A Complete In Vitro Toxicological Assessment of the Biological Effects of Cerium Oxide Nanoparticles: From Acute Toxicity to Multi-Dose Subchronic Cytotoxicity Study.

Engineered nanomaterials (ENMs) are of significant relevance due to their unique properties, which have been exploited for widespread applications. Cerium oxide nanoparticles (CeO2-NPs) are one of most exploited ENM in the industry due to their excellent catalytic and multi-enzyme mimetic properties. Thus, the toxicological effects of these ENMs should be further studied. In this study, the acute and subchronic toxicity of CeO2-NPs were assessed. First, an in vitro multi-dose short-term (24 h) toxicological assessment was performed in three different cell lines: A549 and Calu3 were used to represented lung tissue and 3T3 was used as an interstitial tissue model. After that, a sub-chronic toxicity assessment (90 days) of these NPs was carried out on a realistic and well-established reconstituted primary human airway epithelial model (MucilAir™), cultured at the Air-Liquid Interface (ALI), to study the long-term effects of these particles. Results showed minor toxicity of CeO2-NPs in acute exposures. However, in subchronic exposures, cytotoxic and inflammatory responses were observed in the human airway epithelial model after 60 days of exposure to CeO2-NPs. These results suggest that acute toxicity approaches may underestimate the toxicological effect of some ENMs, highlighting the need for subchronic toxicological studies in order to accurately assess the toxicity of ENM and their cumulative effects in organisms.

Perforin expression by CD4+ regulatory T cells increases at multiple sclerosis relapse: sex differences.

Multiple sclerosis (MS) represents the leading cause of neurological deficit among young adults, affecting women more frequently than men. In MS, the extent of central nervous system lesions is determined by the net balance between self-reactive and regulatory T-cells at any given time, among other factors, as well as by the effect of inflammatory response. Here, we studied both CD4+ and CD8+ T(Reg) in parallel in blood and CSF during MS relapse. A recruitment of both regulatory CD4+ and CD8+ T cells (T(Reg)) within the cerebrospinal fluid (CSF) takes place during MS relapse. Not previously described, the presence of CD4+ T(Reg) in CSF was higher in women than in men, which could account for the sexual dimorphism in the incidence of MS. A direct correlation between plasma oestradiol (E2) and IL-2 levels was observed, in line with a putative circuit of E2 and perforin expression by CD4+ T(Reg) playing a role in MS. Also, serum IFN-alpha was higher in females, with direct correlation with serum E2 levels. This is the first study to analyze perforin expression by CD4+ T(Reg) in MS, which was greatly enhanced in CSF, what points out a relevant role of this molecule in the suppressive effects of the CD4+ T(Reg) in MS, and contributes to the understanding of MS pathophysiology.

Sex-hormone receptors pattern on regulatory T-cells: clinical implications for multiple sclerosis.

Cellular mechanisms underlying sexual dimorphism in the immune response remain largely unknown. Concerning the interactions among the nervous, endocrine and immune systems, we reported that during gestation, a period during which multiple sclerosis (MS) clearly ameliorates, there is a physiological expansion of regulatory T-lymphocytes (T(Reg)). Given that alterations in T(Reg) proportions and suppressive function are involved in MS pathophysiology, we investigated the in vitro effect of sex hormones on T(Reg). Here, we show that both E2 and progesterone (P2) enhance T(Reg) function in vitro, although only E2 further induces a T(Reg) phenotype in activated responder T-cells (CD4(+)CD25(-)) (P < 0.01). E2 receptor beta (ERß) percentages and mean fluorescence intensity (MFI) on T(Reg) were lower in MS patients than in controls (P < 0.05), in parallel with lower E2 plasma levels (P < 0.05). Importantly, percentages and MFI of ERß were higher in T(Reg) than in T-responder cells (P < 0.0001) both in MS patients and controls. We show a unique differential pattern of higher ER and PR levels in T(Reg), which may be relevant for the in vivo responsiveness of these cells to sex hormones and hence to MS physiopathology.

Estradiol-dependent perforin expression by human regulatory T-cells.

