Evolving Identification of Blood Cells Associated with Clinically Isolated Syndrome: Importance of Time since Clinical Presentation and Diagnostic MRI.

It is not clear how the profile of immune cells in peripheral blood differs between patients with clinically isolated syndrome (CIS) and healthy controls (HC). This study aimed to identify a CIS peripheral blood signature that may provide clues for potential immunomodulatory approaches early in disease. Peripheral blood mononuclear cells (PBMCs) were collected from 18 people with CIS, 19 HC and 13 individuals with other demyelinating conditions (ODC) including multiple sclerosis (MS). Individuals with CIS separated into two groups, namely those with early (≤14 days post-diagnostic magnetic resonance imaging (MRI); n = 6) and late (≥27 days; n = 12) blood sampling. Transitional B cells were increased in the blood of CIS patients independently of when blood was taken. However, there were two time-dependent effects found in the late CIS group relative to HC, including decreased CD56bright NK cells, which correlated significantly with time since MRI, and increased CD141+ myeloid dendritic cell (mDC2) frequencies. Higher CD1c+ B cells and lower non-classical monocyte frequencies were characteristic of more recent demyelinating disease activity (ODC and early CIS). Analysing cell populations by time since symptoms (subjective) and diagnostic MRI (objective) may contribute to understanding CIS.

Vitamin D and allergic airway disease shape the murine lung microbiome in a sex-specific manner.

BACKGROUND: Vitamin D is under scrutiny as a potential regulator of the development of respiratory diseases characterised by chronic lung inflammation, including asthma and chronic obstructive pulmonary disease. It has anti-inflammatory effects; however, knowledge around the relationship between dietary vitamin D, inflammation and the microbiome in the lungs is limited. In our previous studies, we observed more inflammatory cells in the bronchoalveolar lavage fluid and increased bacterial load in the lungs of vitamin D-deficient male mice with allergic airway disease, suggesting that vitamin D might modulate the lung microbiome. In the current study, we examined in more depth the effects of vitamin D deficiency initiated early in life, and subsequent supplementation with dietary vitamin D on the composition of the lung microbiome and the extent of respiratory inflammation. METHODS: BALB/c dams were fed a vitamin D-supplemented or -deficient diet throughout gestation and lactation, with offspring continued on this diet post-natally. Some initially deficient offspring were fed a supplemented diet from 8 weeks of age. The lungs of naïve adult male and female offspring were compared prior to the induction of allergic airway disease. In further experiments, offspring were sensitised and boosted with the experimental allergen, ovalbumin (OVA), and T helper type 2-skewing adjuvant, aluminium hydroxide, followed by a single respiratory challenge with OVA. RESULTS: In mice fed a vitamin D-containing diet throughout life, a sex difference in the lung microbial community was observed, with increased levels of an Acinetobacter operational taxonomic unit (OTU) in female lungs compared to male lungs. This effect was not observed in vitamin D-deficient mice or initially deficient mice supplemented with vitamin D from early adulthood. In addition, serum 25-hydroxyvitamin D levels inversely correlated with total bacterial OTUs, and Pseudomonas OTUs in the lungs. Increased levels of the antimicrobial murine ß-defensin-2 were detected in the bronchoalveolar lavage fluid of male and female mice fed a vitamin D-containing diet. The induction of OVA-induced allergic airway disease itself had a profound affect on the OTUs identified in the lung microbiome, which was accompanied by substantially more respiratory inflammation than that induced by vitamin D deficiency alone. CONCLUSION: These data support the notion that maintaining sufficient vitamin D is necessary for optimal lung health, and that vitamin D may modulate the lung microbiome in a sex-specific fashion. Furthermore, our data suggest that the magnitude of the pro-inflammatory and microbiome-modifying effects of vitamin D deficiency were substantially less than that of allergic airway disease, and that there is an important interplay between respiratory inflammation and the lung microbiome.

Short-term changes in frequencies of circulating leukocytes associated with narrowband UVB phototherapy in people with clinically isolated syndrome.

