Heterogeneity of Human Neutrophil CD177 Expression Results from CD177P1 Pseudogene Conversion.

Most humans harbor both CD177neg and CD177pos neutrophils but 1-10% of people are CD177null, placing them at risk for formation of anti-neutrophil antibodies that can cause transfusion-related acute lung injury and neonatal alloimmune neutropenia. By deep sequencing the CD177 locus, we catalogued CD177 single nucleotide variants and identified a novel stop codon in CD177null individuals arising from a single base substitution in exon 7. This is not a mutation in CD177 itself, rather the CD177null phenotype arises when exon 7 of CD177 is supplied entirely by the CD177 pseudogene (CD177P1), which appears to have resulted from allelic gene conversion. In CD177 expressing individuals the CD177 locus contains both CD177P1 and CD177 sequences. The proportion of CD177hi neutrophils in the blood is a heritable trait. Abundance of CD177hi neutrophils correlates with homozygosity for CD177 reference allele, while heterozygosity for ectopic CD177P1 gene conversion correlates with increased CD177neg neutrophils, in which both CD177P1 partially incorporated allele and paired intact CD177 allele are transcribed. Human neutrophil heterogeneity for CD177 expression arises by ectopic allelic conversion. Resolution of the genetic basis of CD177null phenotype identifies a method for screening for individuals at risk of CD177 isoimmunisation.

Autoimmunity in primary antibody deficiency is associated with protein tyrosine phosphatase nonreceptor type 22 (PTPN22).

BACKGROUND: The 1858T allele of protein tyrosine phosphatase nonreceptor type 22 (PTPN22; R620W) exhibits one of the strongest and most consistent associations with sporadic autoimmune disease. Although autoimmunity is common in patients with primary antibody deficiency (PAD), it remains unknown whether its pathogenesis is similar when it arises in this context compared with in immunocompetent patients. OBJECTIVE: We set out to determine whether the 1858T allele of PTPN22 was associated with PAD or with autoimmunity in the context of PAD. METHODS: We genotyped rs2476601 (g.1858C>T), a single nucleotide polymorphism encoding substitution of arginine for tryptophan in PTPN22 (R620W), in 193 patients with PAD and 148 control subjects from an Australian cohort. We also performed a subgroup analysis according to the presence of autoimmunity and B-cell phenotypes. RESULTS: C/T and T/T PTPN22 genotypes were more common in patients with PAD than in the matched control subjects (C/T, 18.1% vs 9.5%; T/T, 1.04% vs 0.6%). The T allele was associated with an increased risk of PAD relative to control subjects (odds ratio, 2.10; 95% CI, 1.11-4.00). The distribution of genotypes in control subjects was similar to those reported previously and did not deviate significantly from Hardy-Weinberg equilibrium. We found a strong association between the 1858T allele and PAD with coexistent autoimmune diseases. In patients with PAD and autoimmunity, 16 (43.2%) of 37 had at least one T allele of PTPN22 compared with 27 (17.3%) of 156 with the C/C genotype (P=.0014; odds ratio, 3.64; 95% CI, 1.68-7.88). We found no evidence that this effect was mediated by enrichment of CD21low B cells. CONCLUSION: The 1858T PTPN22 allele is strongly associated with autoimmunity in patients with PAD.

Development of basic medical sciences in a new medical school with an integrated curriculum: the ANU experience.

BACKGROUND: The development of a basic medical science curriculum in a new medical school with a problem-based focus in Australia has been subject to a number of constraints. We describe the process and early evaluation. AIM: To describe the development of a basic medical science curriculum in an Australian medical school with a problem-based curriculum. METHODS: We describe the process we used for curriculum development and the benefits and constraints that arose from pre-existing strong biomedical science on the Australian National University (ANU) campus. We outline methods we used to inform our curriculum content and report on accreditation and early internal evaluation. RESULTS: Australian medical schools design their curriculum within a relatively restrictive framework put forward by a national accreditation system. The curriculum achieved accreditation from the external accrediting agency, but early student evaluation has been mixed. CONCLUSION: Although our internal faculty evaluation and external review by the accrediting agency has supported the view that this aspect of the curriculum has performed reasonably well, student feedback is mixed and further evaluation is needed and adjustments probably warranted.

