Experimental murine model for autoimmune myocarditis using Klebsiella pneumoniae O3 lipopolysaccharide as a potent immunological adjuvant

SARS-CoV-2 and Its Bacterial Co- or Super-Infections Synergize to Trigger COVID-19 Autoimmune Cardiopathies

Autoimmune cardiopathies (AC) following COVID-19 and vaccination against SARS-CoV-2 occur at significant rates but are of unknown etiology. This study investigated the possible roles of viral and bacterial mimicry, as well as viral-bacterial co-infections, as possible inducers of COVID-19 AC using proteomic methods and enzyme-linked immunoadsorption assays. BLAST and LALIGN results of this study demonstrate that SARS-CoV-2 shares a significantly greater number of high quality similarities to some cardiac protein compared with other viruses; that bacteria such as Streptococci, Staphylococci and Enterococci also display very significant similarities to cardiac proteins but to a different set than SARS-CoV-2; that the importance of these similarities is largely validated by ELISA experiments demonstrating that polyclonal antibodies against SARS-CoV-2 and COVID-19-associated bacteria recognize cardiac proteins with high affinity; that to account for the range of cardiac proteins targeted by autoantibodies in COVID-19-associated autoimmune myocarditis, both viral and bacterial triggers are probably required; that the targets of the viral and bacterial antibodies are often molecularly complementary antigens such as actin and myosin, laminin and collagen, or creatine kinase and pyruvate kinase, that are known to bind to each other; and that the corresponding viral and bacterial antibodies recognizing these complementary antigens also bind to each other with high affinity as if they have an idiotype-anti-idiotype relationship. These results suggest that AC results from SARS-CoV-2 infections or vaccination complicated by bacterial infections. Vaccination against some of these bacterial infections, such as Streptococci and Haemophilus, may therefore decrease AC risk, as may the appropriate and timely use of antibiotics among COVID-19 patients and careful screening of vaccinees for signs of infection such as fever, diarrhea, infected wounds, gum disease, etc.

The role of the gut microbiome in eye diseases

The gut microbiome is a complex ecosystem of microorganisms and their genetic entities colonizing the gastrointestinal tract. When in balanced composition, the gut microbiome is in symbiotic interaction with its host and maintains intestinal homeostasis. It is involved in essential functions such as nutrient metabolism, inhibition of pathogens and regulation of immune function. Through translocation of microbes and their metabolites along the epithelial barrier, microbial dysbiosis induces systemic inflammation that may lead to tissue destruction and promote the onset of various diseases. Using whole-metagenome shotgun sequencing, several studies have shown that the composition and associated functional capacities of the gut microbiome are associated with age-related macular degeneration, retinal artery occlusion, central serous chorioretinopathy and uveitis. In this review, we provide an overview of the current knowledge about the gut microbiome in eye diseases, with a focus on interactions between the microbiome, specific microbial-derived metabolites and the immune system. We explain how these interactions may be involved in the pathogenesis of age-related macular degeneration, retinal artery occlusion, central serous chorioretinopathy and uveitis and guide the development of new therapeutic approaches by microbiome-altering interventions for these diseases.

Unresolved issues in theories of autoimmune disease using myocarditis as a framework

Many theories of autoimmune disease have been proposed since the discovery that the immune system can attack the body. These theories include the hidden or cryptic antigen theory, modified antigen theory, T cell bypass, T cell-B cell mismatch, epitope spread or drift, the bystander effect, molecular mimicry, anti-idiotype theory, antigenic complementarity, and dual-affinity T cell receptors. We critically review these theories and relevant mathematical models as they apply to autoimmune myocarditis. All theories share the common assumption that autoimmune diseases are triggered by environmental factors such as infections or chemical exposure. Most, but not all, theories and mathematical models are unifactorial assuming single-agent causation of disease. Experimental and clinical evidence and mathematical models exist to support some aspects of most theories, but evidence/models that support one theory almost invariably supports other theories as well. More importantly, every theory (and every model) lacks the ability to account for some key autoimmune disease phenomena such as the fundamental roles of innate immunity, sex differences in disease susceptibility, the necessity for adjuvants in experimental animal models, and the often paradoxical effect of exposure timing and dose on disease induction. We argue that a more comprehensive and integrated theory of autoimmunity associated with new mathematical models is needed and suggest specific experimental and clinical tests for each major theory that might help to clarify how they relate to clinical disease and reveal how theories are related.

