Analysis of In Vivo Serpin Functions in Models of Inflammatory Vascular Disease

Serpins have a wide range of functions in regulation of serine proteases in the thrombotic cascade and in immune responses, representing up to 2-10% of circulating proteins in the blood. Selected serpins also have cross-class inhibitory actions for cysteine proteases in inflammasome and apoptosis pathways. The arterial and venous systems transport blood throughout the mammalian body representing a central site for interactions between coagulation proteases and circulating blood cells (immune cells) and target tissues, a very extensive and complex interaction. While analysis of serpin functions in vitro in kinetics or gel shift assays or in tissue culture provides very necessary information on molecular mechanisms, the penultimate assessment of biological or physiological functions and efficacy for serpins as therapeutics requires study in vivo in whole animal models (some also consider cell culture to be an in vivo approach).Mouse models of arterial transplant with immune rejection as well as models of inflammatory vasculitis induced by infection have been used to study the interplay between the coagulation and immune response pathways. We describe here three in vivo vasculitis models that are used to study the roles of serpins in disease and as therapeutics. The models described include (1) mouse aortic allograft transplantation, (2) human temporal artery (TA) xenograft into immunodeficient mouse aorta, and (3) mouse herpes virus (MHV68)-induced inflammatory vasculitis in interferon-gamma receptor (IFNγR) knockout mice.

Susceptibility Loci to Coronary Arteritis in Animal Model of Kawasaki Disease Induced withCandida albicans-Derived Substances

We have established an animal model of coronary arteritis which is histopathologically similar to that observed in cases of Kawasaki disease (KD), is a well-known childhood vasculitis syndrome. Coronary arteritis in this mouse model has been induced by intraperitoneal injection of Candida albicans -derived substances (CADS). Arteritis varied by mouse strain with the highest incidence by 71.1% (27/38) found in C3H/HeN mice, but absent in CBA/JN mice (0%, 0/27), suggesting association of genomic background to develop the disease. The present study aims to elucidate the susceptibility loci associated with coronary arteritis by using this animal model. The association of the onset of arteritis with polymorphic microsatellite markers between the two strains was examined using one hundred and fifteen of N1 backcross progeny [(CBAxC3H)F1xC3H]. Based on our analysis, arteritis-susceptibility loci with suggestive linkage were mapped on D1Mit171 and D1Mit245(map position 20.2 cM) on chromosome 1 (P=0.0019). These loci include several kinds of inflammatory cytokine receptors, such as interleukin 1 receptor and tumor necrosis factor receptor. We also found the cytokine response against CADS, levels of inflammatory cytokines interleukin-1 beta, tumor necrosis factor-alpha, and interleukin-6 in sera increased within 24 hr after CADS injection. Our results may indicate based on genomics that ligand-receptor interaction between these inflammatory cytokines and the receptors of these cytokines may affect the onset of arteritis.

Depletion of B2 but not B1a B cells in BAFF receptor-deficient ApoE mice attenuates atherosclerosis by potently ameliorating arterial inflammation

We have recently identified conventional B2 cells as atherogenic and B1a cells as atheroprotective in hypercholesterolemic ApoE^−/− mice. Here, we examined the development of atherosclerosis in BAFF-R deficient ApoE^−/− mice because B2 cells but not B1a cells are selectively depleted in BAFF-R deficient mice. We fed BAFF-R^−/− ApoE^−/− (BaffR.ApoE DKO) and BAFF-R^+/+ApoE^−/− (ApoE KO) mice a high fat diet (HFD) for 8-weeks. B2 cells were significantly reduced by 82%, 81%, 94%, 72% in blood, peritoneal fluid, spleen and peripheral lymph nodes respectively; while B1a cells and non-B lymphocytes were unaffected. Aortic atherosclerotic lesions assessed by oil red-O stained-lipid accumulation and CD68+ macrophage accumulation were decreased by 44% and 50% respectively. B cells were absent in atherosclerotic lesions of BaffR.ApoE DKO mice as were IgG1 and IgG2a immunoglobulins produced by B2 cells, despite low but measurable numbers of B2 cells and IgG1 and IgG2a immunoglobulin concentrations in plasma. Plasma IgM and IgM deposits in atherosclerotic lesions were also reduced. BAFF-R deficiency in ApoE^−/− mice was also associated with a reduced expression of VCAM-1 and fewer macrophages, dendritic cells, CD4+ and CD8+ T cell infiltrates and PCNA+ cells in lesions. The expression of proinflammatory cytokines, TNF-α, IL1-β and proinflammatory chemokine MCP-1 was also reduced. Body weight and plasma cholesterols were unaffected in BaffR.ApoE DKO mice. Our data indicate that B2 cells are important contributors to the development of atherosclerosis and that targeting the BAFF-R to specifically reduce atherogenic B2 cell numbers while preserving atheroprotective B1a cell numbers may be a potential therapeutic strategy to reduce atherosclerosis by potently reducing arterial inflammation.

