Type 1 and type 2 immune responses in children: their relevance in juvenile arthritis

Sex hormone influence on female-biased autoimmune diseases hints at puberty as an important factor in pathogenesis

The majority of autoimmune diseases affect more women than men, suggesting an important role for sex hormones in regulating immune response. Current research supports this idea, highlighting the importance of sex hormones in both immune and metabolic regulation. Puberty is characterized by drastic changes in sex hormone levels and metabolism. These pubertal changes may be what forms the gulf between men and women in sex bias towards autoimmunity. In this review, a current perspective on pubertal immunometabolic changes and their impact on the pathogenesis of a select group of autoimmune diseases is presented. SLE, RA, JIA, SS, and ATD were focused on in this review for their notable sex bias and prevalence. Due to both the scarcity of pubertal autoimmune data and the differences in mechanism or age-of-onset in juvenile analogues often beginning prior to pubertal changes, data on the connection between the specific adult autoimmune diseases and puberty often relies on sex hormone influence in pathogenesis and established sex differences in immunity that begin during puberty.

Exploring the Evidence for an Immunomodulatory Role of Vitamin D in Juvenile and Adult Rheumatic Disease

Vitamin D is synthesized in the skin following exposure to UVB radiation or is directly absorbed from the diet. Following hydroxylation in the liver and kidneys, vitamin D becomes its bioactive form, 1,25(OH)₂D, which has been described to have potent immunomodulatory capacity. This review will focus on the effect of vitamin D in modulating the dysregulated immune system of autoimmune rheumatic diseases (ARD) patients across age, in particular in arthritis (rheumatoid arthritis and juvenile idiopathic arthritis), and systemic lupus erythematosus (with adult and juvenile onset). As well as delineating the impact of vitamin D on the innate and adaptive immune functions associated with each disease pathology, this review will also summarize and evaluate studies that link vitamin D status with disease prevalence, and supplementation studies that examine the potential benefits of vitamin D on disease outcomes. Exploring this evidence reveals that better designed randomized controlled studies are required to clarify the impact of vitamin D supplementation on ARD outcomes and general health. Considering the accessibility and affordability of vitamin D as a therapeutic option, there is a major unmet need for evidence-based treatment recommendations for the use of vitamin D in this patient population.

Characteristics and relationship of periodontal disease with juvenile idiopathic and rheumatoid arthritis

Background:

Rheumatoid arthritis (RA) is the most prevalent chronic inflammatory disease of the joints. It is correlated with periodontal disease due to similar factors that exist in both diseases. The present study assessed the relationship of periodontal disease with RA and juvenile idiopathic arthritis (JIA).

Materials and Methods:

In this case-control study, 30 RA and 30 JIA patients along with similar number of matched controls were selected among patients referred to Imam Khomeini Hospital, Tehran, Iran. Periodontal parameters including pocket depth (PD), clinical attachment level (CAL), O’Leary and Bay plaque index (PI) and bleeding on probing (BOP) were determined in cases and controls. Erythrocyte sedimentation rate, number of painful and inflamed joints and severity of disease were evaluated in RA and JIA patients. Mann-Whitney U-test nonparametric, Spearman and Pearson's correlation coefficients, and Chi-square tests were used as statistical analysis (α = 0.05).

Results:

PD (4.17 vs. 3.6 mm; P < 0.0001), CAL (4.89 vs. 4.18 mm; P < 0.002), percentage of sites with PD >4 mm (58.83% vs. 44.33%; P < 0.002), percentage of sites with CAL >3 mm (74.13% vs. 64.4%; P < 0.001), percentage of sites with BOP (9.67% vs. 6.87%; P < 0.0001) and PI index (85.73% vs. 80.63%; P < 0.0001) were significantly higher in RA patients than controls. In this group, direct and significant correlations were found between serologic findings, disease severity and number of painful and inflamed joints with periodontal factors. In JIA patients, no significant relationships were found between JIA findings and periodontal parameters.

Conclusion:

Considering the limitations of this study, there was a relationship between RA and periodontal disease. Severity of periodontal disease increases in patients with RA, while no increased risk of periodontal disease or its severity was observed among JIA patients.