Functional rare and low frequency variants in BLK and BANK1 contribute to human lupus.

Systemic lupus erythematosus (SLE) is the prototypic systemic autoimmune disease. It is thought that many common variant gene loci of weak effect act additively to predispose to common autoimmune diseases, while the contribution of rare variants remains unclear. Here we describe that rare coding variants in lupus-risk genes are present in most SLE patients and healthy controls. We demonstrate the functional consequences of rare and low frequency missense variants in the interacting proteins BLK and BANK1, which are present alone, or in combination, in a substantial proportion of lupus patients. The rare variants found in patients, but not those found exclusively in controls, impair suppression of IRF5 and type-I IFN in human B cell lines and increase pathogenic lymphocytes in lupus-prone mice. Thus, rare gene variants are common in SLE and likely contribute to genetic risk.

Inflammatory myositis complicating hypocomplementemic urticarial vasculitis despite on-going immunosuppression.

We present a patient with previously diagnosed hypocomplementemic urticarial vasculitis syndrome, with skin, lung, and renal involvement, who presented with congestive cardiac failure. During the course of her hospitalization, she was also found to have profound proximal muscle weakness in both upper and lower limbs associated with raised creatinine kinase levels. A muscle biopsy was performed, which demonstrated evidence of an inflammatory myositis with vasculitis, which had returned despite on-going immunosuppression. This occurrence of a new autoimmune disease may well be an example of the "waste disposal" hypothesis.

Controversies in the antiphospholipid syndrome and stroke.

Many clinicians providing care and advice to patients with antiphospholipid syndrome (APS), where the principal clinical manifestation is stroke, do so in the setting of an evidence base of mixed quality. Indeed, systematic studies have not particularly helped the practising clinician as they have been characterised by variable criteria used to select subjects, making it impossible to extrapolate to typical clinic patients. This has left us with a number of key questions, each of which attracts controversy in terms of patient management. In this review, these are posed as a series of questions with the answer, or lack of one, considered after each question. The review draws attention to the important questions that require answers for current primary and secondary prevention, as well as treatment of APS and stroke, and suggests a series of studies that are needed to clarify these issues.

Unusually indolent MPO-ANCA: associated vasculitis-report of two cases.

Vasculitis associated with antineutrophil cytoplasmic antibodies specific to myeloperoxidase generally presents as a life- and organ-threatening disease that evolves over several months. It is a syndrome in which prompt diagnosis and therapy are important both in terms of short-term survival and long-term organ damage. Two cases with quite a different course, sustained and indolent with limited progression over many years, are described in this report. They are compared to cases in the literature. Indolent cases of granulomatous polyangiitis associated with antineutrophil cytoplasmic antibodies against proteinase-3 are well recognised, but these two cases of microscopic polyangiitis are almost unique.

Heparanase in primary human osteoblasts.

Heparanase (HPSE) is known to be involved in fracture repair in mice, but its presence and function in human bone formation remains unclear. Our aim was to determine the expression of HPSE in human bone forming osteoblasts and to better understand its role in osteogenesis. HPSE protein expression and enzymatic activity were demonstrated in osteoblasts isolated from trabecular bone specimens of patients with osteoporosis (OP) and from healthy subjects, although the levels differed markedly. Thus, low levels of HPSE expression were observed in osteoporotic osteoblasts, including in the nucleus compared to those from healthy subjects. Notably, HPSE gene expression was associated with alkaline phosphatase (ALP) activity, the bone turnover marker. Gene profile studies demonstrated that osteogenic genes were downregulated in osteoporotic osteoblasts. We further exposed osteoblasts to exogenous HPSE and found that the level of histone H3 phosphorylation was increased. We provide evidence, for the first time, demonstrating that HPSE expresses and functions in human osteoblasts. Our data suggest that previously undescribed function of HPSE-mediated osteoblastogenesis through regulation of osteogenic gene expression and histone H3 modification. HPSE upregulation may be a novel therapeutic approach in the prevention and treatment of OP.

