[Takayasu arteritis. Therapeutic alternatives and long term outcomes]

The aim of this study was to describe the long term prognosis of 34 patients with Takayasu arteritis and the results of surgical and endovascular treatment. A total of 5 central surgeries and 53 endovascular procedures were performed including 18 bypass surgeries (33.8%) and 35 angioplasties (66.2%). The median follow-up was 7.5 years, interquartile range [IQR] 2.6-12.5. Among the 18 bypass surgeries 6 (33.3%) had events, while in the 35 patients with endovascular treatment there were 16 events (45.7%). The overall 1-, 3-, 5-, and 10-year death and arterial complication-free survival rates were 80% (95% CI between 74 and 89%), 68% (95% CI between 58 and 79%), 65% (95% CI between 54 and 76%) and 47% (95% CI between 41 and 62%). Both revascularization techniques were initially successful. In long term follow-up there was a high restenosis recurrence rate with endovascular treatment requiring repeated revascularization to the same vessel in 41% of the cases. Surgery had higher mortality in patients with aortic and ascending aortic valve disease, combined coronary artery disease and carotid disease. In long term follow up Takayasu arteritis frequently requires revascularization and restenosis or new lesions are common. Surgical treatment had better results with less restenosis than angioplasty.

Impact of genetic ancestry and sociodemographic status on the clinical expression of systemic lupus erythematosus in American Indian-European populations

OBJECTIVE

American Indian-Europeans, Asians, and African Americans have an excess morbidity from systemic lupus erythematosus (SLE) and a higher prevalence of lupus nephritis than do Caucasians. The aim of this study was to analyze the relationship between genetic ancestry and sociodemographic characteristics and clinical features in a large cohort of American Indian-European SLE patients.

METHODS

A total of 2,116 SLE patients of American Indian-European origin and 4,001 SLE patients of European descent for whom we had clinical data were included in the study. Genotyping of 253 continental ancestry-informative markers was performed on the Illumina platform. Structure and Admixture software were used to determine genetic ancestry proportions of each individual. Logistic regression was used to test the association between genetic ancestry and sociodemographic and clinical characteristics. Odds ratios (ORs) were calculated with 95% confidence intervals (95% CIs).

RESULTS

The average American Indian genetic ancestry of 2,116 SLE patients was 40.7%. American Indian genetic ancestry conferred increased risks of renal involvement (P < 0.0001, OR 3.50 [95% CI 2.63- 4.63]) and early age at onset (P < 0.0001). American Indian ancestry protected against photosensitivity (P < 0.0001, OR 0.58 [95% CI 0.44-0.76]), oral ulcers (P < 0.0001, OR 0.55 [95% CI 0.42-0.72]), and serositis (P < 0.0001, OR 0.56 [95% CI 0.41-0.75]) after adjustment for age, sex, and age at onset. However, age and sex had stronger effects than genetic ancestry on malar rash, discoid rash, arthritis, and neurologic involvement.

CONCLUSION

In general, American Indian genetic ancestry correlates with lower sociodemographic status and increases the risk of developing renal involvement and SLE at an earlier age.

Argentine population genetic structure: large variance in Amerindian contribution

Argentine population genetic structure was examined using a set of 78 ancestry informative markers (AIMs) to assess the contributions of European, Amerindian, and African ancestry in 94 individuals members of this population. Using the Bayesian clustering algorithm STRUCTURE, the mean European contribution was 78%, the Amerindian contribution was 19.4%, and the African contribution was 2.5%. Similar results were found using weighted least mean square method: European, 80.2%; Amerindian, 18.1%; and African, 1.7%. Consistent with previous studies the current results showed very few individuals (four of 94) with greater than 10% African admixture. Notably, when individual admixture was examined, the Amerindian and European admixture showed a very large variance and individual Amerindian contribution ranged from 1.5 to 84.5% in the 94 individual Argentine subjects. These results indicate that admixture must be considered when clinical epidemiology or case control genetic analyses are studied in this population. Moreover, the current study provides a set of informative SNPs that can be used to ascertain or control for this potentially hidden stratification. In addition, the large variance in admixture proportions in individual Argentine subjects shown by this study suggests that this population is appropriate for future admixture mapping studies.

