Distinguishing characteristics of pediatric patients with primary hyperoxaluria type 1 in PEDSnet.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is an autosomal recessive inborn error of metabolism that causes oxalate deposition, leading to recurrent calcium oxalate kidney stones, chronic kidney disease and systemic oxalosis, which produces a broad range of serious life-threatening complications. Patients with PH1 have delayed diagnosis due to the rarity of the disease and the overlap with early-onset kidney stone disease not due to primary hyperoxaluria. OBJECTIVE: The objective of this study was to determine the clinical features of individuals <21 years of age with PH1 that precede its diagnosis. We hypothesized that a parsimonious set of features could be identified that differentiate patients with PH1 from patients with non-primary hyperoxaluria-associated causes of early-onset kidney stone disease. STUDY DESIGN: We determined the association between clinical characteristics and PH1 diagnosis in a case-control study conducted between 2009 and 2021 in PEDSnet, a clinical research network of eight US pediatric health systems. Each patient with genetically confirmed PH1 was matched by sex and PEDSnet institution to up to 4 control patients with kidney stones without PH of any type. We obtained patient characteristics and diagnostic test results occurring before to less than 6 months after study entrance from a centralized database query and from manual chart review. Differences were examined using standardized differences and multivariable regression. RESULTS: The study sample included 37 patients with PH1 and 147 controls. Patients with PH1 were younger at diagnosis (median age of 3 vs 13.5 years); 75 % of children with PH1 were less than 8 years-old. Patients with PH1 were more likely to have combinations of nephrocalcinosis on ultrasound or CT (43 % vs 3 %), lower eGFR at diagnosis (median = 52 mL/min/1.73 m2 vs 114 mL/min/1.73 m2), and have normal mobility. Patients with PH1 had higher proportion of calcium oxalate monohydrate kidney stones than controls (median = 100 % vs 10 %). There were no differences in diagnosis of failure to thrive, stone size, or echocardiography results. CONCLUSIONS: Children with PH1 are characterized by presentation before adolescence, nephrocalcinosis, decreased eGFR at diagnosis, and calcium oxalate monohydrate stone composition. If externally validated, these characteristics could facilitate earlier diagnosis and treatment of children with PH1.

IL-27 induction of IL-21 from human CD8+ T cells induces granzyme B in an autocrine manner.

Interleukin (IL)-27 exerts an anti-inflammatory effect on human and mice CD4(+) T cells by inducing IL-10-producing T regulatory 1 cells through induction of IL-21. However, the role of IL-27 and how it regulates IL-21 from human CD8(+) T cells is unclear. Here, we show that the IL-27 receptor is expressed on human CD8(+) T cells and stimulation of human naïve CD8(+) T cells in the presence of IL-27 leads to an increase in IL-21 and interferon (IFN)-γ production. IL-21 induction in IL-27-stimulated human CD8(+) T cells correlates specifically with expression of the transcription factor T-bet. IL-27 stimulation of naïve CD8(+) T cells induces a double-positive T-bet(+) IL-21(+) expressing CD8(+) T-cell population. Furthermore, IL-27 stimulation of human naïve CD8(+) T cells greatly increases expression of granzyme B. Antibody-mediated neutralization of IL-21 abrogates IL-27-induced granzyme B expression. Moreover, direct addition of IL-21 greatly amplifies granzyme B expression in human naïve CD8(+) T cells. Our findings identify IL-27-induced IL-21 as a key autocrine regulator of granzyme B expression in human CD8(+) T cells.

Silencing microRNA-155 ameliorates experimental autoimmune encephalomyelitis.

IFN-γ-producing Th1 and IL-17-producing Th17 cells are the key participants in various autoimmune diseases, including multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). Although both of these T cell subsets are known to be regulated by specific transcription factors and cytokines, the role of microRNAs that control these two inflammatory T cell subsets and whether targeting microRNAs can have therapeutic effects are not known. In this study, we show that microRNA-155 (Mir-155) expression is elevated in CD4(+) T cells during EAE, and Mir-155(-/-) mice had a delayed course and reduced severity of disease and less inflammation in the CNS. The attenuation of EAE in Mir-155(-/-) mice was associated with a decrease in Th1 and Th17 responses in the CNS and peripheral lymphoid organs. The T cell-intrinsic function of Mir-155(-/-) was demonstrated by the resistance of Mir-155(-/-) CD4(+) T cell-repleted Rag-1(-/-) mice to EAE. Finally, we found that anti-Mir-155 treatment reduced clinical severity of EAE when given before and after the appearance of clinical symptoms. These findings demonstrate that Mir-155 confers susceptibility to EAE by affecting inflammatory T cell responses and identify Mir-155 as a new target for therapeutic intervention in multiple sclerosis.

