Promotion and prevention of autoimmune disease by CD8+ T cells

Until recently, little was known about the importance of CD8+ T effectors in promoting and preventing autoimmune disease development. CD8+ T cells can oppose or promote autoimmune disease through activities as suppressor cells and as cytotoxic effectors. Studies in several distinct autoimmune models and data from patient samples are beginning to establish the importance of CD8+ T cells in these diseases and to define the mechanisms by which these cells influence autoimmunity. CD8+ effectors can promote disease via dysregulated secretion of inflammatory cytokines, skewed differentiation profiles and inappropriate apoptosis induction of target cells, and work to block disease by eliminating self-reactive cells and self-antigen sources, or as regulatory T cells. Defining the often major contribution of CD8+ T cells to autoimmune disease and identifying the mechanisms by which they alter the pathogenesis of disease is a rapidly expanding area of study and will add valuable information to our understanding of the kinetics, pathology and biology of autoimmune disease.     

Ex‐vivo analysis of human Natural Killer T cells demonstrates heterogeneity between tissues and within established CD4+ and CD4− subsets

Our understanding of human type 1 natural killer T (NKT) cells has been heavily dependent on studies of cells from peripheral blood. These have identified two functionally distinct subsets defined by expression of CD4, although it is widely believed that this underestimates the true number of subsets. Two recent studies supporting this view have provided more detail about diversity of the human NKT cells, but relied on analysis of NKT cells from human blood that had been expanded in vitro prior to analysis. In this study we extend those findings by assessing the heterogeneity of CD4⁺ and CD4⁻ human NKT cell subsets from peripheral blood, cord blood, thymus and spleen without prior expansion ex vivo, and identifying for the first time cytokines expressed by human NKT cells from spleen and thymus. Our comparative analysis reveals highly heterogeneous expression of surface antigens by CD4⁺ and CD4⁻ NKT cell subsets and identifies several antigens whose differential expression correlates with the cytokine response. Collectively, our findings reveal that the common classification of NKT cells into CD4⁺ and CD4⁻ subsets fails to reflect the diversity of this lineage, and that more studies are needed to establish the functional significance of the antigen expression patterns and tissue residency of human NKT cells.     

Activated γδ T cells inhibit osteoclast differentiation and resorptive activity in vitro

Extensive evidence suggests that the immune system exerts powerful effects on bone cells, particularly in chronic disease pathologies such as rheumatoid arthritis (RA). The chronic inflammatory state in RA, particularly the excessive production of T cell‐derived proinflammatory cytokines such as tumour necrosis factor (TNF)‐α and interleukin (IL)‐17, triggers bone erosions through the increased stimulation of osteoclast formation and activity. While evidence supports a role for IL‐17 and TNF‐α secreted by conventional CD4⁺ T cells in RA, recent evidence in animal models of RA have implicated γδ T cells as a major producer of pathogenic IL‐17. However, the capacity of γδ T cells to influence osteoclast formation and activity in humans has not yet been investigated widely. To address this issue we investigated the effects of γδ T cells on osteoclast differentiation and resorptive activity. We have demonstrated that anti‐CD3/CD28‐stimulated γδ T cells or CD4⁺ T cells inhibit human osteoclast formation and resorptive activity in vitro. Furthermore, we assessed cytokine production by CD3/CD28‐stimulated γδ T cells and observed a lack of IL‐17 production, with activated γδ T cells producing abundant interferon (IFN)‐γ. The neutralization of IFN‐γ markedly restored the formation of osteoclasts from precursor cells and the resorptive activity of mature osteoclasts, suggesting that IFN‐γ is the major factor responsible for the inhibitory role of activated γδ T cells on osteoclastogenesis and resorptive activity of mature osteoclasts. Our work therefore provides new insights on the interactions between γδ T cells and osteoclasts in humans.     

