Angiotensin II receptor agonist antibodies are associated with microvascular damage in lupus nephritis.

Angiotensin II type 1 receptor agonist antibodies (AT1R-AAs) have been associated with hypertension, atherosclerosis and vascular inflammation in human diseases. The aim of the study was to evaluate the prevalence of AT1R-AAs in active lupus nephritis (LN) patients and their association with vascular damage. One hundred and seven active LN patients underwent a complete clinical examination, measurement of AT1R-AAs, ambulatory blood pressure monitoring, carotid intima-media thickness measurement and morphometric analysis of subintimal fibrosis and medial hyperplasia of the vessels in the kidney tissue. Plasma AT1R-AAs were positive in 58 (54.2%) patients. The Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score, complement C3 and C4 levels and titers of anti-dsDNA antibodies were higher in the group with positive AT1R-AAs compared with those with negative AT1R-AAs. The AT1R-AA titers correlated with anti-dsDNA antibody titers and with complement C3 and C4 serum levels. In the kidney biopsy, the percentage of subintimal fibrosis and the area of medial hyperplasia were greater in the AT1R-AA-positive patients. No differences in arterial pressure, carotid intima-media thickness and response to therapy were detected. In conclusion, AT1R-AAs are prevalent in active LN patients and are associated with histologic features of microvascular damage.

Latent adeno-associated virus infection elicits humoral but not cell-mediated immune responses in a nonhuman primate model.

Latent infection with wild-type (wt) adeno-associated virus (AAV) was studied in rhesus macaques, a species that is a natural host for AAV and that has some homology to humans with respect to the preferred locus for wt AAV integration. Each of eight animals was infected with an inoculum of 10(10) IU of wt AAV, administered by either the intranasal, intramuscular, or intravenous route. Two additional animals were infected intranasally with wt AAV and a helper adenovirus (Ad), while one additional animal was inoculated with saline intranasally as a control. There were no detectable clinical or histopathologic responses to wt AAV administration. Molecular analyses, including Southern blot, PCR, and fluorescence in situ hybridization, were performed 21 days after infection. These studies indicated that AAV DNA sequences persisted at the sites of administration, albeit at low copy number, and in peripheral blood mononuclear cells. Site-specific integration into the AAVS1-like locus was observed in a subset of animals. All animals, except those infected by the intranasal route with wt AAV alone, developed a humoral immune response to wt AAV capsid proteins, as evidenced by a >/=fourfold rise in anti-AAV neutralizing titers. However, only animals infected with both wt AAV and Ad developed cell-mediated immune responses to AAV capsid proteins. These findings provide some insights into the nature of anti-AAV immune responses that may be useful in interpreting results of future AAV-based gene transfer studies.

Neuronal matrix metalloproteinase-2 degrades and inactivates a neurite-inhibiting chondroitin sulfate proteoglycan.

Chondroitin sulfate proteoglycans (CSPGs) are implicated in the regulation of axonal growth. We previously reported that the neurite-promoting activity of laminin is inhibited by association with a Schwann cell-derived CSPG and that endoneurial laminin may be inhibited by this CSPG as well [Zuo J, Hernandez YJ, Muir D (1998) Chondroitin sulfate proteoglycan with neurite-inhibiting activity is upregulated after peripheral nerve injury. J Neurobiol 34:41-54]. Mechanisms regulating axonal growth were studied by using an in vitro bioassay in which regenerating embryonic dorsal root ganglionic neurons (DRGn) were grown on sections of normal adult nerve. DRGn achieved slow neuritic growth on sections of normal nerve, which was reduced significantly by treatment with metalloproteinase inhibitors. Similar results were obtained on a synthetic substratum composed of laminin and inhibitory CSPG. DRGn expressed the matrix metalloproteinase, MMP-2, which was transported to the growth cone. Recombinant MMP-2 inactivated the neurite-inhibiting CSPG without hindering the neurite-promoting potential of laminin. Similarly, neuritic growth by DRGn cultured on normal nerve sections was increased markedly by first treating the nerve sections with MMP-2. The proteolytic deinhibition by MMP-2 was equivalent to and nonadditive with that achieved by chondroitinase, suggesting that both enzymes inactivated inhibitory CSPG. Additionally, the increases in neuritic growth resulting from treating nerve sections with MMP-2 or chondroitinase were blocked by anti-laminin antibodies. From these results we conclude that MMP-2 provides a mechanism for the deinhibition of laminin in the endoneurial basal lamina and may play an important role in the regeneration of peripheral nerve.

Chondroitin sulfate proteoglycan with neurite-inhibiting activity is up-regulated following peripheral nerve injury.

Numerous findings support the possibility that highly sulfated proteoglycans are inhibitory molecules which, at high concentration relative to growth-promoting signals, may regulate or guide axonal growth. Although most studies implicate sulfated proteoglycans in the poor regenerative capacity of the central nervous system, inhibitory proteoglycans also may play an important role in the successful regeneration of axons within peripheral nerve. Cultured rat schwannoma and Schwann cells produce chondroitin sulfate proteoglycan (CSPG) which binds to and inhibits the neurite-promoting activity of laminin [Muir et al. (1989) J. Cell Biol. 109:2353]. In the present study, we found a similar neurite-inhibiting activity associated with CSPG isolated from normal adult rat sciatic nerve. Following nerve crush injury, this inhibitory activity was increased sevenfold in regenerating nerve distal to the injury. This increase was largely attenuated by in vivo administration of the proteoglycan synthesis inhibitor beta-D-xyloside. In normal adult nerve, immunolabeling for CSPG core protein was concentrated in slender bands surrounding axon-Schwann cell units and within nodes of Ranvier. Following nerve crush injury, immunolabeling of CSPG and laminin became more intense in distal nerve and CSPG increased within endoneurium and surrounding nerve sheaths. Embryonic dorsal root ganglionic neurons cultured on longitudinal nerve sections extended neurites along the exposed surfaces of Schwann cell basal lamina. The length of neurites was increased 58% on normal nerve sections pretreated with chondroitinase. Even though laminin levels were elevated in basal lamina of injured nerve, neuritic growth on sections of injured nerve was not significant increased unless sections were pretreated with chondroitinase. These results indicate that inhibitory CSPG is up-regulated in injured nerve and plays a role in regulating axonal regeneration.