dysfunction (proteinuria). These findings indicate the importance of cellular immune reactions in the pathogenesis of acute murine malarial nephritis.

In situ analysis of adhesion molecule expression in kidneys infected with murine malaria.

The expression of intercellular adhesion molecule-1 (ICAM-1), the ligand leucocyte function antigen-1 (LFA-1, CD11a), and complement receptor type 3 (CR3, or Mac-1, CD11b) has been studied in murine kidneys acutely infected with the fatal malaria parasite Plasmodium berghei ANKA. Thirty-six kidney sections from five groups of C57BL/6J mice on day 5, 10, 15, and 20 post-infection, and normal controls, were stained with monoclonal antibodies against ICAM-1, LFA-1, and Mac-1. There was markedly enhanced expression of ICAM-1 in the glomerular mesangium and the endothelium of blood vessels from day 10 post-infection. ICAM-1 was also found in the proximal tubular epithelial cells in an apical location, with a linear pattern. In addition, the glomeruli showed positive staining for LFA-1 and Mac-1 on day 10 post-infection, mainly in the infiltrating inflammatory cells. Mesangial cells and inflammatory cells in the cortical tubulointerstitium showed positive staining for ICAM-1, LFA-1, and Mac-1 at the later stages of infection. There were strong correlations between ICAM-1 expression on endothelial cells of glomerular/peritubular capillaries with inflammatory cells positive for LFA-1 and Mac-1, which correlated with proteinuria. These findings show that several adhesion molecules are up-regulated in murine malaria-associated nephritis. The expression of ICAM-1 on endothelial cells correlated with the severity of inflammatory responses, indicating the relationship between the expression of adhesion molecules and cell-mediated immune renal injury. It is suggested that adhesion molecules play an important role in the pathogenesis of murine nephritis. Better knowledge of the function of these molecules in malaria infection may open new approaches to antimalarial therapy.

Dysregulation of cytokine expression in tubulointerstitial nephritis associated with murine malaria.

We examined the circulating levels of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 alpha, IL-6, granulocyte macrophage-colony stimulating factor (GM-CSF), and the anti-inflammatory cytokine IL-10, and their expression in kidneys acutely infected with murine malaria parasite P. berghei ANKA in C57BL/6J mice. Groups of six mice sacrificed on days 5, 10, 15, and 20, and normal controls were used for cytokine analysis. High concentrations of TNF-alpha and IL-10 were detected in plasma as shown by ELISA, and elevated levels of mRNA specific for TNF-alpha and IL-10 in infected kidneys were demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Kidney sections stained with antibodies against TNF-alpha, IL-1 alpha, IL-6, GM-CSF and IL-10 for immunohistochemistry showed markedly enhanced staining for TNF-alpha, and progressively increased staining for IL-1 alpha and IL-6 both in the tubules and the walls of arteries during the course of infection. The endothelia of blood vessels and inflammatory cells located around small arteries showed positive staining for GM-CSF from day 10 onwards. Unlike the staining for proinflammatory cytokines, the anti-inflammatory cytokine IL-10 showed strongly positive staining in normal tubules and walls of arteries, especially in the brush border of proximal tubules, but the staining intensity decreased dramatically after day 15 post-infection. A strongly positive correlation was found between the antibody staining for TNF-alpha/IL-1 alpha in tubules, and the severity of proteinuria. In contrast, there was an inverse correlation between the staining for IL-10 with TNF-alpha/IL-1 alpha, and the degree of proteinuria. Plenty of pigmented macrophages showed positive staining both for proinflammatory and anti-inflammatory cytokines in the tubulointerstitium. Our findings imply that the up-regulation of proinflammatory cytokines and the dysregulation of anti-inflammatory cytokines are involved in the pathogenesis of tubulointerstitial nephritis associated with malaria.