Identification of an IL-27/osteopontin axis in dendritic cells and its modulation by IFN-gamma limits IL-17-mediated autoimmune inflammation.

Dendritic cells (DCs) play a central role in determining the induction of T cell responses. IL-27 production by DCs favors induction of IL-10-producing regulatory T cells, whereas osteopontin (OPN) promotes pathogenic IL-17 T cell responses. The regulatory mechanisms in DCs that control these two cells types are not understood well. Here, we show that IFN-gamma induces IL-27 while inhibiting OPN expression in DCs both in vitro and in vivo and that engagement of IFN-gammaR expressed by DCs leads to suppression of IL-17 production while inducing IL-10 from T cells. DCs modified by IFN-gamma acquire IL-27-dependent regulatory function, promote IL-10-mediated T cell tolerance, and suppress autoimmune inflammation. Thus, our results identify a previously unknown pathway by which IFN-gamma limits IL-17-mediated autoimmune inflammation through differential regulation of OPN and IL-27 expression in DCs.

IL-27 is a key regulator of IL-10 and IL-17 production by human CD4+ T cells.

Although the physiologic pathways that control regulatory T cells (Foxp3-expressing regulatory T cells, IL-10-secreting Tr1 cells) and Th17 cells in rodents have been defined, the factors that control these differentiation pathways in humans are not well understood. In this study, we show that IL-27 promotes the differentiation of IL-10-secreting Tr1 cells while inhibiting Th17 generation and molecules associated with Th17 function. Furthermore, IL-27 inhibits IL-17-polarizing cytokines on dendritic cells, which in turn decrease IL-17 secretion from T cells. Our results demonstrate that IL-27 plays a key role in human T cells by promoting IL-10-secreting Tr1 cells and inhibiting Th17 cells and thus provides a dual regulatory mechanism to control autoimmunity and tissue inflammation.

Increased osteopontin expression in dendritic cells amplifies IL-17 production by CD4+ T cells in experimental autoimmune encephalomyelitis and in multiple sclerosis.

Osteopontin (Opn) is a broadly expressed pleiotropic cytokine, and has been shown to play an important role in various autoimmune diseases, including multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). It is reported that Opn exacerbates EAE by skewing T cell differentiation toward IFN-gamma-producing Th1 cells. Opn expression in dendritic cells (DCs) and its role in IL-17 induction from T cells during EAE or MS are unknown. We found that during EAE, Opn expression is elevated in DCs both in the periphery and in the CNS. There was increased expression of Opn receptor on T cells, and Opn induced IL-17 production by CD4(+) T cells via the beta(3) integrin receptor and Opn inhibited IL-10 production via the CD44 receptor. Furthermore, anti-Opn treatment reduced clinical severity of EAE by reducing IL-17 production. Anti-Opn was also effective in reducing clinical severity of EAE when given after the appearance of clinical symptoms. Analogous to EAE, in subjects with MS, we found increased expression of Opn in DCs and increased expression of the Opn receptors CD44, beta(3), and alpha(v) on T cells. Furthermore, Opn-stimulated CD4(+) T cells from MS patients produced significantly higher amounts of IL-17. Our results demonstrate a role for DC-produced Opn both in EAE and MS that is linked to the production of IL-17.

NF-kappaB-dependent regulation of the timing of activation-induced cell death of T lymphocytes.

One of the mechanisms by which activated T cells die is activation-induced cell death (AICD). This pathway requires persistent stimulation via the TCR and engagement of death receptors. We found that TCR stimulation led to transient nuclear accumulation of the NF-kappaB component p65/RelA. In contrast, nuclear c-Rel levels remained high even after extended periods of activation. Loss of nuclear p65/RelA correlated with the onset of AICD, suggesting that p65/RelA target genes may maintain cell viability. Quantitative RNA analyses showed that three of several putative NF-kappaB-dependent antiapoptotic genes were expressed with kinetics that paralleled nuclear expression of p65/RelA. Of these three, ectopic expression only of Gadd45beta protected significantly against AICD, whereas IEX-1 and Bcl-x(L) were much less effective. We propose that the timing of AICD, and thus the length of the effector phase, are regulated by transient expression of a subset of p65/RelA-dependent antiapoptotic genes.