Rethinking Molecular Mimicry in Rheumatic Heart Disease and Autoimmune Myocarditis: Laminin, Collagen IV, CAR, and B1AR as Initial Targets of Disease

RATIONALE

Molecular mimicry theory (MMT) suggests that epitope mimicry between pathogens and human proteins can activate autoimmune disease. Group A streptococci (GAS) mimics human cardiac myosin in rheumatic heart disease (RHD) and coxsackie viruses (CX) mimic actin in autoimmune myocarditis (AM). But myosin and actin are immunologically inaccessible and unlikely initial targets. Extracellular cardiac proteins that mimic GAS and CX would be more likely.

OBJECTIVES

To determine whether extracellular cardiac proteins such as coxsackie and adenovirus receptor (CAR), beta 1 adrenergic receptor (B1AR), CD55/DAF, laminin, and collagen IV mimic GAS, CX, and/or cardiac myosin or actin.

METHODS

BLAST 2.0 and LALIGN searches of the UniProt protein database were employed to identify potential molecular mimics. Quantitative enzyme-linked immunosorbent assay was used to measure antibody cross-reactivity.

MEASUREMENTS

Similarities were considered to be significant if a sequence contained at least 5 identical amino acids in 10. Antibodies were considered to be cross-reactive if the binding constant had a K d less than 10(-9) M.

MAIN RESULTS

Group A streptococci mimics laminin, CAR, and myosin. CX mimics actin and collagen IV and B1AR. The similarity search results are mirrored by antibody cross-reactivities. Additionally, antibodies against laminin recognize antibodies against collagen IV; antibodies against actin recognize antibodies against myosin, and antibodies against GAS recognize antibodies against CX. Thus, there is both mimicry of extracellular proteins and antigenic complementarity between GAS-CX in RHD/AM.

CONCLUSION

Rheumatic heart disease/AM may be due to combined infections of GAS with CX localized at cardiomyocytes that may produce a synergistic, hyperinflammatory response that cross-reacts with laminin, collagen IV, CAR, and/or B1AR. Epitope drift shifts the immune response to myosin and actin after cardiomyocytes become damaged.

CNS immune responses following experimental stroke

BACKGROUND AND PURPOSE

Animals subjected to an inflammatory insult with lipopolysaccharide (LPS) at the time of stroke are predisposed to develop a detrimental autoimmune response to myelin basic protein (MBP). In this study, we sought to determine whether other inflammatory stimuli could similarly invoke central nervous system (CNS) autoimmunity and whether these detrimental autoimmune responses occurred to antigens other than MBP.

METHODS

Male Lewis rats underwent 3 h middle cerebral artery occlusion (MCAO) and received intraperitoneal injections of LPS, staphylococcal enterotoxin B (SEB), lipoteichoic acid (LTA) or saline at the time of reperfusion. Behavioral tests were performed at set time intervals after MCAO and animals were sacrificed at 1 month to analyze the immune response to MBP, neuron specific enolase (NSE) and proteolipid protein (PLP).

RESULTS

Lymphocytes from SEB treated animals were highly reactive to all tested CNS antigens, but treatment with LPS was most likely to lead to a TH: 1(+) response. A TH: 1(+) response to MBP, NSE or PLP in spleen was associated with worse outcome, although the response to NSE was most predictive of poor outcome. Animals with a cell mediated autoimmune response to either MBP or NSE in spleen had a concomitant humoral response to these antigens.

CONCLUSIONS

These data show that LPS, but not other inflammatory stimuli, increase the likelihood of developing a detrimental autoimmune response to an array of brain antigens.