Expansion of circulating T cells resembling follicular helper T cells is a fixed phenotype that identifies a subset of severe systemic lupus erythematosus.

OBJECTIVE: In the sanroque mouse model of lupus, pathologic germinal centers (GCs) arise due to increased numbers of follicular helper T (Tfh) cells, resulting in high-affinity anti-double-stranded DNA antibodies that cause end-organ inflammation, such as glomerulonephritis. The purpose of this study was to examine the hypothesis that this pathway could account for a subset of patients with systemic lupus erythematosus (SLE). METHODS: An expansion of Tfh cells is a causal, and therefore consistent, component of the sanroque mouse phenotype. We validated the enumeration of circulating T cells resembling Tfh cells as a biomarker of this expansion in sanroque mice, and we performed a comprehensive comparison of the surface phenotype of circulating and tonsillar Tfh cells in humans. This circulating biomarker was enumerated in SLE patients (n = 46), Sjögren's syndrome patients (n = 17), and healthy controls (n = 48) and was correlated with disease activity and end-organ involvement. RESULTS: In sanroque mice, circulating Tfh cells increased in proportion to their GC counterparts, making circulating Tfh cells a feasible human biomarker of this novel mechanism of breakdown in GC tolerance. In a subset of SLE patients (14 of 46), but in none of the controls, the levels of circulating Tfh cells (defined as circulating CXCR5+CD4+ cells with high expression of Tfh-associated molecules, such as inducible T cell costimulator or programmed death 1) were increased. This cellular phenotype did not vary with time, disease activity, or treatment, but it did correlate with the diversity and titers of autoantibodies and with the severity of end-organ involvement. CONCLUSION: These findings in SLE patients are consistent with the autoimmune mechanism in sanroque mice and identify Tfh effector molecules as possible therapeutic targets in a recognizable subset of patients with SLE.

Antineutrophil cytoplasmic antibody-associated vasculitides: could geographic patterns be explained by ambient ultraviolet radiation?

OBJECTIVE: This ecological study describes and quantifies the association between ambient ultraviolet (UV) radiation levels, including daily winter vitamin D effective UV radiation levels and the incidence of the 3 antineutrophil cytoplasmic antibody-associated vasculitides (AAVs): Wegener's granulomatosis (WG), microscopic polyangiitis (MPA), and Churg-Strauss syndrome (CSS). Latitudinal variation in occurrence of the AAVs, especially WG, has been previously reported. For other autoimmune diseases such as multiple sclerosis and type 1 diabetes mellitus, inverse associations with latitude are hypothesized to indicate a causative role for low UV radiation exposure, possibly acting via vitamin D status. METHODS: Published epidemiologic studies provided data on incident cases, total population of study regions, age-specific incidence rates, and study location. From these data and online age-specific population data, we calculated crude incidence rates, the expected number of cases (to control for possible age confounding), and measures of ambient UV radiation. Negative binomial regression models were used to calculate the incidence rate ratio (IRR) for a 1,000 joules/m(2) increase in ambient UV radiation. RESULTS: The incidence of WG and CSS increased with increasing latitude and decreasing ambient UV radiation, with a stronger and more consistent effect across different UV radiation measures for WG, e.g., for average daily ambient clear sky erythemal UV radiation (WG: IRR 0.64 [95% confidence interval (95% CI) 0.44-0.94], P = 0.02; CSS: IRR 0.67 [95% CI 0.43-1.05], P = 0.08; MPA: IRR 1.16 [95% CI 0.92-1.47], P = 0.22). There was no apparent latitudinal variation in MPA incidence. CONCLUSION: Our findings are consistent with a protective immunomodulatory effect of ambient UV radiation on the onset of WG and CSS. We discuss possible mechanisms, including the effect of vitamin D on the immune system.