Immunological Homunculus Research Articles

Molecular and Functional Neuroscience in Immunity.

The nervous system regulates immunity and inflammation. The molecular detection of pathogen fragments, cytokines, and other immune molecules by sensory neurons generates immunoregulatory responses through efferent autonomic neuron signaling. The functional organization of this neural control is based on principles of reflex regulation. Reflexes involving the vagus nerve and other nerves have been therapeutically explored in models of inflammatory and autoimmune conditions, and recently in clinical settings. The brain integrates neuro-immune communication, and brain function is altered in diseases characterized by peripheral immune dysregulation and inflammation. Here we review the anatomical and molecular basis of the neural interface with immunity, focusing on peripheral neural control of immune functions and the role of the brain in the model of the immunological homunculus. Clinical advances stemming from this knowledge within the framework of bioelectronic medicine are also briefly outlined.

Cortical stimulation in conscious rats controls joint inflammation

The neuronal control of the immune system is fundamental to the development of new therapeutic strategies for inflammatory disorders. Recent studies reported that afferent vagal stimulation attenuates peripheral inflammation by activating specific sympathetic central and peripheral networks, but only few subcortical brain areas were investigated. In the present study, we report that afferent vagal stimulation also activates specific cortical areas, as the parietal and cingulate cortex. Since these cortical structures innervate sympathetic-related areas, we investigate whether electrical stimulation of parietal cortex can attenuate knee joint inflammation in non-anesthetized rats. Our results show that cortical stimulation in rats increased sympathetic activity and improved joint inflammatory parameters, such as local neutrophil infiltration and pro-inflammatory cytokine levels, without causing behavioral disturbance, brain epileptiform activity or neural damage. In addition, we superposed the areas activated by afferent vagal or cortical stimulation to map common central structures to depict a brain immunological homunculus that can allow novel therapeutic approaches against inflammatory joint diseases, such as rheumatoid arthritis.

Causal Neuro-immune Relationships at Patients with Chronic Pyelonephritis and Cholecystitis. Correlations between Parameters EEG, HRV and White Blood Cell Count.

We aim to analyze in bounds KJ Tracey’s immunological homunculus conception the relationships between parameters of electroencephalogram (EEG) and heart rate variability (HRV), on the one hand, and the parameters of bhite blood cell count, on the other hand.MethodsIn basal conditions in 23 men, patients with chronic pyelonephritis and cholecystitis in remission, recorded EEG (“NeuroCom Standard”, KhAI Medica, Ukraine) and HRV (“Cardiolab+VSR”, KhAI Medica, Ukraine). In portion of blood counted up white blood cell count.ResultsRevealed that canonical correlation between constellation EEG and HRV parameters form with blood level of leukocytes 0.92 (p<10-5), with relative content in white blood cell count stubnuclear neutrophiles 0.93 (p<10-5), segmentonucleary neutrophiles 0.89 (p<10-3), eosinophiles 0.87 (p=0.003), lymphocytes 0.77 (p<10-3) and with monocytes 0.75 (p=0.003).ConclusionParameters of white blood cell count significantly modulated by electrical activity some structures of central and autonomic nervous systems.

