The importance of specific IgG and IgE autoantibodies to retinal S antigen, total serum IgE, and sCD23 levels in autoimmune and infectious uveitis

CCR5-overexpressing mesenchymal stem cells protect against experimental autoimmune uveitis: insights from single-cell transcriptome analysis

Autoimmune uveitis is a leading cause of severe vision loss, and animal models provide unique opportunities for studying its pathogenesis and therapeutic strategies. Here we employ scRNA-seq, RNA-seq and various molecular and cellular approaches to characterize mouse models of classical experimental autoimmune uveitis (EAU), revealing that EAU causes broad retinal neuron degeneration and marker downregulation, and that Müller glia may act as antigen-presenting cells. Moreover, EAU immune response is primarily driven by Th1 cells, and results in dramatic upregulation of CC chemokines, especially CCL5, in the EAU retina. Accordingly, overexpression of CCR5, a CCL5 receptor, in mesenchymal stem cells (MSCs) enhances their homing capacity and improves their immunomodulatory outcomes in preventing EAU, by reducing infiltrating T cells and activated microglia and suppressing Nlrp3 inflammasome activation. Taken together, our data not only provide valuable insights into the molecular characteristics of EAU but also open an avenue for innovative MSC-based therapy.

Autoreactive IgE: Pathogenic role and therapeutic target in autoimmune diseases

Autoimmunity is the break of tolerance to self-antigens that leads to organ-specific or systemic diseases often characterized by the presence of pathogenic autoreactive antibodies (AAb) produced by plasmablast and/or plasma cells. AAb are prevalent in the general population and not systematically associated with clinical symptoms. In contrast, in some individuals, these AAb are pathogenic and drive the development of signs and symptoms of antibody-mediated autoimmune diseases (AbAID). AAb production, isotype profiles, and glycosylations are promoted by pro-inflammatory triggers linked to genetic, environmental, and hormonal parameters. Recent evidence supports a role for pathogenic AAb of the IgE isotype in a number of AbAID. Autoreactive IgE can drive the activation of mast cells, basophils, and other types of FcεRI-bearing cells and may play a role in promoting autoantibody production and other pro-inflammatory pathways. In this review, we discuss the current knowledge on the pathogenicity of autoreactive IgE in AbAID and their status as therapeutic targets. We also highlight unresolved issues including the need for assays that reproducibly quantify IgE AAbs, to validate their diagnostic and prognostic value, and to further study their pathophysiological contributions to AbAID.

Self-reactive IgE and anti-IgE therapy in autoimmune diseases

Growing evidence indicates the pathogenic role of autoreactive IgE in autoimmune diseases. Incidence of autoimmune and allergic diseases in the industrialized countries is consistently icreasing, thus leading to concerted efforts to comprehend the regulation of IgE-mediated mechanisms. The first reports of a presence of IgE autoantibodies in patients with autoimmune diseases have been published a long time ago, and it is now recognized that self-reactive IgE can mediate inflammatory response in bullous pemhigoid, systemic lupus erythematosus, chronic urticaria, and atopic dermatitis. The advances in understanding the pathomechanisms of these disorders brought to a successful use of anti-IgE strategies in their management. The present review discusses the current state of knowledge on the IgE-mediated autoimmunity and anti-IgE treatment, and pave the way for further exploration of the subject.

Regulatory T cells and immunoglobulin E: A new therapeutic link for autoimmunity?

