Vitiligo, rheumatoid arthritis and pernicious anemia

A bidirectional autoimmune cluster between vitiligo and rheumatoid arthritis: a large-scale population-based study

A knowledge gap exists regarding the association between vitiligo and rheumatoid arthritis (RA) due to the absence of large-scale cohort studies designed to investigate this association. To investigate the bidirectional epidemiological association between vitiligo and RA. A population-based study was conducted using Clalit Health Services (CHS) database (2002-2019) using both a cohort study and a case-control study design. Adjusted hazard ratio (HR) and odds ratio (OR) were calculated by multivariate Cox and logistic regressions, respectively. Overall, 20,851 vitiligo patients and 102,475 controls were included. The incidence of new-onset RA was 4.1 (95% CI 3.0-5.4) and 2.9 (95% CI 2.4-3.3) cases per 10,000 person-years among patients with vitiligo and controls, respectively. Patients with vitiligo had a significantly increased risk of developing new-onset RA (adjusted HR, 1.44; 95% confidence interval [CI], 1.02-2.02, P = 0.036). The likelihood of having vitiligo was significantly elevated after a preexisting diagnosis of RA (adjusted OR, 1.67; 95% CI, 1.38-2.03; P < 0.001). Relative to the remaining patients with vitiligo, those with vitiligo and comorbid RA demonstrated an elevated risk of all-cause mortality (adjusted HR, 1.61; 95% CI, 1.03-2.51; P = 0.037). Our study confirms the bidirectional association between vitiligo and RA. Physicians treating patients with vitiligo should be aware of the association in clinical practice.

The importance of inhibition of a catabolic pathway of methotrexate metabolism in its efficacy for rheumatoid arthritis

Methotrexate (MTX), an antifolate, is the anchor drug for the treatment of rheumatoid arthritis (RA). It is inexpensive, effective, and generally safe. When clinical response is inadequate, biological therapies are commonly used in combination with MTX. However, biological agents have safety concerns (i.e. infections, malignancy) and the addition of a biologic agent is expensive, making strategies to improve MTX efficacy important. Inhibition of pathways of folate metabolism involving purine metabolism by MTX, have been traditionally emphasized as important in MTX efficacy. However, inhibition MTX catabolism may also be important. MTX is irreversibly hydroxylated to form 7-hydroxy methotrexate (7-OH-MTX) by aldehyde oxidase (EC 1.2.3.1) (AOX). Catabolism of MTX to 7-OH-MTX is the first metabolic process imposed on an oral dose of MTX and will alter subsequent interactions of MTX with other enzymes. 7-OH-MTX is less potent than MTX in the treatment of rat adjuvant arthritis. RA patients with a low capacity to catabolize MTX to 7-OH-MTX do better clinically than individuals who are rapid formers of 7-OH-MTX. Therefore, altering the catabolism of MTX may be an innovative way to improve MTX efficacy. Raloxifene is a FDA-approved therapy for postmenopausal osteoporosis and for the reduction of invasive breast cancers but has no known activity in RA. Raloxifene is a potent inhibitor of human liver AOX. Postmenopausal women with RA frequently have low bone mineral density and would be candidates for raloxifene and MTX combination therapy. The effect of raloxifene on MTX metabolism has never been studied. Our hypothesis is that in postmenopausal women with RA and osteoporosis treated with MTX and raloxifene, the inhibition of AOX with resultant decreased formation of 7-OH MTX; will increase MTX levels and improve MTX efficacy. This hypothesis could be studied in an open-label, proof of concept clinical study in individuals before and after the addition of raloxifene. Red blood cell MTX and 7-OH-MTX levels and RA disease activity (DAS28) would be measured. In possible future studies, there are dietary substances, as supplements, (e.g. epigallocatechin gallate in green tea and resveratrol) which inhibit human liver AOX which could be evaluated.