Evolution, immunity and the emergence of brain superautoantigens

While some autoimmune disorders remain extremely rare, others largely predominate the epidemiology of human autoimmunity. Notably, these include psoriasis, diabetes, vitiligo, thyroiditis, rheumatoid arthritis and multiple sclerosis. Thus, despite the quasi-infinite number of "self" antigens that could theoretically trigger autoimmune responses, only a limited set of antigens, referred here as superautoantigens, induce pathogenic adaptive responses. Several lines of evidence reviewed in this paper indicate that, irrespective of the targeted organ (e.g. thyroid, pancreas, joints, brain or skin), a significant proportion of superautoantigens are highly expressed in the synaptic compartment of the central nervous system (CNS). Such an observation applies notably for GAD65, AchR, ribonucleoproteins, heat shock proteins, collagen IV, laminin, tyrosine hydroxylase and the acetylcholinesterase domain of thyroglobulin. It is also argued that cognitive alterations have been described in a number of autoimmune disorders, including psoriasis, rheumatoid arthritis, lupus, Crohn's disease and autoimmune thyroiditis. Finally, the present paper points out that a great majority of the "incidental" autoimmune conditions notably triggered by neoplasms, vaccinations or microbial infections are targeting the synaptic or myelin compartments. On this basis, the concept of an immunological homunculus, proposed by Irun Cohen more than 25 years ago, is extended here in a model where physiological autoimmunity against brain superautoantigens confers both: i) a crucial evolutionary-determined advantage via cognition-promoting autoimmunity; and ii) a major evolutionary-determined vulnerability, leading to the emergence of autoimmune disorders in Homo sapiens. Moreover, in this theoretical framework, the so called co-development/co-evolution model, both the development (at the scale of an individual) and evolution (at the scale of species) of the antibody and T-cell repertoires are coupled to those of the neural repertoires (i.e. the distinct neuronal populations and synaptic circuits supporting cognitive and sensorimotor functions). Clinical implications and future experimental insights are also presented and discussed.

Evolution, immunity and the emergence of brain superautoantigens.

While some autoimmune disorders remain extremely rare, others largely predominate the epidemiology of human autoimmunity. Notably, these include psoriasis, diabetes, vitiligo, thyroiditis, rheumatoid arthritis and multiple sclerosis. Thus, despite the quasi-infinite number of "self" antigens that could theoretically trigger autoimmune responses, only a limited set of antigens, referred here as superautoantigens, induce pathogenic adaptive responses. Several lines of evidence reviewed in this paper indicate that, irrespective of the targeted organ (e.g. thyroid, pancreas, joints, brain or skin), a significant proportion of superautoantigens are highly expressed in the synaptic compartment of the central nervous system (CNS). Such an observation applies notably for GAD65, AchR, ribonucleoproteins, heat shock proteins, collagen IV, laminin, tyrosine hydroxylase and the acetylcholinesterase domain of thyroglobulin. It is also argued that cognitive alterations have been described in a number of autoimmune disorders, including psoriasis, rheumatoid arthritis, lupus, Crohn's disease and autoimmune thyroiditis. Finally, the present paper points out that a great majority of the "incidental" autoimmune conditions notably triggered by neoplasms, vaccinations or microbial infections are targeting the synaptic or myelin compartments. On this basis, the concept of an immunological homunculus, proposed by Irun Cohen more than 25 years ago, is extended here in a model where physiological autoimmunity against brain superautoantigens confers both: i) a crucial evolutionary-determined advantage via cognition-promoting autoimmunity; and ii) a major evolutionary-determined vulnerability, leading to the emergence of autoimmune disorders in Homo sapiens. Moreover, in this theoretical framework, the so called co-development/co-evolution model, both the development (at the scale of an individual) and evolution (at the scale of species) of the antibody and T-cell repertoires are coupled to those of the neural repertoires (i.e. the distinct neuronal populations and synaptic circuits supporting cognitive and sensorimotor functions). Clinical implications and future experimental insights are also presented and discussed.

Tumor-associated and disease-associated autoantibody repertoires in healthy colostrum and maternal and newborn cord sera.

