Anti-basement membrane antibodies and antigen--antibody complexes in rabbits injected with mercuric chloride

The Role of Exposomes in the Pathophysiology of Autoimmune Diseases I: Toxic Chemicals and Food

Autoimmune diseases affect 5–9% of the world’s population. It is now known that genetics play a relatively small part in the pathophysiology of autoimmune disorders in general, and that environmental factors have a greater role. In this review, we examine the role of the exposome, an individual’s lifetime exposure to external and internal factors, in the pathophysiology of autoimmune diseases. The most common of these environmental factors are toxic chemicals, food/diet, and infections. Toxic chemicals are in our food, drink, common products, the air, and even the land we walk on. Toxic chemicals can directly damage self-tissue and cause the release of autoantigens, or can bind to human tissue antigens and form neoantigens, which can provoke autoimmune response leading to autoimmunity. Other types of autoimmune responses can also be induced by toxic chemicals through various effects at the cellular and biochemical levels. The food we eat every day commonly has colorants, preservatives, or packaging-related chemical contamination. The food itself may be antigenic for susceptible individuals. The most common mechanism for food-related autoimmunity is molecular mimicry, in which the food’s molecular structure bears a similarity with the structure of one or more self-tissues. The solution is to detect the trigger, remove it from the environment or diet, then repair the damage to the individual’s body and health.

Mercury-induced inflammation and autoimmunity

BACKGROUND

Human exposure to mercury leads to a variety of pathologies involving numerous organ systems including the immune system. A paucity of epidemiological studies and suitable diagnostic criteria, however, has hampered collection of sufficient data to support a causative role for mercury in autoimmune diseases. Nevertheless, there is evidence that mercury exposure in humans is linked to markers of inflammation and autoimmunity. This is supported by experimental animal model studies, which convincingly demonstrate the biological plausibility of mercury as a factor in the pathogenesis of autoimmune disease.

SCOPE OF THE REVIEW

In this review, we focus on ability of mercury to elicit inflammatory and autoimmune responses in both humans and experimental animal models.

MAJOR CONCLUSIONS

Although subtle differences exist, the inflammatory and autoimmune responses elicited by mercury exposure in humans and experimental animal models show many similarities. Proinflammatory cytokine expression, lymphoproliferation, autoantibody production, and nephropathy are common outcomes. Animal studies have revealed significant strain dependent differences in inflammation and autoimmunity suggesting genetic regulation. This has been confirmed by the requirement for individual genes as well as genome wide association studies. Importantly, many of the genes required for mercury-induced inflammation and autoimmunity are also required for idiopathic systemic autoimmunity. A notable difference is that mercury-induced autoimmunity does not require type I IFN. This observation suggests that mercury-induced autoimmunity may arise by both common and specific pathways, thereby raising the possibility of devising criteria for environmentally associated autoimmunity.

GENERAL SIGNIFICANCE

Mercury exposure likely contributes to the pathogenesis of autoimmunity.

An experimental assessment of toxic potential of nanoparticle preparation of heavy metals in streptozotocin induced diabetes

Nanoparticle preparations of heavy metals have attracted enormous scientific and technological interest. Biologically produced nanoparticle preparations of heavy metals are elaborately described in traditional texts and being widely prescribed. The underlying interactions of nano preparations within the physiological fluids are key feature to understand their biological impact. In this perspective, we performed an experimental assessment of the toxicity potential of a marketed metallic preparation named Vasant Kusumakar Ras (VKR), wherein different heavy metals in composite form are reduced to nanoparticle size to produce the desired effect in diabetes and its complications. VKR (50mg/kg) was administered to Albino Wistar rats rendered diabetic using streptozotocin (90mg/kg) in 2 days old neonates. Anti-hyperglycemic effect was observed with VKR along with increased levels of plasma insulin. Renal variables including total proteins and albumin along with glomerular filtration rate were found to improve biochemically. The results were supplemented by effects on different inflammatory and growth factors like TNF-α, nitric oxide, TGF-β and VEGF. However, the results observed in kidney histopathology were not in accordance with the biochemical parameters. Inflammation observed in kidney was confirmed by immunostaining metallothionein, which was due to the accumulation of heavy metals. Furthermore, mercury accumulation in kidney further confirmed by autometallography, which activated mononuclear phagocyte system, which generated an immune response. This was further supported by increase in the extent of apoptosis in kidney tissues. In conclusion, nanoparticle preparations of heavy metals can be toxic to kidney if it is not regulated with respect to its surface chemistry and dosage.