Reactivation of antigen-induced arthritis in mice by oral administration of lipopolysaccharide

We examined whether oral administration of lipopolysaccharide (LPS) from Escherichia coli reactivated antigen-induced arthritis (AIA) in mice that is one of models of human rheumatoid arthritis. To induce AIA, mice were immunized by subcutaneous injection of ovalbumin (OVA) emulsified with complete Freund's adjuvant into the base of the tail (day 0) followed by intraarticular injection of OVA on day 21. To investigate the ability of LPS to reactivate AIA, varying doses of LPS were p.o. administered 48 h after the challenge injection. The results showed that administration of LPS was followed by reactivation of AIA in a dose-related fashion. The reactivation of AIA by LPS was associated with increases in interferon-gamma, interleukin-1beta and tumour necrosis factor-alpha. Polymyxin B sulfate given immediately before administration of LPS suppressed the reactivation of AIA. These findings suggest that LPS from intestinal bacteria may play a role in the reactivation of joint inflammation in which immune responses to pathogenic antigens are involved.

Hypothalamic pituitary adrenal axis and immune responses to endotoxin in rats with chronic adjuvant-induced arthritis

We investigated the effect of immune challenge with LPS in both control rats and rats with adjuvant-induced arthritis (AA). Fourteen day-AA rats showed the expected activation of the hypothalamic-pituitary adrenal axis associated with increases in vasopressin mRNA and paradoxical decreases in corticotropin-releasing hormone (CRH) mRNA in parvocellular neurons of the hypothalamic paraventricular nucleus (PVN). However, following LPS there was an increase in both CRH and vasopressin mRNA in the PVN. Neither control rats nor rats with AA had measurable plasma levels of IL-6, but plasma levels of IL-1beta were 2.7-fold higher in AA animals. Following LPS injection both IL-1beta and IL-6 increased more markedly in AA than in control rats. Neither controls nor AA rats expressed IL-1beta or IL-6 mRNA in the brain. However, following LPS these were induced in the subfornical organ, choroid plexus, and median eminence of both groups of animals. The areas expressing IL-1b mRNA were larger in the AA animals and exhibited a punctate pattern throughout the brain parenchyma and PVN. These data reveal an increased peripheral and central immunological response to LPS during the chronic inflammatory process of AA, providing a mechanism through which inflammatory disease can influence the response to a novel immunological challenge.

Production of experimental autoimmune sialadenitis in mice immunized with homologous salivary gland extract and Klebsiella O3 lipopolysaccharide

An experimental murine model for autoimmune sialadenitis was produced by repeated immunization of homologous salivary gland extract together with Klebsiella O3 lipopolysaccharides as an immunological adjuvant. The cell infiltration was observed in the salivary glands of mice immunized more than twice. Inflammatory cells consisting mainly of CD4+ T cells and CD8+ T cells accumulated at the perivascular regions. There was hyperplasia and enlargement of ductal epithelial cells in the secretory acinar units in salivary glands of repeatedly immunized mice. The repeated immunization developed delayed-type hypersensitivity and autoantibody production to the homologous salivary gland extract. The immunohistochemical analysis showed positive staining on the cuboidal cells in the intercalated ducts, and the columnar pseudostratified cells in the striated ducts. Organ-specific antigens with molecular weights ranging from 20 to 90 kDa were recognized by the sera from immunized mice. Therefore, it was suggested that the sialadenitis was produced by the autoimmune mechanism and might be a new experimental model for characterization of the pathogenesis of autoimmune sialadenitis.

Bacterial lipopolysaccharide acts as an adjuvant to induce autoimmune arthritis in mice

We investigated the ability of lipopolysaccharide (LPS) as an adjuvant to induce autoimmune arthritis. LPS from Escherichia coli was intraperitoneally injected into DBA/1J mice together with the joint cartilage component type II collagen (CII) on day 0. Thereafter, the injection of CII and LPS was continued every 2 weeks up to day 56. The results showed that mice injected with CII plus LPS had signs of arthritis on day 55 and the joint inflammation reached a peak on day 75. Injection of CII or LPS alone induced no arthritis. Histologically, marked oedema of synovium and intense infiltration of inflammatory cells, including neutrophils, were observed 3 days after the onset of joint inflammation. Twenty-one days later, there were marked proliferation of synovial tissues with many mononuclear cells and destruction of cartilage. Anti-CII immunoglobulin G (IgG) and IgG2a antibodies were markedly produced in mice injected with CII plus LPS. Pronounced secretion of cytokines, including interleukins-12 and -1beta, interferon-gamma and tumour necrosis factor-alpha, was also observed in these animals. Arthritis was passively transferred into naive syngeneic mice with sera but not with lymphoid cells from mice given CII with LPS. Other types of LPS from Salmonella enteritidis, Salmonella typhimurium and Klebsiella pneumoniae as well as lipid A from E. coli, induced inflammation in joints when administered with CII. Polymixin B sulphate mixed with LPS or lipid A blocked the induction of joint inflammation. These results indicate that LPS appears to play an important role as an adjuvant in the induction of arthritis in which autoimmunity to CII is involved.