Autoimmune vitiligo in rheumatic disease in the mestizo Mexican population

Vitiligo is a chronic disease characterized by the dysfunction or destruction of melanocytes with secondary depigmentation. The aim of the present study was to determine the prevalence of vitiligo associated with autoimmune rheumatic diseases. The clinical records from a 10-year database of patients with rheumatic diseases and associated vitiligo was analysed, with one group of patients having autoimmune rheumatic disease and another non-autoimmune rheumatic disease. Available serum samples were used to assess the anti-melanocyte antibodies. A total of 5,251 individual clinical files were archived in the last 10 years, and these patients underwent multiple rheumatology consultations, with 0.3% of the group presenting with vitiligo. The prevalence of vitiligo in the autoimmune rheumatic disease group was 0.672%, which was mainly associated with lupus and arthritis. However, patients with more than one autoimmune disease had an increased relative risk to develop vitiligo, and anti-melanocyte antibodies were positive in 92% of these patients. By contrast, the prevalence was 0.082% in the group that lacked autoimmune rheumatic disease and had negative autoantibodies. In conclusion, the association between vitiligo and autoimmune rheumatic diseases was relatively low. However, the relative risk increased when there were other autoimmune comorbidities, such as thyroiditis or celiac disease. Therefore, the presence of multiple autoimmune syndromes should be suspected.

Autoimmunity as an aetiological factor in vitiligo

Vitiligo is a common dermatological disorder characterized by the presence on the skin of depigmented macules resulting from the destruction of cutaneous melanocytes. Autoimmunity is an important hypothesis with regard to vitiligo aetiology and the evidence for autoimmune responses being involved in the pathogenesis of this disorder will be discussed in the present review. All immune system compartments, including innate and adaptive immunity have been implicated in vitiligo development. Particularly relevant are autoantibodies and autoreactive T cells in vitiligo patients that have cytotoxic effects upon pigment cells. Furthermore, predisposition to vitiligo appears to be associated with certain alleles of the major histocompatibility complex class II antigens as well as with other autoimmune-susceptibility genes. Moreover, the association of vitiligo with autoimmune disorders, the animal models of the disease, and the positive response to immunosuppressive therapeutic agents emphasize the role of autoimmunity in the development of this disorder.

New Treatment Modalities for Vitiligo

The development of effective treatment modalities for vitiligo is dependent on an understanding of the events leading to depigmentation. However, the exact pathogenesis of vitiligo is still mostly unknown. Abnormalities in both humoral and cell-mediated immunity have been documented in vitiligo patients and they present a basis for using immunomodulating agents, such as corticosteroids and macrolide immunomodulators, in the treatment of vitiligo. Macrolide immunomodulators, such as tacrolimus and pimecrolimus, which can be used topically, are known as topical immunomodulators (TIMs). TIMs inhibit the action of calcineurin, and consequently inhibit T-cell activation and the production of various cytokines; this is considered the working mechanism of action of TIMs in vitiligo. Several small studies and case reports on the use of TIMs in vitiligo have been published so far. Tacrolimus achieves better results on the face and neck than on other body areas. Particular advantages of TIMs are safety in treating these areas because of lack of skin atrophy and good tolerability. The incidence of application site adverse events in vitiligo seems to be lower than in the treatment of atopic dermatitis. On the face and neck, TIMs may become a useful tool in the treatment of adults and children with vitiligo despite possibly lower efficacy than topical corticosteroids. Further, larger, controlled clinical studies are warranted to determine the definite role of TIMs as monotherapy or in combination with other modalities in the treatment of vitiligo.

Evidence for an autoimmune pathogenesis of vitiligo

Vitiligo is a depigmenting disorder characterized by the development of white patches in various distributions, which are due to the loss of melanocytes from the epidermis. A variety of arguments from clinical observations to research findings in human and animal models support the hypothesis of autoimmunity and are reviewed in this article. The association with autoimmune diseases and organ-specific autoantibodies is well known. Various effective treatment options have an immunosuppressive effect. Today the autoimmune pathogenesis of the disease has become a rapidly evolving field of research. Detection of circulating melanocyte antibodies in human and animal models implicates a possible role of humoral immunity. Histological and immunohistochemical studies in perilesional skin suggest the involvement of cellular immunity in vitiligo. Recently, T-cell analyses in peripheral blood further support this hypothesis. Interestingly, new insights in the association of vitiligo and melanoma may help to clarify the role of autoimmunity in the development of vitiligo.