Neurophysiological Markers for Monitoring Exercise and Recovery Cycles in Endurance Sports.

The current study analyzes the suitability and reliability of selected neurophysiological and vegetative nervous system markers as biomarkers for exercise and recovery in endurance sport. Sixty-two healthy men and women, endurance trained and moderately trained, performed two identical acute endurance tests (running trial 1 and running trial 2) followed by a washout period of four weeks. Exercise protocol consisted of an acute running trial lasting 60 minutes. An intensity corresponding to 95% of the heart rate at individual anaerobic threshold for 40 minutes was followed by 20 minutes at 110%. At pre-exercise, post-exercise, three hours post-exercise and 24 hours post-exercise, experimental diagnostics on Brain-derived neurotrophic factor (BDNF), heart rate variability (HRV), Stroop Color and Word Test (SCWT), and Short-Form McGill Pain Questionnaire (SF-MPQ) were performed. Significant changes over time were found for all parameters (p < .05). Furthermore, there was an approached statistical significance in the interaction between gender and training status in BDNF regulation (F(3) = 2.43; p = 0.06), while gender differences were found only for LF/HF-ratio (3hPoEx, F(3) = 3.40; p = 0.002). Regarding the reliability, poor ICC-values (< 0.5) were found for BDNF, Stroop sensitivity and pNN50, while all other parameters showed moderate ICC-values (0.5-0.75). Plasma-BDNF, SCWT performance, pain perception and all HRV parameters are suitable exercise-sensitive markers after an acute endurance exercise. Moreover, pain perception, SCWT reaction time and all HRV parameters show a moderate reliability, others rather poor. In summary, a selected neurophysiological and vegetative marker panel can be used to determine exercise load and recovery in endurance sports, but its repeatability is limited due to its vaguely reliability.

Reliability and suitability of physiological exercise response and recovery markers.

There is currently insufficient evidence about the reliable quantification of exercise load and athlete's recovery management for monitoring training processes. Therefore, this test-retest study investigated the reliability of various subjective, muscle force, and blood-based parameters in order to evaluate their suitability for monitoring exercise and recovery cycles. 62 subjects completed two identical 60-min continuous endurance exercise bouts intermitted by a four-week recovery period. Before, immediately after, three, and 24 h after each exercise bout, analysis of parameters were performed. Significant changes over time were found for rating of perceived exertion (RPE), multidimensional mood state questionnaire (MDMQ), maximum voluntary contraction parameters (MVCs), and blood-based biomarkers (p < 0.05). Excellent reliability was calculated for MVCs, mean corpuscular volume and 5-bound distance (ICC > 0.90). A good reliability was found for thiobarbituric acid reactive substances (TBARS) (ICC = 0.79) and haematological markers (ICC = 0.75-0.86). For RPE, MDMQ, interleukin (IL-) 1RA, IL-6, IL-8, IL-15, cortisol, lactate dehydrogenase (LDH), creatine kinase (CK) only moderate reliability was found (ICC < 0.75). Significant associations for IL1-RA and CK to MVC were found. The excellent to moderate reliability of TBARS, LDH, IL-1RA, six measured haematological markers, MVCs and MDMQ implicate their suitability as physiological exercise response and recovery markers for monitoring athletes' load management.

Antigen receptor-mediated depletion of FOXP3 in induced regulatory T-lymphocytes via PTPN2 and FOXO1.

Regulatory T-cells induced via IL-2 and TGFß in vitro (iTreg) suppress immune cells and are potential therapeutics during autoimmunity. However, several reports described their re-differentiation into pathogenic cells in vivo and loss of their key functional transcription factor (TF) FOXP3 after T-cell antigen receptor (TCR)-signalling in vitro. Here, we show that TCR-activation antagonizes two necessary TFs for foxp3 gene transcription, which are themselves regulated by phosphorylation. Although the tyrosine phosphatase PTPN2 is induced to restrain IL-2-mediated phosphorylation of the TF STAT5, expression of the TF FOXO1 is downregulated and miR-182, a suppressor of FOXO1 expression, is upregulated. TGFß counteracts the FOXP3-depleting TCR-signal by reassuring FOXO1 expression and by re-licensing STAT5 phosphorylation. Overexpressed phosphorylation-independent active versions of FOXO1 and STAT5 or knockdown of PTPN2 restores FOXP3 expression despite TCR-signal and absence of TGFß. This study suggests novel targets for stabilisation and less dangerous application of iTreg during devastating inflammation.

Unlike αß T cells, γδ T cells, LTi cells and NKT cells do not require IRF4 for the production of IL-17A and IL-22.

Apart from conventional CD4(+) Th17 cells, the cytokines IL-17A and IL-22 can also be produced by γδ T cells, NK cells and lymphoid tissue inducer (LTi) cells. Th17 cells develop from precursor cells after T-cell receptor stimulation in the presence of TGF-ß, IL-6 and IL-23. In contrast, a subset of γδ T cells ("γδT17") is committed for fast IL-17 production already in the thymus; however, γδ T cells can also produce IL-17 after prolonged in vitro stimulation via their γδ T-cell receptor plus IL-23. Here, we show that γδ T-, LTi- and NKT cells differ extensively from Th17 cells in their signalling requirements for the generation of IL-17A and IL-22. While production of these cytokines by Th17 cells totally depends on the transcription factor interferon regulatory factor 4 (IRF4), IRF4 is irrelevant in the other cell types. As for γδ T cells, this finding pertains to both thymic commitment and prolonged in vitro culture. Furthermore, IL-17A-producing γδ T cells accumulate in the central nervous system of IRF4 deficient (Irf4(-/-)) mice during experimental autoimmune encephalomyelitis. IL-17A-producing WT and Irf4(-/-) γδ T cells equally express CCR6 and lack CD27. The underlying IRF4-independent pathway partially involves STAT3 during in vitro stimulation.