Nonarteritic anterior ischemic optic neuropathy is associated with a specific platelet polymorphism located on the glycoprotein Ibalpha gene

OBJECTIVE

To evaluate the association between platelet glycoprotein polymorphisms and the risks of single and second eye involvement with nonarteritic anterior ischemic optic neuropathy (NAION).

DESIGN

Case-control study.

PARTICIPANTS

Ninety-two consecutive patients with NAION, 26 of whom had second eye involvement, and 145 controls who attended the eye clinic for nonvascular entities.

METHODS

Polymerase chain reactions and restriction enzyme analyses were performed for genotyping 5 platelet glycoprotein polymorphisms on DNA extracted from whole blood.

MAIN OUTCOME MEASURES

Frequencies of the various platelet polymorphisms.

RESULTS

One of the 5 platelet glycoprotein polymorphisms analyzed, the B allele of the glycoprotein Ibalpha variable number of tandem repeats (VNTR), was a significant independent risk factor for NAION, with an odds ratio of 4.25 and a 95% confidence interval of 1.67 to 10.82 (P = 0.0026). All other platelet glycoprotein polymorphisms were similarly distributed in patients and controls. In addition, 9 of 16 patients who bore the VNTR B allele (56.3%) had second eye involvement, whereas among patients not harboring the VNTR B allele only 17 of 72 patients (23.6%) had second eye involvement (P = 0.009). Moreover, second eye involvement occurred earlier in patients who bore the specific polymorphism.

CONCLUSIONS

The presence of the VNTR B allele of glycoprotein Ibalpha confers a significant risk for NAION and predisposes affected patients to second eye involvement.

Genetic Complementation in Female (BXSB × NZW)F2 Mice

F(1) hybrids among New Zealand Black (NZB), New Zealand White (NZW), and BXSB lupus-prone strains develop accelerated autoimmunity in both sexes regardless of the specific combination. To identify BXSB susceptibility loci in the absence of the Y chromosome accelerator of autoimmunity (Yaa) and to study the genetics of this complementation, genome-wide quantitative trait locus (QTL) mapping was performed on female (BXSB x NZW)F(2) mice. Six QTL were identified on chromosomes 1, 4, 5, 6, 7, and 17. Survival mapped to chromosomes 5 and 17, anti-chromatin Ab to chromosomes 4 and 17, glomerulonephritis to chromosomes 6 and 17, and splenomegaly to chromosomes 1, 7, and 17. QTL on chromosomes 4 and 6 were new and designated as Lxw1 and -2, respectively. Two non-MHC QTL (chromosomes 1 and 4) were inherited from the BXSB and the rest were NZW-derived, including two similar to previously defined loci. Only two of 11 previously defined non-MHC BXSB QTL using male (Yaa(+)) crosses were implicated, suggesting that some male-defined BXSB QTL may require coexpression of the Yaa. Findings from this and other studies indicate that BXSB and NZB backgrounds contribute completely different sets of genes to complement NZW mice. Identification of susceptibility genes and complementing genes in several lupus-prone strain combinations will be important for defining the epistatic effects and background influences on the heterogeneous genetic factors responsible for lupus induction.