Dose and Hg species determine the T-helper cell activation in murine autoimmunity

Inorganic mercury (mercuric chloride--HgCl(2)) induces in mice an autoimmune syndrome (HgIA) with T cell-dependent polyclonal B cell activation and hypergammaglobulinemia, dose- and H-2-dependent production of autoantibodies targeting the 34 kDa nucleolar protein fibrillarin (AFA), and systemic immune-complex deposits. The organic mercury species methylmercury (MeHg) and ethylmercury (EtHg--in the form of thimerosal) induce AFA, while the other manifestations of HgIA seen after treatment with HgCl(2) are present to varying extent. Since these organic Hg species are converted to the autoimmunogen Hg(2+) in the body, their primary autoimmunogen potential is uncertain and the subject of this study. A moderate dose of HgCl(2) (8 mg/L drinking water--internal dose 148 micro gHg/kg body weight [bw]/day) caused the fastest AFA response, while the induction was delayed after higher (25 mg/L) and lower (1.5 and 3 mg/L) doses. The lowest dose of HgCl(2) inducing AFA was 1.5 mg/L drinking water which corresponded to a renal Hg(2+) concentration of 0.53 micro g/g. Using a dose of 8 mg HgCl(2)/L this threshold concentration was reached within 24 h, and a consistent AFA response developed after 8-10 days. The time lag for the immunological part of the reaction leading to a consistent AFA response was therefore 7-9 days. A dose of thimerosal close to the threshold dose for induction of AFA (2 mg/L drinking water--internal dose 118 micro gHg/kg bw per day), caused a renal Hg(2+) concentration of 1.8 micro g/g. The autoimmunogen effect of EtHg might therefore be entirely due to Hg(2+) formed from EtHg in the body. The effect of organic and inorganic Hg species on T-helper type 1 and type 2 cells during induction of AFA was assessed as the presence and titre of AFA of the IgG1 and IgG2a isotype, respectively. EtHg induced a persistent Th1-skewed response irrespectively of the dose and time used. A low daily dose of HgCl(2) (1.5-3 mg/L) caused a Th1-skewed AFA response, while a moderate dose (8 mg/L) after 2 weeks resulted in a balanced or even Th2-skewed response. Higher daily doses of HgCl(2) (25 mg/L) caused a balanced Th2-Th1 response already from onset. In conclusion, while metabolically formed Hg(2+) might be the main AFA-inducing factor also after treatment with EtHg, the quality of the Hg-induced AFA response is modified by the species of Hg as well as the dose.

Toxicological characteristics of endocrine-disrupting chemicals: developmental toxicity, carcinogenicity, and mutagenicity

It is generally accepted that endocrine-disrupting chemicals (EDCs) play a role in a variety of adverse health effects in an intact organism or its progeny as a consequence of changes in the endocrine system. Primary toxic effects of EDCs were reported to be related to infertility, reduction in sperm count, and teratogenicity, but other important toxic effects of EDCs such as carcinogenicity and mutagenicity have also been demonstrated. The aim of the present study was to systematically analyze the toxicological characteristics of EDCs in pesticides, industrial chemicals, and metals. A comprehensive literature survey on the 48 EDCs classified by the Centers for Disease Control and Prevention (CDC) was conducted using a number of databases which included Medline, Toxline, and Toxnet. The survey results revealed that toxicological characteristics of EDCs were shown to produce developmental toxicity (81%), carcinogenicity (79%, when positive in at least one animal species; 48%, when classified based on IARC evaluation), mutagenicity (79%), immunotoxicity (52%), and neurotoxicity (50%). Regarding the hormone-modulating effects of the 48 EDCs, estrogenic effects were the most predominant in pesticides, while effects on thyroid hormone were found for heavy metals. EDCs showing estrogen-modulating effects were closely related to carcinogenicity or mutagenicity with a high degree of sensitivity. Systematic information on the toxicological characteristics of the EDCs will be useful for future research directions on EDCs, the development of new screening methods, legal regulation, and for investigations of their mechanism of action.

Environmental exposure to mercury and its toxicopathologic implications for public health

Mercury is a toxic and hazardous metal that occurs naturally in the earth's crust. Natural phenomena such as erosion and volcanic eruptions, and anthropogenic activities like metal smelting and industrial production and use may lead to substantial contamination of the environment with mercury. Through consumption of mercury in food, the populations of many areas, particularly in the developing world, have been confronted with catastrophic outbreaks of mercury-induced diseases and mortality. Countries such as Japan, Iraq, Ghana, the Seychelles, and the Faroe Islands have faced such epidemics, which have unraveled the insidious and debilitating nature of mercury poisoning. Its creeping neurotoxicity is highly devastating, particularly in the central and peripheral nervous systems of children. Central nervous system defects and erethism as well as arrythmias, cardiomyopathies, and kidney damage have been associated with mercury exposure. Necrotizing bronchitis and pneumonitis arising from inhalation of mercury vapor can result in respiratory failure. Mercury is also considered a potent immunostimulant and -suppressant, depending on exposure dose and individual susceptibility, producing a number of pathologic sequelae including lymphoproliferation, hypergammaglobulinemia, and total systemic hyper- and hyporeactivities. In this review we discuss the sources of mercury and the potential for human exposure; its biogeochemical cycling in the environment; its systemic, immunotoxic, genotoxic/carcinogenic, and teratogenic health effects; and the dietary influences on its toxicity; as well as the important considerations in risk assessment and management of mercury poisoning.

