Cytokines in the pathophysiology of systemic lupus erythematosus

Genetic contribution of the interferon gamma dinucleotide-repeat polymorphism in South Indian women with endometriosis

AIM

To investigate whether the interferon-gamma (IFNG) gene dinucleotide (CA)-repeat polymorphism is responsible in part for genetic susceptibility to endometriosis in South Indian women.

METHODS

Following extraction of genomic DNA, genotyping of interferon-gamma CA-repeat polymorphism was performed using genescan technology.

RESULTS

The global IFNG allele frequencies in all patients with endometriosis were significantly different from those in the control women (chi(2) = 37.062; 6 degrees of freedom; P < or = 0.0001). Significant difference was observed in global allele frequencies between the control women and each clinical subgroup of patients with endometriosis except for patients suffering from endometriosis associated with adenomyosis. The difference was due to an increase in a12 (112 bp) allele in the patients with endometriosis and each clinical subgroup of patients with endometriosis. The distribution of the IFNG a12 genotypes was significantly different between patients with endometriosis and the control women. (chi(2) = 10.635; 2 degrees of freedom; P = 0.0049). A significant difference in the IFNG a12 genotypes was found only among the three clinical subgroups.

CONCLUSION

These results suggest that the IFNG gene CA-repeat polymorphism is associated with susceptibility to endometriosis in South Indian women.

Cerebellar dysfunction is associated with overexpression of proinflammatory cytokine genes in lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology accompanied by central nervous system involvement in up to 60% of patients. The current study chronicles the expression of cerebellar dysfunction in SLE using MRL-lpr/lpr mice as the experimental model. These mice spontaneously develop an illness that has immunological and clinical features of human lupus. We found that MRL-lpr/lpr mice manifest severe and progressive behavioral disturbances indicative of cerebellar dysfunction beginning at 11 weeks of age. Although the lpr gene is known to induce autoimmune features, immunologically normal mice rendered congenic for lpr failed to exhibit disturbances in cerebellar function. Because lupus is a cytokine-driven disease and overexpression of certain proinflammatory cytokines has been associated with neurodegeneration, the relationship between cerebellar dysfunction and cytokine gene expression was examined. Relative to immunologically normal CBA/J mice, the cerebellum of young (11-15 weeks of age) MRL-lpr/lpr mice contained high levels of interleukin (IL)-6 and interferon-gamma (IFNgamma) mRNA, which became even more pronounced in old (22-30 weeks of age) autoimmune mice. mRNA levels for the cytokines IL-1beta and IL-10 were elevated in the cerebellum of old, but not young, MRL-lpr/lpr mice relative to CBA/J. In contrast, the levels of cerebellar transcripts for IL-3 and tumor necrosis factor-alpha were comparable in autoimmune and normal mice, indicating that enhanced gene expression of IL-6, IFNgamma, IL-1beta, and IL-10 was selective. These results suggest a potential role for certain proinflammatory cytokines in the pathogenesis of cerebellar disturbances in SLE.

Atypical lymphoid infiltrates arising in cutaneous lesions of connective tissue disease

Atypical lymphoid infiltrates occurring in the setting of connective-tissue disease (CTD) comprise malignant neoplasms of B-cell or T-cell phenotypes and various reactive lymphoid hyperplasias, such as myoepithelial sialadenitis, lymphocytic thyroiditis, and lymphocytic interstitial pneumonitis. We describe 17 patients with atypical lymphoid infiltrates arising in cutaneous lesions of CTD, the spectrum of which included lupus erythematosus, dermatomyositis, relapsing polychondritis, and lichen sclerosus et atrophicus. There were two principal categories, pseudolymphoma and malignant lymphoma, the former representing 15 of the 17 cases. The clinical and histologic features and possible pathogenetic mechanisms are discussed.

T-cell cytokine network in cutaneous lupus erythematosus

BACKGROUND

A variety of immunologic abnormalities have been described in systemic and experimental lupus erythematosus (LE). Several T-cell defects, especially in helper T (Th) cell cytokines, have been reported.

OBJECTIVE

Our purpose was to identify the Th cytokine profile in cutaneous LE.

METHOD

Total RNA was extracted from punch biopsy specimens from 19 patients with cutaneous LE (nine, discoid LE; two, subacute cutaneous LE; and eight, systemic LE) and from four healthy control subjects. RNA was reverse transcribed into complementary DNA and amplified with polymerase chain reaction (PCR) primers specific for interleukin-2 (IL-2), IL-4, IL-5, IL-10, interferon gamma (IFN-gamma), and beta actin. PCR products were detected by agarose gel electrophoresis and Southern blot with 32P-labeled, nested probes.

