Successful In Situ Targeting of Pancreatic Tumors in a Novel Orthotopic Porcine Model Using Histotripsy

OBJECTIVE

New therapeutic strategies and paradigms are direly needed to treat pancreatic cancer. The absence of a suitable pre-clinical animal model of pancreatic cancer is a major limitation to biomedical device and therapeutic development. Traditionally, pigs have proven to be ideal models, especially in the context of designing human-sized instruments, perfecting surgical techniques and optimizing clinical procedures for use in humans. However, pig studies have typically focused on healthy tissue assessments and are limited to general safety evaluations because of the inability to effectively model human tumors.

METHODS

Here, we establish an orthotopic porcine model of human pancreatic cancer using RAG2/IL2RG double-knockout immunocompromised pigs and treat the tumors ex vivo and in vivo with histotripsy.

RESULTS

Using these animals, we describe the successful engraftment of Panc-1 human pancreatic cancer cell line tumors and characterize their development. To illustrate the utility of these animals for therapeutic development, we determine for the first time, the successful targeting of in situ pancreatic tumors using histotripsy. Treatment with histotripsy resulted in partial ablation in vivo and reduction in collagen content in both in vivo tumor in pig pancreas and ex vivo patient tumor.

CONCLUSION

This study presents a first step toward establishing histotripsy as a non-invasive treatment method for pancreatic cancer and exposes some of the challenges of ultrasound guidance for histotripsy ablation in the pancreas. Simultaneously, we introduce a highly robust model of pancreatic cancer in a large mammal model that could be used to evaluate a variety biomedical devices and therapeutic strategies.

Horseshoe kidney: Morphologic features, embryologic and genetic etiologies, and surgical implications

The horseshoe kidney (HSK) is the most common congenital abnormality of the upper urinary tract with an incidence of approximately 1 in 500 in the general population. Although individuals with HSK are often asymptomatic, they are at increased risk for neoplasms, infections, ureteropelvic obstruction secondary to lithiasis or vascular compression. Direct injury from trauma is increased in these individuals as is the risk of intraoperative complications secondary to damage involving the typically complex renal or adrenal vascular supply. We briefly review etiological factors including renal and urinary system embryology, genetic mutations, abnormalities related to faulty cell signaling, aberrant cell migration, and other possible causes including environmental exposures and trauma. In addition, we call attention to factors that might influence the success of surgical procedures in patients with HSK. We argue that an understanding of possible etiologies of the HSK and its different subtypes may be useful when planning surgical procedures or considering risk-benefit ratios associated with different surgical options. We briefly present the organization of a HSK in a 100-year-old male demonstrating an unusual vascular supply discovered during a dissection laboratory session in a medical school anatomy course. We describe the structure of the HSK, the position and relationships of the HSK to other structures within the abdomen, and the associated vascular relationships.

An integrated pre-clerkship curriculum to build cognitive medical schema: It’s not just about the content

Both physiology and pathophysiology are essential disciplines in health professional education however, clinicians do not use this knowledge in isolation. Instead, physicians use inter-disciplinary concepts embedded within integrated cognitive schema (illness scripts) established through experience/knowledge that manifest as expert-level thinking. Our goal was to develop a pre-clerkship curriculum devoid of disciplinary boundaries (akin to the physician’s illness script) and enhance learners’ clerkship and early clinical performance. As well as developing curricular content, the model considered non-content design elements such as learner characteristics and values, faculty and resources and the impact of curricular and pedagogical changes. The goals of the trans-disciplinary integration were to develop deep learning behaviors through, 1) developing of integrated, cognitive schema to support the transition to expert-level thinking, 2) authentic, contextualization to promote knowledge transfer to the clinical realm 3) allowing autonomous, independent learning, and 4) harnessing the benefits of social learning. The final curricular model was a case-based approach with independent learning of basic concepts, differential diagnosis and illness scripting writing, and concept mapping. Small-group classroom sessions were team-taught with basic scientists and physicians facilitating learners’ self-reflection and development of clinical reasoning. Specifications grading was used to assess the products (written illness scripts and concept maps) as well as process (group dynamics) while allowing a greater degree of learner autonomy. Although the model we adopted could be transferred to other program settings, we suggest it is critical to consider both content and non-content elements that are specific to the environment and learner.

Ultrasound-guided noninvasive pancreas ablation using histotripsy: feasibility study in an in vivo porcine model

Pancreatic cancer is a malignant disease associated with poor survival and nearly 80% present with unresectable tumors. Treatments such as chemotherapy and radiation therapy have shown overall improved survival benefits, albeit limited. Histotripsy is a noninvasive, non-ionizing, and non-thermal focused ultrasound ablation modality that has shown efficacy in treating hepatic tumors and other malignancies. In this novel study, we investigate histotripsy for noninvasive pancreas ablation in a pig model. In two studies, histotripsy was applied to the healthy pancreas in 11 pigs using a custom 32-element, 500 kHz histotripsy transducer attached to a clinical histotripsy system, with treatments guided by real-time ultrasound imaging. A pilot study was conducted in 3 fasted pigs with histotripsy applied at a pulse repetition frequency (PRF) of 500 Hz. Results showed no pancreas visualization on coaxial ultrasound imaging due to overlying intestinal gas, resulting in off-target injury and no pancreas damage. To minimize gas, a second group of pigs (n = 8) were fed a custard diet containing simethicone and bisacodyl. Pigs were euthanized immediately (n = 4) or survived for 1 week (n = 4) post-treatment. Damage to the pancreas and surrounding tissue was characterized using gross morphology, histological analysis, and CT imaging. Results showed histotripsy bubble clouds were generated inside pancreases that were visually maintained on coaxial ultrasound (n = 4), with 2 pigs exhibiting off-target damage. For chronic animals, results showed the treatments were well-tolerated with no complication signs or changes in blood markers. This study provides initial evidence suggesting histotripsy's potential for noninvasive pancreas ablation and warrants further evaluation in more comprehensive studies.