Transcription factor IRF4 determines germinal center formation through follicular T-helper cell differentiation.

Follicular T-helper (T(FH)) cells cooperate with GL7(+)CD95(+) germinal center (GC) B cells to induce antibody maturation. Herein, we identify the transcription factor IRF4 as a T-cell intrinsic precondition for T(FH) cell differentiation and GC formation. After immunization with protein or infection with the protozoon Leishmania major, draining lymph nodes (LNs) of IFN-regulatory factor-4 (Irf4(-/-)) mice lacked GCs and GC B cells despite developing normal initial hyperplasia. GCs were also absent in Peyer's patches of naive Irf4(-/-) mice. Accordingly, CD4(+) T cells within the LNs and Peyer's patches failed to express the T(FH) key transcription factor B-cell lymphoma-6 and other T(FH)-related molecules. During chronic leishmaniasis, the draining Irf4(-/-) LNs disappeared because of massive cell death. Adoptive transfer of WT CD4(+) T cells or few L. major primed WT T(FH) cells reconstituted GC formation, GC B-cell differentiation, and LN cell survival. In support of a T-cell intrinsic IRF4 activity, Irf4(-/-) T(FH) cell differentiation was not rescued by close neighborhood to transferred WT T(FH) cells. Together with its known B lineage-specific roles during plasma cell maturation and class switch, our study places IRF4 in the center of antibody production toward T-cell-dependent antigens.

DNA methylation of TH1/TH2 cytokine genes affects sensitization and progress of experimental asthma.

BACKGROUND: Epigenetic changes in DNA methylation have recently been demonstrated to be involved in effector T-cell polarization, resulting in differential secretion of T(H)1 and T(H)2 cytokines. However, the contribution to the development of a chronic inflammatory phenotype remains still unclear. OBJECTIVE: We sought to investigate changes in DNA methylation in marker genes of T-cell subsets during allergen sensitization/challenge and their influence on the development of an allergic airway inflammatory response. METHODS: The relationship between changes in DNA methylation and phenotype development were examined in a well-established model of experimental asthma. DNA methylation was investigated at genomic loci associated with T(H)1 (IFNG promoter) or T(H)2 (conserved noncoding sequence 1 [CNS1]) cytokine production by using bisulfite pyrosequencing. RESULTS: Analysis of CD4(+) T cells revealed a significant increase in DNA methylation at the IFNG promoter after allergen sensitization/challenge, which correlated with decreased IFN-γ cytokine expression, whereas only minor changes were observed at the CNS1 locus. Furthermore, the increase in DNA methylation at the IFNG promoter could be reversed with a DNA methyltransferase (DNMT) inhibitor in vitro and in vivo with beneficial effects on sensitization status and allergic phenotype. The specific importance of the DNA methylation status in CD4(+) T cells could be confirmed by using adoptive transfer experiments. CONCLUSION: We here report the novel finding that epigenetic regulation in T cells contributes to the development of experimental asthma and can be targeted pharmacologically.

Interferon-regulatory factor 4 is essential for the developmental program of T helper 9 cells.

Interferon-regulatory factor 4 (IRF4) is essential for the development of T helper 2 (Th2) and Th17 cells. Herein, we report that IRF4 is also crucial for the development and function of an interleukin-9 (IL-9)-producing CD4(+) T cell subset designated Th9. IRF4-deficient CD4(+) T cells failed to develop into IL-9-producing Th9 cells, and IRF4-specific siRNA inhibited IL-9 production in wild-type CD4(+) T cells. Chromatin-immunoprecipitation (ChIP) analyses revealed direct IRF4 binding to the Il9 promoter in Th9 cells. In a Th9-dependent asthma model, neutralization of IL-9 substantially ameliorated asthma symptoms. The relevance of these findings is emphasized by the fact that the induction of IL-9 production also occurs in human CD4(+) T cells accompanied by the upregulation of IRF4. Our data clearly demonstrate the central function of IRF4 in the development of Th9 cells and underline the contribution of this T helper cell subset to the pathogenesis of asthma.

c-Rel is crucial for the induction of Foxp3(+) regulatory CD4(+) T cells but not T(H)17 cells.

The NF-kappaB/Rel family member c-Rel was described to be required for the development of T(H)1 responses. However, the role of c-Rel in the differentiation of T(H)17 and regulatory CD4(+)Foxp3(+) T cells (Treg) remains obscure. Here, we show that in the absence of c-Rel, in vitro differentiation of pro-inflammatory T(H)17 cells is normal. In contrast, generation of inducible Treg (iTreg) within c-Rel-deficient CD4(+) T cells was severely hampered and correlated to reduced numbers of Foxp3(+) T cells in vivo. Mechanistically, in vitro conversion of naive CD4(+) T cells into iTreg was crucially dependent on c-Rel-mediated synthesis of endogenous IL-2. The addition of exogenous IL-2 was sufficient to rescue the development of c-Rel-deficient iTreg. Thus, c-Rel is essential for the development of Foxp3(+) Treg but not for T(H)17 cells via regulating the production of IL-2.