Clinically isolated syndrome (CIS) is the earliest clinical episode in multiple sclerosis (MS). Low environmental exposure to UV radiation is implicated in risk of developing MS, and therefore, narrowband UVB phototherapy might delay progression to MS in people with CIS. Twenty individuals with CIS were recruited, and half were randomised to receive 24 sessions of narrowband UVB phototherapy over a period of 8 weeks. Here, the effects of narrowband UVB phototherapy on the frequencies of circulating immune cells and immunoglobulin levels after phototherapy are reported. Peripheral blood samples for all participants were collected at baseline, and 1, 2, 3, 6 and 12 months after enrolment. An extensive panel of leukocyte populations, including subsets of T cells, B cells, monocytes, dendritic cells, and natural killer cells were examined in phototherapy-treated and control participants, and immunoglobulin levels measured in serum. There were significant short-term increases in the frequency of naïve B cells, intermediate monocytes, and fraction III FoxP3+ T regulatory cells, and decreases in switched memory B cells and classical monocytes in phototherapy-treated individuals. Since B cells are increasingly targeted by MS therapies, the effects of narrowband UVB phototherapy in people with MS should be investigated further.

Investigating the roles of regulatory T cells, mast cells and interleukin-9 in the control of skin inflammation by vitamin D.

Topical application of biologically active vitamin D [1,25-dihydroxyvitamin D (1,25(OH)2D)], or low-calcemic analogues, curb skin inflammation through mechanisms that involve migratory dendritic cells (DCs) and regulatory T (TReg) cells. 1,25(OH)2D also promotes immunoregulation by mast cells, and inhibits the development of T helper type-9 (Th9) cells that secrete interleukin-9 (IL-9). Here, we investigated the ability of topical 1,25(OH)2D to suppress contact dermatitis through an IL-9-dependent process, examining mast cells and IL-9-secreting T cells. Contact dermatitis was modelled in adult BALB/c female mice by initiating a "biphasic ear swelling response" following a single application of 2,4-dinitrofluorobenzene (DNFB). Topical 1,25(OH)2D (125 ng) applied to ear pinnae prior to (but not after) DNFB sensitisation suppressed the efferent phase of the ear swelling response. This dose of 1,25(OH)2D did not cause hypercalcemia. At the peak of the efferent ear swelling response, proportions of TReg (CD3 + Foxp3+) cells and numbers of mast cells were increased in ear skin of 1,25(OH)2D-treated mice. Topical 1,25(OH)2D increased the proportion of Foxp3 + IL-9 + TReg cells and the capacity of TReg cells to secrete IL-9 ex vivo. However, the proportion of the IL-9 + cells of the total TReg cell population was small (< 1%), and the amount of IL-9 secreted by TReg cells from mice treated with IL-9 was low (< 50 pg/ml). Furthermore, injection of anti-IL-9 neutralising antibody (100 µg, intraperitoneally) prior to sensitisation did not significantly reverse the suppressive effects of 1,25(OH)2D. In conclusion, topically applied 1,25(OH)2D suppressed the efferent phase of a biphasic cutaneous ear swelling response through mechanism(s) that may be dependent on mast cells and TReg cells; however, the role of IL-9 in mediating these responses is uncertain. More studies are needed to further characterise the mechanisms by which topical 1,25(OH)2D modulates cell-mediated immune responses central to its suppressive effects upon contact dermatitis.

Higher Serum Immunoglobulin G3 Levels May Predict the Development of Multiple Sclerosis in Individuals With Clinically Isolated Syndrome.

