HLA and genetic predisposition to lupus erythematosus and other dermatologic disorders

HLA molecules and nasal carriage of Staphylococcus aureus isolated from dialysis and kidney transplant patients at a hospital in Southern Brazil

Background

Healthy individuals can host Staphylococcus aureus in the nasopharynx, body surface and vagina. Most invasive infections by this bacterium are endogenous, caused by strains spread from the nasopharynx of carriers. S. aureus is a pathogen involved in the etiology of hospital- and community-acquired infections. Transplant and dialysis patients are at risk of colonization or infection by multi-resistant S. aureus. Infection is directly linked to individual immunity, and the major histocompatibility complex (MHC) plays a crucial role in determining susceptibility to diseases. Different MHC specificities have been shown to be more frequent in individuals suffering from certain diseases. This study aimed to investigate the association between HLA class I (HLA-A and -B) and class II (HLA-DRB1) molecules and nasal carriage of S. aureus in dialysis and kidney transplant patients at a hospital in Southern Brazil.

Results

The sample consisted of 70 dialysis and 46 kidney transplant patients, totaling 116 patients. All subjects were typed for HLA molecules using LABType^® SSO (One Lambda). Nasal swab samples of S. aureus were isolated from the nasal cavity (both nostrils) of patients undergoing dialysis or kidney transplantation.

In renal dialysis patients, HLA-A*02 was the most frequent allele in both carriers (25.5%) and non-carriers (21.2%) of S. aureus. Allele A*68 was not observed in the carrier group, but the allele was observed six times in the non-carrier group (p = 0.0097). Regarding HLA-B and HLA-DRB1, no allele was shown to be involved in protection against or susceptibility to carriage of S. aureus. In kidney transplant patients, allele A*03 was more frequent in the non-carrier (20.83%) than in the carrier (5.88%) group (p = 0.0486). HLA-B*15 was present in carriers (5.88%) and non-carriers (25%) (p = 0.0179). Regarding class II alleles, DRB1*03 appeared to be related to susceptibility to carriage of S. aureus (p = 0.0319).

Conclusions

Our findings suggest that HLA-DRB1*03 may be involved in susceptibility to nasal carriage of S. aureus in transplant patients. In addition, HLA-A*68 (dialysis patients) and HLA-A*03 and HLA-B*15 (transplant patients) appear to be associated with increased resistance to S. aureus nasal carriage.

Genetic aspects of rheumatic diseases

In this review on the genetic aspects of rheumatic diseases, the approach was taken (i) to discuss, in general, important principles in the identification of susceptibility genes and (ii) to focus on five autoimmune rheumatic diseases that have the characteristics of complex diseases and in which important advances have been made in the identification of the genetic component. A decade ago, most reviews on the genetics of rheumatic diseases focused almost exclusively on a discussion of the human leukocyte antigen (HLA) but in this fast-moving field it is now apparent that genes outside the HLA also contribute to susceptibility. Current hypotheses concerning the pathogenesis of autoimmunity have led to the inclusion of hundreds of genes as potential candidates. Almost any molecule involved in immune recognition, cell interaction, intracellular signalling, cytokine pathways or programmed cell death can be reasonably proposed. The identification of the genes involved in complex diseases will contribute to an understanding of disease mechanisms and disease biology. The disease pathways by which the genes exert their effects or functions could lead to the discovery of new therapeutic targets that may be modulated. An increased understanding of the interactions between genes and environment might also be attained.

Recent advances in the genetics of autoimmune diseases

Autoimmune diseases in general are complex genetic diseases where genes and environment interact in unknown ways. In recent years technologies have advanced our knowledge and new genes are being identified very rapidly. We can expect that most genes of major importance for the various autoimmune diseases will be discovered in the coming 5 years. The real challenge comes when we try to understand the mechanisms through which these genes confer disease susceptibility and how the interaction with environment takes place such that clinical expression of the disease results.