Pathophysiology of JIA-associated uveitis

Juvenile idiopathic arthritis (JIA)-associated uveitis is an intriguing manifestation of JIA and an important contributor of long-term damage. Its pathophysiology is still poorly understood. This review summarizes current concepts. JIA is both a multifactorial and polygenetic disease. In the past 2 decades, multiple studies have indicated that the genetic contribution to both JIA and JIA-associated uveitis is modest. From an ophthalmological point of view, much of the pathophysiological data is derived from studies in experimental uveitis animal models. The pathophysiology of the arthritic manifestations of JIA has been studied extensively in humans. These studies have focused on the principal cells of the adaptive immune system, in particular different subsets of regulatory and effector T cells, as well as on antigen presenting cells or dendritic cells. With advancing technology and advancing knowledge of the underlying mechanisms of JIA-associated uveitis, new targets for therapy might evolve in the coming years.

Th1 and Th17 cell subpopulations are enriched in the peripheral blood of patients with systemic juvenile idiopathic arthritis

Objective. The role of the adaptive immune system has not been explored in detail compared with the innate immune system in systemic JIA (sJIA) pathogenesis. The aim of this study was to examine the phenotype of circulating peripheral blood CD4⁺ T-cell subpopulations in a cross-sectional study of sJIA patients during disease remission on medication and during acute flare of the disease.

Methods. Flow cytometry was used to examine the phenotype and cytokine production of IFNγ-, IL-4- and IL-17-producing CD4⁺ T cells in the peripheral blood of 10 sJIA patients with active disease, 9 sJIA with inactive disease, 14 JIA patients with oligoarticular onset, 10 adult control subjects and 10 age-matched control subjects. In parallel, we examined the proportion of FoxP3⁺ Tregs.

Results. IFNγ- and IL-17-producing CD4⁺ T cells and IL-17-producing CD3⁺CD4⁻ T cells were present at higher proportions in the peripheral blood of sJIA patients, irrespective of their disease status. Our data also confirm the known increase of the proportions of IFNγ-producing Th1 cells with increasing age and suggest an increase with age in the IL-17-producing CD4⁺ T-cell population.

Conclusion. This study is the first to describe significantly higher proportions of Th1 and Th17 T helper cell subsets in the peripheral blood of sJIA patients. These proinflammatory cells may play a pathogenic role in sJIA. Our data also emphasize the importance of using paediatric age-matched control subjects when evaluating the T-cell cytokine profile in JIA.

Immunosenescence and juvenile idiopathic arthritis

Aging of the immune system (immunosenescence) is characterized by diminished thymus function, decreased output of recent thymic emigrants, compensatory peripheral proliferation of mature T cells and oligoclonal expansions of specific CD28(-) T cells. Clinical consequences are poor responses to new antigens or vaccinations, increased infection rates with higher morbidity and mortality, and increasing incidence of autoimmune diseases with advancing age. Premature immunosenescence is suggested to play a role in the pathogenesis of adult rheumatoid arthritis and in children with juvenile idiopathic arthritis (JIA). However, so far, there is not enough evidence for supporting one of the two theories: the first, favoring premature immunosenscence in children developing autoimmune conditions as the primary defect causing break-down of self-tolerance; the second, that premature immunosenescence in children with autoimmune disorders is secondary to chronic stimulation and activation of the immune system by inflammatory processes by the autoimmune disease itself. This contradictory view of etiology and pathogenesis of autoimmune diseases in the very young underlines the need for population-based longitudinal studies on immune-risk factors for autoimmune diseases beginning at infancy.

Premature aging of the immune system in children with juvenile idiopathic arthritis

OBJECTIVE

Juvenile idiopathic arthritis (JIA) is an autoimmune disease of the young. The pathogenesis is not completely understood. Premature aging, associated thymic involution, and compensatory autoproliferation could play important roles in the pathogenesis of autoimmunity. We undertook this study to determine whether patients with JIA demonstrate premature immunosenescence.

METHODS

To test this hypothesis, we measured 3 indicators of aging: the percentages and total counts of peripheral blood naive T cells, the frequency of T cell receptor excision circles (TRECs) in naive T cells, and telomeric erosion and Ki-67 expression as estimates of the replicative history of homeostatic proliferation.

RESULTS

JIA patients showed an accelerated loss of CD4+,CD45RA+,CD62L+ naive T cells with advancing age and a compensatory increase in the number of CD4+,CD45RO+ memory T cells. JIA patients demonstrated a significantly decreased frequency of TRECs in CD4+,CD45RA+ naive T cells compared with age-matched healthy donors (P = 0.002). TREC numbers correlated with age only in healthy donors (P = 0.0001). Telomeric erosion in CD4+,CD45RA+ naive T cells was increased in JIA patients (P = 0.01). The percentages of Ki-67-positive CD4+,CD45RA+ naive T cells were increased in JIA patients (P = 0.001) and correlated with disease duration (P = 0.003), which was also an independent factor contributing to telomeric erosion (P = 0.04).

