Systemic lupus erythematosus

Imerslund-Gräsbeck syndrome (IGS) or selective vitamin B₁₂ (cobalamin) malabsorption with proteinuria is a rare autosomal recessive disorder characterized by vitamin B₁₂ deficiency commonly resulting in megaloblastic anemia, which is responsive to parenteral vitamin B₁₂ therapy and appears in childhood. Other manifestations include failure to thrive and grow, infections and neurological damage. Mild proteinuria (with no signs of kidney disease) is present in about half of the patients. Anatomical anomalies in the urinary tract were observed in some Norwegian patients. Vitamin B₁₂ absorption tests show low absorption, not corrected by administration of intrinsic factor. The symptoms appear from 4 months (not immediately after birth as in transcobalamin deficiency) up to several years after birth. The syndrome was first described in Finland and Norway where the prevalence is about 1:200,000. The cause is a defect in the receptor of the vitamin B₁₂-intrinsic factor complex of the ileal enterocyte. In most cases, the molecular basis of the selective malabsorption and proteinuria involves a mutation in one of two genes, cubilin (CUBN) on chromosome 10 or amnionless (AMN) on chromosome 14. Both proteins are components of the intestinal receptor for the vitamin B₁₂-intrinsic factor complex and the receptor mediating the tubular reabsorption of protein from the primary urine. Management includes life-long vitamin B₁₂ injections, and with this regimen, the patients stay healthy for decades. However, the proteinuria persists. In diagnosing this disease, it is important to be aware that cobalamin deficiency affects enterocyte function; therefore, all tests suggesting general and cobalamin malabsorption should be repeated after abolishment of the deficiency.     

Systemic lupus erythematosus; results of treatment with triamcinolone

Twenty-nine patients with systemic lupus erythematosus were treated with a new synthetic unsaturated prednisolone derivative, triamcinolone, for as long as 11 months. This hormone is 1.3 times as powerful as prednisone and 4.4 times more potent than hydrocortisone as an anti-inflammatory agent. The average dose for beginning therapy in cases of mild systemic lupus erythematosus was 20.6 mg. a day. The average maintenance dose used to control mild exacerbations of the disease was 26.0 mg. a day. There was no evidence of sodium retention or potassium loss. Sixteen patients had upper gastrointestinal x-ray studies before and during therapy with triamcinolone. There was no evidence of peptic ulceration except in one patient who was receiving 96 mg. a day. Nine patients had gastric analysis with histamine before and during therapy. No significant changes were noted in results of these tests, even in the patient who had an ulcer. No abnormal increase in uropepsin was noted in cases in which this factor was tested. The pattern of clinical improvement closely paralleled that obtained by previous treatment with older steroids. There was a disappearance of all the clinical and laboratory abnormalities produced by the disease, with the exception of long standing renal involvement. A major difference between triamcinolone and other steroids was a tendency to progressive gradual loss of weight, partly owing to fluid loss. Cushingoid appearance produced by other steroid therapy did not disappear. The cutaneous side effects, particularly Cushingoid appearance, hirsutism and striae were more pronounced than with older steroids. The most serious side effect was muscle weakness which appeared in six patients, all women, in from four to thirty-two weeks after starting triamcinolone. The profound muscle weakness, most pronounced in the quadriceps group, gradually cleared after several weeks of therapy with another steroid. Fourteen patients had received prior steroid therapy with all the older anti-inflammatory hormones and seven of them were better controlled and felt better with triamcinolone.     

Genetic epidemiology: Systemic lupus erythematosus

Systemic lupus erythematosus is the prototype multisystem autoimmune disease. A strong genetic component of susceptibility to the disease is well established. Studies of murine models of systemic lupus erythematosus have shown complex genetic interactions that influence both susceptibility and phenotypic expression. These models strongly suggest that several defects in similar pathways, e.g. clearance of immune complexes and/or apoptotic cell debris, can all result in disease expression. Studies in humans have found linkage to several overlapping regions on chromosome 1q, although the precise susceptibility gene or genes in these regions have yet to be identified. Recent studies of candidate genes, including Fcγ receptors, IL-6, and tumour necrosis factor-α, suggest that in human disease, genetic factors do play a role in disease susceptibility and clinical phenotype. The precise gene or genes involved and the strength of their influence do, however, appear to differ considerably in different populations.     

Systemic lupus erythematosus: two patients treated with danazol

Two women with systemic lupus erythematosus who showed premenstrual flaring of the disease were treated with danazol, which resulted in clinical improvement.This form of treatment needs to be assessed more widely, as there is little reported evidence that hormonal regulation has therapeutic value in systemic lupus erythematosus.     

