Citations

Abstract Background Biomarkers for predicting the development of Ulcerative Colitis (UC) and disease-related complications are lacking. Anti-integrin αvβ6 IgG autoantibodies (anti-αvβ6) have been recently described in patients diagnosed with UC. Here, we sought to determine if anti-αvβ6 autoantibodies predate UC development and to study associations between anti-αvβ6 and disease outcomes in newly diagnosed UC patients. Methods In a unique pre-clinical IBD cohort from the PRoteomic Evaluation and Discovery in an IBD Cohort of Tri-service Subjects (PREDICTS), anti-αvβ6 were measured in longitudinal pre-diagnosis serum samples from 82 subjects who later developed UC as well as in 82 matched subjects that did not develop IBD (HC). Sample A was at the time of UC diagnosis, Sample B was at a median of 2 years before Sample A, Sample C was at a median of 4 years before Sample A and Sample D was at a median of 10 years before Sample A. In a distinct, external validation cohort (the Crohn’s and Colitis Canada Genetics Environment Microbial (GEM) Project), we tested samples from 12 subjects who later developed UC and compared those with 49 matched subjects who remained asymptomatic. Further, anti-αvβ6 were measured in 2 incident IBD cohorts (COMPASS, n=55 and OSCCAR, n=104 UC subjects) and associations between anti-αvβ6 and adverse UC-outcomes were defined using Cox proportional-hazards model. Results Anti-αvβ6 were significantly higher in the PREDICTS cohort among individuals who developed UC compared to HC up to 10 years prior to diagnosis (Figure 1A). The anti-αvβ6 seropositivity was 12.2% 10 years before diagnosis and increased to 52.4% at the time of diagnosis in subjects who developed UC compared with 2.7% in controls across the 4 timepoints. Additionally, the predictive performance of anti-αvβ6 autoantibodies as assessed via area under the receiver operator curves (AUROC) with 10-fold cross validation was at least 0.8 up to 10 years before diagnosis (Figure 1B). Elevated levels of anti-αvβ6 in pre-clinical UC samples were further validated in the GEM cohort (Figure 1C). Finally, high anti-αvβ6 were associated with a composite of adverse UC-outcomes including hospitalization, disease extension, colectomy, systemic steroid use and/or escalation to biologic therapy in both incident cohorts (Figure 1D). Conclusion Anti-integrin αvβ6 autoantibodies precede the clinical diagnosis of UC by up to 10 years and are associated with adverse UC-related outcomes.

Abstract Background The role of ovulation in epithelial ovarian cancer (EOC) is supported by the consistent protective effects of parity and oral contraceptive use. Whether these factors protect through anovulation alone remains unclear. We explored the association between lifetime ovulatory years (LOY) and EOC. Methods LOY was calculated using 12 algorithms. Odds ratios (ORs) and 95% confidence intervals (CIs) estimated the association between LOY or LOY components and EOC among 26 204 control participants and 21 267 case patients from 25 studies. To assess whether LOY components act through ovulation suppression alone, we compared beta coefficients obtained from regression models with expected estimates assuming 1 year of ovulation suppression has the same effect regardless of source. Results LOY was associated with increased EOC risk (OR per year increase = 1.014, 95% CI = 1.009 to 1.020 to OR per year increase = 1.044, 95% CI = 1.041 to 1.048). Individual LOY components, except age at menarche, also associated with EOC. The estimated model coefficient for oral contraceptive use and pregnancies were 4.45 times and 12- to 15-fold greater than expected, respectively. LOY was associated with high-grade serous, low-grade serous, endometrioid, and clear cell histotypes (ORs per year increase = 1.054, 1.040, 1.065, and 1.098, respectively) but not mucinous tumors. Estimated coefficients of LOY components were close to expected estimates for high-grade serous but larger than expected for low-grade serous, endometrioid, and clear cell histotypes. Conclusions LOY is positively associated with nonmucinous EOC. Differences between estimated and expected model coefficients for LOY components suggest factors beyond ovulation underlie the associations between LOY components and EOC in general and for non-HGSOC.