Case Report: Disorder of Sexual Development in a Chinese Crested Dog With XX/XY Leukocyte Chimerism and Mixed Cell Testicular Tumors

A 10-year-old intact female Chinese Crested dog was presented for evaluation and further diagnostics due to persistent symptoms of vulvar swelling, vaginal discharge, and an 8-year history of acyclicity. At presentation, generalized hyperpigmentation and truncal alopecia were identified, with no aberrations of the female phenotype. Vaginal cytology confirmed the influence of estrogen at multiple veterinary visits, and hormonal screening of progesterone and anti-Mullerian hormone indicated gonadal presence. Based on findings from abdominal laparotomy and gonadectomy, the tissue was submitted for histopathology. Histopathologic evaluation identified the gonads to be abnormal testes containing multiple Sertoli and interstitial (Leydig) cell tumors. The histopathologic diagnosis of testes and concurrent normal external female phenotype in the patient lead to a diagnosis of a disorder of sexual development (DSD). Karyotype evaluation by conventional and molecular analysis revealed a two cell line chimeric pattern of 78,XX (80%) and 78,XY (20%) among blood leukocytes, as well as a positive PCR test for the Y-linked SRY gene. Cytogenetic analysis of skin fibroblasts revealed the presence of 78,XX cells exclusively, and PCR tests for the Y-linked SRY gene were negative in the hair and skin samples. These results are consistent with an XX/XY blood chimerism. This is one of the few case reports of a canine with the diagnosis of leukocyte chimerism with normal female phenotypic external genitalia. This case illustrates a distinct presentation for hormonally active Sertoli cell tumorigenesis and demonstrates surgery as a curative treatment option for clinically affected patients.

EGR2 Deletion Suppresses Anti-DsDNA Autoantibody and IL-17 Production in Autoimmune-Prone B6/lpr Mice: A Differential Immune Regulatory Role of EGR2 in B6/lpr Versus Normal B6 Mice

Previous studies have reported that deletion of the transcription factor, early growth response protein 2 (EGR2), in normal C57BL/6 (B6) resulted in the development of lupus-like autoimmune disease. However, increased EGR2 expression has been noted in human and murine lupus, which challenges the notion of the autoimmune suppressive role of EGR2 in B6 mice. In this study, we derived both conditional EGR2^-/-B6/lpr and EGR2^-/-B6 mice to elucidate the immune and autoimmune regulatory roles of EGR2 in autoinflammation (B6/lpr) versus physiologically normal (B6) conditions. We found that conditional EGR2 deletion increased spleen weight, enhanced T cell activation and IFNγ production, and promoted germinal center B cells and LAG3⁺ regulatory T cells development in both B6/lpr and B6 mice. Nevertheless, EGR2 deletion also showed strikingly differential effects in these two strains on T lymphocyte subsets profile, Foxp3⁺ Tregs and plasma cell differentiation, anti-dsDNA autoantibodies and immunoglobulins production, and on the induction of IL-17 in in vitro activated splenocytes. Specifically, EGR2 deletion in B6/lpr mice significantly decreased serum levels of anti-dsDNA autoantibodies, total IgG, IgM, IgG1, and IgG2a with reduced plasma cells differentiation. Furthermore, EGR2 deletion in B6/lpr mice had no obvious effect on IgG immunocomplex deposition, medium caliber vessel, and glomeruli inflammation but increased complement C3 immunocomplex deposition and large caliber vessel inflammation in the kidneys. Importantly, we demonstrated that EGR2 deletion in B6/lpr mice significantly reduced pathogenic CD4^-CD8^-CD3⁺B220⁺ double negative T cells, which correlated with the reduced anti-dsDNA autoantibodies in serum and decreased IL-17 production in splenocytes of EGR2^-/-B6/lpr mice. Together, our data strongly suggest that the role of EGR2 is complex. The immunoregulatory role of EGR2 varies at normal or autoinflammation conditions and should not be generalized in differential experimental settings.

NLRX1 Deficiency Alters the Gut Microbiome and Is Further Exacerbated by Adherence to a Gluten-Free Diet

Patients with gluten sensitivities present with dysbiosis of the gut microbiome that is further exacerbated by a strict adherence to a gluten-free diet (GFD). A subtype of patients genetically susceptible to gluten sensitivities are Celiac Disease (CeD) patients, who are carriers of the HLA DR3/DQ2 or HLA DR4/DQ8 haplotypes. Although 85-95% of all CeD patients carry HLA DQ2, up to 25-50% of the world population carry this haplotype with only a minority developing CeD. This suggests that CeD and other gluten sensitivities are mediated by factors beyond genetics. The contribution of innate immune system signaling has been generally understudied in the context of gluten sensitivities. Thus, here we examined the role of NOD-like receptors (NLRs), a subtype of pattern recognition receptors, in maintaining the composition of the gut microbiome in animals maintained on a GFD. Human transcriptomics data revealed significant increases in the gene expression of multiple NLR family members, across functional groups, in patients with active CeD compared to control specimens. However, NLRX1 was uniquely down-regulated during active disease. NLRX1 is a negative regulatory NLR that functions to suppress inflammatory signaling and has been postulate to prevent inflammation-induced dysbiosis. Using Nlrx1^-/- mice maintained on either a normal or gluten-free diet, we show that loss of NLRX1 alters the microbiome composition, and a distinctive shift further ensues following adherence to a GFD, including a reciprocal loss of beneficial microbes and increase in opportunistic bacterial populations. Finally, we evaluated the functional impact of an altered gut microbiome by assessing short- and medium-chain fatty acid production. These studies revealed significant differences in a selection of metabolic markers that when paired with 16S rRNA sequencing data could reflect an overall imbalance and loss of immune system homeostasis in the gastrointestinal system.