Immunotoxicological investigation in rats dosed repeatedly with combinations of cypermethrin, As(III), and Hg(II)

The effects of the combined exposure of cypermethrin (CY), NaAsO2 (As), and HgCl2 (Hg) were investigated in male Wistar rats following 4 weeks of oral exposure. Standard toxicological (body weight gain, organ weights of brain, thymus, heart, lung, liver, kidneys, adrenals, testes, and popliteal lymph node), haematological (white blood cell, red blood cell, haematocrit, MCV-mean volume of red blood cells, and cell content of the femoral bone marrow), and immune function (IgM-PFC response, delayed type hypersensitivity (DTH) reaction) parameters were measured. The two doses selected for the combination were: a high (H) dose equal to lowest observed effect level determined in preliminary experiments (CY(H)=55.4 mg/kg, As(H)=13.3 mg/kg, Hg(H)=3.20 mg/kg), and a low (L) dose which was ineffective (non-observed effect level); CY(L)=11.1 mg/kg, As(L)=3.33 mg/kg, Hg(L)=0.40 mg/kg). CY(H) was combined with As(L) or Hg(L), and the H doses of the heavy metals were combined with CY(L). Beside vehicle control, the H dose components of the combinations were also used as internal controls. The main finding of this study was that certain combinations, when compared to H dose internal control, significantly altered the body weight gain (As(H)+CY(L)), the relative weight of adrenals and popliteal lymph node (CY(H)+As(L) and CY(H)+Hg(L)), the cell content of the femoral bone marrow (CY(H)+Hg(L)), and the time course of DTH reaction (CY(H)+As(L)). According to the present results, combined exposure with CY and the heavy metals investigated can modify the toxicity and/or the functional detection limit of the single substances.

Resistance to xenobiotic-induced autoimmunity maps to chromosome 1

Although evidence indicates that environmental factors play a major role in precipitating systemic autoimmunity in genetically susceptible individuals, little is known about the mechanisms involved. Certain heavy metals, such as mercury, are potent environmental immunostimulants that produce a number of immunopathologic sequelae, including lymphoproliferation, hypergammaglobulinemia, and overt systemic autoimmunity. Predisposition to such metal-induced immunopathology has been shown to be influenced by both MHC and non-MHC genes, as well as susceptibility to spontaneous lupus, in mice and other experimental animals. Among the various mouse strains examined to date, the DBA/2 appears to uniquely lack susceptibility to mercury-induced autoimmunity (HgIA), despite expressing a susceptible H-2 haplotype (H-2d). To define the genetic basis for this trait, two genome-wide scans were conducted using F2 intercrosses of the DBA/2 strain with either the SJL or NZB strains, both of which are highly susceptible to HgIA. A single major quantitative trait locus on chromosome 1, designated Hmr1, was shown to be common to both crosses and encompassed a region containing several lupus susceptibility loci. Hmr1 was linked to glomerular immune complex deposits and not autoantibody production, suggesting that DBA/2 resistance to HgIA may primarily involve the later stages of disease pathogenesis. Identification and characterization of susceptibility/resistance genes and mechanisms relevant to the immunopathogenesis of mercury-induced autoimmunity should provide important insights into the pathogenesis of autoimmunity and may reveal novel targets for intervention.

Understanding renal toxicity of heavy metals

The mechanisms by which metals induce renal injury are, in general, poorly understood. Characteristic features of metal nephrotoxicity are lesions that tend to predominate in specific regions of the nephron within specific cell types. This suggests that certain regions of the nephron are selectively sensitive to specific metals. Regional variability in sensitivity could result from the localization of molecular targets in certain cell populations and/or the localization of transport and binding ligands that deliver metals to targets within the nephron. Significant progress has been made in identifying various extracellular, membrane, and intracellular ligands that are important in the expression of the nephrotoxicity of metals. As an example, mercuric chloride induces a nephropathy that, at the lowest effective doses, is restricted primarily to the S3 segment of the proximal tubule, with involvement of the S2 and S1 segments at higher doses. This specificity appears to be derived, at least in part, from the distribution of enzymes and transport proteins important for the uptake of mercury into proximal tubule cells: apical gamma-glutamyltranspeptidase and the basolateral organic anion transport system. Regional distributions of transport mechanisms for binding proteins appear to be important in the expression of nephrotoxicity of metals. These and other new research developments are reviewed.