Abstract We recently reported normalization of CSF cytokine levels following successful treatment of drug-resistant epilepsy (DRE) with recombinant interleukin-1 receptor antagonist (rIL1RA). To further understand the mechanism of this therapeutic outcome, we interrogated the ability of serum and CSF factors that are elevated in drug resistant-seizure disorders to promote inflammatory responses in astrocytes and human brain microvessel endothelial cells (HBMVECs). We report that CCL2, TNFa, IL6, and CXCL8/1 were strongly induced in 1) astrocytes and HBMVECs stimulated with IL1β (blocked by rIL1RA) and 2) astrocytes but not HBMVECs in response to DRE patient serum but not control serum (partially blocked by rIL1RA). This suggested that other serum factors contribute to astrocyte activation in this DRE. HMGB1 and IL18 were also dysregulated in DRE patient serum; however, IL18 failed to stimulate cytokine secretion from astrocytes. In contrast, HMGB1 induced cytokine secretion from astrocytes, which was blocked by the TLR4 inhibitor TAK242. Remarkably, TAK242 also prevented cytokine production by astrocytes in response to serum from some patients with DRE. Finally, IL1β induced the polarized uptake and secretion of HMGB1 across transwell inserts harboring confluent monolayers of HBMVECs suggesting that IL1b signaling may cause endothelial cells to transport serum HMGB1 into the perivascular space—promoting TLR4-dependent cytokine release from astrocytes. This translation of an “outside” inflammatory signal into an “inside” inflammatory response may underlie seizure disorders that are resistant to anti-seizure drugs.

Abstract Cognitive impairment in MS is associated with diffuse gray matter injury, which remains poorly understood. Given that axons span both white and gray matter regions, it’s possible that signals within these axons contribute to the spread of diffuse injury in the brain. We show that retrograde IFNg signaling in axons (in vitro human and murine) and demyelination (murine in vivo) cause transcriptional / translational changes in neuronal cell bodies. Chief among the candidate signaling pathways identified is ISGylation, a process whereby a multitude of cellular proteins are modified by the attachment of one or more ISG15 molecules. Using custom adeno-associated viral vectors we tested how altering ISGylation in neurons affects neuronal synaptic function and how it affects neuronal responsiveness to specific inflammatory factors in cell cultures. We also measured ISGylation in MS brain tissues to see if neuronal ISGylation correlates with gray matter injury in MS. We report early evidence that increased neuron ISGylation alters the composition of neuron-derived extracellular vesicles. Microglia treated with extracellular vesicles from neurons overexpressing ISGylation pathway genes exhibited morphology consistent with increased phagocytic activity and increased mRNA expression of inflammatory cytokines including: CCL2, IL1b, TNFa, iNOS, CXCL10, CCL5, and IL6. At this point, it is still unclear how these changes are related to gray matter pathology. However, it is possible that microglial activation by these vesicles is involved with driving synapse loss as activated microglia are known to be capable of stripping neuronal synapses.

Abstract Cytotoxic CD8+ T cells outnumber CD4+ T cells within multiple sclerosis (MS) lesions, yet the pathogenic role for these cells and the relevant target antigen(s) involved in neuropathology remain unknown. We predict that a subset of lesion-infiltrating CD8+ T cells are specific for neuronal antigens and contribute to axon or neuron injury, thereby driving disease progression and accumulation of disability. To test this, we are developing protocols to measure MS patient-derived T cell reactivity against neuronal and control antigens. Peripheral blood mononuclear cells (PBMCs) isolated from whole blood were incubated with GM-CSF and IL-4 to selectively expand dendritic cells (DCs) or with IL-7 to promote survival and maintenance of T cells. After resting, patient T cells were combined 1:1 with autologous DCs in the presence of vaccine antigens or peptides derived from common pathogens. We tested responses against a pool of cytomegalovirus, Epstein Barr virus, and influenza peptides (CEF) and against mumps viral protein extract. We also tested responses in T cells derived from patients with autoimmune neurological disorders following incubation with autologous DCs and disease-specific proteins. Activation profiles were assessed using CD69, CD44, and LFA-1 by conventional flow cytometry. Cellular responses were also assessed using mass cytometry (cytometry by time of flight; CyTOF). Our next steps include testing MS patient-derived T cell responses against neuronal and axonal protein libraries, with the goal of identifying potential autoantigens that underlie disease progression.