No evidence of association between genetic variants of the PDCD1 ligands and SLE

PDCD1, an immunoreceptor involved in peripheral tolerance has previously been shown to be genetically associated with systemic lupus erythematosus (SLE). PDCD1 has two ligands whose genes are located in close proximity on chromosome 9p24. Our attention was drawn to these ligands after finding suggestive linkage to a marker (gata62f03, Z=2.27) located close to their genes in a genome scan of Icelandic families multiplex for SLE. Here, we analyse Swedish trios (N=149) for 23 single nucleotide polymorphisms (SNPs) within the genes of the PDCD1 ligands. Initially, indication of association to eight SNPs was observed, and these SNPs were therefore also analysed in Mexican trios (N=90), as well as independent sets of patients and controls from Sweden (152 patients, 448 controls) and Argentina (288 patients, 288 controls). We do not find support for genetic association to SLE. This is the first genetic study of SLE and the PDCD1 ligands and the lack of association in several cohorts implies that these genes are not major risk factors for SLE.

Parvovirus B19: another agent associated with remitting seronegative symmetrical synovitis with pitting edema

A number of conditions have been associated with remitting seronegative symmetrical synovitis with pitting edema (RS3PE) and the controversy of whether this should be considered a syndrome rather than a disease continues. There are few reports on the role of infectious agents in the etiology of RS3PE, and human parvovirus B19 has not previously been linked to this syndrome. We describe a patient with RS3PE syndrome in association with positive serology and viremia for parvovirus B19. A 9-year followup failed to uncover another cause for RS3PE.

Chromosome 17p12-q11 harbors susceptibility loci for systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the presence of autoantibodies against intracellular components, the formation of immune complexes, and inflammation in various organs, typically the skin and kidney glomeruli. The etiology of the disease is not well understood but is most likely the result of the interaction between genetic and environmental factors. In order to identify susceptibility loci for SLE, we have performed genome scans with microsatellite markers covering the whole genome in families from Argentina, Italy, and Europe. The results reveal a heterogeneous disease with different susceptibility loci in different family sets. We have found significant linkage to chromosome 17p12-q11 in the Argentine set of families. The maximum LOD score was given by marker D17S1294 in combination with D17S1293, when assuming a dominant inheritance model (Z = 3.88). We also analyzed a repeat in the promoter region of the NOS2A gene, a strong candidate gene in the region, but no association was found. The locus on chromosome 17 has previously been identified in genetic studies of multiple sclerosis families. Several other interesting regions were found at 1p35, 1q31, 3q26, 5p15, 11q23 and 19q13, confirming previously identified loci for SLE or other autoimmune diseases.

Regulation of differentiation of peritoneal B-1a (CD5+) B cells. Activated peritoneal macrophages release prostaglandin E2, which inhibits IgM secretion by peritoneal B-1a cells

The B-1a (CD5+) subset of B cells comprises the majority of B cells in the peritoneal cavity and is implicated in the pathogenesis of certain autoimmune diseases and lymphoproliferative disorders. When we stimulated purified B-1a cells with LPS, they produced more than four times as much IgM as similarly stimulated whole peritoneal cells (containing the same number of B-1a cells). Reconstitution experiments using FACS-purified peritoneal cell populations revealed that resident peritoneal macrophages (Mac1+, B220-) profoundly inhibited the LPS response of peritoneal B-1a cells. Culture of B-1a cells with peritoneal macrophages at a ratio of 3:1 (reflecting the in vivo ratio) resulted in a fivefold or greater reduction in the IgM response to LPS. LPS activation of macrophages resulted in production of a soluble factor that inhibited LPS-induced B cell differentiation by 86% when used at a concentration of 5%. When [3H]arachidonic acid-pulsed macrophages were stimulated with LPS, the major arachidonic acid metabolite secreted was PGE2 (a potent inhibitor of B cell differentiation). The inhibitory capacity of the macrophage-derived supernatant was reversed by the addition of anti-PGE2. These findings indicate that macrophage-derived PGE2 functions as an important regulator of polyclonal response of B-1a cells to LPS.