The role of lipopolysaccharide injected systemically in the reactivation of collagen-induced arthritis in mice

1. We investigated the role of bacterial lipopolysaccharide (LPS) in the reactivation of autoimmune disease by using collagen-induced arthritis (CIA) in mice in which autoimmunity to the joint cartilage component type II collagen (CII) was involved. 2. CIA was induced by immunization with CII emulsified with complete Freund's adjuvant at the base of the tail (day 0) followed by a booster injection on day 21. Varying doses of LPS from E. coli were i.p. injected on day 50. 3. Arthritis began to develop on day 25 after immunization with CII and reached a peak on day 35. Thereafter, arthritis subsided gradually but moderate joint inflammation was still observed on day 50. An i.p. injection of LPS on day 50 markedly reactivated arthritis on a dose-related fashion. Histologically, on day 55, there were marked oedema of synovium which had proliferated by the day of LPS injection, new formation of fibrin, and intense infiltration of neutrophils accompanied with a large number of mononuclear cells. The reactivation of CIA by LPS was associated with increases in anti-CII IgG and IgG2a antibodies as well as various cytokines including IL-12, IFN-gamma, IL-1beta, and TNF-alpha. LPS from S. enteritidis, S. typhimurium, and K. neumoniae and its component, lipid A from E. coli also reactivated the disease. Polymyxin B sulphate suppressed LPS- or lipid A-induced reactivation of CIA. 4. These results suggest that LPS may play an important role in the reactivation of autoimmune joint inflammatory diseases such as rheumatoid arthritis in humans.

Production of murine collagen-induced arthritis using Klebsiella pneumoniae O3 lipopolysaccharide as a potent immunological adjuvant

Collagen-induced arthritis (CIA) was produced in mice with non H-2q and H-2r haplotypes by repeated immunization of porcine type-II collagen (CII) together with Klebsiella O3 lipopolysaccharide (KO3 LPS) as an immunological adjuvant. Histological changes that appeared in joints of repeatedly immunized mice were characterized by destruction of normal joint structure, synovial hyperplasia with proliferation of synovial cells, and infiltration of inflammatory cells. No such lesions were produced in mice receiving repeated injections of CII alone or KO3 LPS alone. Development of the humoral antibody and the delayed-type hypersensitivity to CII was exclusively found in mice immunized with the mixture of CII and KO3 LPS. It was therefore suggested that arthritis lesions induced by repeated immunization with the mixture of CII and KO3 LPS might be caused by an autoimmune mechanism, and that the experimental model might be useful for characterization of human rheumatoid arthritis (RA).

Oral Administration of Lipopolysaccharide Exacerbates Collagen-Induced Arthritis in Mice

We investigated whether oral administration of LPS exacerbated collagen-induced arthritis (CIA) in mice, which was an experimental model of autoimmune disease. CIA was induced by s.c. injection of type II collagen emulsified with CFA into the base of the tail (day 0) followed by a booster injection on day 21. To examine the ability of LPS to exacerbate CIA, varying doses of LPS were orally administered on day 50. The results showed that administration of LPS was followed by reactivation of CIA in a dose-related fashion. Histologically, on day 55 there were marked edema of synovium proliferated by day 50, new formation of fibrin, and intense infiltration of neutrophils accompanied with a large number of mononuclear cells. Severe destruction of cartilage and subchondral bone was also observed on day 70. The reactivation of CIA by oral administration of LPS was associated with increase in anti-type II collagen IgG and IgG2a Abs as well as varying kinds of cytokines including IL-12, IFN-γ, IL-1β, and TNF-α. Polymyxin B sulfate given either orally or i.v. suppressed the recurrence of CIA. Increased amounts of LPS were found in sera of mice given the endotoxin orally. LPS from Salmonella enteritidis, Salmonella typhimurium, and Klebsiella pneumoniae and its component, lipid A from Escherichia coli, also reactivated the disease. These findings suggest that LPS from intestinal bacteria may play a role in the exacerbation of autoimmune joint inflammation.