Diminished noncanonical NF-κB signaling induces colitis-associated colorectal cancer susceptibility upon de-differentiation of epithelial cells

Patients with a medical history of Inflammatory Bowel Disease are predisposed to developing colitis-associated colorectal cancer (CAC), with greater than 20% developing CAC within 30 years of disease onset. CAC is a form of inflammation-induced tumorigenesis, where unregulated inflammation causes cells in the colon to accumulate mutations poising them for neoplasia. We demonstrate that NF-κB inducing kinase (NIK) is a critical regulator of intestinal epithelial cell (IEC) regeneration. We hypothesize that IECs exposed to chronic inflammatory conditions mitigated by dysregulated noncanonical NF-κB signaling are most prone to mutagenesis and cancer-initiating events termed Top-down tumorigenesis. In CAC, NIK depletion results in the accumulation of mature IECs that are increasingly susceptible to mutation and neoplastic transformation. This suggests that terminally differentiated IECs dedifferentiate into a stem-like phenotype. Our work has clinical relevancy, where human CAC biopsy samples have diminished noncanonical NF-κB signaling and NIK (MAP3K14) gene expression. Murine models with NIK deletion in IECs have increased susceptibility to inflammation-induced tumorigenesis following the chemical induction of AOM/DSS to induce colitis. Our mechanistic studies evaluating crypts demonstrate accumulation of mature, non-dividing IECs, which are more susceptible to mutations and malignant transformation. Here, we present a novel role for noncanonical NF-κB signaling in regulating intestinal epithelial cell turnover in protecting against CAC development. Focusing on the key niche signaling interplay following noncanonical NF-κB dysregulation gives greater insight into the CAC tumor microenvironment.

Supported by grants from the iTHRIVE Pilot Translational and Clinical Studies Program, VCOM Center for One Health Research, Virginia Tech Carilion Research Acceleration Program, and the Virginia-Maryland College of Veterinary Medicine.

EGR2 deletion displays similar and differential effects on immunological development and function in autoinflammation-prone B6/lpr and normal B6 mice

Transcription factor early growth response protein 2 (EGR2) prevents the development of lupus-like autoimmune disease in C57BL/6 (B6) mice by negatively regulating T cell activation, inflammatory cytokine IFNγ and IL-17 production and by suppressing humoral responses. However, increased EGR2 expression has been observed in lupus and also other autoimmune disorders, which contradicts the autoimmune suppressive role of EGR2. Here, we derived conditional EGR2−/−B6/lpr and EGR2−/−B6 mice to investigate and compare the immune regulatory role of EGR2 in autoinflammation (B6/lpr) versus normal physiological (B6) conditions. Significantly, we found that in B6/lpr mice, but not in B6 mice, EGR2 deletion dramatically suppressed serum levels of anti-dsDNA autoantibodies, total IgG, IgG1, IgG2a, and IgM. We further demonstrated that while EGR2 deletion promoted germinal center B (GCB) cell development in both B6 and B6/lpr mice, it significantly reduced the differentiation of plasma and plasmablasts cells in B6/lpr mice. EGR2 deletion promoted splenomegaly and T cell activation in both B6 and B6/lpr mice, but it differentially regulated the profiles of immune cell subpopulations in the spleens of B6 and B6/lpr mice. Especially, EGR2 deletion dramatically suppressed the development of double negative T cells in B6/lpr mice. Moreover, we found that EGR2 had an opposite role in regulating IL-17 production in in vitro activated splenocytes from B6/lpr and B6 mice, although EGR2 had a similar suppressive role for IFNγ production. Together, our data strongly suggest that the immune and autoimmune regulatory roles of EGR2 are context dependent, and should not be generalized in normal physiology and different pathological conditions.

Supported by VMCVM-VCOM Center for One Heath Research Seed Grant Program  

Histotripsy Ablation in Preclinical Animal Models of Cancer and Spontaneous Tumors in Veterinary Patients: A Review

New therapeutic strategies are direly needed in the fight against cancer. Over the last decade, several tumor ablation strategies have emerged as stand-alone or combination therapies. Histotripsy is the first completely noninvasive, nonthermal, and nonionizing tumor ablation method. Histotripsy can produce consistent and rapid ablations, even near critical structures. Additional benefits include real-time image guidance, high precision, and the ability to treat tumors of any predetermined size and shape. Unfortunately, the lack of clinically and physiologically relevant preclinical cancer models is often a significant limitation with all focal tumor ablation strategies. The majority of studies testing histotripsy for cancer treatment have focused on small animal models, which have been critical in moving this field forward and will continue to be essential for providing mechanistic insight. While these small animal models have notable translational value, there are significant limitations in terms of scale and anatomical relevance. To address these limitations, a diverse range of large animal models and spontaneous tumor studies in veterinary patients have emerged to complement existing rodent models. These models and veterinary patients are excellent at providing realistic avenues for developing and testing histotripsy devices and techniques designed for future use in human patients. Here, we provide a review of animal models used in preclinical histotripsy studies and compare histotripsy ablation in these models using a series of original case reports across a broad spectrum of preclinical animal models and spontaneous tumors in veterinary patients.

Noncanonical NF-κB Signaling Upregulation in Inflammatory Bowel Disease Patients is Associated With Loss of Response to Anti-TNF Agents

Objectives: Targeting tumor necrosis factor (TNF) with biologic agents, such as infliximab and adalimumab, is a widely used and effective therapeutic strategy in inflammatory bowel disease (IBD). Unfortunately, a significant number of patients fail to respond or lose response over time to these agents. Previous studies have defined multiple complex roles for canonical NF-κB signaling in the pathogenesis of IBD. However, preliminary evidence suggests that the lesser defined noncanonical NF-κB signaling pathway also contributes to disease pathogenesis and response to anti-TNF agents. The objective of this study was to evaluate this hypothesis in Crohn’s disease (CD) and ulcerative colitis (UC) patients.

Design: A total of 27 subjects with IBD (19 with CD and 8 with UC) and 15 control subjects were tested. Clinical criteria, patient history, and endoscopic disease activity were factors used to categorize patients and define therapeutic response. Biopsy specimens were collected during colonoscopy and expression was determined for 88 target genes known to be associated with noncanonical NF-κB signaling and IBD.

Results: Noncanonical NF-κB signaling was significantly upregulated in IBD patients and was associated with increased gastrointestinal inflammation, epithelial cell death, lymphocyte migration, and Nod-like receptor signaling. Furthermore, noncanonical NF-κB signaling was further upregulated in patients unresponsive to anti-TNF agents and was suppressed in responsive patients. MAP3K14, NFKB2, CCL19, CXCL12, and CXCL13 were significantly dysregulated, as were genes that encode pathway regulators, such as CYLD, NLRP12, and BIRC2/3.

