Taissa M. Kasahara

The Ex Vivo Production of IL-6 and IL-21 by CD4+ T Cells is Directly Associated with Neurological Disability in Neuromyelitis Optica Patients

Neuromyelitis optica (NMO), also known as Devic’s disease, is an autoimmune, inflammatory disorder of the central nervous system (CNS) in which the immune system attacks myelin of the neurons located at the optic nerves and spinal cord, thus producing a simultaneous or sequential optic neuritis and myelitis. The objective of this study was evaluated the background T-cell function of patients suffering from neuromyelitis optica (NMO), an autoimmune disorder of the central nervous system. In our study, the in vitro T cell proliferation and the production of Th1 cytokines were significantly lower in cell cultures from NMO patients, as compared with healthy individuals. In contrast, a dominant Th17-like phenotype, associate with higher IL-23 and IL-6 production by LPS-activated monocytes, was observed among NMO patients. The release of IL-21 and IL-6 by polyclonaly activated CD4+ T cells was directly correlated to neurological disability. In addition, the in vitro release of IL-21, IL-6 and IL-17 was significantly more resistant to glucocorticoid inhibition in NMO patients. In conclusion, the results indicate dominate Th17-related response in NMO patients that was directly proportional to neurological disability. Furthermore, our results can help to explain why NMO patients trend to be more refractory to corticoid treatment.

Dopamine favors expansion of glucocorticoid-resistant IL-17-producing T cells in multiple sclerosis.

Dopamine (DA) is a neurotransmitter produced mainly in the central nervous system (CNS) that has immunomodulatory actions on T cells. As the multiple sclerosis (MS) has long been regarded as an autoimmune disease of CNS mediated by T cells, the objective of this study was to evaluate the impact of DA on in vitro functional status of T cells from relapsing-remitting (RR)-MS patients. Peripheral T-cells from RR-MS patients were activated by mitogens and cell proliferation and cytokine production were assayed by [(3)H]-thymidine uptake and ELISA, respectively. Our results demonstrated that DA enhanced in vitro T cell proliferation and Th17-related cytokines in MS-derived cell cultures. In addition, this catecholamine reduced Treg-related cytokines (IL-10 and TGF-β) release by activated CD4(+) T cells. These DA-induced effects on T cells were mainly dependent on IL-6 production by both polyclonally-activated CD4(+) T cells and LPS-stimulated monocytes. Furthermore, the production of IL-17 and IL-6 by MS-derived T cells was directly related with neurological disability (EDSS score), and the release of these cytokines was less sensitive to glucocorticoid inhibition in MS patients than in control group, mainly after DA addition. In conclusion, our data suggest that DA amplifies glucocorticoid-resistant Th17 phenotype in MS patients, and this phenomenon could be, at least in part, due to its ability to induce IL-6 production by monocytes and CD4(+) T cells.

Dopamine up-regulates Th17 phenotype from individuals with generalized anxiety disorder

Our objective was to evaluate the effect of stress-related dose of dopamine (DA) on the in vitro proliferation and cytokine production in polyclonally-activated T cells from healthy individuals or individuals with generalized anxiety disorder (GAD). Our results demonstrated that cell cultures from GAD group proliferated less following T cell activation, as compared with control group. The addition of DA reduced the proliferative response in cell cultures from healthy but not from GAD individuals. The cytokine profile in GAD individuals revealed Th1 and Th2 deficiencies associated with a dominant Th17 phenotype, which was enhanced by DA. A similar DA-induced immunomodulation was also observed in PPD-activated cell cultures from GAD individuals. Unlike the control, DA-enhanced Th17 cytokine production in GAD individuals was not affected by glucocorticoid. In conclusion, our results show that the T cell functional dysregulation in GAD individuals is significantly amplified by DA. These immune abnormalities can have impact in increasing the susceptibility of individuals with anxiety disorders to infectious diseases and inflammatory/autoimmune disorders.