Autoimmune diseases have a prevalence of approximately 7 to 9% and are classified as either organ-specific diseases, including type I diabetes, multiple sclerosis, inflammatory bowel disease and myasthenia gravis, or systemic diseases, including systemic lupus erythematosus, rheumatoid arthritis and Sjögren's syndrome. While many advancements have been made in understanding of the mechanisms of autoimmune disease, including the nature of self-tolerance and its breakdown, there remain unmet needs in terms of effective and highly targeted treatments. T regulatory cells (Tregs) are key mediators of peripheral tolerance and are implicated in many autoimmune diseases, either as a result of reduced numbers or altered function. Tregs may be broadly divided into those generated in the thymus (tTregs) and those generated in the periphery (pTregs). Tregs target many different immune cell subsets and tissues to suppress excessive inflammation and to support tissue repair and homeostasis: there is a fine balance between Treg cell stability and the plasticity that is required to adjust Tregs' regulatory purposes to particular immune responses. The central role of immunoglobulin E (IgE) in allergic disease is well recognized, and it is becoming increasingly apparent that this immunoglobulin also has a wider role encompassing other diseases including autoimmune disease. Anti-IgE treatment restores the capacity of plasmacytoid dendritic cells (pDCs) impaired by IgE- high-affinity IgE receptor (FcεR1) cross-linking to induce Tregs in vitro in atopic patients. The finding that anti-IgE therapy restores Treg cell homeostasis, and that this mechanism is associated with clinical improvement in asthma and chronic spontaneous urticaria suggests that anti-IgE therapy may also have a potential role in the treatment of autoimmune diseases in which Tregs are involved.

Correlation between serum immunoglobulin levels and retinal structure in patients with newly diagnosed Vogt‑Koyanagi‑Harada disease

Immunoglobulins serve immunomodulatory roles in numerous autoimmune diseases. The aim of the present study was to investigate the correlations between serum Ig levels and retinal structural parameters in patients with newly diagnosed acute Vogt‑Koyanagi‑Harada (VKH) disease. A total of 138 participants were enrolled and the foveal thickness (FT), serous retinal detachment (SRD), sensory retinal thickness, central FT (CFT), cube volume (V) and cube average thickness (AT) were assessed by optical coherence tomography. The patients were divided, according to the extent of SRD, into a high‑detachment group (>500 µm) and a low‑detachment group (≤500 µm). Rate‑scattering turbidimetry was performed to measure the Ig levels. The high‑detachment group comprised 51 (36.96%) patients. The proportion of males was significantly greater in the high‑detachment group compared with the low‑detachment group (58.82 vs. 40.23%; P<0.05) and best‑corrected visual acuity was significantly worse in the high‑detachment group compared with the low‑detachment group (P<0.001). The IgE levels in the high‑detachment group were significantly greater compared with the low‑detachment group (P<0.05). FT, SRD, CFT, V and AT were significantly greater in the high‑detachment group compared with the low‑detachment group (P<0.001). The IgE levels were positively associated with SRD, CFT and AT (P<0.05). Multivariate binary logistic regression analysis demonstrated that male sex (B=2.447; P<0.05) and serum IgE levels (B=0.997, P<0.05) may be independent risk factors for severe SRD. The results of the present study demonstrated that males are more likely to develop severe SRD and that serum IgE levels were associated with the extent of detachment. These data suggested that IgE may be involved in the progression of VKH disease.

Elevated Serum Immunoglobulin E Levels are Associated with the Severity of Newly Diagnosed, Acute Vogt-Koyanagi-Harada Disease

OBJECTIVE

To investigate the correlation between serum immunoglobulin E (IgE) levels and severity of Vogt-Koyanagi-Harada (VKH) disease.

METHODS

The medical records of patients with VKH disease between 2015 and 2020 were reviewed. Serum immunoglobulins (IgA, IgE, IgG, and IgM), tumor necrosis factor α (TNFα) and C-reactive protein (CRP) were measured. Patients were divided into IgE-positive (IgE ≥ 100 IU/mL) and IgE-negative (IgE < 100 IU/mL) groups. The best-corrected visual acuity (BCVA) and macular morphologic characteristics including foveal thickness (FT), serous retinal detachment (SRD), sensory retinal thickness (SRT), central foveal thickness (CFT), cube volume (V), and cube average thickness (AT) were determined in patients in both groups.

