Autoantibodies in leprosy among Thai patients

Long-term presence of autoantibodies in plasma of cured leprosy patients

Autoantibodies have been detected in leprosy patients, indicating that infection with M. leprae may lead to autoimmune disorders. However, whether autoimmune response last until patients are cured is unknown. Knowing the autoimmune response in cured leprosy patients is essential to identify whether symptoms are caused by leprosy itself or by other immune-related diseases. This knowledge is essential for the ongoing health management in cured leprosy patients where autoimmune disorders still exist. In our study, we selected six autoantibodies, including anticardiolipin antibody of IgG (ACA), anti-nuclear antibody (ANA), extractable nuclear antigen antibody (ENA), anti-streptolysin O (ASO), anti-double stranded DNA antibody (dsDNA), and rheumatoid factor (RF), that had been reported in leprosy patients as typical autoantibodies. We tested the six typical autoantibodies combined with LACC1, which encodes a protein associated with autoimmune disease such as Crohn's disease and is also the susceptible gene conferring leprosy risk, in cured leprosy patients through ELISA to assess the cured patient's immune status. We observed high positive rates of autoantibodies in cured leprosy patients, and the average plasma levels of five (ACA, ANA, ENA, ASO, and RF) out of the six autoantibodies were significantly higher in cured leprosy patients than in controls. The positive detection of autoantibodies is independent of the recovery period. Moreover, the level of these autoantibodies showed a strong positive correlation with the level of LACC1 in both controls and cured patients. This study showed that there is long-term autoimmunological activation in leprosy patients, even after decades of recovery. Autoimmune responses may influence the development and prognosis of leprosy. Special care should be given to posttreatment or cured leprosy patients regarding long-term autoimmunological activation.

Corroboration of cross-reactivity between Mycobacterium leprae and hosts' salivary and cutaneous proteins: A hope for prognostic biomarkers for the pathogenesis of reactions in leprosy

Introduction

Immunological reactions are frequent complications that may occur either before, during, or after treatment and affect 30-50% of leprosy patients. The presence of autoantibodies like rheumatoid factor, antinuclear factor, and antibodies to host collagen, keratin, actin, myosin, endothelial cells, and myelin basic protein (MBP) has been earlier reported in leprosy patients. The purpose of this study was to identify cross-reactive proteins in clinical samples such as saliva and slit skin scrapings (SSS) of leprosy patients which could be utilised as prognostic biomarkers for Type 1 Reaction (T1R) in leprosy.

Method

A total of 10 leprosy patients in T1R and 5 healthy volunteers were recruited. The protein was extracted from their SSS and saliva samples, thereafter, isoelectric focusing (IEF) and two-dimensional PAGE were performed to analyse the proteins. Furthermore, the cross-reactivity was identified by western blotting host proteins in gel against purified IgG from Mycobacterium leprae soluble antigen (MLSA)- hyperimmunized rabbit sera, thereafter, cross-reactive proteins were identified by MS/MS. The cross-reactive host proteins were analysed for homologous bacterial proteins and B cell epitopes (BCEs) were predicted by using bioinformatic tools.

Results

A total of five spots of salivary proteins namely S100-A9, 35.3 kDa, and 41.5 kDa proteins, Serpin peptidase inhibitor (clade A), Cystatin SA-III, and four spots of SSS namely 41.4 kDa protein, Alpha-1 antitrypsin, vimentin, and keratin 1, were identified as cross-reactive. Further, a total of 22 BCEs of cross-reactive host proteins were predicted and visualised.

Discussion

This data provides strong evidence of cross-reactivity/molecular mimicry between host and pathogen in leprosy patients with reaction. These BCEs of cross-reactive proteins could be further studied to predict reactions and may be utilised as an early diagnostic biomarker for T1R in leprosy.