Endogenous interleukin‐6 amplifies interleukin‐17 production and corticoid‐resistance in peripheral T cells from patients with multiple sclerosis

Interleukin‐6 (IL‐6) has been implicated in the induction of pathogenic IL‐17‐producing T cells in autoimmune diseases, and studies evaluating the role of this cytokine in T‐cell function in patients with multiple sclerosis (MS) are lacking. Our objective was to evaluate the role of IL‐6 receptor (IL‐6R) signalling on in vitro functional status of T cells from patients with relapsing–remitting MS during clinical remission. Our results demonstrated that, even during the remission phase, activated T cells from patients produce higher levels of IL‐17, and this cytokine was positively correlated with disease severity, as determined by Expanded Disability Status Scale score. In the MS group, the blockade of IL‐6R signalling by anti‐IL‐6R monoclonal antibody reduced IL‐17 production and elevated IL‐10 release by activated CD4+ T cells, but it did not alter the production of these cytokines by activated CD8+ T cells. Blockade of IL‐6R signalling also reduced the ability of monocytes to up‐regulate T helper type 17 phenotype in patients with MS. Finally, both cell proliferation and IL‐17 release by CD4+ and, mainly, CD8+ T cells from patients with MS were less sensitive to hydrocortisone inhibition than control group. Interestingly, IL‐6R signalling blockade restored the ability of hydrocortisone to inhibit both T‐cell proliferation and IL‐17 production. Collectively, these results suggest that IL‐6 might be involved in MS pathogenesis by enhancing IL‐17 production and reducing corticoid inhibitory effects on activated T cells.

Vitamin D modulates different IL-17-secreting T cell subsets in multiple sclerosis patients.

Vitamin D deficiency is an environmental risk factor for MS, a Th17 cell-mediated autoimmune disease that results in demyelination in the CNS. Therefore, we aimed to evaluate the ability of in vitro 1,25(OH)2D in modulating different Th17 cell subsets in MS patients in remission phase. In the present study, the production of Th17-related cytokines (IL-1β, IL-6, IL-17, IL-22), as well as GM-CSF, was significantly higher in cell cultures from MS patients than in healthy subjects (HS). The 1,25(OH)2D reduced all pro-inflammatory cytokines essayed, mainly those released from HS cell cultures. The proportion of both IL-17+IFN-γ+ (CD4+ and CD8+) T cells and IL-17+IFN-γ-CD8+ T cells was positively related with neurological disorders, determined by EDSS score. The addition of 1,25(OH)2D reduced not only these pathogenic T cell subsets but elevated the percentage of IL-10-secreting conventional (FoxP3+CD25+CD127-CD4+) and non-conventional (IL-17+) regulatory-like T cells. Taken together, the results indicate that the active form of vitamin D should benefit MS patients by attenuating the percentage of pathogenic T cells. This effect could be direct and/or indirect, by enhancing classical and non-classical regulatory T cells.

Low sensitivity to glucocorticoid inhibition of in vitro Th17-related cytokine production in multiple sclerosis patients is related to elevated plasma lipopolysaccharide levels.

Exogenous glucocorticoid plays an important role in controlling clinical relapses of multiple sclerosis (MS), but the response to this treatment differs among patients. In this study, T-cell proliferation and IL-17 production were less sensitive to hydrocortisone (HC) inhibition in MS patients than healthy individuals, mainly in CD8(+) compartment. Furthermore, in vitro IL-17 production was positively related with neurological disability and its release was proportional to IL-23 and IL-6 productions by LPS-activated monocytes. Interestingly, elevated LPS levels were quantified in the plasma of MS patients, and their levels were directly related to in vivo IL-6 production. Finally, HC-resistance in reducing IL-17 production by polyclonally-activated CD8(+) T cells was particularly observed among MS patients with higher in vivo LPS levels. In summary, the results indicate that T-cells derived from MS patients show an enhanced Th17-like phenotype that is directly associated with neurological disability, resistance to glucocorticoid inhibition and elevated bacterial translocation.

Interleukin-17- and interleukin-22-secreting myelin-specific CD4(+) T cells resistant to corticoids are related with active brain lesions in multiple sclerosis patients.

Multiple sclerosis (MS) is thought to be an autoimmune disorder. It is believed that immunological events in the early stages have great impact on the disease course. Therefore, we aimed to evaluate the cytokine profile of myelin basic protein (MBP)‐specific T cells from MS patients in the early phase of the disease and correlate it to clinical parameters, as well as to the effect of in vitro corticoid treatment. Peripheral T cells from MS patients were stimulated with MBP with our without hydrocortisone for 5 days. The cytokines level were determined by ELISA. The number of active brain lesions was determined by MRI scans, and the neurological disabilities were assessed by Expanded Disability Status Scale scores. Our results demonstrated that MS‐derived T cells responded to MBP by producing high levels of T helper type 1 (Th1) and Th17 cytokines. Although the production of interleukin‐6 (IL‐6), granulocyte–macrophage colony‐stimulating factor, IL‐17 and IL‐22 was less sensitive to hydrocortisone inhibition, only IL‐17 and IL‐22 levels correlated with active brain lesions. The ability of hydrocortisone to inhibit IL‐17 and IL‐22 production by MBP‐specific CD4+ T cells was inversely related to the number of active brain lesions. Finally, the production of both cytokines was significantly higher in cell cultures from Afrodescendant patients and it was less sensitive to hydrocortisone inhibition. In summary, our data suggest that IL‐17‐ and IL‐22‐secreting CD4+ T cells resistant to corticoids are associated with radiological activity of the MS in early stages of the disease, mainly among Afrodescendant patients who, normally, have worse prognosis.