BACKGROUND: CD4+CD25+FoxP3+ regulatory T-cells (nT(Reg)) have been shown to suppress immune responses to autoantigens and to other diverse antigens, this suppression is mainly mediated by a cell contact-dependent mechanism not yet fully defined. It has been reported that both human natural and induced T(Reg) exert cytotoxic activity against autologous target cells, which suggests that the perforin/granzyme pathway may be a relevant candidate mechanism for the suppressive function of T(Reg). Previous reports have shown that oestradiol (E2) modulates T(Reg) percentages and function. METHODS: We have evaluated in pregnant and non-pregnant subjects perforin intracellular expression in CD4+CD25+FoxP3+ regulatory T-cells by flow cytometry in whole blood, ex-vivo purified nT(Reg) and ex-vivo purified nT(Reg) after TCR and E2 stimulation. The expression of cellular degranulation markers was also phenotypically determined. RESULTS: We show that E2 expands T(Reg), enhances in vitro T(Reg) function and induces a T(Reg) phenotype in activated responder (CD4+CD25) T-cells, further increasing the expression of perforin on T(Reg) than in vitro T-cell receptor activation alone. We found surface lysosomal-associated membrane glycoproteins (LAMP)-1 and LAMP-2 expression by T(Reg), which is a sign of cell degranulation and therefore of cytotoxicity exerted by these cells. CONCLUSION: Our data demonstrates the presence of functional T(Reg) cytotoxic properties in biological systems and support the concept that E2 enhances the number and function of T(Reg) suggesting the potential interaction between E2 and immunoregulatory mechanisms.

IFNbeta-1a therapy for multiple sclerosis expands regulatory CD8+ T cells and decreases memory CD8+ subset: a longitudinal 1-year study.

The beneficial effects of interferon beta-1a (IFNbeta-1a) in multiple sclerosis (MS) remain only partially understood. CD8(+) T cells are key cells in MS pathogenesis that contribute to axonal damage in MS, whereas CD4(+) regulatory T cells (T(Reg)) and CD8(+) regulatory/suppressor T cells (Ts) play an important role in protecting against subsequent MS activity. We analysed ex vivo changes on T(Reg) and on the different subsets of CD4(+) and CD8(+) T lymphocytes, before IFNbeta-1a (Rebif) therapy and at 3, 6, and 12 months after treatment, in 23 MS patients and in 26 healthy controls. IFNbeta-1a significantly increased the proportions of CD4(+) T(Reg) and regulatory CD8(+) T cells (Tr). Memory CD8(+) T cells were significantly decreased after 1 year of treatment, maybe reflecting down-regulation of abnormally persistent systemic activation in MS patients. After 1 year of IFNbeta-1a, a direct correlation was observed between plasmacytoid dendritic cells and effector CD8(+) T cells.

Clinical response to interferon-beta-1a may be linked to low baseline circulating BDCA1 myeloid dendritic cells Differential role of circulating dendritic cells and CD4+ regulatory T-cells in relapsing-remitting multiple sclerosis: a 1-year longitudinal study.

Many variables with association with better response to interferon-beta-1a (IFNbeta-1a) have been described, but none has yet been shown to be predictive of clinical response. In this real-life observational 1-year longitudinal study of 23 relapsing-remitting multiple sclerosis (RRMS) patients treated with subcutaneous IFNbeta-1a, we have shown a lower proportion of circulating myeloid dendritic cells (mDCs) than in healthy controls at baseline. Both univariate (Kaplan-Meier) and multivariate (Cox regression) analyses were conducted to determine which variables (age, sex, baseline EDSS, MS relapse rates 1 year and 2 years before initiating IFNbeta-1a, mDCs and plasmacytoid (pDCs) subsets, activated and regulatory CD4(+) T-cells (T(Reg))) were associated with clinical response to IFNbeta-1a. During 1 year of treatment, we observed a shift towards lower proportions of CD123(+) pDCs expression and higher numbers and function of the T(Reg). Univariate analysis disclosed that MS activity was significantly associated with baseline BDCA1(+) mDCs below < or = 0.4% (p<0.0025). Cox model analysis revealed that baseline BDCA1(+) mDCs was the most closely associated factor with MS activity on IFN treatment during the 1-year follow-up (p<0.01). A better understanding of the rules that govern the T(Reg)-DC relationship will enable scientists to better manage the immune response in MS patients.

Expansion of regulatory CD8+ T-lymphocytes and fall of activated CD8+ T-lymphocytes after i.v. methyl-prednisolone for multiple sclerosis relapse.

