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Objectives: Very‐long‐chain acyl‐CoA dehydrogenase deficiency (VLCADD) is a disorder of fatty acid oxidation. Symptoms are managed by dietary supplementation with medium‐chain fatty acids that bypass the metabolic block. However, patients remain vulnerable to hospitalisations because of rhabdomyolysis, suggesting pathologic processes other than energy deficit. Since rhabdomyolysis is a self‐destructive process that can signal inflammatory/immune cascades, we tested the hypothesis that inflammation is a physiologic dimension of VLCADD. Methods: All subjects (n = 18) underwent informed consent/assent. Plasma cytokine and cytometry analyses were performed. A prospective case analysis was carried out on a patient with recurrent hospitalisation. Health data were extracted from patient medical records. Results: Patients showed systemic upregulation of nine inflammatory mediators during symptomatic and asymptomatic periods. There was also overall abundance of immune cells with high intracellular expression of IFNγ, IL‐6, MIP‐1β (CCL4) and TNFα, and the transcription factors p65‐NFκB and STAT1 linked to inflammatory pathways. A case analysis of a patient exhibited already elevated plasma cytokine levels during diagnosis in early infancy, evolving into sustained high systemic levels during recurrent rhabdomyolysis‐related hospitalisations. There were corresponding activated leukocytes, with higher intracellular stores of inflammatory molecules in monocytes compared to T cells. Exposure of monocytes to long‐chain free fatty acids recapitulated the cytokine signature of patients. Conclusion: Pervasive plasma cytokine upregulation and pre‐activated immune cells indicate chronic inflammatory state in VLCADD. Thus, there is rationale for practical implementation of clinical assessment of inflammation and/or translational testing, or adoption, of anti‐inflammatory intervention(s) for personalised disease management. [ABSTRACT FROM AUTHOR]

Suppression of the insulin‐like growth factor‐1 (IGF‐1) signaling pathway reduces age‐related disorders and increases lifespan across species, making the IGF‐1 pathway a key regulator of aging. Previous in vitro intervertebral disc cell studies have reported the pro‐anabolic effect of exogenously adding IGF‐1 on matrix production. However, the overall effects of suppressing IGF‐1 signaling on age‐related intervertebral disc degeneration (IDD) is not known. Here, the effects of suppressing IGF‐1 signaling on age‐related IDD in vivo were examined using PAPPA−/− mice. These are animals with targeted deletion of pregnancy‐associated plasma protein A (PAPPA), the major protease that cleaves inhibitory IGF binding proteins that control bioavailability of IGF‐1 for cell signaling. Compared to age‐matched wild‐type (Wt) littermates, reduced levels of matrix proteoglycan (PG) and aggrecan were seen in discs of 23‐month old PAPPA−/− mice. Decreased aggrecanolysis and expression of two key catabolic markers, matrix metalloproteinase‐3 and a disintegrin and metalloproteinase with thrombospondin motifs‐4, were also observed in discs of old PAPPA−/− mice compared to Wt littermates. Suppressing IGF‐1 signaling has been implicated to shift cellular metabolism toward maintenance rather than growth and decreasing cellular senescence. Along this line, discs of old PAPPA−/− mice also exhibited lower cellular senescence, assessed by p53 and lamin B1 markers. Collectively, the data reveal complex regulation of disc matrix homeostasis by PAPPA/IGF‐1 signaling during chronologic aging, that is, reduced IGF‐1 bioavailability confers the benefit of decreasing disc cellular senescence and matrix catabolism but also the disadvantage of decreasing disc PG matrix anabolism. This pathway requires further mechanistic elucidation before IGF‐1 could be considered as a therapeutic growth factor for treating IDD. [ABSTRACT FROM AUTHOR]