Clinically isolated syndrome (CIS) is a first episode of neurological symptoms that may precede a diagnosis of multiple sclerosis (MS). Therefore, studying individuals with CIS may lead to breakthroughs in understanding the development and pathogenesis of MS. In this study, serum levels of immunoglobulin (Ig)G, IgA, IgM, and IgG1-4 were measured in 20 people with CIS and compared with those in 10 healthy controls (HC) and 8 people with MS. Serum Ig levels in individuals with CIS were compared with (a) the time to their conversion from CIS to MS, (b) serum levels of antibodies to Epstein-Barr virus, (c) frequencies of T regulatory (Treg), T follicular regulatory (Tfr), and B cell subsets, and (d) Treg/Tfr expression of Helios. Serum IgG, IgM, and IgG2 levels were significantly lower in people with CIS than HC, and IgG, IgM, and IgG1 levels were significantly lower in people with CIS than MS. After adjusting for age, sex, and serum 25(OH) vitamin D3 [25(OH)D] levels, CIS was associated with lower serum levels of IgG and IgG2 compared with HC (p = 0.001 and p < 0.001, respectively). People with MS had lower IgG2 levels (p < 0.001) and IgG2 proportions (%IgG; p = 0.007) compared with HC. After adjusting for age, sex, and 25(OH)D, these outcomes remained, in addition to lower serum IgA levels (p = 0.01) and increased IgG3 levels (p = 0.053) in people with MS compared with HC. Furthermore, serum from people with MS had increased proportions of IgG1 and IgG3 (p = 0.03 and p = 0.02, respectively), decreased proportions of IgG2 (p = 0.007), and greater ratios of "upstream" to "downstream" IgG subclasses (p = 0.001) compared with HC. Serum IgG3 proportions (%IgG) from people with CIS correlated with the frequency of plasmablasts in peripheral blood (p = 0.02). Expression of Helios by Treg and Tfr cell subsets from individuals with CIS correlated with levels of serum IgG2 and IgG4. IgG3 levels and proportions of IgG3 (%IgG) in serum at CIS diagnosis were inversely correlated with the time until conversion to MS (p = 0.018 and p < 0.001, respectively), suggesting they may be useful prognostic markers of individuals with CIS who rapidly convert to MS.

A randomised, controlled clinical trial of narrowband UVB phototherapy for clinically isolated syndrome: The PhoCIS study.

BACKGROUND: The natural history of multiple sclerosis (MS) typically presents with the clinically isolated syndrome (CIS), an episode of neurological symptoms caused by central nervous system inflammation or demyelination that does not fulfil the diagnostic criteria for MS. OBJECTIVE: As preclinical studies have suggested that exposure to ultraviolet radiation (UVR) could regulate the development of MS, the Phototherapy for CIS (PhoCIS trial) was established to examine the effects of narrowband UVB phototherapy on patients with CIS, and their conversion to MS. METHODS: Of the 20 participants, half received 24 sessions of narrowband UVB exposure over eight weeks; participants in both arms were followed for 12 months. All participants were supplemented to 25-hydroxyvitamin D3 levels of >80 nmol/l. RESULTS: By 12 months, 100% of those in the no phototherapy arm and 70% in the phototherapy arm had converted to MS, although this difference was not statistically significant. CONCLUSION: This study provides a basis for further studies to determine if there are any benefits of the therapeutic effects of narrowband UVB radiation on MS progression.

Altered regulatory T-cell fractions and Helios expression in clinically isolated syndrome: clues to the development of multiple sclerosis.

Development of multiple sclerosis (MS) is frequently preceded by an acute or subacute neurological disturbance referred to as clinically isolated syndrome (CIS). The specific immunological disturbances present in CIS remain underexamined. This study analysed peripheral blood mononuclear cells from n=18 treatment-naive individuals with recently diagnosed CIS (<120 days) for disturbances in the phenotype of T regulatory (Treg), follicular T regulatory (Tfr), T helper (Th), follicular T helper (Tfh) and B cells. Relative to healthy controls (n=19), CIS was associated with lower proportions of suppressive CD45RA+FoxP3lo Treg and Tfr cells and greater proportions of non-suppressive CD45RA-FoxP3lo and Th17-like Treg and Tfr. Lower Helios expression (maen fluorescent intensity) was measured across all Treg and Tfr fractions in the CIS group, suggesting less potent regulatory function. Greater frequencies of activated, efficient B-cell helper Tfh subsets and a trend for a higher proportion of IgD-CD27- B cells was also detected in the CIS group, characteristics that were positively correlated with Treg and Tfr Helios expression. These results indicate that Treg and Tfr impairment is an early feature in MS.

Response to the Boucher et al. Comments on Fleury et al. Sun Exposure and Its Effects on Human Health: Mechanisms through Which Sun Exposure Could Reduce the Risk of Developing Obesity and Cardiometabolic Dysfunction. Int. J. Environ. Res. Public Health 2016, 13, 999.

We thank Boucher et al. [1] for their interest in our recently published review [2]. [...].

Sun Exposure and Its Effects on Human Health: Mechanisms through Which Sun Exposure Could Reduce the Risk of Developing Obesity and Cardiometabolic Dysfunction.