INTRODUCTION: Multiple sclerosis (MS) is a multifocal chronic inflammatory demyelinating disease of the central nervous system. Axonal damage correlates with the presence of macrophages and CD8+ T-lymphocytes at brain lesions. The gold standard of therapy at MS relapse are iv glucocorticoids (GC). The aim of the study was to assess the changes on the different subsets of circulating CD8+ T-lymphocytes at relapse and after iv GC therapy. PATIENTS AND METHODS: We consecutively studied 20 patients at MS relapse before and at day 5 after initiation of i.v. methyl-prednisolone (MP) therapy (1 g/day for 3-5 days). CD4+ and CD8+ T-lymphocytes subsets were studied by multiparametric flow-cytometry. As control group, 18 healthy subjects were studied. RESULTS: Treatment with i.v. MP suppressed activated (CD8+CD38+HLA-DR+, p=0.05) and effector memory (CD8+CD27-CD45RO+) T-lymphocytes (p=0.07). By contrast, an increase of naïve (CD8+CD27+CD45RO-) (p=0.07) and regulatory CD8+CD25+ T-lymphocytes was observed (p<0.002). At MS relapse, there was an inverse correlation between regulatory CD8+CD25+CD28- T-lymphocytes and activated CD4+ (r = -0.6; p=0.012) and CD8+ (r = -0.66; p=0.004) T-lymphocytes. After i.v. MP treatment, positive correlation between regulatory CD4+CD25+high T-lymphocytes and CD8+CD25+ T-lymphocytes was observed (r=0.74; p<0.0001). CONCLUSIONS: Our data suggest that i.v. MP may contribute to changes observed on the differentiation of CD8+ T-lymphocytes, namely blocking their complete maturation, and expansion of regulatory CD8+ T-lymphocytes. We hypothesize an additional effect of i.v. MP in inhibiting axonal damage which may add a neuroprotective effect on MS relapse.

Interferon beta-1a therapy enhances CD4+ regulatory T-cell function: an ex vivo and in vitro longitudinal study in relapsing-remitting multiple sclerosis.

Interferon beta-1a (IFNâ-1a) has demonstrated efficacy in multiple sclerosis (MS), although its mechanism of action remains only partly understood. We evaluated the ex vivo and in vitro effects of IFNâ-1a (Rebif) on regulatory T-cell (T(Reg)) function in 22 relapsing-remitting MS patients and 16 healthy controls. T(Reg) function was significantly enhanced after 3 and 6 months of IFNbeta-1a therapy. Furthermore, there was a trend towards increasing proportions of total CD4(+)CD25(+) and CD4(+)CD25(+)GITR(+) T(Reg) after 6 months of IFNbeta-1a therapy when compared with baseline. In conclusion, IFNbeta-1a therapy enhances T(Reg) function, and this may be relevant in the inflammatory environment of MS lesions.

Circulating dendritic cells subsets and regulatory T-cells at multiple sclerosis relapse: differential short-term changes on corticosteroids therapy.

Glucocorticoids remain the treatment of choice for MS relapses. However, little is known on the effect of intravenous methylprednisolone (IVMP) on dendritic cells (DCs) and regulatory T-cells (TReg). Our main goal was to quantify circulating myeloid and plasmacytoid DCs (mDCs and pDCs), and TReg at MS relapse versus healthy controls; and to analyse the short-term changes after IVMP for MS relapse. MS patients at relapse compared to controls showed higher %CD4+CD25high+ TReg (p<0.01). After 5-days of IVMP, activated T-lymphocytes (p=0.001), pDCs (p<0.0001), and CD11c+ mDCs (p<0.0001) decreased. By contrast, CD4+CD25+ and CD4+CD25high+ TReg further increased (p<0.0001 both). Changes on these subsets may play a relevant role in the immunosuppressive activity of this drug.

Pregnancy-induced expansion of regulatory T-lymphocytes may mediate protection to multiple sclerosis activity.

Pregnancy represents a physiological transitory state of immune tolerance to avoid the rejection of the foetus, and concomitantly of stabilisation of many autoimmune diseases, such as multiple sclerosis (MS). Alterations in regulatory T-lymphocytes (T(Reg)) are known to be involved in organ-specific autoimmune disease pathophysiology. Our goal was to quantify CD4+ CD25+ and CD4+ CD25hi+ T(Reg) and activated (CD4+ HLA-DR+ CD38+) T-lymphocytes during pregnancy and puerperium in 13 MS patients in comparison with healthy pregnant and non-pregnant women. During pregnancy, a progressive parallel increase in CD4+ CD25+ T-lymphocytes in healthy pregnants as well as MS pregnant patients was observed. The proportion of T(Reg) was significantly higher in all pregnants than in non-pregnant women (p=0.01), whereas no differences were observed neither in the percentages of total nor activated CD4+ T-lymphocytes. In MS patients, CD4+ CD25+ T-lymphocytes significantly decreased when comparing the third trimester with the puerperal period proportions (p = 0.01), whereas CD4+ CD25hi+ T-lymphocytes significantly increased (p = 0.002). Our findings are consistent with the expansion of circulating regulatory CD4+ CD25+ T-lymphocytes pool with suppressive activity during normal pregnancy and in MS. A different pattern of CD+ CD25hi+ T-lymphocytes between healthy pregnants and MS women, which may represent relevant factors in the activity course of MS.