Objective CD8+ T cells lacking CD28 were originally reported to be a characteristic feature of juvenile idiopathic arthritis (JIA), but the relevance of these unusual cells to this disease remains to be elucidated. Because of recent evidence that loss of CD28 cells is typical of terminally differentiated lymphocytes, the aim of this study was to examine functional subsets of CD8+ T cells in patients with JIA. Methods Blood and/or waste synovial fluid samples were collected from children with a definite diagnosis of JIA (n = 98). Deidentified peripheral blood (n = 33) and cord blood (n = 13) samples from healthy donors were also collected. CD8+ and CD4+ T cells were screened for novel receptors, and where indicated, bioassays were performed to determine the functional relevance of the identified receptor. Results JIA patients had a naive T cell compartment with shortened telomeres, and their entire T cell pool had reduced proliferative capacity. They had an overabundance of CD31+CD28nullCD8+ T cells, which was a significant feature of oligoarticular JIA (n = 62) as compared to polyarticular JIA (n = 36). CD31+ CD28nullCD8+ T cells had limited mitotic capacity and expressed high levels of the senescence antigens histone γH2AX and/or p16. Ligation of CD31, which was independent of the T cell receptor (TCR), sufficiently induced tyrosine phosphorylation, vesicle exocytosis, and production of interferon-γ and interleukin-10. Conclusion These data provide the first evidence of cell senescence, as represented by CD31+CD28null CD8+ T cells, in the pathophysiology of JIA. Activation of these unusual cells in a TCR-independent manner suggests that they are maladaptive and could be potential targets for immunotherapy. [ABSTRACT FROM AUTHOR]

The article focuses on the study that examines the composition, organization, and molecular milieu of the cellular infiltrates in the muscles of juvenile dermatomyositis (DM) children-patients. It states that researchers investigated the in situ formation of lymphoid microstructures since plasmacytoid dendrtic cells (PDCs) and lymphocyte infiltrates express CCL19 and CCl21. The study suggests that lymphoneogenesis is an early disease component in juvenile DM.

The article presents a study which examined whether dendritic cells (DCs) are constituents of muscle inflammation in juvenile dermatomyositis (DM). Chemokine expression of the muscle-infiltrating cells was studied by laser capture microdissection and quantitative polymerase chain reaction. It concludes that the results of the study are consistent with the idea that plasmacytoid DCs are mediators of muscle inflammation in juvenile DM.

The loss of CD28 expression on T cells is the most consistent biological indicator of aging in the human immune system, and the frequency of CD28null T cells is a key predictor of immune incompetence in the elderly. There is also mounting evidence for the high frequency of these unusual T cells among patients with inflammatory syndromes or with chronic infections disproportionate with their age. In these pathological states, CD28null T cells likely represent prematurely senescent lymphocytes due to persistent immune activation. Unlike the situation inCD28gene knockout mice that have anergic CD280/0 T cells, human CD28null T cells are functionally active, long-lived, oligoclonal lymphocytes that lack or have limited proliferative capacity. Results of replicative senescence studies show that CD28null T cells are derived from CD28+ precursors that have undergone repeated stimulation, indicating that CD28 silencing underlies the program of T-cell aging. Dissection of the machinery regulating CD28 expression is paving the way in elucidating the molecular events leading to immune senescence as well as providing clues into the functional rejuvenation of senescent T cells. [ABSTRACT FROM AUTHOR]