Mercury induces polyclonal B cell activation, autoantibody production and renal immune complex deposits in young (NZB x NZW)F1 hybrids

It is well established that in susceptible mouse strains, chronic treatment with subtoxic doses of mercuric chloride (HgCl2) induces a systemic autoimmune disease, which is characterized by increased serum levels of IgG1 and IgE antibodies, by the production of anti-nucleolar antibodies and by the development of immune complex-mediated glomerulonephritis. Susceptibility to mercury is partly under the control of major histocompatibility complex genes. To study the susceptibility to mercury further, we investigated the in vivo effects of mercury in young autoimmune disease prone (NZB x NZW)F1 (H-2d/z) mice prior to establishment of spontaneous autoimmune disease. Mercury-susceptible SJL (H-2s) mice and mercury low-responder BALB/c (H-2d) mice were used as positive and negative controls, respectively. In (NZB x NZW)F1 mice, treatment with mercury stimulated an intense antibody formation characterized by increased numbers of splenic IgG1 and IgG3 antibody-producing cells as well as by elevated serum IgE levels. Injection with mercury also induced an increased production of IgG1, IgG2b and IgE antibodies in SJL, but not in BALB/c mice. The mercury-induced IgG1 response in (NZB x NZW)F1 and SJL mice was found to be polyclonal and autoantibodies against double-stranded (ds)DNA, IgG, collagen, cardiolipin, phosphatidylethanolamine as well as antibodies against the hapten trinitrophenol were produced. In addition, SJL, but not (NZB x NZW)F1 or BALB/c mice, produced IgG1 anti-nucleolar antibodies after treatment with mercury. Further studies demonstrated that (NZB x NZW)F1 and SJL mice developed high titers of renal mesangial immune complex deposits containing IgG1 antibodies 3 weeks after injection with mercury. Thus, a mouse strain genetically prone to develop spontaneous autoimmune diseases is highly susceptible to mercury-induced immunopathological alterations.

Antigenic specificities of glomerular-bound autoantibodies in membranous glomerulopathy induced by mercuric chloride

The present study describes the development of membranous glomerulopathy (MGP) with high proteinuria in DZB rats exposed to mercuric chloride (HgCl2). IgG1 and IgG2a antibodies, eluted from glomeruli with subepithelial immune deposits, bind to the interface of the GBM and epithelial cells. High reactivity to GBM was demonstrated by ELISA and Western blotting, which could be absorbed for 30% by laminin or laminin-associated extracellular matrix components. No reactivity was found with type IV collagen, fibronectin, heparan sulfate proteoglycans, or tubular brush border antigens. Absorption to GBM removed the reactivity to renal antigens. Passively transferred eluted antibodies bind in a predominantly linear pattern along the GBM, causing focal ultrastructural transformations of the podocytes. These results suggest that this type of HgCl2-induced MGP, associated with epithelial cell injury and proteinuria, is caused by autoantibodies to basement membrane components which are located at the epithelial cell-basement membrane interface and may be involved in cell-matrix binding.

TH2 cells in systemic autoimmunity: insights from allogeneic diseases and chemically-induced autoimmunity

Systemic autoimmune diseases can be induced experimentally in rodents by graft-versus-host or host-versus-graft reactions and by chemicals such as HgCl2, gold salts and D-penicillamine. These models share several features, such as productions of anti-nuclear antibodies, immune glomerulonephritis, MHC class II hyperexpression on B cells, hyper-IgE, increased IL-4 activity and impairment of IL-2 production. This profile of cytokines suggests a central role for TH2-type cells in their pathogenesis. Here, Michel Goldman and colleagues review the data supporting this hypothesis and discuss the possible molecular bases for T-cell activation in chemically-induced systemic autoimmunity.

Reduction of the RT6.2+ subset of T lymphocytes in brown Norway rats with mercury-induced renal autoimmunity