B6.g7 mice reconstituted with BDC2·5 non‐obese diabetic (BDC2·5NOD) stem cells do not develop autoimmune diabetes

In BDC2·5 non‐obese diabetic (BDC2·5NOD) mice, a spontaneous model of type 1 diabetes, CD4⁺ T cells express a transgene‐encoded T cell receptor (TCR) with reactivity against a pancreatic antigen, chromogranin. This leads to massive infiltration and destruction of the pancreatic islets and subsequent diabetes. When we reconstituted lethally irradiated, lymphocyte‐deficient B6.g7 (I‐A^g7+) Rag^–/– mice with BDC2·5NOD haematopoietic stem and progenitor cells (HSPC; ckit⁺Lin^–Sca‐1^hi), the recipients exhibited hyperglycaemia and succumbed to diabetes. Surprisingly, lymphocyte‐sufficient B6.g7 mice reconstituted with BDC2·5NOD HSPCs were protected from diabetes. In this study, we investigated the factors responsible for attenuation of diabetes in the B6.g7 recipients. Analysis of chimerism in the B6.g7 recipients showed that, although B cells and myeloid cells were 98% donor‐derived, the CD4⁺ T cell compartment contained ～50% host‐derived cells. These host‐derived CD4⁺ T cells were enriched for conventional regulatory T cells (T_regs) (CD25⁺forkhead box protein 3 (FoxP3)⁺] and also for host‐ derived CD4⁺CD25^–FoxP3^– T cells that express markers of suppressive function, CD73, FR4 and CD39. Although negative selection did not eliminate donor‐derived CD4⁺ T cells in the B6.g7 recipients, these cells were functionally suppressed. Thus, host‐derived CD4⁺ T cells that emerge in mice following myeloablation exhibit a regulatory phenoytpe and probably attenuate autoimmune diabetes. These cells may provide new therapeutic strategies to suppress autoimmunity.     

Effects of O-GlcNAcylation on functional mitochondrial transfer from astrocytes

Mitochondria may be transferred from cell to cell in the central nervous system and this process may help defend neurons against injury and disease. But how mitochondria maintain their functionality during the process of release into extracellular space remains unknown. Here, we report that mitochondrial protein O-GlcNAcylation is a critical process to support extracellular mitochondrial functionality. Activation of CD38-cADPR signaling in astrocytes robustly induced protein O-GlcNAcylation in mitochondria, while oxygen-glucose deprivation and reoxygenation showed transient and mild protein modification. Blocking the endoplasmic reticulum – Golgi trafficking with Brefeldin A or slc35B4 siRNA reduced O-GlcNAcylation, and resulted in the secretion of mitochondria with decreased membrane potential and mtDNA. Finally, loss-of-function studies verified that O-GlcNAc-modified mitochondria demonstrated higher levels of neuroprotection after astrocyte-to-neuron mitochondrial transfer. Collectively, these findings suggest that post-translational modification by O-GlcNAc may be required for supporting the functionality and neuroprotective properties of mitochondria released from astrocytes.     

CD117 expression in operable oesophageal squamous cell carcinomas predicts worse clinical outcome

Aims

To investigate the aberrant expression of CD117 in oesophageal squamous cell carcinoma (SCC) and its prognostic significance.

Methods and results

Immunohistochemical staining for CD117 was performed on tissue microarray and routine tissue sections from 157 oesophageal SCC patients and 10 normal oesophageal epithelia adjacent to tumour. The positive rate of CD117 expression was 29.9% in oesophageal SCC tissues, whereas no CD117 expression was detected in the 10 normal oesophageal epithelia. CD117 expression was significantly associated with T stage (P < 0.001), distant metastasis (P = 0.015), lymph node metastasis (P = 0.019), and clinical stage (P = 0.021). Progression‐free survival in the patients with CD117‐positive tumours was shorter than that in the patients with CD117‐negative tumours (P = 0.010). In univariate analyses, CD117 expression was the most significant factor for overall survival of oesophageal SCC patients (P < 0.001), followed by lymph node metastasis (P = 0.001), T stage (P = 0.002), clinical stage (P = 0.006), distant metastasis (P = 0.020), and histological grade (P = 0.027). Multivariate analyses verified that CD117 expression was an independent prognostic marker for oesophageal SCC patients (P = 0.002). In addition, CD117 expression predicted poorer survival in patients without distant metastases.

Conclusions

CD117 expression in operable oesophageal SCC may be a valuable prognostic marker, and detection of its expression in clinical samples may be useful in defining a subclass of oesophageal SCCs with extremely poor clinical outcome, which may require a specially targeted treatment modality.     