RESULTS

Of 128 patients included in the study, 35 (27.34%) patients were IgE-positive, BCVA (logMAR) was worse in the IgE-positive group. The mean CRP (P= .012) and TNFα (P≤ 0.001) levels were greater in the IgE-positive group than in the IgE-negative group. Regarding macular morphologic characteristics, FT (P= .010), SDR (P= .004), CFT (P= .008), V (P= .013), and AT (P= .006) were significantly greater in the IgE-positive group than in the IgE-negative group.

CONCLUSIONS

Elevated serum IgE levels were associated with more severe macular changes in patients with VKH disease. These findings suggest that IgE may be involved in the progression of VKH disease.

Autoantibodies Against Ubiquitous and Confined Antigens in Patients With Ocular, Neuro-Ophthalmic and Congenital Cerebral Toxoplasmosis

Toxoplasma gondii infection can trigger autoreactivity by different mechanisms. In the case of ocular toxoplasmosis, disruption of the blood-retinal barrier may cause exposure of confined retinal antigens such as recoverin. Besides, cross-reactivity can be induced by molecular mimicry of parasite antigens like HSP70, which shares 76% identity with the human ortholog. Autoreactivity can be a determining factor of clinical manifestations in the eye and in the central nervous system. We performed a prospective observational study to determine the presence of autoantibodies against recoverin and HSP70 by indirect ELISA in the serum of 65 patients with ocular, neuro-ophthalmic and congenital cerebral toxoplasmosis. We found systemic autoantibodies against recoverin and HSP70 in 33.8% and 15.6% of individuals, respectively. The presence of autoantibodies in cases of OT may be related to the severity of clinical manifestations, while in cases with CNS involvement they may have a protective role. Unexpectedly, anti-recoverin antibodies were found in patients with cerebral involvement, without ocular toxoplasmosis; therefore, we analyzed and proved cross-reactivity between recoverin and a brain antigen, hippocalcin, so the immunological phenomenon occurring in one immune-privileged organ (e.g. the central nervous system) could affect the environment of another (egg. the eye).

Autoimmunity, IgE and FcεRI-bearing cells

Antibody-mediated autoimmune diseases (AAID) involve several isotypes of autoreactive antibodies. In a growing number of AAID, autoreactive IgE are present with a significant prevalence and are often associated with the presence of IgG anti-IgE and/or anti-FcεRIα (high affinity IgE receptor α chain). FcεRI-bearing cells, such as basophils or mast cells, are key players in some of these AAID. Recent advances in the pathophysiology of these diseases led to the passed or current development of anti-IgE strategies that showed very potent effects in some of them. The present review centralizes the information on the relevance of autoreactive IgE and FcεRI-bearing cells in the pathophysiology of different AAID and the ones where the anti-IgE therapeutic strategy shows or may show some benefits for the patients.

AllergoOncology: ultra-low IgE, a potential novel biomarker in cancer-a Position Paper of the European Academy of Allergy and Clinical Immunology (EAACI)

Elevated serum IgE levels are associated with allergic disorders, parasitosis and specific immunologic abnormalities. In addition, epidemiological and mechanistic evidence indicates an association between IgE-mediated immune surveillance and protection from tumour growth. Intriguingly, recent studies reveal a correlation between IgE deficiency and increased malignancy risk. This is the first review discussing IgE levels and links to pathological conditions, with special focus on the potential clinical significance of ultra-low serum IgE levels and risk of malignancy. In this Position Paper we discuss: (a) the utility of measuring total IgE levels in the management of allergies, parasitosis, and immunodeficiencies, (b) factors that may influence serum IgE levels, (c) IgE as a marker of different disorders, and d) the relationship between ultra-low IgE levels and malignancy susceptibility. While elevated serum IgE is generally associated with allergic/atopic conditions, very low or absent IgE may hamper anti-tumour surveillance, indicating the importance of a balanced IgE-mediated immune function. Ultra-low IgE may prove to be an unexpected biomarker for cancer risk. Nevertheless, given the early stage of investigations conducted mostly in patients with diseases that influence IgE levels, in-depth mechanistic studies and stratification of malignancy risk based on associated demographic, immunological and clinical co-factors are warranted.