Prediction of disease severity in neuromyelitis optica by the levels of interleukin (IL)-6 produced during remission phase

T helper type 17 (Th17) cytokines have been implicated in the pathogenesis of neuromyelitis optica (NMO). As humanized anti‐interleukin (IL)‐6R (tocilizumab) immunoglobulin (Ig)G has been used as disease‐modifying therapy for NMO, the objective of our study was to investigate the role of endogenous IL‐6 on NMO‐derived CD4+ T cell behaviour. High production of IL‐6, IL‐17 and IL‐21 by CD4+ T‐cells was detected in NMO patients. Further, IL‐21 and IL‐6 levels were related directly to the level of neurological disabilities. The addition of anti‐IL‐6R IgG not only reduced directly the production of these cytokines, but also almost abolished the ability of activated autologous monocytes in enhancing IL‐6, IL‐17 and IL‐21 release by CD4+ T cells. In contrast, the production of IL‐10 was amplified in those cell cultures. Further, anti‐IL‐6R monoclonal antibodies (mAb) also potentiated the ability of glucocorticoid in reducing Th17 cytokines. Finally, the in‐vivo and in‐vitro IL‐6 levels were significantly higher among those patients who experienced clinical relapse during 2‐year follow‐up. In summary, our results suggest a deleterious role of IL‐6 in NMO by favouring, at least in part, the expansion of corticoid‐resistant Th17 cells.

High in vitro immune reactivity to Escherichia coli in neuromyelitis optica patients is correlated with both neurological disabilities and elevated plasma lipopolysaccharide levels

The pathogenesis of neuromyelitis optica (NMO) is influenced by a combination of genetic and environmental factors, including infectious agents. Several infectious diseases can both trigger or exacerbate autoimmunity. The objective of the present work was to evaluate the in vitro immune responsiveness to Escherichia coli (EC), Staphylococcus aureus (SA) and Candida albicans (CA) in remittent-recurrent NMO patients, and correlate it with the level of neurological disability. Our results revealed that the extent of lymphoproliferation and cytokine profile in response to SA- and CA-stimulated PBMC cultures was similar between NMO patients and healthy individuals. Nevertheless, a higher in vitro CD4(+) T cell proliferation associated with elevated IL-1β, IL-6 and IL-17 release was observed in NMO-derived EC-stimulated cell cultures. Additionally, in these last cultures, the IL-10 production was significantly lower as compared with control group. The in vitro EC-induced levels of IL-6 and IL-17 were positively related with neurological disabilities. This higher tendency to produce Th17-related cytokines was proportional to the production of IL-23 and IL-6 by LPS-activated monocytes. Interestingly, elevated LPS levels were quantified in the plasma of NMO patients. The results suggest that a higher Th17-responsiveness to E. coli could be involved in the NMO pathogenesis.

High IL-10 production by aged AIDS patients is related to high frequency of Tr-1 phenotype and low in vitro viral replication

This work aims to elucidate the effects of age and HIV-1 infection on the frequency and function of T cell subsets in response to HIV-specific and non-specific stimuli. As compared with the younger AIDS group, the frequencies of naive and central memory T cells were significantly lower in aged AIDS patients. Although there was also a dramatic loss of classical CD4(+)FoxP3(+)CD25(+)Treg cells in this patient group, high frequencies of IL-10-producing CD4(+)FoxP3(-) T cells were observed. In our system, the increased production of IL-10 in aged AIDS patients was mainly derived from Env-specific CD4(+)FoxP3(-)CD152(+) T cells. Interestingly, while the blockade of IL-10 activity by monoclonal antibody clearly enhanced the release of IL-6 and IL-1β by Env-stimulated PBMC cultures from aged AIDS patients, this monoclonal antibody enhanced in vitro HIV-1-replication. In conclusion, HIV infection and aging undoubtedly contribute synergistically to a complex immune dysfunction in T cell compartment of HAART-treated older HIV-infected individuals.