CARD15 mutations in familial granulomatosis syndromes: a study of the original Blau syndrome kindred and other families with large-vessel arteritis and cranial neuropathy

OBJECTIVE

To analyze the CARD15 gene in families with heritable multi-organ granulomatoses, including the original Blau syndrome kindred as well as other families with related granulomatous conditions.

METHODS

Linkage mapping was performed in 10 families. Observed recombination events were used to exclude regions centromeric or telomeric to 16q12.1, and the Blau gene critical region was refined to <3 cM, corresponding to a physical distance of 3.5 megabasepairs. Based on its known biochemical function, CARD15 was analyzed as a positional candidate for the Blau syndrome susceptibility gene, by direct DNA sequencing.

RESULTS

These studies resulted in the identification, in 5 of the families, of 2 sequence variants at position 334 of the gene product (R334W and R334Q). Affected family members from the original Blau syndrome kindred were heterozygous for the R334W missense mutation; mutations at the same position were also observed in several unrelated Blau syndrome families, some of whose phenotypes included large-vessel arteritis and cranial neuropathy. The missense mutations segregated with the disease phenotype in the families, and were not seen in 208 control alleles.

CONCLUSION

These findings demonstrate that CARD15 is an important susceptibility gene for Blau syndrome and for other familial granulomatoses that display phenotypic traits beyond those of classic Blau syndrome.

A transgenic mouse model of autoimmune glomerulonephritis and necrotizing arteritis associated with cryoglobulinemia

Mice implanted with hybridoma secreting 6-19 IgG3 anti-IgG2a rheumatoid factor (RF) with cryoglobulin activity develop acute glomerulonephritis and cutaneous leukocytoclastic vasculitis. As the RF activity is implicated in the skin, but not glomerular lesions, it is still unclear whether the renal pathogenicity is determined by 6-19 H chains alone or their combination with L chains. To address this question, we have generated transgenic mice expressing only the H chain gene or both H and L chain genes of the 6-19 IgG3 anti-IgG2a RF and determined the development of glomerular and vascular lesions. H-single and H/L-double transgenic mice displayed comparable high amounts of IgG3 cryoglobulins, but only H/L-double transgenic mice having 10-fold higher levels of IgG3 anti-IgG2a RF progressively developed chronic, lethal glomerulonephritis. The severe glomerular lesions observed at 8-10 mo of age were very heterogeneous (membranoproliferative changes, crescents, and sclerosis); in addition, one-third of them had necrotizing arteritis in the kidneys and skeletal muscles. These renal and vascular changes were very different from those observed in the acute cryoglobulinemia, characterized by mainly "wire-loop" glomerular lesions and a cutaneous leukocytoclastic form of vasculitis. Thus, our data demonstrate the importance of a unique combination of the H and L chains for the expression of the pathogenic activity of IgG3 cryoglobulins and that a single autoantibody is able to induce different types of glomerular and vascular complications, depending on its production levels and kinetics.

Association of the HLA-DRB1 gene with susceptibility to aortoarteritis in a Chinese Han population

Aortoarteritis is a chronic inflammatory disease mainly affecting the aorta and its major branches. Recent immunogenetic studies indicate that certain human leucocyte antigen (HLA) alleles are significantly associated with aortoarteritis in several populations. The purpose of the present study was to investigate the relationship between the HLA-DRB1 alleles and aortoarteritis in a Chinese Han population. HLA-DRB1 genotypes were identified by PCR-SSP and PCR-RFLP in 84 Chinese patients with aortoarteritis and 102 healthy Chinese controls. It was found that the HLA-DRB1*04 allele (38.1% in patients vs. 15.7% in controls, p<0.001, relative risk (RR)=2.43) and the HLA-DRB1*07 allele (47.6% vs. 10.8%, p<0.001, RR = 4.42) were significantly associated with aortoarteritis. Furthermore, there was no significant difference in the frequency of the DRB1*0405 subtype between the patient and control groups. Thus the susceptibility to aortoarteritis in this Chinese Han population was closely related with the HLA-DRB1*04 and DRB1*07 alleles. Thus individuals with the HLA-DRB1*04 and DRB1*07 alleles may be at higher risk for developing aortoarteritis.