CONCLUSION

Our findings suggest that age-inappropriate T cell senescence and disturbed T cell homeostasis may contribute to the development of JIA. In patients with JIA, dysfunction in the ability to reconstitute the T cell compartment should be considered when exploring new therapeutic strategies.

A comprehensive review of the genetics of juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic arthropathy of childhood which is believed to be influenced by both genetic and environmental factors. The progress in identifying genes underlying JIA susceptibility using candidate gene association studies has been slow. Several associations between JIA and variants in the genes encoding the human leukocyte antigens (HLA) have been confirmed and replicated in independent cohorts. However it is clear that genetic variants outside the HLA also influence susceptibility to JIA. While a large number of non-HLA candidate genes have been tested for associations, only a handful of reported associations such as PTPN22 have been validated. In this review we discuss the principles behind genetic studies of complex traits like JIA, and comprehensively catalogue non-HLA candidate-gene association studies performed in JIA to date and review several validated associations. Most candidate gene studies are underpowered and do not detect associations, and those that do are often not replicated. We also discuss the principles behind genome-wide association studies and discuss possible implications for identifying genes underlying JIA. Finally we discuss several genetic variants underlying multiple clinically distinct autoimmune phenotypes.

Association of two functional polymorphisms in the CCR5 gene with juvenile rheumatoid arthritis

Juvenile rheumatoid arthritis (JRA) is mediated by Th1-immune responses. In children with JRA, synovial T cells express high levels of the Th1-chemokine receptor CC chemokine receptor 5 (CCR5), which has been implicated in susceptibility to rheumatoid arthritis. To test the hypothesis that genetic variation in CCR5 is associated with susceptibility to JRA, we analyzed patterns of variation in the 5'cis-regulatory region of CCR5 in 124 multiplex families from a JRA-affected sibpair registry. After sequencing the upstream region of CCR5, variants were tested for association with JRA by transmission disequilibrium testing. A single nucleotide polymorphism, C-1835T, was significantly undertransmitted to children with early-onset JRA (P<0.01). C-1835T was genotyped in 424 additional simplex and multiplex families. CCR5-1835T allele was undertransmitted in the cohort of all probands with JRA (P<0.02), as well as in those with early-onset (P<0.01) or pauciarticular JRA (P<0.05). Another variant, a 32-bp deletion in the open reading frame of CCR5 (CCR5-Delta32) was also tested in approximately 700 simplex and multiplex families. CCR5-Delta32 was also significantly undertransmitted to probands with early-onset JRA (P<0.05). Both variants are in regions under natural selection, and result in functional consequences. Our results suggest these CCR5 variants are protective against early-onset JRA.

Periodontal conditions in patients with juvenile idiopathic arthritis

OBJECTIVE

Our aim was to compare the periodontal conditions in a group of juvenile idiopathic arthritis (JIA) patients with those in a control group of healthy subjects (CTR).

MATERIAL AND METHODS

Thirty-two patients with JIA and 24 controls were selected. The measurements used to diagnose periodontal disease included plaque and bleeding scores, probing depths (PDs) and clinical attachment loss (CAL). Laboratory indicators of JIA activity included the erythrocyte sedimentation rate (ESR) and capsule-reactive protein (CRP). The Mann-Whitney test was used to evaluate the data (alpha = 0.05).

RESULTS

The mean ages were 15.9 (+/- 2.7) years and 14.7 (+/- 2.3) years for groups JIA and CTR, respectively. The median ESR was 42 mm/h 13 mm/h in the CTR group (p = 0.032) and the median CRP was 1.9 and 0.4 mg/l, respectively (p = 0.001). The prevalence of patients with a proximal attachment loss of 2mm or more in the JIA group was 25% and in controls it was 4.2%. The mean percentages of visible plaque and marginal bleeding were similar in the JIA (54 +/- 22 and 30 +/- 16, respectively) and CTR groups (44 +/- 18 and 29 +/- 11, respectively). The mean percentages of sites with PD > or = 4 mm were significantly higher in the JIA group (3 +/- 4.7) than in the CTR group (0.4 +/- 1.7) (p = 0.012). The mean percentages of sites with proximal CAL > or = 2 mm were 0.7 (+/- 1.4) in the JIA group and 0.001 (+/- 0.2) in the CTR group (p = 0.022).