Abstract NKG2D is expressed on cytotoxic lymphocytes and is an important immunosurveillance receptor that recognizes stress ligands such as MICA on tumor cells or virally infected cells. Unlike traditional immune activating receptors, NKG2D couples to the non-ITAM-containing transmembrane adaptor DAP10, which recruits PI3K and Grb2 to initiate target cell lysis. Current understanding predicts an ITAM-independent mechanism of NKG2D-mediated cytotoxicity. However, we show that in primary human NK cells, the ITAM-containing adaptors DAP12, FcϵR1γ, and CD3ζ selectively regulate the Grb2-Vav1 branch of NKG2D-mediated signal transduction and cytotoxicity. Furthermore, this ITAM-adaptor regulation of NKG2D is independent of ITAM activation. Thus our data reveal a more complex interplay between NKG2D and other activating receptors than was previously imagined, and we have uncovered a novel mechanism of ITAM-adaptor regulation of cell-mediated cytotoxicity. A more thorough understanding of immunoreceptor signaling networks will lead to more precise therapies when fighting diseases such as cancer, autoimmunity, and infection.

Abstract The NK cell activating receptor NKG2D plays a critical role in the destruction of malignant cells, but many of the cell-signaling mechanisms governing NKG2D-mediated cellular cytotoxicity are unknown. We have identified an NKG2D-mediated signaling pathway that governs both conjugate formation and cytotoxic granule polarization. We demonstrate that an interaction between the regulatory subunit of PI3K, p85, and the adaptor protein CrkL is required for efficient NKG2D-mediated cellular cytotoxicity. We show decreased NK cell - target cell conjugate formation in NK cells treated with PI3K inhibitors or depleted of CrkL. Independent of adhesion, we find that microtubule organization center polarization toward target cells expressing the NKG2D ligand MICA or toward anti-NKG2D coated beads is impaired in the absence of CrkL. Antibody-stimulated granule release is also impaired in NK cells depleted of CrkL. Furthermore, our data indicate that the small Ras-family GTPase Rap1 is required for NK cell killing and is activated downstream of NKG2D engagement in a PI3K- and CrkL-dependent manner. Taken together, our data identify an NKG2D-activated signaling pathway that collectively orchestrates NK cell adhesion, cell polarization and granule release.

Abstract Stimulation of NK cell-mediated cytotoxicity involves the coupling of proximal Src and Syk family protein tyrosine kinases to downstream effectors. However, the mechanisms linking these second messenger pathways are incompletely understood. Here, we describe a key role for the LAT (p36) adaptor protein in human NK cell activation. LAT is tyrosine phosphorylated upon stimulation of NK cells through FcγRIII receptors and following direct contact with NK-sensitive target cells. This NK stimulation induces the association of LAT with several phosphotyrosine-containing proteins. In addition to the biochemical evidence showing LAT involvement in NK cell activation, a genetic model shows that LAT is required for FcR-dependent phosphorylation of phospholipase C-γ. Furthermore, overexpression of LAT in NK cells leads to increased Ab-dependent cell-mediated cytotoxicity and “natural cytotoxicity,” thus demonstrating a functional role for LAT in NK cells. These data suggest that LAT is an important adaptor protein for the regulation of human NK cell-mediated cytotoxicity.

Abstract NK cell-mediated killing is inversely proportional to the amount of MHC class I expression on certain tumor targets. Two hypotheses have been proposed to explain why class I-bearing targets are more resistant to NK cell-mediated lysis: 1) the presence of class I prevents NK cell recognition of a triggering molecule on the target cell surface, or 2) class I recognition transmits a separate inhibitory signal to the NK cell. To differentiate between these potential mechanisms, we have used cloned human CD16+/CD3- NK cells, the class I-deficient cell line C1R, and C1R cells expressing high levels of transfected HLA class I gene products. If class I expression blocks NK cell recognition of the targets, then proximal cell signaling events such as phospholipase C-mediated hydrolysis of membrane phosphoinositides should be decreased in the NK cells interacting with the class I transfectants. However, we found that increases in the level of target cell class I expressions did not decrease phosphoinositide turnover or calcium signaling in NK cells. We also examined the effect of treating HLA-transfected C1R cells with mAb specific for the transfected MHC class I gene product. If class I expression has a negative regulatory influence on NK cell activation, then treating the targets with anti-HLA mAb should block the transmission of this negative signal. Consistent with this notion, addition of anti-HLA mAb (either whole Ig or F(ab’)2 fragments) led to increased lysis of the class I-transfected targets. In contrast, addition of isotype-matched mAb specific for other cell surface markers did not alter sensitivity to lysis. All of these results suggest that MHC class I expression on target cells can initiate inhibitory signals in NK cells without blocking access to target structures.