In this work, we studied autoantibody repertoires and Ig isotypes in 71 mothers and their 104 healthy newborns (including twins and triplets delivered term or premature). Newborns receive maternal IgG Abs via the placenta before birth, but developing infants must produce their own IgM and IgA Abs. We used an Ag microarray analysis to detect binding to a selection of 295 self-Ags, compared with 27 standard foreign Ags. The magnitude of binding to specific self-Ags was found to be not less than that to the foreign Ags. As expected, each newborn shared with its mother a similar IgG repertoire-manifest as early as the 24th week of gestation. IgM and IgA autoantibody repertoires in cord sera were highly correlated among the newborns and differed from their mothers' repertoires; the latter differed in sera and milk. The autoantibodies bound to self-Ags known to be associated with tumors and to autoimmune diseases. Thus, autoantibody repertoires in healthy humans--the immunological homunculus--arise congenitally, differ in maternal milk and sera, and mark the potential of the immune system to attack tumors, beneficially, or healthy tissues, harmfully; regulation of the tissue site, the dynamics, and the response phenotype of homuncular autoimmunity very likely affects health.

DC specific Smad7 deficiency promotes differentiation of tolerogenic DCs able to attenuate EAE

The immune network is a complex system for host defenses comprising various types of inflammatory and regulatory cells. Autoimmune diseases occur because of dysregulation in homeostasis caused by imbalance of these cells. The pattern of imbalance depends on the disease. Most autoimmune diseases are chronic, and the mechanism underlying this chronic nature is yet to be determined. Monoclonal antibody therapy is highly specific to the molecules targeted and is therefore highly effective. However, this therapy cannot be applied to all autoimmune diseases, and even the most effective therapy is incapable of completely inhibiting disease activity. Antigen-specific therapies have the ability to inhibit disease activity; however, their application is limited because of the presence of various disease-specific antigens. Regulatory cell therapies also have potential, but pose a plasticity problem. By focusing our research on experimental autoimmune encephalomyelitis (EAE), which is a multiple sclerosis (MS) model and normally initially has a relapse or remission course, followed by a progressive course, we can develop alternative therapies for the treatment of autoimmune diseases by exploring the mechanism of relapse and remission. From the phenomena that immunizing peptide itself determines the difference between monophasic-EAE and relapsingEAE, we found out that two-correlated non-genetic factors can shut down the reactivation in the EAE. One is kinetics and the component of CD4CD25 regulatory T cells (Treg), which are characterized by their later expansion after emerging of encephalitogenic T cells and by their subset expressing both CD69 and CD103 (=DP-Treg). DP-Treg is the most efficacious subset showing the highest Treg-compatible signatures with high antigen-specificity exerting stability due to downregulation of IL-6R expression, nevertheless with activated effector phenotype. The other is a hierarchy of encephalitogenic peptide itself to be immunized, which means that the more dominant peptide can develop acute EAE, the less relapse and re-induction of EAE occurs. This superiority of dominant peptide is characterized by specificity to itself, that is, it can suppress response to other peptides broadly and establish permanent remission. Peptide tolerance induced orally or intravenously could not get such wide suppression. Taken together, efficient induction of DP-Treg is correlated with superiority of self-peptide itself, suggesting ‘immunological homunculus’. This can be applied for treatment such as tissue-specific inverse vaccination for autoimmune diseases.

Heat-Shock Proteins in Autoimmunity

Heat-Shock Proteins in Autoimmunity

HLA-DRBeta1, circulating Th1/Th2 cytokines and immunological homunculus in coronary atherosclerosis.

Coronary atherosclerotic disease is one of the most endangering health disorder worldwide. This study was designed to investigate the correlation between HLA-DR1 alleles and circulating Th1/Th2 type cytokines in coronary atherosclerosis. By Elisa, Th1/Th2 type cytokines were determined in serum samples of 31 subjects with unstable angina, 27 subjects with chronic stable angina and 24 individuals as normal control. By SSP-PCR, more than 100 alleles of HLA-DRBeta1 were typed in 24 subjects who had skewed serum levels of Th1/Th2 type cytokines. Lipid profiles were determined by the routine methods of clinical laboratory in all subjects. The mean serum concentration of IL-10 in normal control subjects was higher in comparison to the patient groups.0.33±0.59 pg/ml versus 0.064±0.3 pg/ml in unstable angina pectoris group (p<0.028) and 0.22±0.6 pg/ml in chronic stable subjects. There was no statistically significant difference among the groups in serum levels of other desired cytokines (IFN-Gamma, IL-4). 33.33% of normal control subjects were HLA-DR16 positive whereas none of the subjects with chronic stable angina or individuals with unstable angina pectoris was positive for this antigen. The mean concentration of serum LDL-cholesterol in normal control group was high 142.046±35.40 (pg/ml).This preliminary study shows that the atherogenic effect of the LDL- cholesterol may be dampened by HDL-cholesterol through anti inflammatory cytokine IL-10 and HLA-DR16, a phenomenon interpretable via immunological homunculus theory.