Effects of anti-endothelial cell antibodies in leprosy and malaria

As a result of damaging endothelial cells (ECs), Mycobacterium leprae triggers the production of antibodies (Abs). These anti-EC Abs (AECAs) can be divided into two types. The first type nonspecifically reacts with components of the cytosol (CY) and can be detected by enzyme-linked immunosorbent assay (ELISA). The second specifically reacts with the EC membrane (MB) and requires fluorescence-activated cell sorter (FACS) analysis to be detected. The presence of both types of AECAs was determined in 68 leprosy patients. The ELISA was positive for 35 of them but also for 30 of 34 malaria patients and 17 of 50 healthy African controls. However, whereas FACS analysis showed MB reactivity in only three malaria patients and four controls, this reactivity was found in 27 leprosy patients, more of those having the lepromatous than the tuberculoid form. Specificity for MB, which we failed to absorb by incubation with CY lysates, predominated over that for CY in leprosy, unlike malaria, where the EC reactivity was restricted to the CY. Western blot analysis and two-dimensional electrophoresis revealed that calreticulin, vimentin, tubulin, and heat shock protein 70 were targeted by AECAs from leprosy patients, but other proteins remained unidentified. These auto-Abs, but not those from malaria patients, did activate ECs, as indicated by the E-selectin and intercellular adhesion molecule 1 upregulation, and/or induced them into apoptosis, as documented by four different methods. Our findings suggest that, in some but not all leprosy patients, AECAs may play a role in pathogenesis.

Humoral immunity in Hansen's disease

For many years immune response in leprosy has been studied. Since 1960 several reports dealing with humoral immunity have been described in the literature. Different autoantibody rates occur in leprosy. There is an increase in the prevalence of autoantibodies in elderly patients with long standing disease, in lepromatous leprosy and in those with reactional states. The differences in rates among various studies are attributed to different methods and variations among patient samples concerning age, gender, polar forms, therapy and other elements. The prevalence of numerous antibodies, immune complexes, cryoglobulins and complement levels have been studied by many authors. This also highlights the importance of the more recent reviews of anti-Mycobacterium leprae glycolipid antibodies such as the anti-phenolic glycolipid-I antibodies in which titers are variable and depend on genetic factors.

Autoantibodies and tropical infections

Autoantibodies against diverse autoantigens have long been known to exist in the sera of several tropical infections. The introduction of monoclonal antibody technology has allowed immortalization of autoantibody secreting B-lymphocytes and subsequent analysis of these autoantibodies. This paper discusses the current literature on the induction, origins, significance and analysis of autoantibodies.

Rheumatoid factors in leprosy and parasitic diseases

Rheumatoid factors (RFs) occur with higher frequency and in higher titres in multibacillary forms of leprosy and several parasitic diseases than in healthy controls. The selection of controls is essential in studies of this kind. They should be individuals without signs of the disease under study living under similar socioeconomic conditions as the patients in the endemic country. In three studies where this matter was considered, RFs in lepromatous leprosy and Chagas' disease reacted more strongly with rabbit than human IgG, a feature generally considered to be quite restricted to rheumatoid arthritis. RFs interfere in various test systems, particularly in inducing false positive reactions for specific IgM antibodies in parasitic and other infectious diseases. Model experiments in rats, in vitro culture studies, and observations in humans indicate that RFs may have a protective role in trypanosome infections, malaria and schistosomiasis respectively.

Autoaggressive hanseniasis

I have given the name autoaggressive hanseniasis to a syndrome with immunopathologic and clinical pictures resembling autoaggressive systemic diseases observed in some cases of lepromatous and borderline hanseniasis. It is probably caused by B cell stimulation by antigenic complex of Mycobacterium leprae plus autologous tissue, along with a dysfunction of the T-suppressor lymphocytes.

Immunoglobulin deposits in leprosy skin

An immunofluorescent study was carried out on skin biopsies from 12 leprosy patients who had been suffering from the disease for periods of one to 30 years; all were treated with dapsone and clofazimine at one stage. Skin biopsies made from reactive nodular lesions showed that all 12 had IgG deposits and seven had IgM deposits in the dermal-epidermal junction. No IgA, IgE, C3 and fibrinogen were found deposited in any biopsy. All patients had significantly raised levels of serum immunoglobulins and rheumatoid factor. Anti-epithelial (eight patients) and anti-nuclear (three patients) antibodies were also found. The possible role of autoantibodies in the present findings is discussed.