**6. Metabolome as applicable to T1D management at subclinical stages to prevent or minimize the imbalance**

In a recent study, a comparison of blood sera from children with type 1 diabetes (T1D), non diabetic children and children without autoimmune antibodies revealed metabolic disturbances (significant reduction of serum levels of succinate, phosphatidylcholine, phospholipin and ketoleucine, drastic elevation of glutamate, etc.) in the T1D group. , (Bougnères et al., 2008) The true reason for these disturbances is difficult to establish, since all these changes can be associated, with an equal degree of probability, with asymptomatic damage of liver and body musculature, T1D, metabolic imbalance caused by environmental factors, etc.

High lysophosphatidylcholine levels are detected in patients' blood as early as several years before the first clinical manifestations of T1D. It should be noted, however, that the aforecited studies were performed on children, but not on adults with T1D; therefore, their clinical significance is ambiguous.

Notable elevation of blood sera levels of glutamate potentiates the activity of GAD65, the major autoimmune antigen for autoAbs. The figure below shows the dynamics of the "glutamine–GABA–GADA" sequence. As can be seen, neither GADA and IAA, nor unlimited

Preclinical and Predictive Algorithms in Monitoring

**8. Phase 2 characteristics** 

candidates for T1D-triggering factors.

**8.3 Nutritional factors** 

autoagression and development of various immune disorders.

**8.1 Viral infections as triggering factors in type 1 diabetes** 

**8.2 Bacterial infections as triggering factors of T1D** 

Patients with Autoimmune Diseases and Their Relatives-at-Risks 209

Continuous exposure to hazardous effects of environmental factors and large-scale application of chemical substances in food industry, pharmaceutics and other sectors of national economy are harmful for human immune system, since all of them trigger pathological reactions resulting in diabetes. Furthermore, uncontrolled intake of drugs and frequent viral and bacterial infections form predisposition to allergic reactions and provoke

The large body of evidence (serological, epidemiological, biological, etc.) obtained thus far testifies to the ability of certain viruses to provoke type 1 diabetes mellitus (T1D) in human beings. Among the immense diversity of other disease-provoking factors, enteroviruses, retroviruses, reoviruses, parotiditis viruses, cytomegalovirus, Epstein-Barr virus and a clinical variant of the diabetogenic encephalomyocarditis virus are the most likely

Viral infections provoke diabetes by operating at different regulatory levels, e.g., by disregulating immune mechanisms, by stimulating the activity of pathological systems or by

The risks of viral infection and T1D development correlate with the functional stability of the organism and its genetic and immune backgrounds. It is well known that morbidity from seasonal (especially, in the winter period) virus-borne infections correlates with very high incidence of autoimmune diseases including T1D. The reason is in shorter (in comparison with summertime) duration of the daylight period and, as a consequence, low level of vitamin D synthesis and increased morbidity from viral infections and autoimmune disorders. Additional support in favor of this hypothesis can be derived from much greater

interfering with the normal course of regulatory processes occurring in the organism.

incidence of T1D in North European countries in comparison with Southern Europe.

of bacteria in initiating diabetes in adult individuals. (Giongo et al., 2010)

Recent advances in immunologic research and numerous animal and human model studies shed new light on the role of enteric bacteria in triggering autoimmune reactions. It was shown, in particular, that certain bacteria (e.g., *Bacteroides ovatus*) induce diabetes in young children predisposed to T1D. The mechanisms whereby bacterial agents interfere with immune homeostasis and provoke diabetes are still poorly understood; it is known, however, that intestinal bacteria trigger autoimmune responses that initiate destructive insulitis. The strongest argument in favor of this viewpoint is an ever increasing (by 20% in comparison with control) number of affected individuals infected with sporadic variants of these bacteria. The extent of bacterial infection is especially apparent in young children whose autoimmune microbiome is the least stable and diversified. Continuous sophistication and diversification of the microbiome with ageing point to the decreasing role

For quite a long period of time, viruses were considered to be the only etiogenic external factors in T1D. Today, there is evidence that nutritional factors also play a role in T1D development. Although the pathogenetic mechanisms of the disease are not yet completely

elevation of glutamine and moderate elevation of GABA take place in the initial steps. However, in the course of time the concentration of glutamic acid begins to decrease, while that of GABA increases; however, autoAbs are not generated even under these conditions. Subsequent decreases of glutamic acid and GABA are noted only against the background of increasing titers of anti-GAD65 and anti-insulin autoAbs (seroconversion). After T1D passes to the clinical diagnosis stage, auto-Abs titers begin to decrease gradually to a nearly undetectable level (this widely occurring phenomenon usually lasts 10 to 20 years).

Fig. 6. The dynamics of changes in the concentrations of Glu / GABA / GADA and insulin Abs in the period between the commencement of the effect of the irreversible diabetesinducing factor and first clinical manifestations of T1D. There is a clear seroconversion sequence Glu / GABA / GADA with a period of about 1 year. By the moment of appearance of first clinical manifestations, some antibodies detected several years theretofore, may be missing. (Noteworthy, each individual case may be different from the average).

There is evidence that in addition to the aforesaid metabolites T1D is characterized by fluctuations in the levels of succinic acid, phosphatidylcholine (even in newborns), triglycerides and phospholipids.

## **7. Environmental factors triggering T1D**

Estimation of the role of environmental factors in triggering one or another pathology and development of adequate approaches to diagnosis within maximally short intervals of time is one of currently central problems in preclinical medicine. Here, it is necessary to draw a demarcation line between autoimmune disorders and background events in order to select optimal diagnostic procedures and reliable criteria, since clinical tests do not always provide unfailing results that are crucial for diagnosis. Therefore, development of strict elaborate protocols is of vital importance for identification and analysis of environmental factors.

Continuous exposure to hazardous effects of environmental factors and large-scale application of chemical substances in food industry, pharmaceutics and other sectors of national economy are harmful for human immune system, since all of them trigger pathological reactions resulting in diabetes. Furthermore, uncontrolled intake of drugs and frequent viral and bacterial infections form predisposition to allergic reactions and provoke autoagression and development of various immune disorders.