Location-specific activation of the paraventricular nucleus of the hypothalamus by localized inflammation

The existence of an immunological homunculus has been proposed, but evidence for location-specific response of the central nervous system to immunological stimulation is lacking. In this study, we show that inflammation induced by injection of casein into one of the causes c-fos expression in the paraventricular nucleus of the hypothalamus (PVN) in an asymmetrical manner: much stronger activation is always induced in the contralateral PVN. Unilateral sciatic nerve transection abolished the casein-induced PVN activation if casein was injected into the hindlimb with the nerve transection, but had no effect if casein was injected into the hindlimb with intact nerve innervation. Injection of casein into one the forelimbs also caused contralateral PNV activation. Further, stronger PVN activation was found in the anterior PVN after the forelimb injection, but in the posterior PVN after the hindlimb injection. Casein-induced PVN activation is absent in IL-1R1 KO, IL-6 KO, TNFα KO, and in C3H/HeJ (TLR4 mutant) animals. In comparison, injection of LPS, a systemic inflammagen, into one hindlimb induced bilateral PVN activation but injection of live Escherichia coli into one hindlimb induced contralateral PVN activation. These results support the notion that local inflammation may activate the PVN by neural routes in a location-specific manner.

From CNI-1493 to the immunological homunculus: physiology of the inflammatory reflex

The inflammatory reflex is a neurophysiological mechanism that regulates the immune system. The efferent branch of the reflex the cholinergic anti-inflammatory pathway, which inhibits inflammation by suppressing cytokine synthesis via release of acetylcholine in organs of the reticuloendothelial system, including the spleen, liver, and gastrointestinal tract. Acetylcholine binds to alpha7 nicotinic acetylcholine receptors expressed by macrophages and other cytokine-producing cells. Receptor-ligand engagement suppresses proinflammatory cytokines and prevents tissue damage. Herein is a review of some of the experimental studies that define the inflammatory reflex and its anatomic and physiologic components.

Physiology and immunology of the cholinergic antiinflammatory pathway

Cytokine production by the immune system contributes importantly to both health and disease. The nervous system, via an inflammatory reflex of the vagus nerve, can inhibit cytokine release and thereby prevent tissue injury and death. The efferent neural signaling pathway is termed the cholinergic antiinflammatory pathway. Cholinergic agonists inhibit cytokine synthesis and protect against cytokine-mediated diseases. Stimulation of the vagus nerve prevents the damaging effects of cytokine release in experimental sepsis, endotoxemia, ischemia/reperfusion injury, hemorrhagic shock, arthritis, and other inflammatory syndromes. Herein is a review of this physiological, functional anatomical mechanism for neurological regulation of cytokine-dependent disease that begins to define an immunological homunculus.

Detection of citrate synthase-reacting autoantibodies after heart transplantation: an epitope mapping study