RESULTS

Sixteen of 19 cutaneous LE specimens lacked IL-2, all were negative for IL-4, and 10 of 19 had detectable IL-10, whereas IFN-gamma and IL-5 messenger RNAs were present in the majority of LE specimens. IFN-gamma and IL-10 mRNAs were found in all normal skin controls, whereas IL-2, IL-4, and IL-5 mRNAs were undetectable. Functional IFN-gamma protein was evidenced by intercellular adhesion molecule-1 and HLA-DR staining of keratinocytes in nine of nine LE specimens but not in normal skin. The pattern of cytokine mRNAs, intercellular adhesion molecule-1, and/or HLA-DR expression in cutaneous LE specimens did not vary with different subtypes of LE, antinuclear antibody titer, or the magnitude of inflammation.

CONCLUSION

The presence of IL-5 mRNA in cutaneous LE specimens suggests that Th type 2 cells combine with local IFN-gamma production to augment disease and may be related to the pathophysiology of cutaneous LE.

Subacute cutaneous lupus erythematosus arising in the setting of calcium channel blocker therapy

After 6 months to 5 years of calcium channel blocker (CCB) therapy for arterial hypertension, nine patients developed photoinduced annular or papulosquamous eruptions consonant clinically with subacute cutaneous lupus erythematosus (SCLE). Four patients were receiving diltiazem, four received verapamil, and one was taking nifedipine. Serology showed antinuclear antibodies (ANA) in seven of nine patients, anti-Ro antibodies in five, and anti-La antibodies in five, with three patients having only anti-La antibodies. Skin biopsy specimens in all nine patients were held to be characteristic of SCLE based on light microscopy, direct, and indirect immunofluorescence. The CCB was discontinued in all; in 8 patients in whom the CCB was stopped, the eruption resolved. A proposed mechanism by which the CCBs may have precipitated the eruptions is offered.

Disease severity in patients with systemic lupus erythematosus correlates with an increased ratio of interleukin-10:interferon-gamma-secreting cells in the peripheral blood

OBJECTIVE

To compare the phenotype and frequency of cells that actively secrete type 1 and type 2 cytokines in systemic lupus erythematosus (SLE) patients (n = 46), versus normal controls (n = 60).

METHODS

ELISPOT analysis of freshly isolated peripheral blood mononuclear cells (PBMC).

RESULTS

T cells were the major source of interleukin-2 (IL-2), IL-4, and interferon gamma (IFN gamma), whereas monocytes were the primary source of IL-6 and IL-10 in the PB of lupus patients. Significantly fewer PBMC spontaneously secreted IFN gamma and IL-2 (P > or = 0.03), while significantly more PBMC produced IL-6 and IL-10 (P < 0.001), in lupus patients versus controls. Disease severity in lupus patients correlated with an elevated ratio of IL-1O:IFN gamma-secreting cells (P < 0.001).

CONCLUSION

SLE is characterized by an imbalance in the ratio of type 1:type 2 cytokine-secreting PBMC.

The glomerular basement membrane in lupus nephritis

Systemic lupus erythematosus is a disease that is particularly suited for studies of glomerular basement membrane pathology. Classification of the renal pathology of lupus nephritis is usually based on light microscopic features, combined with immunofluorescence findings and electron microscopic alterations. Study of renal biopsy helps to distinguish potentially reversible and irreversible disease, and to estimate prognosis of patients with lupus nephritis. Moreover, studies of human disease, as well as the availability of animal models and in vitro cell culture systems employing biochemical and molecular biological studies of extracellular matrix, have led to a considerable increase in knowledge of the pathogenetic events underlying derangements of the glomerular basement membrane in lupus nephritis.

T- and B-cell abnormalities in systemic lupus

A wealth of T- and B-cell abnormalities has been described in systemic lupus erythematosus (SLE). In general, T and B cells manifest evidence of intense in vivo activation, yet perform poorly when tested for in vitro responsiveness to exogenous antigen. The immune system behaves as if its commitment to self-responsiveness overrides the normal capacity to respond to immunogenic challenges. Many immunoregulatory abnormalities have been characterized, but their relation to disease remains controversial. Although a widely accepted unifying hypothesis for the vigorous autoantibody production and associated immune deficiency of SLE is lacking, it seems certain that the profound abnormalities of T and B cells in SLE are intertwined with the fundamental cause of this illness.

In vivo treatment with a monoclonal antibody to interferon-gamma neither affects the survival nor the incidence of lupus-nephritis in the MRL/lpr-lpr mouse

The effects of the in vitro treatment with a mAb (DB-1) that neutralizes mouse IFN-gamma on the development of the SLE-like syndrome in MRL/lpr-lpr (MRL-lpr) mice were studied. The results show that the i.p. administration of 2.6 mg/week of DB-1 from the 12th to the 20th week of age neither affected the survival nor the incidence and severity of lupus nephritis in MRL-lpr mice. This study argues against the pathogenic relevance of IFN-gamma in this experimental model of human SLE.