Conclusion: Our study identifies a previously uncharacterized role for the understudied noncanonical NF-κB signaling pathway in the pathogenesis of IBD and anti-TNF therapy responsiveness. The genes and pathways identified may ultimately prove useful in IBD management and could potentially be used as biomarkers of drug response.

Quaternary Ammonium Compound Disinfectants Reduce Lupus-Associated Splenomegaly by Targeting Neutrophil Migration and T-Cell Fate

Hypersensitivity reactions and immune dysregulation have been reported with the use of quaternary ammonium compound disinfectants (QACs). We hypothesized that QAC exposure would exacerbate autoimmunity associated with systemic lupus erythematosus (lupus). Surprisingly, however, we found that compared to QAC-free mice, ambient exposure of lupus-prone mice to QACs led to smaller spleens with no change in circulating autoantibodies or the severity of glomerulonephritis. This suggests that QACs may have immunosuppressive effects on lupus. Using a microfluidic device, we showed that ambient exposure to QACs reduced directional migration of bone marrow-derived neutrophils toward an inflammatory chemoattractant ex vivo. Consistent with this, we found decreased infiltration of neutrophils into the spleen. While bone marrow-derived neutrophils appeared to exhibit a pro-inflammatory profile, upregulated expression of PD-L1 was observed on neutrophils that infiltrated the spleen, which in turn interacted with PD-1 on T cells and modulated their fate. Specifically, QAC exposure hindered activation of splenic T cells and increased apoptosis of effector T-cell populations. Collectively, these results suggest that ambient QAC exposure decreases lupus-associated splenomegaly likely through neutrophil-mediated toning of T-cell activation and/or apoptosis. However, our findings also indicate that even ambient exposure could alter immune cell phenotypes, functions, and their fate. Further investigations on how QACs affect immunity under steady-state conditions are warranted.

Quaternary Ammonium Compound Disinfectants Reduce Lupus-Associated Splenomegaly by Targeting Neutrophil Migration and T-Cell Fate

Hypersensitivity reactions and immune dysregulation have been reported with the use of quaternary ammonium compound disinfectants (QACs). We hypothesized that QAC exposure would exacerbate autoimmunity associated with systemic lupus erythematosus (lupus). Surprisingly, however, we found that compared to QAC-free mice, ambient exposure of lupus-prone mice to QACs led to smaller spleens with no change in circulating autoantibodies or the severity of glomerulonephritis. This suggests that QACs may have immunosuppressive effects on lupus. Using a microfluidic device, we showed that ambient exposure to QACs reduced directional migration of bone marrow-derived neutrophils toward an inflammatory chemoattractant ex vivo. Consistent with this, we found decreased infiltration of neutrophils into the spleen. While bone marrow-derived neutrophils appeared to exhibit a pro-inflammatory profile, upregulated expression of PD-L1 was observed on neutrophils that infiltrated the spleen, which in turn interacted with PD-1 on T cells and modulated their fate. Specifically, QAC exposure hindered activation of splenic T cells and increased apoptosis of effector T-cell populations. Collectively, these results suggest that ambient QAC exposure decreases lupus-associated splenomegaly likely through neutrophil-mediated toning of T-cell activation and/or apoptosis. However, our findings also indicate that even ambient exposure could alter immune cell phenotypes, functions, and their fate. Further investigations on how QACs affect immunity under steady-state conditions are warranted.

Inflammation-Induced Tumorigenesis: Diminished Noncanonical NF-κB Signaling is Associated with Pathogenesis of Colitis-associated Colorectal Cancer

Colitis-associated colorectal cancer (CAC) is mediated by inflammation-induced tumorigenesis, causing DNA damage in susceptible cell populations. Dysregulation of inflammatory pathways in the colon is attributed to cancer pathogenesis and such signaling is attributed to NF-κB signaling. Transcription factor NF-κB is the master regulator of gene transcription and is activated through one of two pathways. Our focus is on the understudied noncanonical NF-κB signaling pathway, including NF-κB inducing kinase (NIK). NIK must be stabilized for activation of this pathway. Noncanonical signaling is attributed to the production of pro-inflammatory cytokines, recruitment of immune cells, and cell proliferation. We hypothesize that this pathway maintains gut homeostasis and when dysregulated causes cell populations to become tumorigenic. The objective of this study is to validate the clinical relevance of noncanonical signaling. We observe that diminished noncanonical signaling via whole-body Nik knockout mice results in reduced stem cell marker expression, enhanced proliferative capacity, altered microbiome composition, and increased susceptibility towards inflammation-induced tumorigenesis in the colon. Using CAC mouse models, conditional knockout strains show deletion of noncanonical signaling in epithelial cells results in increased susceptibility to colorectal tumorigenesis. Likewise, human colonic biopsy samples collected from CAC patients show significantly decreased expression levels of genes related to the noncanonical NF-kB pathway. This data suggests that the noncanonical NF-κB pathway has a protective role against colorectal cancer by regulating immune system homeostasis in the GI tract.

Noncanonical NF-κB signaling is suppressed through the negative regulation of the essential kinase NIK and attenuation is associated with eosinophilic esophagitis pathogenesis

Eosinophilic esophagitis (EoE) is an allergic disease of the esophagus driven by T cell and eosinophil responses to dietary allergens, resulting in chronic mucosal inflammation. NF-κB signaling is a master regulator of gene transcription and drives diverse biological processes of relevance to EoE. NF-κB activation occurs through either canonical or noncanonical pathways. In general, there is a relative paucity of knowledge regarding noncanonical NF-κB regulation and signaling. Previously, we have shown that mice with hyperactive noncanonical NF-κB signaling are more susceptible to Th1/Th17 mediated experimental colitis and cancer. Conversely, mice with attenuated noncanonical NF-κB signaling spontaneously develop EoE. The objective of our current study is to translate these findings from mouse models to human patients. Clinical specimens were collected from a cohort of 16 EoE patients and representative controls. Gene expression and protein analysis revealed a significant decrease in p52, RelB, and chemokines specifically associated with noncanonical NF-κB signaling correlated with EoE. However, we also identified a significant change in several mediators that should increase noncanonical NF-κB signaling upstream of the essential kinase NIK. Thus, our data suggest a disconnect between pathway activation and p52/RelB mediated gene transcription, with NIK functioning as a key regulatory target. Further analysis identified 6 regulatory proteins that target NIK in EoE patient specimens and robustly attenuate downstream noncanonical NF-κB signaling. Together, these data demonstrate the significance of this understudied pathway in human EoE and identify potential targets for future therapeutic strategies.

