RANTES deficiency attenuates autoantibody-induced glomerulonephritis.

Experimental autoimmune nephritis in mice and spontaneous lupus nephritis are both associated with elevated expression of several chemokines in the kidneys. Nevertheless, the role that different chemokines play in mediating renal inflammation is far from complete. This study focuses on elucidating the functional role of RANTES, a chemokine that has been noted to be hyper-expressed within the kidneys, both in experimental renal disease as well as in spontaneous lupus nephritis. To elucidate if RANTES was essential for immune-mediated glomerulonephritis, DBA/1 mice that are highly sensitive to nephrotoxic serum nephritis were rendered RANTES-deficient and then tested for disease susceptibility. Nephritis-sensitive DBA/1 mice expressed more RANTES within the diseased kidneys. Compared to wild-type DBA/1 mice, RANTES-deficient DBA/1 mice developed significantly less proteinuria, azotemia, and renal inflammation, with reduced crescent formation and tubulo-interstitial nephritis. These findings indicate that RANTES ablation attenuates immune-mediated nephritis and suggest that this chemokine could be a potential therapeutic target in these diseases.

Shared signaling networks active in B cells isolated from genetically distinct mouse models of lupus.

Though B cells play key roles in lupus pathogenesis, the molecular circuitry and its dysregulation in these cells as disease evolves remain poorly understood. To address this, a comprehensive scan of multiple signaling axes using multiplexed Western blotting was undertaken in several different murine lupus strains. PI3K/AKT/mTOR (mTOR, mammalian target of rapamycin), MEK1/Erk1/2, p38, NF-kappaB, multiple Bcl-2 family members, and cell-cycle molecules were observed to be hyperexpressed in lupus B cells in an age-dependent and lupus susceptibility gene-dose-dependent manner. Therapeutic targeting of the AKT/mTOR axis using a rapamycin (sirolimus) derivative ameliorated the serological, cellular, and pathological phenotypes associated with lupus. Surprisingly, the targeting of this axis was associated with the crippling of several other signaling axes. These studies reveal that lupus pathogenesis is contingent upon the activation of an elaborate network of signaling cascades that is shared among genetically distinct mouse models and raise hope that targeting pivotal nodes in these networks may offer therapeutic benefit.

Abrogation of TGF-beta1-induced fibroblast-myofibroblast differentiation by histone deacetylase inhibition.

Idiopathic pulmonary fibrosis (IPF) is a devastating disease with no known effective pharmacological therapy. The fibroblastic foci of IPF contain activated myofibroblasts that are the major synthesizers of type I collagen. Transforming growth factor (TGF)-beta1 promotes differentiation of fibroblasts into myofibroblasts in vitro and in vivo. In the current study, we investigated the molecular link between TGF-beta1-mediated myofibroblast differentiation and histone deacetylase (HDAC) activity. Treatment of normal human lung fibroblasts (NHLFs) with the pan-HDAC inhibitor trichostatin A (TSA) inhibited TGF-beta1-mediated alpha-smooth muscle actin (alpha-SMA) and alpha1 type I collagen mRNA induction. TSA also blocked the TGF-beta1-driven contractile response in NHLFs. The inhibition of alpha-SMA expression by TSA was associated with reduced phosphorylation of Akt, and a pharmacological inhibitor of Akt blocked TGF-beta1-mediated alpha-SMA induction in a dose-dependent manner. HDAC4 knockdown was effective in inhibiting TGF-beta1-stimulated alpha-SMA expression as well as the phosphorylation of Akt. Moreover, the inhibitors of protein phosphatase 2A and 1 (PP2A and PP1) rescued the TGF-beta1-mediated alpha-SMA induction from the inhibitory effect of TSA. Together, these data demonstrate that the differentiation of NHLFs to myofibroblasts is HDAC4 dependent and requires phosphorylation of Akt.

Strain distribution pattern of immune nephritis--a follow-up study.

Previous studies have indicated that the NZW, DBA/1, 129/sv and BUB strains are particularly sensitive to experimental anti-glomerular basement membrane (GBM)-induced immune nephritis. The present study extends previous observations by examining eight additional inbred mouse strains for their susceptibility to immune nephritis. Unlike the ALR/Lt, CAST/Ei, DDY/JclSidSeyFrk, FVB/NJ, PERA/Ei, SB/Le and BALB/c strains, the C58 mouse strain was observed to be particularly susceptible to experimental immune nephritis, with CBA mice being a close second. In contrast to the other strains, C58 mice uniformly developed heavy proteinuria, azotemia and severe glomerulonephritis with prominent crescent formation and tubulointerstitial nephritis following challenge with anti-GBM sera. These differences were associated with increased murine Ig deposition, leukocyte infiltration and IFN-gamma production within the kidneys of C58 mice. Studies aimed at elucidating the genetic factors and molecular pathways responsible for the enhanced renal disease in C58 mice are warranted.

Enhanced susceptibility to immune nephritis in DBA/1 mice is contingent upon IL-1 expression.

The DBA/1 mouse strain is particularly sensitive to experimental immune-mediated nephritis. Previous studies have indicated that various chemokines/cytokines are elevated in strains of mice susceptible to immune-mediated glomerulonephritis. One of the many elevated cytokines is IL-1. This study was designed to determine if IL-1 is essential for the development of immune-mediated nephritis in the DBA/1 mouse strain that is particularly sensitive to this disease. Both male and female DBA/1 mice and DBA/1.IL-1R1(-/-) mice were challenged with anti-GBM sera. We then compared DBA/1 mice to DBA/1.IL-1R1(-/-) mice to determine the influence of IL-1 on immune-mediated nephritis. Compared to DBA/1 mice, DBA/1.IL-1R1(-/-) mice excreted significantly less protein post anti-GBM serum challenge. None of the DBA/1.IL-1R1(-/-) mice, male or female, had a BUN higher than 22 mg/dl post-challenge whereas wild-type DBA/1 mice had significantly elevated BUN. Wild-type DBA/1 mice exhibited pronounced glomerulonephritis, with crescent formation, as well as tubulo-interstitial disease compared to DBA/1.IL1R1(-/-) mice. These findings indicate that IL-1 is necessary for the development of nephritis in DBA/1 mice and suggest that the elevated IL-1 levels in these mice may be one reason why the DBA/1 strain is particularly sensitive to multiple end organ diseases.