Citations

Abstract Regulatory T-cells (Tregs) play a dual role in colon cancer, promoting immune tolerance and suppressing inflammation. Two types of Tregs infiltrate the gut. Thymic derived Helios+CD4+Foxp3+ Tregs have high affinity for self-antigens, including tumor-antigens and protect the tumor, while Helios−CD4+Foxp3+ extra-thymic Tregs that are generated in the gut have microbial specificity and suppress harmful inflammation. In colon cancer, there is a preferential expansion of a population of Helios−CD4+Foxp3+RORγt+ Tregs with enhanced T-cell suppressive properties and pro-inflammatory properties that promote tumor growth. We showed that this population of Tregs in cancer patients expresses elevated levels of β-catenin. To test the role of canonical Wnt signaling in the generation of pro-inflammatory Tregs, we stabilized β-catenin or deleted its DNA binding partner TCF-1 in Tregs. In both instances expression of RORγt was upregulated. While the stabilization of β-catenin led to loss of Treg functions, ablation of TCF-1 reproduced the phenotype and functional characteristics of Tregs in colon cancer. The TCF-1 deficient Tregs were pro-inflammatory, potent T-cell suppressive, and tumor promoting.

Abstract Microglia are central nervous system (CNS) resident immune cells for which the impact of MHC class I antigen presentation is still being defined. To directly address if microglia contribute to CD8 T cell-mediated immunity of the CNS, we generated a novel tamoxifen inducible CX3CR1-creER H-2Kb MHC class I conditional knockout mouse. In this transgenic mouse, the H-2Kb MHC class I molecule is deleted on all CX3CR1-expressing cells following tamoxifen treatment. By two weeks post tamoxifen treatment, peripheral CX3CR1-expressing cells repopulate, restoring normal expressing of H-2Kb. This leaves only microglia as the sole MHC class I-deficient cell type. We hypothesized that deletion of H-2Kb on microglia would reduce CD8 T cell responses in the CNS. We challenged these animals and cre-negative littermates with intracranial picornavirus infection with Theiler’s murine encephalomyelitis virus expressing ovalbumin (TMEV-OVA). We also challenged mice with experimental GL261 gliomas. We found that microglia-specific H-2Kb deletion reduces the CD8 T cell response in the CNS and attenuates the activation status of brain-infiltrating CD8 T cells in both models of neuroinflammation. We conclude that microglia are functional antigen presenting cells, and are required for a complete antigen-specific CD8 T cell response in the brain. These findings are the first to definitively address the role of microglia-expressed MHC class I in CNS immunological challenges.

Abstract Background/Purpose Interferon (IFN) gene expression signatures have been observed in whole blood and mixed immune cell populations in systemic lupus erythematosus (SLE), but the significance of this IFN signaling in immune cell subsets is not well understood. We examined gene expression in individual SLE patient monocytes to explore the impact of increased IFN-induced transcription in single cells. Methods CD14++CD16- classical monocytes and CD14dimCD16+ non classical monocytes from SLE patients were purified by magnetic separation. Single cells were isolated, and gene expression in each individual cell was examined by rtPCR. Results Monocytes from the same SLE patient blood sample demonstrated varying levels of IFN-induced gene expression. In classical monocytes, high IFN score correlated with CD32a, IL1B, and IL8 expression. In non-classical monocytes, high IFN score was correlated with a larger number of inflammatory mediators, including cytokines such as IL12, IL23, and IL15; the immune receptors CD36, CD32a, CD80, and TLR7; and inflammatory signaling genes such as RELA, STAT2, IRAK1, IRAK4, and MyD88. ConclusionWe observed striking diversity in the IFN responses of individual monocytes, demonstrating that IFN signaling has distinct effects upon classical and non-classical monocytes. Single cell studies can reveal effects of IFN on single immune cells and uncommon populations such as non-classical monocytes, which would be masked in whole blood or mixed cell populations.

Abstract Type 1 diabetes can be induced by virus expressing SIINFEKL in Rat Isulin Promoter (RIP)-OVA transgenic mice harboring adoptively transferred naïve antigen-specific OT1 T cells. By titrating the number of transferred OT-1 cells, disease outcome can be manipulated. Mice receiving high numbers of OT-1 cells develop autoimmunity and rapidly succumb to disease. Mice receiving limiting numbers develop hyperglycemia transiently and then over 10 days recover glucose homeostasis. Recovered mice exhibit restored normal resting blood sugar levels and are able to regulate glucose during a stress test. Histological examination of the pancreas showed extensive pancreatic destruction with no or very few remaining insulin-positive islets. Using RIP-OVA mice expressing luciferase under the mouse insulin promoter, pancreatic insulin promoter activity was extinguished, while liver expression increased in recovered animals, suggesting an ectopic source of insulin can support glucose homeostasis in mice with extensively damaged islets. Pancreatic infiltrates during peak inflammation contained host-derived CD8 T cells in addition to the infiltrating OT-1 cells. These host CD8 T cells were absent in CD8 deficient RIP-OVA mice, and diabetes occurred with fewer transferred OT-1 cells and was quickly fatal. Reconstitution of the CD8 compartment protected these animals. These findings indicate the importance of host CD8 T cells in limiting autoreactive T cell-mediated destruction of islets.