Arterial inflammation and atherosclerosis

Arterial inflammation is a significant component of atherosclerotic disease and it has been suggested that specific immune responses directed against autoantigens or pathogen-derived antigens presented in the vascular wall could initiate and/or maintain atherosclerotic processes. Atherogenic cofactors such as altered cholesterol metabolism may not only impact locally on inflammatory responses in atherosclerotic lesions, but may also alter general immune-responsiveness. The evidence to date suggests that the mutual chronic perpetuation of immune mediated vascular inflammation and cholesterol-induced atherosclerosis is a key step in atherogenesis.

The role of angiotensin converting enzyme and angiotensin II type 1 receptor gene polymorphisms in patients with nonarteritic anterior ischemic optic neuropathy

OBJECTIVE

To determine the role of angiotensin converting enzyme (ACE) and angiotensin II type 1 receptor (AT1R) polymorphisms in the pathogenesis of nonartertic anterior ischemic optic neuropathy (NAION).

DESIGN

Retrospective, case-control study.

PARTICIPANTS

Seventy-four patients with NAION diagnosed from 1984 through 1999. Seventy-one patients who visited the Eye Institute comprised the control group. TESTING INTERVENTION: DNA was extracted from whole blood obtained from all patients and control participants. Polymerase chain reaction (PCR) was used for analysis of ACE and AT1R polymorphisms.

RESULTS

The frequency of the polymorphism for ACE among the NAION patients (39.2% deletion allele [DD], 54.0% deletion/insertion [D/I] locus, 6.8% insertion allele [II]) was similar to that of the control group (50.7% DD, 39.4% D/I, 9.9% II), with P = 0.21. The frequency of the polymorphism of AT1R in the NAION patients was 5.4% CC, 44.6% CA, 50% AA, and in the control group it was 4.2% CC, 33.8% CA, 62.0% AA, with P = 0.35. Participants less than 55 years of age and those more than 55 had quite similar distributions.

CONCLUSIONS

Angiotensin converting enzyme and AT1R polymorphisms have no part in the mechanism of NAION. Thus drugs such as ACE inhibitors or AT1R antagonists are not specifically indicated for treatment of these patients.

Arterial inflammation in mice lacking the interleukin 1 receptor antagonist gene

Branch points and flexures in the high pressure arterial system have long been recognized as sites of unusually high turbulence and consequent stress in humans are foci for atherosclerotic lesions. We show that mice that are homozygous for a null mutation in the gene encoding an endogenous antiinflammatory cytokine, interleukin 1 receptor antagonist (IL-1ra), develop lethal arterial inflammation involving branch points and flexures of the aorta and its primary and secondary branches. We observe massive transmural infiltration of neutrophils, macrophages, and CD4(+) T cells. Animals appear to die from vessel wall collapse, stenosis, and organ infarction or from hemorrhage from ruptured aneurysms. Heterozygotes do not die from arteritis within a year of birth but do develop small lesions, which suggests that a reduced level of IL-1ra is insufficient to fully control inflammation in arteries. Our results demonstrate a surprisingly specific role for IL-1ra in the control of spontaneous inflammation in constitutively stressed artery walls, suggesting that expression of IL-1 is likely to have a significant role in signaling artery wall damage.

Genetic dissection of the complex pathological manifestations of collagen disease in MRL/lpr mice

An MRL strain of mice bearing a Fas-deletion mutant gene, lpr, MRL/MpJ-lpr/lpr (MRL/lpr) develops collagen disease involving vasculitis, glomerulonephritis, arthritis and sialoadenitis, each of which has been studied as a model for polyarteritis, lupus nephritis, rheumatoid arthritis and Sjögren's syndrome, respectively. Development of such lesions seems dependent on host genetic background since the congenic C3H/HeJ-lpr/lpr (C3H/lpr) mice rarely develop them. To identify the gene loci affecting each lesion, a genetic dissection of these complex pathological manifestations was carried out. First, histopathological features in MRL/lpr, C3H/lpr, (MRL/lpr x C3H/lpr) F1 intercross, and MRL/lpr x (MRL/lpr x C3H/lpr) F1 backcross mice were analyzed. Genomic DNA of the backcross mice were subjected to association studies by Chi-squared analysis for determining which polymorphic microsatellite locus occurs at higher frequency among affected compared to unaffected individuals for each lesion. As a result, gene loci recessively associated with each lesion were mapped on different chromosomal positions. We concluded that each of these lesions in MRL/lpr mice is under the control of a different set of genes, suggesting that the complex pathological manifestations of collagen disease result from polygenic inheritance.