Regulation of differentiation of peritoneal B-1a (CD5+) B cells. Activated peritoneal macrophages release prostaglandin E2, which inhibits IgM secretion by peritoneal B-1a cells

The B-1a (CD5+) subset of B cells comprises the majority of B cells in the peritoneal cavity and is implicated in the pathogenesis of certain autoimmune diseases and lymphoproliferative disorders. When we stimulated purified B-1a cells with LPS, they produced more than four times as much IgM as similarly stimulated whole peritoneal cells (containing the same number of B-1a cells). Reconstitution experiments using FACS-purified peritoneal cell populations revealed that resident peritoneal macrophages (Mac1+, B220-) profoundly inhibited the LPS response of peritoneal B-1a cells. Culture of B-1a cells with peritoneal macrophages at a ratio of 3:1 (reflecting the in vivo ratio) resulted in a fivefold or greater reduction in the IgM response to LPS. LPS activation of macrophages resulted in production of a soluble factor that inhibited LPS-induced B cell differentiation by 86% when used at a concentration of 5%. When [3H]arachidonic acid-pulsed macrophages were stimulated with LPS, the major arachidonic acid metabolite secreted was PGE2 (a potent inhibitor of B cell differentiation). The inhibitory capacity of the macrophage-derived supernatant was reversed by the addition of anti-PGE2. These findings indicate that macrophage-derived PGE2 functions as an important regulator of polyclonal response of B-1a cells to LPS.

Regulation of apoptosis in vitro in mature murine spleen T cells

Previously it has been shown that thymocytes undergo apoptosis, a form of programmed cell death, in response to glucocorticoids. This classic form of apoptosis is prevented by inhibition of protein synthesis. The current paper demonstrates that mature T cells also undergo apoptosis, but that the regulation of apoptosis in spleen T cells differs from that of thymocytes. Mature mouse spleen T cells were shown to die by apoptosis, not necrosis, when cultured without an added stimulus. Assays for apoptosis included internucleosomal DNA cleavage by gel electrophoresis, percent fragmentation of DNA by the diphenylamine method, and percent of cells with hypodiploid DNA by flow cytometry. The percent of apoptotic cells was 2% in fresh spleen T cells, and increased at least until 16 h, when 21% were apoptotic. Dexamethasone caused apoptosis in both thymus and spleen T cells, but only thymocytes showed a requirement for protein synthesis in dexamethasone-induced death. Cycloheximide increased apoptosis in spleen T cells, indicating that apoptosis was controlled by newly synthesized protective proteins. Spontaneous apoptosis was decreased in spleen T cells by protein kinase C activation, and was increased by H7 and staurosporine, which inhibits protein kinases, in contrast with the behavior of thymocytes. The protein kinase A/G inhibitor HA1004 also decreased spleen T cell apoptosis. The contrasting effects of cycloheximide on thymocytes and spleen T cells occurred over the same concentration range, and the same was true for PMA. The dexamethasone dose-response curves were similar, except that a greater proportion of spleen T cells were dexamethasone-resistant. These data support the hypothesis that the apoptosis program in T cells undergoes a transition during their maturation, such that apoptosis in mature T cells is regulated more like that of mature B cells than that of thymocytes.

Regulation of apoptosis in vitro in mature murine spleen T cells

Previously it has been shown that thymocytes undergo apoptosis, a form of programmed cell death, in response to glucocorticoids. This classic form of apoptosis is prevented by inhibition of protein synthesis. The current paper demonstrates that mature T cells also undergo apoptosis, but that the regulation of apoptosis in spleen T cells differs from that of thymocytes. Mature mouse spleen T cells were shown to die by apoptosis, not necrosis, when cultured without an added stimulus. Assays for apoptosis included internucleosomal DNA cleavage by gel electrophoresis, percent fragmentation of DNA by the diphenylamine method, and percent of cells with hypodiploid DNA by flow cytometry. The percent of apoptotic cells was 2% in fresh spleen T cells, and increased at least until 16 h, when 21% were apoptotic. Dexamethasone caused apoptosis in both thymus and spleen T cells, but only thymocytes showed a requirement for protein synthesis in dexamethasone-induced death. Cycloheximide increased apoptosis in spleen T cells, indicating that apoptosis was controlled by newly synthesized protective proteins. Spontaneous apoptosis was decreased in spleen T cells by protein kinase C activation, and was increased by H7 and staurosporine, which inhibits protein kinases, in contrast with the behavior of thymocytes. The protein kinase A/G inhibitor HA1004 also decreased spleen T cell apoptosis. The contrasting effects of cycloheximide on thymocytes and spleen T cells occurred over the same concentration range, and the same was true for PMA. The dexamethasone dose-response curves were similar, except that a greater proportion of spleen T cells were dexamethasone-resistant. These data support the hypothesis that the apoptosis program in T cells undergoes a transition during their maturation, such that apoptosis in mature T cells is regulated more like that of mature B cells than that of thymocytes.