OBJECTIVE Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has been used to treat degenerative lumbar spondylolisthesis and is associated with expedited recovery, reduced operative blood loss, and shorter hospitalizations compared to those with traditional open TLIF. However, the impact of MI-TLIF on long-term patient-reported outcomes (PROs) is less clear. Here, the authors compare the outcomes of MI-TLIF to those of traditional open TLIF for grade I degenerative lumbar spondylolisthesis at 60 months postoperatively. METHODS The authors utilized the prospective Quality Outcomes Database registry and queried for patients with grade I degenerative lumbar spondylolisthesis who had undergone single-segment surgery via an MI or open TLIF method. PROs were compared 60 months postoperatively. The primary outcome was the Oswestry Disability Index (ODI). The secondary outcomes included the numeric rating scale (NRS) for back pain (NRS-BP), NRS for leg pain (NRS-LP), EQ-5D, North American Spine Society (NASS) satisfaction, and cumulative reoperation rate. Multivariable models were constructed to assess the impact of MI-TLIF on PROs, adjusting for variables reaching p < 0.20 on univariable analyses and respective baseline PRO values. RESULTS The study included 297 patients, 72 (24.2%) of whom had undergone MI-TLIF and 225 (75.8%) of whom had undergone open TLIF. The 60-month follow-up rates were similar for the two cohorts (86.1% vs 75.6%, respectively; p = 0.06). Patients did not differ significantly at baseline for ODI, NRS-BP, NRS-LP, or EQ-5D (p > 0.05 for all). Perioperatively, MI-TLIF was associated with less blood loss (108.8 ± 85.6 vs 299.6 ± 242.2 ml, p < 0.001) and longer operations (228.2 ± 111.5 vs 189.6 ± 66.5 minutes, p < 0.001) but had similar lengths of hospitalizations (MI-TLIF 2.9 ± 1.8 vs open TLIF 3.3 ± 1.6 days, p = 0.08). Discharge disposition to home or home health was similar (MI-TLIF 93.1% vs open TLIF 91.1%, p = 0.60). Both cohorts improved significantly from baseline for the 60-month ODI, NRS-BP, NRS-LP, and EQ-5D (p < 0.001 for all comparisons). In adjusted analyses, MI-TLIF, compared to open TLIF, was associated with similar 60-month ODI, ODI change, odds of reaching ODI minimum clinically important difference, NRS-BP, NRS-BP change, NRS-LP, NRS-LP change, EQ-5D, EQ-5D change, and NASS satisfaction (adjusted p > 0.05 for all). The 60-month reoperation rates did not differ significantly (MI-TLIF 5.6% vs open TLIF 11.6%, p = 0.14). CONCLUSIONS For symptomatic, single-level grade I degenerative lumbar spondylolisthesis, MI-TLIF was associated with decreased blood loss perioperatively, but there was no difference in 60-month outcomes for disability, back pain, leg pain, quality of life, or satisfaction between MI and open TLIF. There was no difference in cumulative reoperation rates between the two procedures. These results suggest that in appropriately selected patients, either procedure may be employed depending on patient and surgeon preferences.

Abstract Recent guidelines by the American Society of Clinical Oncologists recommend that obese individuals receive chemotherapy based on their actual body weight (ABW) without dose reduction. Contrary to prior reports, our own data demonstrate that ABW-dosed chemotherapy or immunotherapy is as effective and well tolerated by obese mice as by lean mice. Nonetheless, obese mice develop significantly greater weight loss in a dose-dependent manner during the entire period that they receive therapy, with corresponding quantifiable reductions in visceral fat depots. This disparity is not explained by altered food intake, as both lean and obese mice experience less than a week of anorexia which does not recur after Cycle 1 of treatment. Furthermore, malabsorption is absent. These observations are relevant to multiple classes of chemo agents. Altered pharmacokinetics of chemotherapy agents in adipose tissue have been reported, yet the pharmacodynamics of obesity remain speculative. Fasting blood glucose monitoring demonstrates glucose level variances which are temporally linked to treatment, rendering it likely that chemotherapy and immunotherapy provoke adipose tissue lipolysis, or alternatively cytoreduction or immunomodulation of adipocyte progenitor cells. Understanding these effects could contribute to improved treatment regimens in the setting of obesity.