Obesity is a significant burden on global healthcare due to its high prevalence and associations with chronic health conditions. In our animal studies, ongoing exposure to low dose ultraviolet radiation (UVR, found in sunlight) reduced weight gain and the development of signs of cardiometabolic dysfunction in mice fed a high fat diet. These observations suggest that regular exposure to safe levels of sunlight could be an effective means of reducing the burden of obesity. However, there is limited knowledge around the nature of associations between sun exposure and the development of obesity and cardiometabolic dysfunction, and we do not know if sun exposure (independent of outdoor activity) affects the metabolic processes that determine obesity in humans. In addition, excessive sun exposure has strong associations with a number of negative health consequences such as skin cancer. This means it is very important to "get the balance right" to ensure that we receive benefits without increasing harm. In this review, we detail the evidence around the cardiometabolic protective effects of UVR and suggest mechanistic pathways through which UVR could be beneficial.

Dietary Vitamin D Increases Percentages and Function of Regulatory T Cells in the Skin-Draining Lymph Nodes and Suppresses Dermal Inflammation.

Skin inflammatory responses in individuals with allergic dermatitis may be suppressed by dietary vitamin D through induction and upregulation of the suppressive activity of regulatory T (TReg) cells. Vitamin D may also promote TReg cell tropism to dermal sites. In the current study, we examined the capacity of dietary vitamin D3 to modulate skin inflammation and the numbers and activity of TReg cells in skin and other sites including lungs, spleen, and blood. In female BALB/c mice, dietary vitamin D3 suppressed the effector phase of a biphasic ear swelling response induced by dinitrofluorobenzene in comparison vitamin D3-deficient female BALB/c mice. Vitamin D3 increased the percentage of TReg (CD3+CD4+CD25+Foxp3+) cells in the skin-draining lymph nodes (SDLN). The suppressive activity of TReg cells in the SDLN, mesenteric lymph nodes, spleen, and blood was upregulated by vitamin D3. However, there was no difference in the expression of the naturally occurring TReg cell marker, neuropilin, nor the expression of CCR4 or CCR10 (skin-tropic chemokine receptors) on TReg cells in skin, SDLN, lungs, and airway-draining lymph nodes. These data suggest that dietary vitamin D3 increased the percentages and suppressive activity of TReg cells in the SDLN, which are poised to suppress dermal inflammation.

Vitamin D and immunity.

Vitamin D deficiency has been linked to an increased risk of a wide range of adverse health outcomes. The active form of vitamin D has an important role in calcium metabolism and in bone mineralisation, but the evidence for other health outcomes is mixed, with the strongest effects seen in the weakest epidemiological study designs. There are plausible pathways whereby vitamin D deficiency can impair immune function, resulting in both overactivity and increased risk of autoimmune disease, as well as immune suppression with poorer resistance to infection. Vitamin D status may influence the bacterial flora that constitute the microbiome and affect immune function through this route. Exposure of the skin to ultraviolet radiation causes the production of a range of chemicals, including vitamin D, and new research is exploring possible vitamin D-independent immunomodulatory pathways.

Ultraviolet radiation suppresses obesity and symptoms of metabolic syndrome independently of vitamin D in mice fed a high-fat diet.

The role of vitamin D in curtailing the development of obesity and comorbidities such as the metabolic syndrome (MetS) and type 2 diabetes has received much attention recently. However, clinical trials have failed to conclusively demonstrate the benefits of vitamin D supplementation. In most studies, serum 25-hydroxyvitamin D [25(OH)D] decreases with increasing BMI above normal weight. These low 25(OH)D levels may also be a proxy for reduced exposure to sunlight-derived ultraviolet radiation (UVR). Here we investigate whether UVR and/or vitamin D supplementation modifies the development of obesity and type 2 diabetes in a murine model of obesity. Long-term suberythemal and erythemal UVR significantly suppressed weight gain, glucose intolerance, insulin resistance, nonalcoholic fatty liver disease measures; and serum levels of fasting insulin, glucose, and cholesterol in C57BL/6 male mice fed a high-fat diet. However, many of the benefits of UVR were not reproduced by vitamin D supplementation. In further mechanistic studies, skin induction of the UVR-induced mediator nitric oxide (NO) reproduced many of the effects of UVR. These studies suggest that UVR (sunlight exposure) may be an effective means of suppressing the development of obesity and MetS, through mechanisms that are independent of vitamin D but dependent on other UVR-induced mediators such as NO.