Chemically induced autoimmunity is a recently recognized environmental hazard that may affect individuals genetically predisposed to autoimmune disease and chronically exposed to certain chemicals. For example, moderate concentrations of mercury may lead to renal autoimmune disease in a small but significant percentage of the exposed population. Mercury also induces autoimmune glomerulonephritis in susceptible Brown Norway (BN) and MAXX inbred strain rats. Autoimmune responses, directed to epitopes of the renal glomerular basement membrane (GBM), are rapid in onset and have a self-limiting course in mercury-treated rats. Both regulatory T cells and idiotype-anti-idiotype network have been implicated in the resolution of this autoimmune process. In our investigations of immune regulation of mercury-induced autoimmune glomerulonephritis, we have used flow cytometry to quantitate lymphocyte subpopulations in the spleen and lymph nodes of mercury-treated and control BN rats. Of particular interest was the RT6+ T cell subset, that appears to have important immunoregulatory properties in a rat model of autoimmune insulin-dependent diabetes mellitus. Spleen and lymph nodes from control BN rats contained 22 and 52%, respectively, RT6+ cells. Spleens from mercury-treated animals contained 21% RT6+ cells on Day 10 of treatment, 13% on Day 17, 16% on Day 24 and 20% on Day 30. Lymph nodes from the same rats had 36% RT6+ cells on Day 10, 23% on Day 17, 29% on Day 24, and 28% on Day 30. The decrease in RT6+ cells correlated inversely with autoimmune responses to GBM, which peaked on Days 17-24 and declined by Day 30. Moreover, autoimmune responses were also associated with elevated RT6-:RT6+ T cell ratios. Similar results were obtained in two additional groups of BN rats, comprising both younger and older animals, sacrificed at Day 18 of mercury treatment. Analysis of other lymphocyte subpopulations demonstrated a decrease of CD4+ and CD5+ cells, whereas B cells as well as CD8+, IL-2 receptor+, and MHC class II+ subsets showed no consistent correlation with the onset or resolution of the autoimmune process. These findings suggest that mercury-induced changes in RT6+ T lymphocytes may be related to the development of renal autoimmune disease in genetically predisposed BN rats.

Non-systemic glomerulonephritis: exposure to nephro- and immunotoxic chemicals predispose to immunologic harassment

Glomerulonephritis is thought to be caused by immune complexes trapped or formed in the glomeruli. But immune complexes are found in the glomeruli of many normal mammals and of patients with non-renal diseases, and immune complexes trapped or formed experimentally in the glomeruli induce mild proteinuria at most suggesting that additional factors must be responsible. An induction of serious renal damage in experimental glomerulonephritis demands a chronic supply of antigen, rarely seen in human glomerulonephritis; or the use of heterologous antibodies, a design with questionable clinical relevance; or immuno- and nephrotoxic chemicals; or Freund's adjuvant which is also nephrotoxic. It is therefore suggested that the pathogenesis of human non- systemic glomerulonephritis includes exposure to nephro- and immunotoxic chemicals, the deposition of glomerular immune complexes being secondary. The hypothesis has clinical support: a majority of patients have been exposed to such chemicals, mainly hydrocarbons; and the tubulointerstitial changes in glomerulonephritis are better correlated to renal function and clinical course than are the glomerular changes. The chemicals enhance or derange immunizations and sensitize the kidneys to immunological reactions.

Contribution of immunological reactions to nephrotoxicity

Several toxic agents, such as mercurials and agents with a sulphydryl group (e.g., gold salts, D-penicillamine and captopril), are associated with the occurrence of membranous glomerulopathy. DR3 antigen-positive subjects and poor sulphoxidators are at higher risk than other patients when treated with gold salts or D-penicillamine. Other drugs, mainly nonsteroidal anti-inflammatory agents and lithium salts, are responsible for the nephrotic syndrome with minimal glomerular changes, a T-cell-mediated disease. Several models of drug-induced membranous glomerulonephritis have been developed. These have been used to confirm the role of most of the above-mentioned agents and have made it possible to shed some light on the possible mechanisms involved. Mercurials induce a polyclonal activation of B cells in rats which is related to the appearance of autoreactive T cells. Finally, numerous agents may induce immunologically mediated acute interstitial nephritis. Although cell-mediated immunity appears to be involved in most cases, experimental models are lacking to substantiate this hypothesis.

Experimental immune complex disease of the intestine

The effect of immune complex deposition in intestine was studied in a mercuric chloride-induced experimental autoimmune disease model in the Brown Norway rat. Whereas deposition of autoantibodies in a linear pattern along the basement membrane did not lead to any functional changes, presence of immune complexes along the intestinal basement membrane, occurring after week 35 of the experiment, was associated with intestinal protein loss.

Mercury-induced renal autoimmunity in the MAXX rat

Inbred Brown Norway (BN) rats treated with mercuric chloride develop autoantibodies to renal basement membranes and an immunologically mediated membranous glomerulonephritis. To date, this experimental rat model of chemically induced autoimmunity has been obtained only in the BN strain, whereas rats from 17 other strains were found to be resistant. This is a disadvantage for mechanistic studies, especially since BN rats have poor fertility. In the present paper we report that the same model can be obtained in another inbred strain of rats, the MAXX, which after exposure to mercury develop a glomerulonephritis characterized by the production of autoantibodies to renal basement membranes. The kinetics of the autoimmune response observed in MAXX rats, as well as the immunohistopathology, histopathology, and proteinuria, are similar to those previously described in BN rats. In addition, the MAXX strain is endowed with excellent fertility. Therefore, both rat strains can be used for comparative studies of the mechanisms of mercury-induced autoimmunity.