Selective Histone Deacetylase 6 Inhibition Normalizes B Cell Activation and Germinal Center Formation in a Model of Systemic Lupus Erythematosus

Autoantibody production by plasma cells (PCs) plays a pivotal role in the pathogenesis of systemic lupus erythematosus (SLE). The molecular pathways by which B cells become pathogenic PC secreting autoantibodies in SLE are incompletely characterized. Histone deactylase 6 (HDAC6) is a unique cytoplasmic HDAC that modifies the interaction of a number of tubulin- associated proteins; inhibition of HDAC6 has been shown to be beneficial in murine models of SLE, but the downstream pathways accounting for the therapeutic benefit have not been clearly delineated. In the current study, we sought to determine whether selective HDAC6 inhibition would abrogate abnormal B cell activation in SLE. We treated NZB/W lupus mice with the selective HDAC6 inhibitor, ACY-738, for 4 weeks beginning at 20 weeks-of age. After only 4 weeks of treatment, manifestation of lupus nephritis (LN) were greatly reduced in these animals. We then used RNAseq to determine the genomic signatures of splenocytes from treated and untreated mice and applied computational cellular and pathway analysis to reveal multiple signaling events associated with B cell activation and differentiation in SLE that were modulated by HDAC6 inhibition. PC development was abrogated and germinal center (GC) formation was greatly reduced. When the HDAC6 inhibitor-treated lupus mouse gene signatures were compared to human lupus patient gene signatures, the results showed numerous immune, and inflammatory pathways increased in active human lupus were significantly decreased in the HDAC6 inhibitor treated animals. Pathway analysis suggested alterations in cellular metabolism might contribute to the normalization of lupus mouse spleen genomic signatures, and this was confirmed by direct measurement of the impact of the HDAC6 inhibitor on metabolic activities of murine spleen cells. Taken together, these studies show HDAC6 inhibition decreases B cell activation signaling pathways and reduces PC differentiation in SLE and suggest that a critical event might be modulation of cellular metabolism.

High-frequency irreversible electroporation is an effective tumor ablation strategy that induces immunologic cell death and promotes systemic anti-tumor immunity

Background

Despite promising treatments for breast cancer, mortality rates remain high and treatments for metastatic disease are limited. High-frequency irreversible electroporation (H-FIRE) is a novel tumor ablation technique that utilizes high-frequency bipolar electric pulses to destabilize cancer cell membranes and induce cell death. However, there is currently a paucity of data pertaining to immune system activation following H-FIRE and other electroporation based tumor ablation techniques.

Methods

Here, we utilized the mouse 4T1 mammary tumor model to evaluate H-FIRE treatment parameters on cancer progression and immune system activation in vitro and in vivo.

Findings

H-FIRE effectively ablates the primary tumor and induces a pro-inflammatory shift in the tumor microenvironment. We further show that local treatment with H-FIRE significantly reduces 4T1 metastases. H-FIRE kills 4T1 cells through non-thermal mechanisms associated with necrosis and pyroptosis resulting in damage associated molecular pattern signaling in vitro and in vivo. Our data indicate that the level of tumor ablation correlates with increased activation of cellular immunity. Likewise, we show that the decrease in metastatic lesions is dependent on the intact immune system and H-FIRE generates 4T1 neoantigens that engage the adaptive immune system to significantly attenuate tumor progression.

Interpretation

Cell death and tumor ablation following H-FIRE treatment activates the local innate immune system, which shifts the tumor microenvironment from an anti-inflammatory state to a pro-inflammatory state. The non-thermal damage to the cancer cells and increased innate immune system stimulation improves antigen presentation, resulting in the engagement of the adaptive immune system and improved systemic anti-tumor immunity.

Noncanonical NF-κB controls stem cell signatures in the colonic mucosa and affects susceptibility to inflammation-induced carcinogenesis

NF-κB signaling is divided into two distinct pathways, defined as either canonical or noncanonical. Canonical NF-κB signaling is well described and characterized. However, significantly less is known regarding mechanisms regulated by the noncanonical NF-κB pathway, especially outside of the lymphoid system. Recently, interest in the role of noncanonical NF-κB in the mucosal immune system has been increasing, with emphasis on NF-κB inducing kinase (NIK). NIK is an essential kinase in this cascade. Our data shows that lack of noncanonical signaling through the complete knockout of Nik in mice results in an aberrant large intestine phenotype characterized by reduced stem cell marker expression, altered regeneration and differentiation capacity under stress, changes in the microbiome, and predisposition to inflammation-associated tumorigenesis. Subsequent mechanistic studies utilizing novel mice with cell type specific deletions of either RelA/p65 or Nik revealed separate and distinct rolls for canonical and noncanonical NF-κB signaling in attenuating inflammation and tumor progression. RelA/p65 attenuates disease progression through the myeloid compartment in the gut, whereas Nik functions through the intestinal epithelial cell compartment. Dysregulation of noncanonical signaling is also observed in human colorectal cancer patients, which have marked suppression of this pathway in colonic biopsy samples. Together, these findings indicate that noncanonical NF-κB signaling is a critical regulator of immune system homeostasis in the gastrointestinal tract and plays a vital protective role against colorectal cancer.