Autoimmune mechanisms play an important role in the pathogenesis of allograft vasculopathy following heart transplantation, but the autoantigens involved have been only sparsely studied. Citrate synthase (CS) enzyme is a conserved molecule, and, as an important mitochondrial autoantigen, it is protected by the "immunological homunculus". Tissue destruction and alteration of the immune regulatory mechanisms can induce pathological immune response against CS in other autoimmune diseases. In our present study we aimed to detect CS-specific autoantibodies in heart transplant patients, therefore, prospective, randomised clinical tests were conducted on 33 heart transplant patients and compared with 130 healthy blood donors. The level and isotype of CS antibodies were detected by simple binding indirect enzyme-linked immunosorbent assay (ELISA). The epitope specificities of the autoantibodies were measured on synthetic overlapping peptide sequences of CS enzyme by an indirect multi-pin ELISA method. Mainly IgM isotype CS autoantibodies were found in healthy controls, while IgG was found at higher levels and frequency (four-times higher) in heart transplant patients. Autoantibodies of IgG isotype recognise different epitopes than do autoantibodies of IgM isotype, even within the same group and individual. New epitope-specific IgG and IgM isotype autoantibodies appeared in heart transplant patients when compared with the controls. Our findings suggest a possible role of CS-specific autoantibodies in the pathomechanism of allograft vasculopathy.

Detection of citrate synthase-reacting autoantibodies after heart transplantation: an epitope mapping study

Abstract Autoimmune mechanisms play an important role in the pathogenesis of allograft vasculopathy following heart transplantation, but the autoantigens involved have been only sparsely studied. Citrate synthase (CS) enzyme is a conserved molecule, and, as an important mitochondrial autoantigen, it is protected by the “immunological homunculus”. Tissue destruction and alteration of the immune regulatory mechanisms can induce pathological immune response against CS in other autoimmune diseases. In our present study we aimed to detect CS-specific autoantibodies in heart transplant patients, therefore, prospective, randomised clinical tests were conducted on 33 heart transplant patients and compared with 130 healthy blood donors. The level and isotype of CS antibodies were detected by simple binding indirect enzyme-linked immunosorbent assay (ELISA). The epitope specificities of the autoantibodies were measured on synthetic overlapping peptide sequences of CS enzyme by an indirect multi-pin ELISA method. Mainly IgM isotype CS autoantibodies were found in healthy controls, while IgG was found at higher levels and frequency (four-times higher) in heart transplant patients. Autoantibodies of IgG isotype recognise different epitopes than do autoantibodies of IgM isotype, even within the same group and individual. New epitope-specific IgG and IgM isotype autoantibodies appeared in heart transplant patients when compared with the controls. Our findings suggest a possible role of CS-specific autoantibodies in the pathomechanism of allograft vasculopathy.

Peptide therapy for Type I diabetes: the immunological homunculus and the rationale for vaccination.

The autoimmune process that produces Type I (insulin-dependent) diabetes mellitus seems to respond favourably to therapeutic vaccination with a peptide of the 60 kDa heat shock protein. This article is a personal review of the observations and the thinking that gave rise to the idea of therapeutic peptide vaccination. The rationale for vaccination therapy is compared to other approaches aimed at specific immunological treatment for autoimmune disease.

The immunological homunculus (immunculus) in normal state and pathology.

The immunculus is considered as the system (general network) of constitutively expressed natural autoantibodies against different extracellular, membrane, cytoplasmic, and nuclear self-antigens (ubiquitous and organ-specific). It is specially noted that the repertoires of natural autoantibodies are surprisingly constant in healthy persons, independent of gender and age, and characterized by only minimal individual peculiarities (individual immune fingerprints). On the other hand, abnormal metabolic changes which precede the clinical manifestation of different diseases showed easily detected changes, rather quantitative than qualitative, in the systems of natural autoantibodies in patients' sera (immunculus distortions). This phenomena could supposedly be used for "mapping" the state of physiological norm in terms of the millions of natural autoantibody repertoires, and for elaboration of the methods for early (preclinical) detection of potentially pathogenic metabolic changes. Could the individual features of the general network of constitutively expressed natural autoantibodies reflect the functional state of the body and be used for "mapping" of normal and pathological functional state? Could the changes in production of some biologically active natural autoantibodies not only reflect the state of the body, but be used for partial compensation of functional deficiency of certain molecular systems? These and related questions are discussed in this article. The research project "immunculus" is proposed for international cooperative investigations.