Autoimmunity induced by chemicals

Immunotoxicologic studies have demonstrated that autoimmune responses and/or autoimmune diseases are induced in humans and experimental animals by chronic exposure to various chemicals. The present review is focused on seven groups of chemically induced human disorders, i.e. systemic lupus erythematosus, autoimmune hemolytic anemia, myasthenia gravis, pemphigus, glomerulonephritis, thyroiditis and hepatitis. Results obtained from studies of the available experimental counterparts of these diseases, i.e. those models obtained from the exposure of laboratory animals to various chemicals, are then analyzed. Finally, we present the lessons that can be derived from immunotoxicologic investigations regarding mechanisms of induction, heterogeneity of chemicals involved, humoral vs. cellular immune responses and genetic predisposition to chemically induced autoimmunity.

Studies on the formation of glomerular immune deposits in brown Norway rats injected with mercuric chloride

Brown Norway rats injected with mercuric chloride (HgCl2) develop autoantibodies which immunolocalize along the glomerular basement membrane at first in a linear pattern and then in a granular pattern. The aim of this study was to characterize the specificity of these antibodies and to investigate the mechanisms responsible for the formation of granular immune deposits in the subepithelial zone of the glomerular basement membrane. The rats were found to develop circulating anti-laminin, anti-type IV collagen, anti-heparan sulfate proteoglycan, and anti-entactin antibodies. Antibodies against laminin and type IV collagen were found in relatively high titers in the sera and were specifically concentrated in the nephritic kidneys. Antibodies eluted from the nephritic kidneys with either linear or granular deposits reacted with basement membrane antigens synthesized and secreted by cultured rat glomerular visceral epithelial cells. Thus, in this model, the interaction of anti-laminin and type IV collagen antibodies with antigens secreted by glomerular visceral epithelial cells might, together with other mechanisms, contribute to the formation of granular immune deposits in the subepithelial part of the glomerular basement membrane.

Alteration of humoral and cellular immunity in manganese chloride-treated mice

Immunological effects of manganese chloride (MnCl2) were determined in male CD-1 mice injected (ip) daily with MnCl2 (0, 1, 3, or 10 mg/kg) for 4 wk. Liver and spleen weights increased in the 10-mg/kg MnCl2 treatment group. The weights of thymus, kidney, and adrenal glands were not affected by MnCl2 treatment. No significant differences in peripheral erythrocyte or leukocyte counts were observed; however, packed cell volumes decreased in the medium- and high-dose groups. Manganese treatment significantly increased the uptake of [3H]thymidine (3H-TdR) by cultured splenic cells. The lymphoproliferative responses to phytohemagglutinin (PHA) and concanavalin A (Con A) increased at all levels of MnCl2 exposure. No differences in the responses to lipopolysaccharide (LPS) were observed. Mixed lymphocyte responses increased significantly with exposure to 10 mg MnCl2/kg. Another immunological alteration induced by MnCl2 was a dose-dependent immunosuppressive effect on the development of antibody-forming cells. The production of anti-sheep red blood cell antibody (alpha-SRBC) nearly ceased following exposure to 10 mg MnCl2/kg. This effect was apparently reversible, as the number of plaque-forming cells in the 10-mg/kg treatment group increased after MnCl2 treatment had been halted for 2 wk. The alpha-SRBC titer also decreased significantly in the 10-mg/kg treatment group, corresponding to the reduction of antibody producing cells. MnCl2 treatment was immunomodulatory to the reduction of antibody producing cells. MnCl2 treatment was immunomodulatory in male CD-1 mice, as indicated by the increase in mitogen and mixed lymphocyte responses and decrease in antibody production.

Prenatal and early postnatal intoxication by inorganic mercury resulting from the maternal use of mercury containing soap

A case of slight renal tubular dysfunction associated with cataract and anaemia was diagnosed in a 3-month-old black boy in whom high levels of mercury were found in blood and urine. Several arguments suggest that the renal, ocular and haematological defects may have resulted from exposure to mercury during foetal life and the 1-month lactation period due to the extensive use of inorganic mercury containing cosmetics by the mother.

Autoimmune disease induced by oral administration of mercuric chloride in Brown-Norway rats

Only few reports are available on the consequences of chronic oral administration of low doses of mercuric chloride (HgCl2). Forty Brown-Norway rats received 150 micrograms HgCl2/100 g body weight 3 times a week by gavage or by i.m. injection with 100 micrograms twice per week. After 2 weeks of oral HgCl2 administration, the rats lost weight and hair. Phases of proteinuria were observed in weeks 5-8 and then continuously from week 12 until the end of the experiment at week 39. Antibodies binding to renal, intestinal, and vascular basement membrane developed after 2 weeks; circulating immune complexes were detectable in increasing titers starting at week 3. There were linear deposits of IgG, IgM, and IgA in the glomerular basement membrane and tubular basement membrane, and along the intestinal basement membrane. After week 11, the first granular immune deposits were observed in renal and intestinal basement membranes. Light microscopy showed thickening of glomerular basement membrane, mesangial matrix, and tubular basement membrane. In addition, interstitial nephritis was observed in some animals. Interestingly, kidney involvement was as severe in the orally as the i.m.-treated animals.

