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OBJECTIVE—Perforin plays a key role in cell-mediated cytotoxicity. Mutations of its gene, PRF1, cause familial hemophagocytic lymphohistiocytosis but have also been associated with lymphomas and the autoimmune/lymphoproliferative syndrome. The aim of this work was to investigate the role of PRF1 variations in type 1 diabetes. RESEARCH DESIGN AND METHODS—We typed for the N252S and A91V variations in an initial population of 352 type 1 diabetic patients and 816 control subjects and a second population of 365 patients and 964 control subjects. Moreover, we sequenced the coding sequence and intron-exons boundaries in 200 patients and 300 control subjects. RESULTS—In both cohorts, allelic frequency of N252S was significantly higher in patients than in control subjects (combined cohorts: 1.5 vs. 0.4%; odds ratio 6.68 [95% CI 1.83–7.48]). Sequencing of the entire coding region detected one novel mutation in one patient, causing a P477A amino acid change not detected in 199 patients and 300 control subjects. Typing for HLA-DQA1 and DQB1 alleles showed that type 1 diabetes–predisposing DQα/DQβ heterodimers were less frequent in patients carrying N252S or P477A than in those carrying wild-type PRF1. We previously found that natural killer (NK) activity is not decreased in most N252S heterozygotes, but we detected one whose NK activity was normal at the age of 12 but strikingly low in early childhood. Here, we discovered that NK function was low in three heterozygotes in early childhood, one homozygous adult, and in the subject carrying P477A. CONCLUSIONS—These data suggest that N252S and possibly other PRF1 variations are susceptibility factors for type 1 diabetes development.

Objective Hereditary periodic fever syndromes (HPFs) develop as a result of uncontrolled activation of the inflammatory response, with a substantial contribution from interleukin-1β or tumor necrosis factor α (TNFα). The HPFs include familial Mediterranean fever (FMF), hyperimmunoglobulinemia D with periodic fever syndrome (HIDS), TNF receptor–associated syndrome (TRAPS), and cryopyrinopathies, which are attributable to mutations of the MEFV, MVK, TNFRSF1A, and CIAS1 genes, respectively. However, in many patients, the mutated gene has not been determined; therefore, the condition in these patients with an HPF-like clinical picture is referred to as idiopathic periodic fever (IPF). The aim of this study was to assess involvement of X-linked inhibitor of apoptosis (XIAP), which plays a role in caspase inhibition and NF-κB signaling, both of which are processes that influence the development of inflammatory cells. Methods The XIAP gene (X-linked) was sequenced in 87 patients with IPF, 46 patients with HPF (13 with HIDS, 17 with TRAPS, and 16 with FMF), and 182 healthy control subjects. The expression of different alleles was evaluated by sequencing XIAP-specific complementary DNA mini-libraries and by real-time polymerase chain reaction and Western blot analyses. The functional effect of XIAP on caspase 9 activity was assessed by a fluorimetric assay, and cytokine secretion was evaluated by enzyme-linked immunosorbent assay. Results Sequencing disclosed a 1268A>C variation that caused a Q423P amino acid substitution. The frequency of 423Q-homozygous female patients and 423Q-hemizygous male patients was significantly higher in the IPF group than in the control group (69% versus 51%; odds ratio 2.17, 95% confidence interval 1.23–3.87, P = 0.007), whereas no significant difference was detected in the HPF group (59%) compared with controls. In primary lymphocytes and transfected cell lines, 423Q, as compared with 423P, was associated with higher XIAP protein and messenger RNA expression and lower caspase 9 activation. In lipopolysaccharide-activated monocytes, 423Q was associated with higher secretion of TNFα. Conclusion These results suggest that 423Q is a predisposing factor for IPF development, possibly through its influence on monocyte function.