Newfound role for noncanonical NF-κB signaling in Inflammatory Bowel Disease: Gene expression levels serve as a proxy for predicting anti-TNF therapy responsiveness

The canonical arm of NF-κB signaling is well studied in Inflammatory Bowel Disease (IBD) while its noncanonical counterpart has yet to be fully defined. The activation of the noncanonical pathway initiates the nuclear transcription of chemokines associated with chronic inflammation and other diverse immunological processes. Infliximab is an effective anti-TNF treatment that reduces inflammation in IBD, yet a significant percentage of patients are unresponsive or lose responsiveness. Here, we show that noncanonical NF-κB signaling has more relevant implications on IBD and its expression levels correlate to infliximab responsiveness. Our study evaluated noncanonical NF-κB signaling in 27 IBD patient and 9 non-IBD control patient tissue biopsies. Data from these studies were analyzed using bioinformatics to predict its influence on cellular pathways. Genes related to the noncanonical NF-κB pathway were significantly upregulated in IBD lesions compared to healthy tissue. IBD patients that positively respond to infliximab had significantly decreased expression levels compared to nonresponsive patients. These results suggest infliximab, when effective, decreases noncanonical signaling to lessen inflammation. Through targeting in part, the noncanonical NF-κB pathway has prominent emerging roles in IBD pathobiology and is an indicator for improving drug efficacy.

Irreversible electroporation stimulates a pro-inflammatory tumor microenvironment in pancreatic cancer

Pancreatic cancer is a major cancer with a survival rate of only 6% due to late diagnosis and the aggressiveness of the malignancy. There is also a severe lack of viable treatment options due to the localization of the primary tumor near major blood vessels and bile ducts as well as the highly immunosuppressive nature and metastatic potential of pancreatic cancer. New ablative techniques for pancreatic tumors are being developed; however most are thermal and can cause damage to the delicate surrounding structures. Non-thermal irreversible electroporation (IRE) uses short, high frequency electrical pulses to permeabilize cancer cell membranes and illicit cell death. IRE has shown promising results in clinical trials of late-stage, locally advanced cases. Here we utilize several models of pancreatic cancer in vitro, ex vivo, and in vivo to determine the effect of IRE on cell death pathways, cancer pathways, and immune signaling. IRE elicits pro-inflammatory cell death via necrosis and pyroptosis in immunocompetent murine and human patient-derived xenograft models. This pro-inflammatory environment can stimulate immune cell infiltration to the tumor site, halting tumor progression. Moreover, a non-thermal ablative approach also preserves cancer cell antigens that can lead to better immunosurveillance against reoccurrence and metastatic lesions. With the advent of these new techniques, the impact of such technologies to the tumor microenvironment and immune system need to be assessed to determine their clinical application. IRE is proving to be a safe and effective treatment for pancreatic cancer as it not only ablates the primary tumor site but also stimulates the immune system to recognize and combat the tumor throughout the body.

Maternal Influence and Murine Housing Confound Impact of NLRP1 Inflammasome on Microbiome Composition

The NLRP1 inflammasome attenuates inflammatory bowel disease (IBD) progression and colitis-associated tumorigenesis. A possible mechanism postulates that the lack of the NLRP1 inflammasome creates permissive niches in the gut for pathogenic bacteria to flourish, causing dysbiosis and increased IBD susceptibility. To evaluate this hypothesis, we characterized the gut microbiome of wild-type, Nlrp1b-/-, and Asc-/- mice under naïve conditions by sequencing the V3 region of the 16s rRNA gene. For both genetically modified mouse lines, the microbiome composition reflected overrepresentation of bacteria associated with dysbiosis relative to wild-type animals. Measurement of short- and medium-chain fatty acids by mass spectrometry further revealed significant differences between genotypes. However, prior to concluding that the NLRP1 inflammasome plays a role in regulating the composition of the microbiome, we evaluated two additional strategies for cohousing wild-type and Nlrp1b-/- mice: breeding homozygous parents and cohousing at weaning, and breeding from heterozygous parents and cohousing littermates. We found that maternal influence was the greater predictor of microbiome composition rather than genotype. With the rise in microbiome research across disciplines, our study should be viewed as a cautionary example that illustrates the importance of careful breeding and housing strategies when evaluating host-microbiome interactions.

Adoptive Transfer Colitis

Lymphocytes are an important component of inflammatory bowel disease (IBD) pathogenesis. T cells in particular are potent inducers of inflammation in this disease as well as recurrent players in chronic lesion formation. Here we describe a method for adoptive transfer colitis in mice, which serves as a T cell-based model of inflammatory bowel disease. Adoptive transfer utilizes naïve CD4⁺ T cells that are administered to immunodeficient mice, which then induce a chronic pancolitis. Here, protocols are provided for the isolation and purification of naïve CD4⁺ T cells, as well as proper administration to test mice and important points to consider in monitoring disease progression and potential downstream applications. This method provides a way to target the contribution of T cells to IBD models, as well as providing a repeatable and physiologically relevant model of disease.

Persistence of self-injury, aggression and property destruction in children and adults with tuberous sclerosis complex

BACKGROUND

Individuals with tuberous sclerosis complex (TSC) are at increased risk of developing self-injurious behaviour. The persistence of this deleterious behaviour over years is reported in aetiologically heterogeneous samples to be between 60% and 80% but is unknown for TSC.

METHOD

In this study, we determined the 3-year persistence of self-injury in a sample (n = 52) of children (with and without ID) and adults (with ID) with TSC and examined characteristics associated with persistence.

RESULTS

Findings for self-injury were contrasted to those for aggression and property destruction to examine the specificity of results to this behaviour. Self-injury was persistent in 84.6% of those with TSC who showed this behaviour, in contrast to 66.7% both for aggression and destruction. Persistent self-injury was associated with poor self-help skills, greater overactivity/impulsivity and more behavioural indicators of pain. These latter two characteristics were also associated with persistent aggression. No characteristics were associated with persistence of property destruction.

CONCLUSION

These findings suggest that self-injurious behaviours in individuals with TSC, together with aggressive and destructive behaviours, are highly persistent and would benefit from targeted intervention. Poor adaptive skills, overactivity/impulsivity and painful health conditions may differentiate those at most risk for persistent self-injury or aggression.