Immune-mediated glomerulonephritis induced by mercuric chloride in mice

The BALB/c mouse developed mesangial deposits of immune constituents and light microscopical changes characteristic of immune complex glomerulonephritis after 8 weeks' treatment with mercuric chloride given by s.c. injection. There were no signs of linear of granular immune deposits along the glomerular capillary basement membrane after 2 or 8 weeks. The antigen could not be identified. No antibodies to nuclear or renal structures were found. Using a histochemical method (silver amplification) mercury was detected by light and electron microscopy in tubular and glomerular structures. Mercury was present in secondary lysosomes of the mesangial cells after eight weeks of mercury poisoning.

Simultaneous anti-glomerular basement membrane and membranous glomerulonephritis: case report and literature review

A 20-year-old male experienced a sore throat, fever, and lumbar pain. Examination revealed haematuria, proteinuria, and transiently impaired renal function. Renal biopsy revealed minor mesangial widening and small cellular crescents in 20% of the glomeruli under the light microscope, whereas immunofluorescence showed bright, linear staining of IgG along the glomerular basement membrane (GBM). Ultrastructural analysis showed minute subepithelial deposits analogous to early membranous glomerulonephritis (MGN). Anti-GBM antibodies were detected in the patient's serum. These findings were suggestive of simultaneous anti-GBM and immune complex glomerulonephritis in a patient with a mild, reversible renal illness.

IgA-IgG disease in the intestine of Brown-Norway rats ingesting mercuric chloride

In Brown-Norway (BN) rats, oral administration of mercuric chloride (HgCl2) induced morphological lesions of the ileum and, in lesser degree, of the colon, with abnormal deposits of IgA in the basement membranes of intestinal glands and of IgG in the basement membranes and in the lamina propria. IgG reactive with renal and intestinal basement membranes and in the lamina propria. IgG reactive with renal and intestinal basement membranes and with the lamina propria of a normal BN rat was found in the serum and IgG deposits were present in renal glomeruli of BN rats receiving HgCl2. Thus, it is conceivable that the deposits of IgG present in the intestine resulted from local fixation of circulating autoantibodies. In contrast, IgA with basement membrane reactivity was not detected in the sera nor in the renal glomeruli, suggesting that the intestinal deposits of IgA were formed in situ. This IgA-IgG intestinal disease inducible in BN rats may provide a model for the study of alterations of the secretory IgA system, as well as for testing the possibility that abnormal deposits IgA-IgG in the intestinal structures are associated with local functional changes.

Glomerular and vascular IgG deposits in HgCl2 nephritis: role of circulating antibodies and of immune complexes

The respective roles of circulating anti-glomerular basement membrane antibodies and of circulating immune complexes in the appearance of glomerular linear and granular IgG deposition during HgCl2-induced glomerulonephritis in the Brown-Norway rat has been studied. Syngeneic kidney transplantations have been performed at various phases of the disease. Results show that circulating antibodies are responsible for linear IgG deposition which did not change to granular deposits during the course of the disease. Electron-dense subepithelial deposits occurred only when circulating immune complexes were detected. These experiments strongly suggest that, in the mercury model, circulating immune complexes are responsible for granular IgG deposits observed in arteries and in the subepithelial space of glomeruli.

Glomerular antigens in glomerulonephritis

Ideas on the immunopathogenesis of glomerulonephritis are evolving to embrace a concept of a dynamic and constantly fluctuating involvement of immune reactants in the production of glomerular inflammation. The glomerulus should be regarded as a template around which the antibody-induced inflammatory events that constitute glomerulonephritis are initiated. Such lesions may be produced by direct antibody attack on glomerular antigens of either intrinsic structural or "planted" type, as discussed in this review, or by the deposition of circulating soluble immune complexes containing extraglomerular antigens. These mechanisms are not mutually exclusive and both may play a role in some situations. Intrinsic glomerular antigens are being increasingly better defined as to site, structure, function, and experimental animal models of spontaneous and induced glomerular injury resulting from direct antibody binding to nonclassic GBM capillary wall antigens are available for study. Similar nonclassic GBM antigens are likely to be found of importance in man. Anti-GBM antibody-induced glomerulonephritis continues to be the best understood example of direct attack on the glomerulus by antibody, and its nephritogenic noncollagenous GBM antigenic constituents are being characterized. The incorporation of extraneous substances as "planted" antigens within glomerular structures is now recognized in experimental animal models, and there is suggestive evidence to support the concept in man. Emphasis needs to be placed on the continuing interplay of free antibody and antigen with deposited reactants which, together with complement components, modulate the quality and quantity of the glomerular immune deposits.