Experimental murine model for autoimmune enterocolitis using Klebsiella pneumoniae O3 lipopolysaccharide as a potent immunological adjuvant

An experimental model for autoimmune enterocolitis was produced in mice by repeated immunization of homologous colon extract together with Klebsiella 03 lipopolysaccharide (KO3 LPS) as an immunological adjuvant. Histological changes in the intestinal lesions were characterized by infiltration with polymorphonuclear leukocytes in the lamina propria, muscularis mucosae and submucosa of repeatedly immunized mice. No such intestinal lesions were produced in mice receiving injections of colon extract alone or KO3 LPS alone. Development of the autoantibody and delayed-type hypersensitivity against colon extract were found in mice immunized with the mixture of colon extract and KO3 LPS. Distinct positive staining was detected specifically on the columnar epithelium of villi. Sera from hyperimmunized mice defined organ-specific antigens present in the intestine. Therefore, it was suggested that the intestinal lesions might be caused by an autoimmune mechanism.

Silicone gel and octamethylcyclotetrasiloxane (D4) enhances antibody production to bovine serum albumin in mice

The purpose of the present study was to determine whether components of silicone breast implants [silicon (polydimethylsiloxane) oil, silicone gel, and octamethylcyclotetrasiloxane (D4)] potentiate the antibody response to bovine serum albumin (BSA) in mice. Seventy A/J mice were divided into seven groups which received the following: group I--phosphate buffer solution (PBS); group II--20 centistoke (cs) silicone oil; group III--50% silicone gel homogenized in silicone oil; group IV--incomplete Freunds' adjuvant (IFA); group V--IFA mixed with an equal volume of silicone oil; group VI--D4; and group VII--IFA mixed with an equal volume of DA. Each 0.1 mL of treatment material(s) was mixed or emulsified with an equal 0.1-mL volume of 250 micrograms/mL BSA in PBS solution. Antibodies to BSA were measured using an enzyme-linked immunosorbent assay. Our study demonstrates for the first time that both D4 and the silicone gel potentiate antibody production to BSA in mice. Histopathologic evaluation of the injection sites reveals granulomas for mice injected with IFA and D4 preparations. Whether D4 or silicone gel acts as an adjuvant against self-antigens has yet to be determined.

Autoimmune myocarditis induced in mice by cardiac C-protein. Cloning of complementary DNA encoding murine cardiac C-protein and partial characterization of the antigenic peptides

Autoimmune myocarditis is considered to play a major role in the pathogenesis of dilated cardiomyopathy. A new autoimmune myocarditis model was attained by repeated immunization using murine cardiac C-protein with the immunological adjuvant, Klebsiella pneumoniae O3 lipopolysaccharide. For further analysis of a pathological epitope, the cDNA encoding C-protein was isolated; a fusion protein encoded by part of this cDNA induced myocarditis in SMA mice as well as in three other strains: DBA/1J (H-2q), O20/A (H-2pz1), and SJL (H-2s). The nucleotide sequence and its deduced amino acid analysis revealed that this protein had immunoglobulin-like and fibronectin-like repeats. This study provides a new animal model of autoimmune myocarditis which may shed light on the pathogenesis of dilated cardiomyopathy.

Murine experimental autoimmune uveoretinitis induced by interphotoreceptor retinoid-binding protein and Klebsiella pneumoniae 03 lipopolysaccharide (K03-LPS): a relation between H-2 haplotype and EAU induction

The pathogenicity of interphotoreceptor retinoid-binding protein (IRBP) in the mouse and H-2 restriction of IRBP-induced experimental autoimmune uveoretinitis (EAU) was tested by repeated immunization using Klebsiella pneumoniae 03 lipopolysaccharide (K03-LPS) as an adjuvant. It was shown that IRBP had a greater capacity to induce EAU than S-antigen. Based on the incidence of EAU induction using B10 congenic mice and other strains, the susceptibility to EAU was, at least in part, controlled by the I-Ak haplotype of the H-2 subregion. The results also indicated that non-major histocompatibility complex (MHC) genes play some role in disease susceptibility.