Noncanonical NF-κB signaling and the essential kinase NIK modulate crucial features associated with eosinophilic esophagitis pathogenesis

Eosinophilic esophagitis (EoE) is an allergic disease of the esophagus driven by T cell and eosinophil responses to dietary allergens, resulting in chronic mucosal inflammation. Few spontaneous animal models of esophageal eosinophilia exist, with most studies relying on artificial sensitization procedures. NF-κB-inducing kinase (NIK; MAP3K14) is a key signaling molecule of the noncanonical NF-κB (NFKB1) pathway, an alternative signaling cascade producing chemokines involved in lymphoid stroma development and leukocyte trafficking. Nik-/- mice have been shown to develop a hypereosinophilic syndrome in peripheral blood and major filtering organs; however, the gastrointestinal mucosa of these mice has not been well characterized. We show that Nik-/- mice develop significant, localized eosinophilic esophagitis that mimics human EoE, including features such as severe eosinophil accumulation, degranulation, mucosal thickening, fibrosis and basal cell hyperplasia. The remainder of the GI tract, including the caudal stomach, small intestine and colon, in mice with active EoE are unaffected, also similar to human patients. Gene expression patterns in esophageal tissue of Nik-/- mice mimics human EoE, with thymic stromal lymphopoetin (TSLP) in particular also elevated at the protein level. In gene expression data sets from human biopsy specimens, we further show that many genes associated with noncanonical NF-κB signaling are significantly dysregulated in EoE patients, most notably a paradoxical upregulation of NIK itself with concurrent upregulation of powerful protein-level destabilizers of NIK. These findings suggest that Nik-/- mice could be useful as a spontaneous model of specific features of EoE and highlight a novel role for noncanonical NF-κB signaling in human patients.

Antibiotics ameliorate lupus-like symptoms in mice

Gut microbiota and the immune system interact to maintain tissue homeostasis, but whether this interaction is involved in the pathogenesis of systemic lupus erythematosus (SLE) is unclear. Here we report that oral antibiotics given during active disease removed harmful bacteria from the gut microbiota and attenuated SLE-like disease in lupus-prone mice. Using MRL/lpr mice, we showed that antibiotics given after disease onset ameliorated systemic autoimmunity and kidney histopathology. They decreased IL-17-producing cells and increased the level of circulating IL-10. In addition, antibiotics removed Lachnospiraceae and increased the relative abundance of Lactobacillus spp., two groups of bacteria previously shown to be associated with deteriorated or improved symptoms in MRL/lpr mice, respectively. Moreover, we showed that the attenuated disease phenotype could be recapitulated with a single antibiotic vancomycin, which reshaped the gut microbiota and changed microbial functional pathways in a time-dependent manner. Furthermore, vancomycin treatment increased the barrier function of the intestinal epithelium, thus preventing the translocation of lipopolysaccharide, a cell wall component of Gram-negative Proteobacteria and known inducer of lupus in mice, into the circulation. These results suggest that mixed antibiotics or a single antibiotic vancomycin ameliorate SLE-like disease in MRL/lpr mice by changing the composition of gut microbiota.

NF-κB-inducing kinase (NIK): A novel modulator of eosinophilic esophagitis (EoE) in mouse models and human patients

Eosinophilic esophagitis (EoE) is an allergic disease of the esophagus driven by T cell and eosinophil responses to dietary allergens resulting in chronic mucosal inflammation and fibrosis. NF-κB inducing kinase (NIK) is a key signaling molecule of the noncanonical NF-κB pathway, an alternative signaling cascade producing chemokines involved in lymphoid stroma development and leukocyte trafficking. Nik−/− mice have been shown to develop a spontaneous hypereosinophilic syndrome in major organs; however, the gastrointestinal mucosa of these mice have not been evaluated. Here we show that Nik−/− mice develop significant eosinophilic esophagitis that mimics human EoE, including intraepithelial eosinophil accumulation, degranulation, mucosal thickening, fibrosis, and basal cell hyperplasia. Additionally, these mice display mucosal hyperplasia in the cranial glandular stomach surrounding the gastroesophageal junction. Interestingly, the remainder of the gastrointestinal tract including the caudal stomach, small intestine, and colon are unaffected, also similar to human EoE. Esophageal tissue from Nik−/− mice contains elevations in Th2 cytokines as well as TSLP, a gene implicated in human EoE. Retrospective metadata analysis of biopsies from human EoE patients shows many significant changes in gene expression throughout the noncanonical NF-κB pathway that are consistent with our murine model. Given that current models of this disease involve artificial sensitization or infectious agents, we conclude that Nik−/− mice may a useful spontaneous model of eosinophilic disease of the esophageal mucosa with improved physiologic relevance. These findings also highlight a novel role for noncanonical NF-κB signaling in EoE.

Map3K14 signaling attenuates the development of colorectal cancer through activation of the non-canonical NF-κB signaling cascade

Dysregulation of NF-κB signaling is a common feature in Colorectal Cancer (CRC). While the canonical signaling pathway is well characterized, the non-canonical NF-κB signaling cascade is understudied. Thus, we evaluated the hypothesis that non-canonical NF-κB signaling significantly modulates CRC pathogenesis. To evaluate this hypothesis, we initially conducted a meta-analysis of human gene expression data. Using this approach, we found that non-canonical NF-κB signaling is significantly down-regulated in CRC patients and the extent of pathway attenuation is correlated with disease severity. These findings were confirmed in patient biopsy specimens, where we found significantly reduced expression of ligands, receptors, regulators, and chemokines associated with non-canonical NF-κB signaling. Notably, we observed significantly reduced CCL19, CCL21, CXCL12, and CXCL13 expression in CRC patients compared to healthy controls. To gain mechanistic insight, we utilized genetically modified mice lacking the kinase Map3K14 (NIK), which is essential for non-canonical NF-κB signaling. Nik−/− mice exhibited ablation of non-canonical NF-κB signaling and significantly increased epithelial cell proliferation in the GI tract compared to wild type mice in both in vivo and in vitro studies. Together, our data defines a protective role for non-canonical NF-κB signaling in the gut during CRC and identifies a highly protective role for Map3K14 in attenuating epithelial cell proliferation.