Antibodies to collagen in scleroderma

Using the enzyme-linked immunosorbent assay (ELISA), we detected antibodies to interstitial (type I) and basement membrane (type IV) collagens in the sera of patients with scleroderma (systemic sclerosis). Antibodies against type IV collagen were found in significant levels in these patients and correlated with the presence of abnormal pulmonary diffusion capacity. Levels of antibodies to type I collagens also correlated significantly with pulmonary diffusion capacity. Absorption of sera with type I or type IV collagens before analysis in the ELISA eliminated reactivity in an antigen-specific pattern, indicating that these antibodies reacted with determinants specific for either type I or type IV collagens. The removal of immune complexes by ultracentrifugation had no effect on serum antibody levels. Autoantibodies to basement membrane and interstitial collagens may participate in the pathogenesis of scleroderma.

Mercuric chloride induced autoimmune disease in Brown-Norway rats: sequential search for anti-basement membrane antibodies and circulating immune complexes

Mercuric chloride induces in the Brown-Norway rat a biphasic autoimmune disease characterized initially by linear IgG deposits along the glomerular basement membrane followed later by granular IgG deposition. In the present study, anti-glomerular basement membrane antibodies and immune complex-like material were sequentially assessed in serial serum samples. Both were transiently found at the same period. Glomerular linear IgG deposits were present on day 11 but circulating anti-glomerular basement membrane antibodies were only found later on day 16. Circulating immune complexes were first detectable on day 8 before the earliest granular IgG deposits were first observed in the spleen vessels on day 16. The disappearance of circulating anti-glomerular basement membrane antibodies and of circulating immune complexes, although HgCl2 injections were pursued, is in agreement with the self-limited character of mercuric chloride induced autoimmune disease and suggests the induction of immunosuppressive mechanisms.

Experimental induction of glomerulonephritis mediated by anti-glomerular basement membrane and anti-brush border antibodies in a single rat

This report describes induction of nephritis, which was concurrently mediated by [anti-glomerular basement membrane antibody (anti-GBM) and anti-brush border antibody, in the Wistar rat immunized with a solubilized renal antigen (S-RA). The antigen was prepared by digestion of rat cortical tissue with trypsin and pronase. Ouchterlony test using antisera to the rat GBM and brush border showed that the S-RA contained both antigens. From the S-RA the brush border antigen was isolated by affinity chromatography. At the 8th week rats injected with the S-RA showed a linear or combined linear and granular distribution of rat IgG and C3 along the GBM in immunofluorescence. The capillary granular pattern was only observed at the 16th week. In contrast rats injected with the brush border antigen remained in a capillary granular pattern throughout the experimental course. It was suggested that the rat nephritis injected with the S-RA was mediated by the antibodies capable of reacting with at least two different antigens, namely the GBM and the brush border. The possibility was confirmed by demonstrating the coexistence of these two kinds of antibodies in the serum and kidney eluate from the nephritic rats.

Immune response to connective tissue components of the basement membrane

The immune response to connective tissue components of basement membrane (type IV collagen and laminin) and to interstitial collagen (type I) has been examined in human and murine systems. We also examined the role that immunologic sensitization to autologous connective tissue components might play in inducing an inflammatory response resulting in pathologic sequelae. Mice receiving a single subcutaneous injection of 5 micrograms type IV or type I murine collagens, or murine laminin in complete Freund's adjuvant mount a delayed-type hypersensitivity response characterized by a mononuclear cell infiltrate when challenged in the footpad with the sensitizing antigen. Cell-mediated immunity to these connective tissue antigens can be transferred to normal syngeneic mice with sensitized T-lymphocytes. In addition, repeated immunizations with these homologous connective tissue components elicit antibody responses in mice. Our data demonstrate the immunogenic nature of types IV and I collagen, and of laminin in a syngeneic murine model. We have demonstrated autoantibodies to the basement membrane and interstitial collagens in the sera of patients with scleroderma (systemic sclerosis); ELISA ratios correlate directly with the extent of pulmonary fibrosis in these patients. Anti-type IV collagen autoantibodies were found to be primarily IgM and anti-type I collagen antibodies, primarily IgG. An antibody response to autologous connective tissue antigens could lead to complement activation, immune complex formation, and deposition of the complexes along vascular endothelium with recruitment of blood monocytes in situ, mirroring the early scleroderma lesion (perivascular mononuclear cell filtrates). In vitro we examined the role of human peripheral blood mononuclear cells in the activation of fibroblasts. Adherent human blood monocytes release mediators which stimulate fibroblast proliferation and collagen deposition. A model is presented for the induction of immunity to autologous connective tissue components, leading to mononuclear cell inflammation, fibroblast activation and fibrosis. Selective immunity to basement membrane collagens may influence the clinical expression of diffuse connective tissue syndromes such as scleroderma (systemic sclerosis).