Modeling the influence of TH1- and TH2-type cells in autoimmune diseases

Mathematical modeling in autoimmune diseases: from theory to clinical application

The research & development (R&D) of novel therapeutic agents for the treatment of autoimmune diseases is challenged by highly complex pathogenesis and multiple etiologies of these conditions. The number of targeted therapies available on the market is limited, whereas the prevalence of autoimmune conditions in the global population continues to rise. Mathematical modeling of biological systems is an essential tool which may be applied in support of decision-making across R&D drug programs to improve the probability of success in the development of novel medicines. Over the past decades, multiple models of autoimmune diseases have been developed. Models differ in the spectra of quantitative data used in their development and mathematical methods, as well as in the level of "mechanistic granularity" chosen to describe the underlying biology. Yet, all models strive towards the same goal: to quantitatively describe various aspects of the immune response. The aim of this review was to conduct a systematic review and analysis of mathematical models of autoimmune diseases focused on the mechanistic description of the immune system, to consolidate existing quantitative knowledge on autoimmune processes, and to outline potential directions of interest for future model-based analyses. Following a systematic literature review, 38 models describing the onset, progression, and/or the effect of treatment in 13 systemic and organ-specific autoimmune conditions were identified, most models developed for inflammatory bowel disease, multiple sclerosis, and lupus (5 models each). ≥70% of the models were developed as nonlinear systems of ordinary differential equations, others - as partial differential equations, integro-differential equations, Boolean networks, or probabilistic models. Despite covering a relatively wide range of diseases, most models described the same components of the immune system, such as T-cell response, cytokine influence, or the involvement of macrophages in autoimmune processes. All models were thoroughly analyzed with an emphasis on assumptions, limitations, and their potential applications in the development of novel medicines.

A structural methodology for modeling immune-tumor interactions including pro- and anti-tumor factors for clinical applications

The immune system turns out to have both stimulatory and inhibitory factors influencing on tumor growth. In recent years, the pro-tumor role of immunity factors such as regulatory T cells and TGF-β cytokines has specially been considered in mathematical modeling of tumor-immune interactions. This paper presents a novel structural methodology for reviewing these models and classifies them into five subgroups on the basis of immune factors included. By using our experimental data due to immunotherapy experimentation in mice, these five modeling groups are evaluated and scored. The results show that a model with a small number of variables and coefficients performs efficiently in predicting the tumor-immune system interactions. Though immunology theorems suggest to employ a larger number of variables and coefficients, more complicated models are here shown to be inefficient due to redundant parallel pathways. So, these models are trapped in local minima and restricted in prediction capability. This paper investigates the mathematical models that were previously developed and proposes variables and pathways that are essential for modeling tumor-immune. Using these variables and pathways, a minimal structure for modeling tumor-immune interactions is proposed for future studies.

Autoimmunity as an immune defense against degenerative processes: a primary mathematical model illustrating the bright side of autoimmunity

Self-tolerance, or the ability of the immune system to refrain from destroying the organism's own tissues, is a prerequisite for proper immune system operation. How such self-tolerance is achieved is still a subject of debate. The belief that autoimmunity poses a continuous threat to the organism was challenged by data demonstrating that autoimmunity has a protective function after traumatic injury to the central nervous system. This finding led us to suggest the 'comprehensive immunity' approach by which autoimmunity is viewed as a special case of immunity, namely as a defense mechanism that operates by fighting against the threat of potential destructive activity originated or mediated within the organism, similarly to the immune defense that operates against the threat from exogenous pathogens. We present a primary mathematical spatio-temporal model that supports this concept. The numerical solutions of this model illustrate the beneficial operation of a well-controlled immune response specific to self-antigens residing in the site of lesion. The model also explains how the response to self might be tolerated on a day-to-day basis. In addition, we demonstrate that the same autoimmune response, operating at different levels of regulation, can lead to either an autoimmune disease or a degenerative disorder. This preliminary qualitative model supports our contention that the way autoimmunity is perceived should be revised.

Increased incidence of autoimmune disorders as a late complication in children with early onset dermatitis and/or milk allergy

Subjects with atopic dermatitis and autoimmune disorders share some similar immune response disorders. The aim of this study was to see whether subjects with early onset atopic dermatitis run a risk of eventually developing autoimmune diseases. The results of a questionnaire of 145 adolescents (70 f, 75 m, mean age 18.2 years, range 16-23 years) was compared with those of a group of 262 controls (112 f, 150 m, mean age 17.5 years, range 16-21 years), 164 of whom reported no atopic symptoms and were treated as a separate group for statistical analysis. As compared with the non-atopic controls, the study group subjects showed a significantly increased incidence of autoimmune disorders (9% vs. 1%), the relative risk ratio of a subject with infantile onset atopic eczema getting a gastrointestinal (GI) immune-mediated disease being 2.4 (CI(95)2.1-2.8) and of getting some other autoimmune disorder 3.1 (CI(95)2.8-9.7). The positive skin prick tests showed a negative association with the manifestation of a GI or other autoimmune disorder. The subjects with infantile dermatitis also reported recurrent abdominal pains (23% vs. 15%), and milk-induced gastrointestinal symptoms (19% vs. 10%) significantly more even as young adults than the controls. Our study showed that infantile atopy increases a predisposition to autoimmune disorders, suggesting that these two entities might have a common immunological determinant. While a high incidence of chronic GI complaints among the study subjects suggests the ongoing activity of local immune responses. However, more detailed prospective studies are needed to confirm these observations.