The Influences of CD14 −260C>T Polymorphism on Survival in ICU Critically Ill Patients

In order to analyze the effect of the two different versions of the cluster of differentiation 14 (CD14) receptor recognizing gene on survival, we determined the ?260C>T single nucleotide polymorphism (SNP) frequencies in 514 critically ill patients. We compared the ?260TT homozygotes with ?260C allele carriers (?260CC and ?260CT genotypes) and we demonstrated—260TT patients had the highest survival rate (82% vs 64%; p < 0.001; OR = 2.52, 95% CI = 1.43–4.46). We performed binary logistic regression, incorporating both ?260C>T genotype groups and the main clinical predictors to exclude other risk factors that could influence the outcome from critical illness: higher age, APACHE II score, and length of stay at hospital, and the occurrence of sepsis and septic shock were risk factors to Intensive Care Unit (ICU) patient's mortality, but the ?260TT genotype was protective factor toward survival (p = 0.001; OR = 3.08 95%CI = 1.54–5.98). Among septic and septic shock patients, ?260TT genotype was also protective factor toward survival (p = 0.001; OR = 3.11 95%CI = 1.63–6.66 to septic patients, and p = 0.001; OR = 3.80 95%CI = 1.68–8.58 to patients with septic shock). Our results and our hypothesis suggest that the higher ?260TT genotype frequency in ICU survivor patients is possibly explained by a beneficial effect on innate immunity signaling.     

Trophoblast Immune Receptors in Maternal-Fetal Tolerance

During pregnancy, interactions between maternal immune cells and fetal trophoblast cells of the placenta would seemingly lead to disaster, as the trophoblast cells are semi-allogeneic and should trigger rejection by the maternal immune response. A fundamental immunologic question of pregnancy as posed by Sir Peter Medawar centers on how immunologic disaster is averted. It is becoming clear that many different mechanisms act during gestation to render the maternal immune system tolerant of the fetus. These include, among others, restricted major histocompatibility complex (MHC) protein expression, the presence of immunosuppressive B7 family members, immunomodulatory adhesion molecules, the expression of apoptosis-inducing proteins, and complement regulatory proteins. Understanding of maternal-fetal tolerance has clinically important implications for the fields of reproduction, autoimmunity and transplantation. Herein are discussed mechanisms by which trophoblast cells are protected from maternal immune cell attack. Specifically the role of trophoblast cell surface proteins at the maternal-fetal interface is considered.     

NKT Cells at the Maternal-Fetal Interface

Establishment of the maternal-fetal interface is characterized by the influx of maternal NK cells, macrophages, and T cells into the decidua. Although a great deal has been learned about the function of NK cells in the decidua, comparatively little is known of decidual T cell function. NKT cells are an unusual T cell subset capable of producing both Th1-like and Th2-like cytokines. Unlike conventional αβ T cells that recognize peptides in the context of MHC molecules, NKT cells recognize glycolipids presented by the MHC class I-like molecule, CD1d. Recent reports have demonstrated that NKT cells and CD1d are present at the maternal-fetal interface. Moreover, activation of NKT cells can have dramatic effects on pregnancy. In this article, we will review basic aspects of NKT cell biology and summarize the recent literature on NKT cells at the maternal-fetal interface.     

Association of CD1A +622 T/C, +737 G/C and CD1E +6129 A/G Genes Polymorphisms with Multiple Sclerosis

Antibodies and specific T cells to glycolipids have been found in MS patients. CD1 molecules are involved in presentation of lipid antigens to T-cells. Therefore, functional polymorphisms in two CD1 genes (+622 T/C and +737 G/C in CD1A along with +6129 A/G in CD1E) might be associated with susceptibility to MS. First, 351 MS patients and 342 controls were enrolled in this study. Allele-specific oligonucleotide polymerase chain reaction and PCR-RFLP methods were used for genotyping. The frequency of CD1A genotypes was not different between cases and controls. However, investigating females, the frequency of CD1A*01 allele was significantly higher in patients with PP-MS compared to controls (p = 0.028) as well as to RR-MS and SP-MS (p = 0.042 and 0.021, respectively). The distribution of CD1E +6129 A allele (CD1E*01) and CD1E*01/01 genotype is more frequent in normal controls in comparison with MS patients (p = 0.001 and p = 0.0003, respectively). In addition, after categorization of study groups according to disease types, differences between alleles and genotypes of CD1E gene polymorphism remained significant for RR-MS patients compared to those of normal controls (p = 0.0001 and p = 0.0003, respectively). CD1E and CD1A genes may be involved in networks which determine susceptibility to RR-MS and PP-MS, respectively.