Apoptosis in splenic B lymphocytes. Regulation by protein kinase C and IL-4

Small dense splenic B lymphocytes from adult specific pathogen-free mice were shown to undergo apoptosis in vitro as indicated by internucleosomal DNA fragmentation, hypodiploid DNA content of isolated nuclei, and morphologic features by electron microscopy. Unstimulated cultures showed spontaneous apoptosis increasing gradually and monotonically from &lt; 2 to 32% of B cells by 16 h. The rate of accumulation of apoptotic cells was reduced by the addition of IL-4 or PMA, but not by the inactive phorbol ester, 4 alpha PDD. In contrast, inhibitors of protein kinase C (H7 and staurosporine) increased the percentage of cells undergoing apoptosis to &gt; 70% by 12 h; HA 1004, genistein, and herbimycin A all had no effect on apoptosis. Thus, protein kinase C activity regulates apoptosis, but there is no evidence that protein kinases A and G and tyrosine kinases are involved. Cycloheximide increased apoptosis, indicating that apoptosis may be restrained in B cells by the presence of one or more labile protective proteins. The percentage of apoptotic cells measured by flow cytometry and the percentage of fragmented DNA measured by the diphenylamine method were nearly equal, regardless of the method of apoptotic regulation. Together with the absence of nuclei with flow cytometric properties intermediate between normal and apoptotic, these results suggest that in individual B cells apoptosis progresses rapidly to completion. These data suggest a fundamental change in our concept of the life-style of the "resting" B cell: instead of a dormant cell remaining unchanged until it receives activation signals, the mature spleen B cell appears programmed to die by apoptosis unless rescued by specific agents, such protein kinase C activators or IL-4.

Apoptosis in splenic B lymphocytes. Regulation by protein kinase C and IL-4

Small dense splenic B lymphocytes from adult specific pathogen-free mice were shown to undergo apoptosis in vitro as indicated by internucleosomal DNA fragmentation, hypodiploid DNA content of isolated nuclei, and morphologic features by electron microscopy. Unstimulated cultures showed spontaneous apoptosis increasing gradually and monotonically from < 2 to 32% of B cells by 16 h. The rate of accumulation of apoptotic cells was reduced by the addition of IL-4 or PMA, but not by the inactive phorbol ester, 4 alpha PDD. In contrast, inhibitors of protein kinase C (H7 and staurosporine) increased the percentage of cells undergoing apoptosis to > 70% by 12 h; HA 1004, genistein, and herbimycin A all had no effect on apoptosis. Thus, protein kinase C activity regulates apoptosis, but there is no evidence that protein kinases A and G and tyrosine kinases are involved. Cycloheximide increased apoptosis, indicating that apoptosis may be restrained in B cells by the presence of one or more labile protective proteins. The percentage of apoptotic cells measured by flow cytometry and the percentage of fragmented DNA measured by the diphenylamine method were nearly equal, regardless of the method of apoptotic regulation. Together with the absence of nuclei with flow cytometric properties intermediate between normal and apoptotic, these results suggest that in individual B cells apoptosis progresses rapidly to completion. These data suggest a fundamental change in our concept of the life-style of the "resting" B cell: instead of a dormant cell remaining unchanged until it receives activation signals, the mature spleen B cell appears programmed to die by apoptosis unless rescued by specific agents, such protein kinase C activators or IL-4.

Mycobacterium gastri arthritis: septic arthritis due to Mycobacterium gastri in a patient with a renal transplant

We describe an 18-year-old man with a renal transplant who developed septic metacarpophalangeal arthritis due to Mycobacterium gastri. He had several episodes of crystal induced synovitis, and treatment with intraarticular steroids was complicated 3 months later by iatrogenic septic arthritis. Appropriate treatment based on in vitro drug susceptibility was successful. This seems to be the first case of articular infection and the third report of human infection caused by this atypical mycobacteria.