Systemic lupus erythematosus and the type I interferon system

Patients with systemic lupus erythematosus (SLE) have ongoing interferon-α (IFN-α) production and serum IFN-α levels are correlated with both disease activity and severity. Recent studies of patients with SLE have demonstrated the presence of endogenous IFN-α inducers in such individuals, consisting of small immune complexes (ICs) containing IgG and DNA. These ICs act specifically on natural IFN-α-producing cells (NIPCs), often termed plasmacytoid dendritic cells (PDCs). Given the fact that the NIPC/PDC has a key role in both the innate and adaptive immune response, as well as the many immunoregulatory effects of IFN-α, these observations might be important for the understanding of the etiopathogenesis of SLE. In this review we briefly describe the biology of the type I IFN system, with emphasis on inducers, producing cells (especially NIPCs/PDCs), IFN-α actions and target immune cells that might be relevant in SLE. On the basis of this information and results from studies in SLE patients, we propose a hypothesis that explains how NIPCs/PDCs become activated and have a pivotal etiopathogenic role in SLE. This hypothesis also indicates new therapeutic targets in this autoimmune disease.     

Systemic and discoid lupus erythematosus: analysis of pulmonary function

To determine the prevalence of pulmonary dysfunction in lupus erythematosus, 24 patients with systemic lupus erythematosus (SLE) and 5 patients with discoid lupus erythematosus (DLE) were studied. Diffusing capacity for carbon monoxide was abnormal in 17 (71 percent) SLE patients. A restrictive ventilatory defect was present in 6 (25 percent) and arterial hypoxemia in 4 of 23 (17 percent). The mean ratio of forced expiratory volume in one second to forced vital capacity (FVC) was 83 percent. To test for the presence of small airways disease, maximum expiratory flow rate at 50 percent of FVC was measured on air and on an 80 percent helium-20 percent oxygen mixture. Ten patients (5 smokers and 5 nonsmokers) with SLE were nonresponders to helium suggesting small airways disease. Pulmonary dysfunction was present in 90 percent (9/10) of SLE patients with a previous history of pleuritis and/or pneumonitis, and in 71 percent (10/14) without respiratory symptoms or history of lung disease and with a normal chest radiograph. Pulmonary function tests were normal in DLE patients except for an abnormal response to helium and/or mild arterial hypoxemia in two patients, all of whom were smokers. These data indicate that there is a high prevalence of pulmonary function abnormalities in SLE including patients without clinically evident pleuropulmonary disease.     

Systemic lupus erythematosus susceptibility loci defined by genome scan meta-analysis

To date, several susceptibility loci for systemic lupus erythematosus (SLE) have been identified by individual genome-wide scans, but many of these loci have shown inconsistent results across studies. Additionally, many individual studies are at the lower limit of acceptable power recommended for declaring significant linkage. The genome search meta-analysis (GSMA) has been proposed as a valid and robust method for combining several genome scan results. The aim of this study is to investigate whether there is any consistent evidence of linkage across multiple studies, and to identify novel SLE susceptibility loci by using GSMA method. Twelve genome scan results generated from nine independent studies have been used for the present GSMA. All together, the data consists of 605 families with 1,355 SLE affected individuals from three self-reported ethnicities; Caucasian, African-American, and Hispanic. For each study, the genome was divided into 120 bins (30 cM) and ranked according to the maximum evidence of linkage within each bin. The ranks were summed and averaged across studies following which the significance was assessed by the permutation tests. The present study identified two genomic locations at 6p22.3–6p21.1 and 16p12.3–16q12.2 that met genome-wide significance (p<0.000417). The identified region at 6p22.3–6p21.1 contains the HLA region. The combined p-values using Fisher’s method also supported the significance in these regions. Clustering of significant adjacent bins was observed for chromosomes 6 and 16. Additionally, there are 12 other bins with two point-wise p-values (Psumrnk and Pord) <0.05, suggesting that these bin regions are highly likely to contain SLE susceptibility loci. Among them, present GSMA also identified two novel regions at 4q32.1–4q34.3 and 13q13.2–13q22.2. However, separate analysis using only Caucasian populations identified the strongest evidence for linkage at chromosome 6p21.1–6q15 (Psumrnk=0.00021). One interesting novel region suggests that 3q22.1–3q25.33 (Psumrnk=0.01376) may be an ethnicity-specific SLE linkage. In summary, the present GSMA have identified two statistically significant genomic regions that reconfirmed the SLE linkage at chromosomes 6 and 16.     

Systemic lupus erythematosus in Staphylococcus aureus hyperimmunoglobulinaemia E syndrome.

The prevalence of autoimmune diseases, including systemic lupus erythematosus, is increased in failure of certain host defence mechanisms. Systemic lupus erythematosus, however, has not been recorded as a late complication of the Staphylococcus aureus hyperimmunoglobulinaemia E (hyper-IgE) syndrome. Such a case was investigated in a man suffering from a classic example of the syndrome. Antinuclear antibodies were analysed on a molecular basis. The emergence of immunological and clinical features of systemic lupus erythematosus in patients with defective host defence mechanisms against staphylococcal infections is unlikely to be fortuitous and may help elucidate the pathogenesis of systemic lupus erythematosus. The observations will also aid the long term management of patients with S aureus hyper-IgE syndrome.