Background/Purpose: JIA is the banner diagnosis for a heterogenous group of rheumatic conditions characterized by local inflammation and destruction of the joint space and systemic manifestations. Pro-inflammatory cytokines derived from T cells are considered effectors of disease. Recent data has shown that some of these cytokines come directly from a distinct subset of T cells expressing CD31, an adhesion molecule expressed by granulocytes and endothelial cells. In the present work, we examined whether the array of cytokines in blood and synovial fluid of patients are the same array produced by T cells activation through CD31 ligation independent of the TCR. We propose that CD31-driven cytokine production by T cells is a self-perpetuating mechanism of local and systemic inflammation in JIA. Methods: Following informed consent/assent, blood and/or synovial fluid were collected from patients with oligoarticular and polyarticular JIA. Similar blood samples were also collected from healthy subjects. Cytokine composition of the plasma and/or fluid were subjected to multiplex analysis using the Luminex platform. Phenotypes of mononuclear cells in blood and synovial fluid were examined by multicolor flow cytometry. Drawing from the results of the Luminex assay, receptor crosslinking bioassays using primary CD31+ T cells (in blood and/or synovial fluid) and CD31+ T cell lines were conducted. Cytokine production by these cells were assessed by flow cytometry and/or by Luminex. Results: The overall cytokine signature of JIA characterized by the dominance of IL-6, IL-10 and TNFα. Unexpectedly, patients with oligoarticular disease showed higher levels of IFNγ and IL-17 family cytokines than those with polyarticular disease. Both types of patients however showed a similar cellular signature characterized by the preponderance of T cells deficient in CD4, CD8, and CD28, but expressing CD31. Results of CD31 cross-linking bioassays, using either specific antibody or its recombinant ligand CD38, showed high levels of induction of IL-2, IL-17 and IFNγ. Specificity of CD31-driven, TCR-dependent cytokine production was verified by similar bioassays using somatic somatic T cell line mutants Loucy and JRT3 that lack TCR and TCR/CD3, respectively, but are both CD31+. The observed cytokine production was associated with the phosphorylation of the signaling substrates ZAP70, cAbl, and p65-NFKB. Conclusion: Our data show that the cytokine signature of oligoarticular JIA appears distinct with the dominance of IFNγ and IL17. TCR independent, CD31-driven induction of these cytokines suggests maladaptive T cell function in JIA. Further investigation on the relevance of IFNγ and IL-17 to disease activity/clinical outcomes, and the CD31 signaling pathway will pave way to innovations in immunotherapy in JIA. [ABSTRACT FROM AUTHOR]

Objective: To examine whether dendritic cells (DCs) are constituents of muscle inflammation in juvenile dermatomyositis (DM)., Methods: The types, numbers, and activation state of DC subsets in inflamed muscle tissue from patients with juvenile DM and in noninflamed muscle tissue from control subjects were examined by multicolor immunofluorescence. Chemokine expression of the muscle-infiltrating cells was examined by laser capture microdissection and quantitative polymerase chain reaction., Results: Plasmacytoid DCs were the predominant component of the inflamed muscle tissue from patients with juvenile DM. These cells were identified by coexpression of CD4 and CD123, but not CD11c, and also expressed CD83, indicating maturity of the cells. In contrast, in noninflamed muscle, plasmacytoid DCs were scarce and did not express CD83. Mononuclear cells surrounding the blood vessels of inflamed muscle contained abundant transcripts of CCL19 and CCL21, but very little CCL18 transcripts. In contrast, cells from noninflamed muscle contained negligible amounts of CCL19 and CCL21, but had high amounts of CCL18. Both the inflamed and noninflamed muscle tissue had equivalent levels of CXCL12 transcripts, but inflamed muscle contained more transcripts of the CXCL12 receptor CXCR4., Conclusion: These findings are consistent with the idea that plasmacytoid DCs are mediators of muscle inflammation in juvenile DM. The abundance of CD83+ plasmacytoid DCs in perivascular areas and the overexpression of CCL19 and CCL21 in perivascular cellular foci suggest that in situ activation and maturation of resident plasmacytoid DCs are central to the initiation and perpetuation of muscle inflammation in juvenile DM.