The shaping of the brain-specific T lymphocyte repertoire in the thymus.

We have shown in several distinct experimental systems that the immune system of intact Lewis rats contains T cells which, upon activation, are able to mediate autoimmune brain inflammation. These T cells seem to differentiate within the thymus although the autoantigens are produced (and presumably expressed in a recognizable fashion) within the thymic medulla. Furthermore, an intact fully MHC compatible thymic microenvironment seems to be required for the development of all features of the autoimmune TCR repertoire. Biased utilization of V beta 8.2 gene for the TCR, a hallmark of the Lewis rat T cell response to MBP, is only seen in T cells having matured in thymuses entirely composed of stroma elements of rat origin. It seems that the thymus contains a large spectrum of protein structures, which hitherto had been considered autoantigens specific for "peripheral" tissues, and, most surprisingly, components of the CNS, the classical "sequestered" organ. Deletion of autoreactive T cell clones by many local intrathymic autoantigens is leaky, at best. The reduced expression of CD4 on thymus-derived autoreactive T cells may be construed to reflect abortive efforts of negative selection. Alternatively, however, it may be worthwhile to consider a positive role for intrathymic autoantigens and their complementary T cells clones. It is possible that the requirement of an intact thymus milieu for the typical, V beta 8.2 dominated MBP specific T cell repertoire in the Lewis rat could reflect self peptide presentation by thymus epithelium cells in positive selection stages. In that case, the unusual diversity of thymic autoantigens could indeed have a role in shaping the immune system's TCR diversity, possible in the sense of an "immunological homunculus" as postulated by Cohen (Cohen 1992). Finally, there is a need to explain the mechanisms that in the healthy organism prevent the numerous, potentially autoaggressive T cell clones from attacking the body's own tissues. This is especially important, as T cells reactive against potentially pathogenic autoantigens, e.g. MBP (Ota et al. 1990, Pette et al. 1990b) and acetylcholine receptor (Salvetti et al. 1991, Sommer et al. 1991), are seen at especially high frequency in the human immune repertoire. Clearly, in all experimental paradigms investigated, activation of self-reactive T cells was the critical prerequisite for induction of autoimmune disease. Thus, in principle, prevention of such activation would be one way to maintain self tolerance. The mechanisms that achieve this goal in most individuals remain to be elucidated.

Global analysis of antibody repertoires. II. Evidence for specificity, self‐selection and the immunological “homunculus” of antibodies in normal serum

The serum IgM repertoires of C57BL/6, DBA/2 and BALB/c mouse strains were analyzed using a recently developed global and quantitative assay that measures antibody reactivities to a very large number of antigens. A characteristic repertoire could be assigned to each strain. The different repertoires could be successfully classified with multivariate statistics. Many common reactivities were also observed among the different strains, which allows the definition of a mouse-specific repertoire. Analysis of human sera support this notion. To investigate the impact of minor genetic differences on the serum IgM repertoire, the congenic strains B10.D2/oSn and B10.D2/nSn, which differ in the expression of the C5 component of complement, were analyzed. The two strains could be separated based on the reactivity profiles obtained. The analysis of the results reveals that many antigenic proteins are not recognized at all by natural antibodies, while others are disproportionately reactive, the resulting patterns giving rise to what could be the definition of an "immunological homunculus". The relevance of this type of analysis for clinical applications is discussed.

On the Regulation of EAE

This paper describes some of the factors involved in the regulation of EAE and of autoimmunity in general. The immunological homunculus is discussed.

The cognitive paradigm and the immunological homunculus

In last month's issue of Immunology Today, Irun Cohen discussed the inadequacies of the clonal selection paradigm and proposed a cognitive paradigm in which preformed internal images guide and restrict the process of clonal activation. Here he clarifies the nature of these internal images, drawing on concrete examples from the image of infection and the image of self, the immunological homunculus.