Assessment of specific antibodies as biological indicators of human chronic exposure to microcystins

Cyanobacteria can produce potent natural toxins known as cyanotoxins. Blooms of cyanobacteria, produced mainly as result of the pollution of water bodies with excessive amounts of phosphorus, represent a severe environmental problem; not only do they affect the normal equilibrium of the aquatic ecosystem but may also affect animal and human health. The occurrence of algal blooms have been increasing globally (it has been recently reported in at least 100 countries) and it has been considered by WHO as an emerging public health issue. The toxic effects of cyanotoxins have been thoroughly demonstrated in laboratory experiments, however, the effects on humans and the extent of these effects have been more difficult to assess. Epidemiological research is difficult as there are no specific symptoms or routine biomarkers to diagnose intoxication with cyanotoxins, in particular those cases associated with chronic exposure. The objectives of this study were to assess the exposure of a population settled near a lake with recurrent cyanobacteria blooms and to investigate the presence of biological markers of chronic exposure to cyanotoxins, in particular the microcystins (MCs). We first investigated the exposure of the population to cyanobacteria by using a questionnaire on how the population used the water and by analyzing water samples for the presence of cyanobacteria and total microcystins (TMCs). Secondly, we investigated the presence of biological indicators by analyzing the biochemical and immunological parameters in sera of the exposed population. The questionnaires and the water analyses revealed that the population under study (n = 47) is exposed to several exposure routes. The biochemical analyses of the sera showed the alteration of at least one hepatic enzyme in 25% of the exposed people, but this cannot be associated solely to MCs exposure. On the contrary, the immunological analyses, which included microcystin-LR specific antibodies IgE and IgG, showed significant differences between the exposed and non-exposed groups. The presence of MCs specific antibodies confirms the exposure to MCs. We propose the study of specific antibodies as a non-complex biomarker to detect chronic exposure to the toxin and to assist epidemiological studies.

Immunoglobulin E-Mediated Autoimmunity

The study of autoimmunity mediated by immunoglobulin E (IgE) autoantibodies, which may be termed autoallergy, is in its infancy. It is now recognized that systemic lupus erythematosus, bullous pemphigoid (BP), and chronic urticaria, both spontaneous and inducible, are most likely to be mediated, at least in part, by IgE autoantibodies. The situation in other conditions, such as autoimmune uveitis, rheumatoid arthritis, hyperthyroid Graves’ disease, autoimmune pancreatitis, and even asthma, is far less clear but evidence for autoallergy is accumulating. To be certain of an autoallergic mechanism, it is necessary to identify both IgE autoantibodies and their targets as has been done with the transmembrane protein BP180 and the intracellular protein BP230 in BP and IL-24 in chronic spontaneous urticaria. Also, IgE-targeted therapies, such as anti-IgE, must have been shown to be of benefit to patients as has been done with both of these conditions. This comprehensive review of the literature on IgE-mediated autoallergy focuses on three related questions. What do we know about the prevalence of IgE autoantibodies and their targets in different diseases? What do we know about the relevance of IgE autoantibodies in different diseases? What do we know about the cellular and molecular effects of IgE autoantibodies? In addition to providing answers to these questions, based on a broad review of the literature, we outline the current gaps of knowledge in our understanding of IgE autoantibodies and describe approaches to address them.