KSR1 is a mitogen-activated protein (MAP) kinase scaffold that enhances the activation of the MAP kinase extracellular signal-regulated kinase (ERK). The function of KSR1 in NK cell function is not known. Here we show that KSR1 is required for efficient NK-mediated cytolysis and polarization of cytolytic granules. Single-cell analysis showed that ERK is activated in an all-or-none fashion in both wild-type and KSR1-deficient cells. In the absence of KSR1, however, the efficiency of ERK activation is attenuated. Imaging studies showed that KSR1 is recruited to the immunological synapse during T-cell activation and that membrane recruitment of KSR1 is required for recruitment of active ERK to the synapse.

Macrophage colony stimulating factor (MCSF) influences proliferation and survival of mononuclear phagocytes through the CSF-1 receptor. The DAP12 adaptor protein, which transduces signals emanating from various myeloid receptors, is critical for mononuclear phagocyte function. DAP12-mutant mice and humans show defects in osteoclasts and microglia and exhibit brain and bone abnormalities. Here, we demonstrated that DAP12 deficiency impairs MCSF-induced macrophage proliferation and survival in vitro. In addition, DAP12-deficient mice show fewer microglia in defined central nervous system areas, and DAP12-deficient progenitors regenerate myeloid cells inefficiently following BM transplantation. MCSF-CSF1-R signaling induced stabilization and nuclear translocation of β-catenin, which activates cell cycle genes. DAP12 was essential for phosphorylation and nuclear accumulation of β-catenin. These results outline a mechanistic explanation for the multiple defects in DAP12-deficient mononuclear phagocytes.

6 páginas, 2 figuras, 3 tablas -- PAGS nros. 193-198, Human ICOS is a T cell costimulatory molecule supporting IL10 secretion. A pilot study investigating variations of the ICOS gene 3'UTR detected 8 polymorphisms forming three haplotypes (A, B, C). Haplotype-A and -C displayed the highest difference. Activated T cells from healthy AA homozygotes expressed significantly less ICOS and secreted more IL10 than AC heterozygotes, whereas AB heterozygotes displayed intermediate levels. Analysis of 441 multiple sclerosis patients and 793 controls showed that frequency of AA homozygosity was significantly lower in MS patients with relapsing–remitting onset (N = 416) than in controls (OR = 0.70). Moreover, AA patients with relapsing–remitting onset had lower relapse rate and multiple sclerosis severity score than non-AA patients, This work was partially supported by Telethon grant E1170 (Rome), FISM grant 2005/R/10 (Genoa), AIRC (Milan), PRIN Project (MIUR, Rome), Fondazione Cariplo (Milan), Compagnia di San Paolo (Turin), Fondazione Cassa di Risparmio di Cuneo (Cuneo), Regione Piemonte (Turin), and Associazione “Amici di Jean” (Turin)

Mutations decreasing function of the Fas death receptor cause the autoimmune lymphoproliferative syndrome (ALPS) with autoimmune manifestations, spleen/lymph node enlargement, and expansion of CD4/CD8-negative T cells. Dianzani Autoimmune Lymphoproliferative Disease (DALD) is a variant lacking this expansion. Perforin is involved in cell-mediated cytotoxicity and its biallelic mutations cause familial hemophagocytic lymphohistiocytosis (HLH). We previously described an ALPS patient carrying heterozygous mutations of the Fas and perforin genes and suggested that they concurred in ALPS. This work extends the analysis to 14 ALPS, 28 DALD, and 816 controls, and detects an N252S amino acid substitution in 2 ALPS, and an A91V amino acid substitution in 6 DALD. N252S conferred an OR = 62.7 (P = .0016) for ALPS and A91V conferred an OR = 3 (P = .016) for DALD. Copresence of A91V and variations of the osteopontin gene previously associated with DALD conferred an OR = 17 (P = .0007) for DALD. In one N252S patient, NK activity was strikingly defective in early childhood, but became normal in late childhood. A91V patients displayed lower NK activity than controls. These data suggest that perforin variations are a susceptibility factor for ALPS/DALD development in subjects with defective Fas function and may influence disease expression.