Objective: T cells deficient in CD28 expression have been implicated in the pathogenesis of rheumatoid arthritis (RA). Given that CD28-null T cells are functionally heterogeneous, we undertook this study to screen for novel receptors on these cells., Methods: Seventy-two patients with RA (ages 35-84 years) and 53 healthy persons (32 young controls ages 19-34 years, 21 older controls ages 39-86 years) were recruited. Phenotypes and proliferative capacity of T cells from fresh leukocytes and of long-term cultures were monitored by flow cytometry. Lung biopsy specimens from patients with RA-associated interstitial pneumonitis (IP) were examined by immunohistochemistry. Receptor functionality was assessed by crosslinking bioassays., Results: Chronic stimulation of CD28(+) T cells in vitro yielded progenies that lacked CD28 but that gained CD56. Ex vivo analysis of leukocytes from patients with extraarticular RA showed a higher frequency of CD56(+),CD28-null T cells than in patients with disease confined to the joints or in healthy controls. CD56(+),CD28-null T cells had nil capacity for proliferation, consistent with cellular senescence. CD56(+) T cells had skewed T cell receptor (TCR) alpha/beta-chain usage and restricted TCR third complementarity-determining region spectra. Histologic studies showed that CD56(+) T cells were components of cellular infiltrates in RA-associated IP. CD56 crosslinking on T cells sufficiently induced cytokine production, although CD56/TCR coligation induced higher production levels., Conclusion: Chronic activation of T cells induces counterregulation of CD28 and CD56 expression. The loss of CD28 is accompanied by the gain of CD56 that confers TCR-independent and TCR-dependent activation pathways. We propose that accumulation of CD56(+) T cells in RA contributes to maladaptive immune responses and that CD56(+) T cells are potential targets for therapy.

Objective: The immune system of patients with rheumatoid arthritis (RA) is characterized by the accumulation of CD4+ T cells deficient in CD28 expression and the up-regulation of tumor necrosis factor alpha (TNFalpha). Previous in vitro studies have shown that TNFalpha induces transcriptional silencing of the CD28 gene. Because reduced expression of CD28 in T cells compromises immunocompetence, we examined whether CD28 expression is reduced in patients with RA in vivo and whether the reduction is related to TNFalpha., Methods: Patients with RA and age-matched individuals were recruited. Peripheral blood mononuclear cells were stained for CD3, CD4, CD8, CD28, TNF receptor I (TNFRI), and TNFRII, and analyzed by quantitative flow cytometry. The number of CD28 and TNFR molecules was monitored in a subgroup of patients with RA undergoing treatment with anti-TNFalpha., Results: In addition to higher frequencies of CD28null T cells, patients with RA had significantly reduced numbers of CD28 and TNFRI molecules on CD4+,CD28+ T cells. Normal expression could be restored in vitro by overnight culture, suggesting that CD28 in patients was modulated by exogenous factors. In contrast, treatment with TNFalpha in vitro resulted in further down-regulation. CD28 expression was normalized in patients undergoing TNFalpha-neutralizing therapy., Conclusion: Overproduction of TNFalpha in RA induces a global down-regulation of CD28 in CD4+ T cells and may cause reduced sensitivity to costimulatory signals in T cell responses.

Objective: Lymphotoxin beta (LTbeta), a cytokine produced by T cells and B cells, plays a central role in the normal development of lymph nodes and is critical in the formation of ectopic germinal center reactions in rheumatoid synovitis. Because resident fibroblast-like synoviocytes (FLS) express receptors for LTbeta, we examined the consequences of FLS activation by LTbeta., Methods: FLS from patients with rheumatoid arthritis were isolated and examined for the expression of LTbeta receptor. FLS were incubated with LTalpha1beta2 and assayed for the production of cytokines and chemokines and the up-regulation of adhesion molecules., Results: Exposure of FLS to recombinant LTalpha1beta2 resulted in the production of multiple inflammatory cytokines and metalloproteinases, implicating FLS as amplifiers of the inflammatory process in the inflamed joint. Additionally, LTalpha1beta2 was found to up-regulate the expression of cell adhesion molecules, rendering FLS to efficient adhesion substrates for T cells. LTalpha1beta2 also induced production of the chemokines CCL2 and CCL5, which elicited transmigration activity of T cells. Upon stimulation with LTalpha1beta2, FLS did not acquire characteristics of follicular dendritic cells., Conclusion: These data document that FLS are involved in multiple stages of the inflammatory process, including the recruitment and retention of lymphocytes in the synovial microenvironment. We propose that the heterotypic interaction between LTbeta-producing lymphocytes and responding FLS contributes to the establishment of complex lymphoid microstructures, and that this may be one element that defines susceptibility of the synovial membrane to lymphoid organogenesis.