Role of IgE in autoimmunity

There is accumulating evidence to suggest that IgE plays a significant role in autoimmunity. The presence of circulating self-reactive IgE in patients with autoimmune disorders has been long known but, at the same time, largely understudied. However, studies have shown that the increased IgE concentration is not associated with higher prevalence for atopy and allergy in patients with autoimmune diseases, such as systemic lupus erythematosus. IgE-mediated mechanisms are conventionally known to facilitate degranulation of mast cells and basophils and promote TH2 immunity, mechanisms that are not only central to mounting an appropriate defense against parasitic worms, noxious substances, toxins, venoms, and environmental irritants but that also trigger exuberant allergic reactions in patients with allergies. More recently, IgE autoantibodies have been recognized to participate in the self-inflicted damaging immune responses that characterize autoimmunity. Such autoimmune responses include direct damage on tissue-containing autoantigens, activation and migration of basophils to lymph nodes, and, as observed most recently, induction of type 1 interferon responses from plasmacytoid dendritic cells. The importance of IgE as a central pathogenic mechanism in autoimmunity has now been clinically validated by the approval of omalizumab, an anti-IgE mAb, for patients with chronic spontaneous urticaria and for the clinical benefit of patients with bullous pemphigoid. In this review we summarize recent reports describing the prevalence of self-reactive IgE and discuss novel findings that incriminate IgE as central in the pathogenesis of inflammatory autoimmune disorders.

The role of serology in active ocular toxoplasmosis

Our purpose was to examine toxoplasmic serology in relation to episodes of suspected acute toxoplasmic retinochoroiditis and evaluate its use in the appraisal of patients. The mean values of enzymatic immunoassay (EIA) titers for toxoplasmic antibodies were retrospectively compared in patients with active and inactive toxoplasmosis and in a third group of uveitis cases not caused by toxoplasmosis. The proportion of cases under and above a predefined serology value above cut-off was compared in all groups. Between 1995 and 2010, 97 out of 1,276 new uveitis cases seen at the Centre for Ophthalmic Specialized Care (COS), Lausanne, Switzerland were diagnosed as toxoplasmic retinochoroiditis, of which 51 had documented serology available. The mean EIA values for immunoglobulin (Ig) G were 147.75 ± 259.4 IU/ml for patients with active disease, 18.93 ± 23.09 (p < 0.05) for patients with inactive toxoplasmosis and 18.35 ± 20.82 for controls (p < 0.017). The proportion of cases under the designated limit value were 2/51 (4%) in the active retinitinochoroiditis group, 14/27 (52%) (p < 0.05) in the control group, and 7/7 (100%) in the inactive toxoplasmic group (p < 0.001). Three out of 51 cases showed high IgM values in addition to IgG elevation and were primary infections. Toxoplasmosis serology, contrary to popular belief, is useful to confirm active toxoplasmic retinochoroiditis; it is easy to perform, cheap and supports clinical diagnosis in up to 96% of cases, not only by showing positivity but by also showing a significant elevation of titers. In atypical cases serology is not only useful but essential.

Anti-retinal autoantibodies in experimental ocular and systemic toxoplasmosis

BACKGROUND

Patients with ocular toxoplasmosis (OT) develop autoreactivity to several retinal antigens, including retinal S-antigen. By establishing an experimental rabbit model of systemic and of primary and secondary ocular toxoplasmosis, we wished to investigate the onset and development of humoral response to retinal S-antigen.

METHODS

Of twelve infection-naïve rabbits, six were left untreated, and the other six were infected subcutaneously with 5,000 tachyzoites of the highly virulent, non-cyst-forming BK-strain of Toxoplasma gondii. Three months later, the left eye of each animal was infected transvitreally with 5,000 tachyzoites of the same strain. The right eye of each rabbit served as an uninfected control. Blood and aqueous humor were collected prior to infection, and up to 90 days thereafter. Using the ELISA technique, all samples were analyzed in parallel for total IgG, and antibodies against toxoplasmic, bovine retinal S-antigen and peptide 35 from human S-antigen.

RESULTS

In infection-naïve rabbits Toxoplasma-specific antibodies were detected 10 to 15 days after systemic and ocular infection. Serum antibodies against retinal S-antigen and peptide 35 were not detected in response to systemic Toxoplasma infection. After ocular challenge, aqueous-humour levels of antibodies against retinal S-antigen and peptide 35 in the infected eye began to rise 10 to 15 days later in infection-naïve, but not in infection-immunized animals. During the early post-infection period, the concentrations of anti-retinal antibodies in the infected eye correlated with the severity of inflammatory tissue destruction, but returned to baseline later even though the inflammatory response persisted. In the uninfected partner eye, concentrations of anti-retinal and toxoplasmic antibodies did not correlate with each other.