Abstract IL-9 is a cytokine that is primarily associated with mast cells and airway inflammation, however it also plays a role in T regulatory cell (Treg) survival and recruitment to tumors. We previously reported that 4-1BB treatment of Tregs inhibits both Treg function and IL-9 secretion. Neutralization of IL-9 with an anti-IL-9 antibody inhibits the suppressive function of Tregs without affecting the function of CD4+ and CD8+ T effector cells. Furthermore, the combination of intra-tumoral CpG and anti-IL-9 induced tumor rejection in BALB-neuT and MUC1 tolerant transgenic mice. Here we show that the lack of IL-9 inhibits Treg suppression of T cell proliferation, using IL-9 knockout (IL-9ko) mice. Phenotypic analysis of Treg markers showed that tumor draining lymph nodes of 4T1 bearing mice contain fewer CTLA-4+ and CD103+ Tregs, and that these also have reduced of CTLA-4 and CD103 expression. We also observed that IL-9ko mice spontaneously reject TUBO and 4T1 mammary carcinoma cells and that rejection is abrogated by CD8+ T cell depletion. Finally, preliminary studies of human CD4+ T cell proliferation revealed that IL-9 neutralization led to greater proliferation than isotype control treated cells. Taken together our results suggest that IL-9 can have an immunosuppressive function that comes into play in the tumor microenvironment, and that the blockade of IL-9 could serve as a novel strategy to perturb the function of Tregs to enhance the antitumor effect of tumor vaccines.

Abstract We have engineered an attenuated picornavirus vaccine using Theiler’s murine encephalomyelitis virus (TMEV) and are exploring its usefulness in immunotherapy. We find that two different insertion sites within the leader protein of the TMEV genome allow for effective production of virus vaccine strains. One site is at the amino terminal end of the protein after the third amino acid position (p3); the other is at the XhoI restriction site further downstream. We find that vaccine antigen insertion at p3 disrupts the ability of the virus to inhibit type I interferon production by infected cells, whereas XhoI insertion does not. Further, the p3 modified virus can be cleared from animals lacking functional T and B-cells but replicates to high titer in IFNα/β receptor knockout mice, suggesting that innate immune mechanisms are sufficient for viral clearance. In spite of rapid clearance, p3 vaccines readily stimulate proliferation of transgenic T-cells and induce de novo responses to T-cell antigens in wild-type mice, although to a lesser extent than the XhoI modified vaccines strains. The use of either vaccine however effectively delays tumor growth and enhances survival in mice bearing melanoma and breast tumors. This vaccine provides a safe and effective vaccine strategy for the induction of CD8+ T-cell immunity directed towards cancer and provides support for the development of picornaviruses as vaccine vectors for treating human disease.

Abstract We have induced acute diabetes following immune attack on the pancreas with islet specific CD8+ T cells, but surprisingly many animals subsequently recovered blood glucose homeostasis. The recovered animals exhibited nearly normal glucose tolerance and produced normal levels of blood insulin following glucose challenge. Remarkably very few islets were present in these animals and those remaining were virtually insulin free. In this model B6 RIP-OVAhi mice receive 100 to 600 naïve OT-1 CD8+ T cells prior to activation by an infection with Theilers murine encephalomyelitis virus encoding the SIINFEKL ovalbumin antigen. When greater numbers of T cells are transferred, this protocol causes acute and fatal diabetes. However, when limiting numbers of T cells are used, animals can recover from the acute phase of the disease. Under these limiting conditions, we find that the mice develop acute pancreatitis by day 5 following infection and stop producing insulin by day 8. By day 11 to 14 some animals begin to recover. Early in the recovery process, insulin positive beta cells are evident in islets. However, late after recovery (days &gt;56) animals that regulate blood sugar normally are found devoid of insulin producing beta cells, though insulin levels are near normal. This raises important questions about how these animals recover glucose homeostasis following cellular immune attack on their islets. Our hypothesis is that insulin is produced outside of the pancreas in these animals.

Abstract We have developed a mouse model of diabetes by adoptively transferring small numbers of OT1 cells into animals expressing OVA under the rat insulin promoter (RIP-OVA). These cells are activated in vivo with a Picornavirus (TMEV) expressing OVA antigen. Titrating the dose of adoptively transferred cells, changes disease outcome. Mice receiving low amounts of cells develop hyperglycemia, and recover homeostasis. Investigation of recovered animals revealed normal blood glucose regulation. Pancreatic histology of recovered mice showed extensive pancreatic destruction with no or very few remaining insulin-positive islets. While adoptively transferred OT1 cells were present, pancreas infiltrating T cells were largely endogenous. To evaluate the functional importance of the host T cells, we tested disease progression using RAG KO, CD4 KO, and CD8 KO RIP-OVA hosts. Without RAG, CD4, or CD8 we observed increased disease severity. This change is not attributed to homeostatic proliferation in the CD4 and CD8 KO animals, as adoptively transferred OT1 cells behaved similarly in the KO hosts in comparison to RIP-OVA mice. However there is significant homeostatic proliferation occurring in the RIP-OVA RAG KO animals. Our studies reveal the importance of CD4 and CD8 T cells in limiting autoimmune attack in the pancreas. Although populations of CD4 T regulatory cells are well known, the importance of CD8 T cells in limiting inflammation are less well characterized.