CONCLUSION

Adolescents with JIA present more periodontal attachment loss than healthy controls, in spite of similar plaque and marginal bleeding levels.

Atopic eczema in early childhood could be protective against Type 1 diabetes

AIMS/HYPOTHESIS

According to the Th1/Th2 paradigm Type 1 diabetes and atopic diseases are assumed to be mutually exclusive on the individual level. We analysed the association between Type 1 diabetes and atopic diseases in a case-control design in order to test the hypothesis that atopic diseases in early childhood could protect against Type 1 diabetes.

METHODS

We carried out a nationwide population-based case-control study enrolling 760 cases newly-diagnosed with Type 1 diabetes under five years of age between July 1992 and December 1995 and 1871 controls randomly selected from the general population and individually matched on sex, age and place of residence. Information on atopic diseases was obtained by a mailed parent-administered questionnaire. Data were analysed by multivariate logistic regression adjusting for potential confounders (family history of diabetes, social status, duration of overall breast feeding, number of children in family, maternal age at delivery).

RESULTS

Atopic eczema was less frequent in diabetic (13.3%) than in non-diabetic children (18.0%) and was significantly associated with a reduced risk of Type 1 diabetes. The adjusted odds ratio was 0.71 (95% CI 0.53-0.96). Hay fever and asthma were not significantly associated with diabetes risk (OR 0.98 (95% CI 0.47-2.01) and 1.46 (95% CI 0.70-3.06), respectively).

CONCLUSION/INTERPRETATION

In this large population-based case-control study in pre-school children an inverse association was observed between atopic eczema and Type 1 diabetes. Thus, in accordance with the Th1/Th2 paradigm development of atopic eczema in early childhood could be protective against childhood Type 1 diabetes.

Ontogeny of Th1 memory responses against a Brucella abortus conjugate

Protective immune responses to intracellular pathogens such as Brucella abortus are characteristically Th1-like. Recently we demonstrated that heat-killed B. abortus (HKBa), a strong Th1 stimulus, conjugated to ovalbumin (HKBA-OVA), but not B. abortus alone, can alter the antigen-specific cytokine profile from Th2- to Th1-like. In this report we study the ability of a single injection of B. abortus to switch a Th2 to a Th1 response in immature mice. One-day- and 1-week-old mice were given a single injection of B. abortus in the absence or presence of OVA, and at maturity mice were challenged with an allergenic preparation, OVA with alum (OVA-A). B. abortus given without OVA did not diminish the subsequent Th2 response in either age group. In contrast, mice receiving a single injection of B. abortus-OVA at the age of 1 week, but not those injected at the age of 1 day, had reversal of the ratio of OVA-specific Th1 to Th2 cells and decreased immunoglobulin E levels after allergen challenge as adults. Within 6 h both 1-day- and 1-week-old mice expressed interleukin-12 p40 mRNA following either B. abortus or B. abortus-OVA administration. However, only the 1-week-old mice exhibited increased expression of gamma interferon (IFN-gamma) mRNA. The absence of the early IFN-gamma response in 1-day-old mice may explain their inability to generate a Th1 memory response. These results suggest that at early stages of immune development, responses to intracellular bacteria may be Th2- rather than Th1-like. Furthermore, they suggest that the first encounter with antigen evokes either a Th1- or a Th2-like response which becomes imprinted, so that subsequent memory responses conform to the original Th bias. This has implications for protection against infectious agents and development of allergic responses.

T-cell and T-cell receptor abnormalities in the immunopathogenesis of juvenile rheumatoid arthritis

Several lines of indirect evidence suggest that the pathologic autoimmune responses in juvenile rheumatoid arthritis may be antigen-driven and T cell-mediated. These include (1) activation markers expressed on synovial T cells suggestive of previous activation in vivo; (2) persistent oligoclonally expanded T-cell populations accumulating preferentially in the synovial compartment; (3) some T-cell receptor complementarity-determining region 3 sequence similarities between different clones in an individual patient; and (4) T-cell derived cytokines of predominantly Th1 type. Whether T-cell contribution is limited to only early stages of the disease (as appears to be the case in collagen-induced arthritis) or T cells are required for the perpetuation of the inflammation at later stages as well, still remains to be determined.