CONCLUSION

Our data afford no evidence of similarities between toxoplasmic and retinal antigens, nor of infection-induced humoral autoimmunity. They indicate rather that retinal autoantigens are liberated in the context of inflammatory tissue destruction due to ocular toxoplasmosis.

Linking allergy to autoimmune disease

Type I allergy is a classical Th2-driven hypersensitivity disease based on IgE recognition of environmental allergens. Exposure of allergic individuals to exogenous allergens leads to immediate type inflammation caused by degranulation of mast cells via IgE-allergen immune complexes and the release of inflammatory mediators, proteases and pro-inflammatory cytokines. However, allergic inflammation can occur and persist in the absence of exposure to exogenous allergens and might paradoxically resemble a Th1-mediated chronic inflammatory reaction. We summarize evidence supporting the view that autoimmune mechanisms might contribute to these processes. IgE recognition of autoantigens might augment allergic inflammation in the absence of exogenous allergen exposure. Moreover, autoantigens that activate Th1-immune responses could contribute to chronic inflammation in allergy, thus linking allergy to autoimmunity.

Detection of Serum Antibodies to S‐Antigen by Surface Plasmon Resonance (SPR)

Serum autoantibodies to visual arrestin, also termed S-antigen, have been shown to accompany several autoimmune-related diseases. However, they were also detected in sera of healthy individuals; there is lack of a sensitive and fast method for evaluation of putative differences between those two groups of antibodies. We show that, using biosensor technology based on surface plasmon resonance (SPR), it was possible to characterize real-time interactions of immune sera with immobilized arrestin. Binding characteristics revealed different interaction kinetics of antiarrestin antibodies present in two distinct rabbit sera and, thus, broadened results of immunoblotting analysis. Therefore, we suggest that SPR-based biosensor technology might be a valuable method for monitoring and evaluation of antiarrestin antibodies in patients' sera.

Determinants of immunodiagnostic success in human ocular toxoplasmosis

Ocular toxoplasmosis is a local manifestation of systemic infection in which Toxoplasma spreads into the eye, affecting mainly the posterior segment of the eye. Reactivation of the initial retinal condition presumably results from the rupture of quiescent parasitic cysts lying adjacent to pre-existing scars and may secondarily involve the choroid (leading to retinochoroiditis). Although the molecular mechanisms underlying host-parasite interaction are largely unknown, toxoplasmic retinochoroiditis usually remains a local event, and does not necessarily evoke a detectable systemic immune response. Local immunotolerance mechanisms may likewise confound attempts to confirm the clinical diagnosis by serology. Aqueous humour may be analysed for the presence of parasite DNA or of specific antibodies, but the DNA burden therein is low, and a more definite confirmation would require risky puncturing of the vitreous. Laboratory confirmation of the diagnosis is also frustrated by marked individual differences in the time elapsing between the onset of clinical symptoms and the activation of specific antibody production, resulting in a high proportion of false negative results. Whether a delay in the onset of local specific antibody production reflects immunotolerance in cases of congenital - but not obviously in those of acquired - infection remains an open question, but it could account for a relatively low confirmation rate in laboratory tests for local antibody production. Against this background, current diagnostic strategies need to be re-evaluated with a view to future improvements.