HLA class II antigens associated with lupus nephritis in Italian SLE patients

Human leukocyte antigen DR2 (HLA-DR2), namely the allelic variant HLA-DR15, have been associated with lupus nephritis (LN) in Caucasians. The study investigated the relationships between HLA class II alleles and lupus nephritis in Italian patients. Two hundred forty-four patients fulfilling the American Rheumatism Association criteria for systemic lupus erythematosus (SLE) were typed for HLA-DRB1*, -DQA1*, -DQB1*, and -DPB1* alleles by polymerase chain reaction-sequence-specific oligonucleotide and polymears chain reaction-single-strand polymorphism; 71 patients had renal damage assessed by renal biopsy. Glomerulonephritis was classified using WHO criteria. Significance was tested by X(2) on 2x2 tables. HLA-DQA1*0101 was strongly associated with LN (OR = 2.72 [1.43-5.19]; p = 0.002), whereas HLA-DRB1*1501 was only marginally associated (OR = 1.94 [0.88-4.26]; p = not significant). HLA-DQA1*0102 demonstrated a significant protective effect (OR = 0.31 [0.14-0.86]; p = 0.002). On analyzing the distribution of HLA-DRB1*1501 bearing haplotypes in our SLE patients we found that the HLA-DRB1*1501 greatly enhanced the risk of developing LN conferred by the DQA1*0101 allele (OR = 65.96 [9.35-1326.25]), whereas DQA1*0102 suppressed the nephritogenic effect of DRB1*1501. At renal biopsy, 80% of DRB1*15 positive patients were classified as having class IV LN with the remaining 20% having class III LN. The figures were 19% and 21%, respectively, among the HLA-DR15 negative patients. In the Italian population HLA-DQA and HLA-DR alleles interact in conferring susceptibility to or protection against lupus nephritis, the diffuse proliferative glomerulonephritis (i.e., the most severe form of nephritis) is associated with the HLA-DR15 bearing haplotypes.

The NOD mouse as a model of SLE

In addition to developing a high incidence of type 1 diabetes caused by a specific autoimmune response against pancreatic beta cells in the islets of Langerhans, NOD mice also demonstrate spontaneous autoimmunity to other targets including the thymus, adrenal gland, salivary glands, thyroid, testis, nuclear components and red blood cells. Moreover, treatment of pre-diabetic NOD mice with an intravenous dose of heat killed Mycobacterium bovis (M. bovis; bacillus Calmette-Guèrin (BCG)) protects them from developing type 1 diabetes, but instead precipitates an autoimmune rheumatic disease similar to systemic lupus erythematosus (SLE), characterised by accelerated and increased incidence of haemolytic anaemia (HA), anti-nuclear autoantibody (ANA) production, exacerbation of sialadenitis, and the appearance of immune complex-mediated glomerulonephritis (GN). The reciprocal switching between the two phenotypes by a single environmental trigger (mycobacterial exposure) raised the possibility that genetic susceptibility for type 1 diabetes and SLE may be conferred by a single collection of genes in the NOD mouse. This review will focus on the genetic components predisposing NOD mice to SLE induced by BCG treatment and compare them to previously determined diabetes susceptibility genes in this strain and SLE susceptibility genes in the BXSB, MRL and the New Zealand mouse strains.

Antigens of the major histocompatibility complex in patients with chronic discoid lupus erythematosus

The frequencies of the major histocompatibility complex class I, class II and class III antigens were determined in 130 patients (88 women and 42 men) with chronic discoid lupus erythematosus, and compared with those of 764 healthy controls. A significant increase in HLA-B7 (38.0% in the patients vs. 25.8% in the control group), HLA-B8 (29.5% vs. 17.4%), HLA-Cw7 (58.9% vs. 26.1%), HLA-DR2 (46.9% vs. 29.7%), HLA-DR3 (32.0% vs. 19.4%), HLA-DQw1 (76.6% vs. 60.5%), and a decrease in HLA-A2 (41.9% vs. 55.7%) was found. The calculated relative risk values for the respective antigens markedly increased when two or more antigens were present in one patient, with a maximum relative risk value of 7.4 for the combinations of HLA-Cw7, DR3, DQw1 and HLA-B7, Cw7 and DR3, which were found in 17.2% of the patients and in only 2.3% of the controls.

Subacute cutaneous lupus erythematosus: clinicopathologic findings in thirteen cases

The clinicopathologic and serologic findings of thirteen patients with subacute cutaneous lupus erythematosus are reported. The clinical and immunologic features are similar to those described by most other authors. From a histologic point of view, however, two aspects could be emphasized: the presence of a larger number of epidermal colloid bodies and severe epidermal necrosis (more than 60% of cases). All patients with this microscopic picture have a similar clinical and serologic pattern: annular lesions, anti-Ro antibodies and human leukocyte antigen-DR3.

Lupus erythematosus in a patient with long-standing multiple sclerosis

The occurrence of both lupus erythematosus and multiple sclerosis in several members within the same family has been previously documented. In the past, patients manifesting symptoms and findings compatible with both of these diseases have posed difficult diagnostic problems. This report concerns a patient with long-standing multiple sclerosis and in whom cutaneous and serologic lupus erythematosus developed. To our knowledge this is the first such case reported in the English literature. A daughter of this patient had developed serologic lupus erythematosus. The intensified study of patients with both of these diseases and those families with several members with one of these diseases may lead to new insights into the cause and pathogenesis of these disorders.