Arteritis in a novel congenic strain of mice derived from MRL/Lpr lupus mice: genetic dissociation from glomerulonephritis and limited autoantibody production

An MRL/Mp strain of mice bearing the Fas deletion mutant gene, lpr (MRL/lpr), spontaneously develop systemic vasculitis and glomerulone phritis in the same individual, and both have been thought to be associated with an increase in circulating immune complexes and autoantibodies. However, the genetic basis of these diseases is poorly understood. A novel recombinant congenic mouse strain, McH5-lpr/lpr, which was established by rearrangement of the genetic background of MRL/lpr mice by hybridization with C3H/HeJ-lpr/lpr mice, developed severe granulomatous polyarteritis, as did the MRL/lpr strain, but not glomerulonephritis. Serum levels of anti-DNA and anti-myeloperoxidase antibodies in these mice were significantly reduced, as compared with MRL/lpr mice, although rheumatoid factors were not. These results indicate that each of these two diseases, arteritis and glomerulonephritis, is under the control of different background gene(s), suggesting a different pathological basis of these diseases, and that anti-DNA and anti-myeloperoxidase autoantibodies appear to have a limited pathogenic role in granulomatous arteritis in the mouse strain described.

Genetic control of the inflammatory response induced by oxidized lipids

The fatty streak begins with entrapment of apolipoprotein B (apoB)-containing lipoproteins in the subendothelial space at susceptible sites in the arterial wall. Minimally oxidized low density lipoprotein (MM-LDL) induces endothelial cells to bind monocytes and produce message and protein for monocyte chemotactic protein-1 and macrophage colony-stimulating factor. In culture, human endothelial and smooth muscle cells in arterial wall configuration sequester LDL, protecting it from antioxidants and giving rise to MM-LDL-like species. In mice, MM-LDL induces monocyte binding at susceptible aortic sites; the monocytes may then differentiate into macrophages that release reactive oxygen and active aldehydes, resulting in highly oxidized LDL leading to foam cell formation. Feeding mice an atherogenic diet induces expression of several inflammatory and oxidative stress genes, including serum amyloid A, which binds exclusively to HDL. This may contribute to a decrease in protective HDL levels seen in mice susceptible to fatty streak formation.

Pulmonary vasculitis with hypereosinophilia and episodic pulmonary hypertension: report of three siblings

Three siblings with eosinophilia who developed pulmonary hypertension are reported. They consisted of a 3 year old boy (case 1), a 9 year old boy (case 2) and a 13 year old girl (case 3), all of whom died within an 18 month period of severe episodic attacks of pulmonary hypertension and the resultant low cardiac output. Marked peripheral eosinophilia was found in cases 1 and 2, and mild eosinophilia in case 3. Open lung biopsy of case 1 revealed pulmonary arteritis with massive eosinophilic infiltration and intimal thickening of muscular arteries of 300-1500 microns in diameter. At autopsy, cases 2 and 3 showed almost similar findings, comprising widespread obliteration of the pulmonary arteries by concentric intimal thickening, medial hypertrophy and recanalized thrombi of arterioles. Rarely, there were foci of granulomas in the thickened intima surrounding birefringent foreign bodies. There were small areas of infarction in the lungs and heart due to arterial thrombi. Vascular lesions other than those in the lungs were mild and almost limited to the branches of the coronary arteries. Therefore, the present cases appear to be a single disease of pulmonary hypertension secondary to endothelial injury and the resultant intimal fibrosis probably evoked by toxic substances, although such agents were not confirmed.