Aqueous humor and serum immunoblotting for immunoglobulin types G, A, M, and E in cases of human ocular toxoplasmosis

The purpose of this study was to compare the local and systemic Toxoplasma-specific humoral immune responses in individuals with ocular toxoplasmosis (OT). To this end, paired aqueous humor and serum samples from 46 individuals with active OT and from 30 individuals without inflammatory eye disease (controls) were analyzed by immunoblotting for anti-Toxoplasma immunoglobulin G (IgG), IgA, IgM, and IgE directed against 20- to 120-kDa antigens. The presence in the aqueous humor of a unique band, or of at least three bands that were at least three times more intense in aqueous humor than in serum, was taken as evidence of local antibody production. IgG bands were detected in 98% of the aqueous humor samples, while IgA bands were detected in 76%, IgM bands were detected in 8%, and IgE bands were not detected in any. Evidence of local production of specific antibodies was found in 32 cases (70%) (IgG in 23 [50%]; IgA in 16 [35%]). In 10 instances (22%), routine laboratory tests were not indicative of OT. In 14 cases (30%), no local antibody production was detected by immunoblotting; 3 of these cases yielded evidence of local antibody production according to the Goldmann-Witmer coefficient. Local antibody production was revealed for 7 of the 30 controls (23%). Hence, the sensitivity of immunoblotting for IgG and IgA is 70%, and the specificity is 77%. We conclude that immunoblotting for local specific IgG and IgA supports the clinical diagnosis of OT in 70% of cases. In 22% of these, the diagnosis is not confirmed by other laboratory tests. Hence, immunoblotting increases the sensitivity of routine laboratory tests and should be considered for samples that register negative by such tests.

Ocular manifestations of toxoplasmosis

PURPOSE OF REVIEW

The concepts of toxoplasmosis and its ocular manifestations in humans have thoroughly changed in the past 3 years. This review addresses new epidemiologic data, specifically the occurrence of ocular disease in postnatal infections, and puts the changed views on the frequency and pathogenesis of toxoplasmic ocular manifestations into historical perspective.

RECENT FINDINGS

Newly described clinical presentations are discussed together with their recent diagnostic possibilities. The new data on congenital or postnatal acquisition of infection and their importance for ocular involvement are presented as well as the high prevalence of 79% of recurrent disease in ocular toxoplasmosis, which cannot be prevented by short-term treatments. Recently published analyses of literature showed, unexpectedly, the lack of efficacy of short-term treatments for ocular disease as well as of the long-term prenatal treatments on fetal transmission rate and the severity of congenital disease.

SUMMARY

The recent guidelines for treatment are included together with the up-to-date recommendations for the treatment of ocular toxoplasmosis in the immunosuppressed host.

Anti-galectin-1 autoantibodies in human Trypanosoma cruzi infection: differential expression of this beta-galactoside-binding protein in cardiac Chagas' disease

The pathogenesis of Chagas' disease has been subject of active research and still remains to be ascertained. Galectin-1 (Gal-1), a member of a conserved family of animal beta-galactoside-binding proteins, localized in human heart tissue, has been suggested to play key roles in immunological and inflammatory processes. In the present study we demonstrated the occurrence of anti-Gal-1 autoAb in sera from patients in the acute and chronic stages of Chagas' disease (ACD and CCD) by means of ELISA and Western blot analysis. We found a marked increase in the level and frequency of Ig E anti-Gal-1 antibodies in sera from patients with ACD, but a low frequency of Ig M anti-Gal-1 immunoreactivity. Moreover, Ig G immunoreactivity to this beta-galactoside-binding protein was found to be correlated with the severity of cardiac damage in CCD, but was absent in nonrelated cardiomyopathies. We could not detect immunoreactivity with Trypanosoma cruzi antigens using a polyclonal antibody raised to human Gal-1 and no hemagglutinating activity could be specifically eluted from a lactosyl-agarose matrix from parasite lysates. Moreover, despite sequence homology between Gal-1 and shed acute phase antigen (SAPA) of T. cruzi, anti-Gal-1 antibodies eluted from human sera failed to cross-react with SAPA. In an attempt to explore whether Gal-1 immunoreactivity was originated from endogenous human Gal-1, we finally investigated its expression levels in cardiac tissue (the main target of Chagas' disease). This protein was found to be markedly upregulated in cardiac tissue from patients with severe CCD, compared to cardiac tissue from normal individuals.