Analysis of granulomatous arteritis in MRL/Mp autoimmune disease mice bearing lymphoproliferative genes. The use of mouse genetics to dissociate the development of arteritis and glomerulonephritis

MRL/Mp mice bearing the lymphoproliferation gene (lpr) spontaneously develop systemic granulomatous arteritis coincident with glomerulonephritis (GNP). Although the association of lpr-dependent lymphoproliferation in these mice seems to be a prerequisite for the development of granulomatous arteritis, the genetic basis is poorly understood. The first approach to this problem was to study the ability of another, nonallelic, lymphoproliferative gene, gld (generalized lymphoproliferative disease), inducing arteritis in MRL/Mp mice. The gld gene was placed on an MRL/Mp background by producing reciprocal (MRL/Mp-+/+ X C3H/Hej-gld/gld)F2 hybrid mice. Seventeen percent of these mice with lymphoproliferation had arteritis and GNP, suggesting that more than one lymphoproliferative gene could induce GNP and arteritis in an MRL/Mp background. Next, the effect of rearrangements in the genetic background of MRL/Mp-lpr/lpr mice by hybridization with non-autoimmune lpr-bearing mice was examined. This was done by making MRL/Mp-lpr/lpr X reciprocal (MRL/Mp-lpr/lpr X C57BL/6-lpr/lpr)F1 mice. Thirty-three percent of these mice developed arteritis, but one third of these did not get GNP, thus showing that susceptibility to arteritis was separate from GNP. The histopathologic features of the arteritis in both the F2 hybrids and the backcross mice were granulomatous and were identical to those seen in MRL/Mp-lpr/lpr mice. These findings suggested that it might be possible to dissociated two components (arteritis and GNP) of a severe autoimmune disease of MRL/Mp mice and to study their pathogenesis separately.

Spontaneous disseminated panarteritis in laboratory beagle dogs in a toxicity study: a possible genetic predilection

Disseminated panarteritis was found in 16 (9 males and 7 females) of 49 laboratory beagle dogs (25 males and 24 females) from one breeding kennel. The dogs had been used in a 6-month oral toxicity study. Panarteritis was not associated with clinical or gross abnormalities. The incidence was similar in the control and test article-treated groups. Mainly medium-sized arteries throughout the body, particularly intercostal arteries (at their aortic origin), and coronary, epididymal and thymic vessels were affected. Chronic mononuclear-cell periarteritis was the predominant feature. Mixed cellular inflammation of the wall, proliferation or degeneration of muscle cells, focal "fibrinoid" material in the tunica media, fragmented internal elastic lamina and intimal thickening associated with myointimal cellular proliferation also occurred. These histologic changes are compatible with those of immune arteritis. Round worm intestinal infestation and granulomas of visceral larva migrans were common in several organs. Statistical analyses suggested that the pedigree of dogs is related to panarteritis, but the presence or absence of parasitization alone is not. The possible roles of genetic predilection and/or parasites in the pathogenesis are discussed. This panarteritis is spontaneous and may complicate the interpretation of lesions in toxicity studies.

Variable expression of Lactobacillus casei cell wall-induced coronary arteritis: an animal model of Kawasaki's disease in selected inbred mouse strains

Mice receiving a single intraperitoneal injection of Lactobacillus casei cell wall fragments in aqueous suspension develop an asymmetric inflammatory coronary arteritis which histologically mimics the lesions seen in the coronary arteritis of children with Kawasaki's disease. A large variety of mice with genetically determined defects of the immune system were evaluated in this study to determine the influence of these defects on disease expression. Only the C3H/Hej mouse with defective macrophage function and poor production of IL-1 and TNF following stimulation with LPS failed to develop disease. This study suggests that further evaluation of macrophage function in children with Kawasaki's disease may provide important clues to its pathogenesis and treatment.

HLA DR4 and giant cell arteritis

We reported the data of HLA-DR frequencies in a new series of 40 unrelated patients suffering from giant cells arteritis (Horton's disease). As previously reported by us, a large increase of HLA-DR4 antigen frequency is noted in patients compared with 146 healthy controls. Moreover, gathering together these 40 patients with the 48 other patients of our first published data, increase of the DR4 frequency is largely confirmed with a Pc less than 0.001.