Noncanonical NF-κB signaling is elevated in inflammatory bowel disease patients and may be associated with therapeutic response

The canonical NF-κB signaling pathway is well characterized in the context of inflammatory bowel disease (IBD). However, noncanonical NF-κB signaling has not been evaluated. This pathway is key for the production of specific chemokines with diverse immunological effects in the gut. To evaluate this pathway, biopsy specimens from control patients and patients with IBD (CD and UC) were collected and pathways associated with inflammation were assessed via custom RT-PCR arrays. These expression data were compared to lesion status, IBD subtype (CD or UC), and treatment. Our analysis revealed significant up-regulation of several key genes associated with noncanonical NF-κB signaling in lesion tissue from IBD patients compared to controls and non-lesion areas. Interestingly, CD patients displayed increased noncanonical signaling compared to both control and UC patients in over 20 genes directly involved in the noncanonical pathway. Treatment with the anti-TNF biologic infliximab resulted in down-regulation of these and other noncanonical NF-κB signaling molecules in CD patients. Subsequent bioinformatics analysis of CD patients revealed that elevation of chemokines associated with noncanonical NF-κB signaling are indicators of infliximab responsiveness, with patients refractory to infliximab showing significantly elevated levels of gene expression. Together, these data indicate that noncanonical NF-κB signaling is elevated in IBD patients and may have links to therapeutic response.

Selective HDAC6 inhibitor decreases lupus in mice

Histone deacetylase 6 (HDAC6) is a Class IIb HDACs enzyme primarily residing in the cytoplasm. HDAC6 alters gene transcription by removing acetyl groups from lysine residues on transcription factors. We, and others, have previously demonstrated that HDAC6 expression is increased in systemic lupus erythematosus (SLE) patients and animal models of lupus and that inhibition of HDAC6 decreased disease. In our current studies, we tested if an orally active selective HDAC6 inhibitor would decrease disease pathogenesis in a lupus mouse model with established early disease. Importantly, we sought to delineate the cellular and molecular mechanism(s) of action for the HDAC6 inhibitor. We treated 20-week-old early-diseased NZB/W F1 (lupus) female mice with two different doses of the selective HDAC6 inhibitor (ACY-738) for five weeks. At the termination of the study, our results showed a reduced germinal center B cell response, decreased T follicular helper cells and diminished IFN-g production from T helper cells in splenic tissue. Additionally, we found the IFNa-producing ability of plasmacytoid dendritic cells was decreased along with immunoglobulin isotype switching and the generation of pathogenic autoantibodies. Renal tissue showed decreased immunoglobulin deposition and reduced inflammation as judged by glomerular and interstitial inflammation. Taking together, these studies show selective HDAC inhibition decreased several parameters of disease pathogenesis in lupus prone mice. The decrease was in part due to inhibition of autoreactive B cell differentiation. Studies are currently underway to define further the mechanism of how HDAC6 inhibits auto-reactive B cell differentiation.

NLRX1 Regulates Effector and Metabolic Functions of CD4+ T Cells

Nucleotide oligomerization domain-like receptor X1 (NLRX1) has been implicated in viral response, cancer progression, and inflammatory disorders; however, its role as a dual modulator of CD4⁺ T cell function and metabolism has not been defined. The loss of NLRX1 results in increased disease severity, populations of Th1 and Th17 cells, and inflammatory markers (IFN-γ, TNF-α, and IL-17) in mice with dextran sodium sulfate-induced colitis. To further characterize this phenotype, we used in vitro CD4⁺ T cell-differentiation assays and show that NLRX1-deficient T cells have a greater ability to differentiate into an inflammatory phenotype and possess greater proliferation rates. Further, NLRX1^-/- cells have a decreased responsiveness to immune checkpoint pathways and greater rates of lactate dehydrogenase activity. When metabolic effects of the knockout are impaired, NLRX1-deficient cells do not display significant differences in differentiation or proliferation. To confirm the role of NLRX1 specifically in T cells, we used an adoptive-transfer model of colitis. Rag2^-/- mice receiving NLRX1^-/- naive or effector T cells experienced increased disease activity and effector T cell populations, whereas no differences were observed between groups receiving wild-type or NLRX1^-/- regulatory T cells. Metabolic effects of NLRX1 deficiency are observed in a CD4-specific knockout of NLRX1 within a Citrobacter rodentium model of colitis. The aerobic glycolytic preference in NLRX1^-/- effector T cells is combined with a decreased sensitivity to immunosuppressive checkpoint pathways to provide greater proliferative capabilities and an inflammatory phenotype bias leading to increased disease severity.

Beyond the inflammasome: regulatory NOD-like receptor modulation of the host immune response following virus exposure

A complex interaction exists between elements of the host innate immune system and viral pathogens. It is essential that the host mount a robust immune response during viral infection and effectively resolve inflammation once the pathogen has been eliminated. Members of the nucleotide-binding domain leucine-rich repeat [NBD-LRR; known as NOD-like receptor (NLR)] family of cytosolic pattern-recognition receptors are essential components of these immunological processes and have diverse functions in the host antiviral immune response. NLRs can be subgrouped based on their general function. The inflammasome-forming subgroup of NLRs are the best-characterized family members, and several have been found to modulate the maturation of IL-1β and IL-18 following virus exposure. However, the members of the regulatory NLR subgroups are significantly less characterized. These NLRs uniquely function to modulate signalling pathways initiated by other families of pattern-recognition receptors, such as Toll-like receptors and/or Rig-I-like helicase receptors. Regulatory NLRs that augment pro-inflammatory pathways include nucleotide-binding oligomerization domain-containing protein 1 (NOD1) and NOD2, which have been shown to form a multiprotein complex termed the NODosome that significantly modulates IFN and NF-κB signalling following viral infection. Conversely, a second subgroup of regulatory NLRs functions to negatively regulate inflammation. These inhibitory NLRs include NLRX1, NLRP12 and NLRC3, which have been shown to interact with TRAF molecules and various kinases to modulate diverse cellular processes. Targeting NLR signalling following infection with a virus represents a novel and promising therapeutic strategy. However, significant effort is still required to translate the current understanding of NLR biology into effective therapies.

Clinical Features and Magnetic Resonance Imaging Findings in 7 Dogs with Central Nervous System Aspergillosis

Background

Systemic aspergillosis is a manifestation of Aspergillus sp. infection that can result in central nervous system (CNS) involvement with marked alterations in CNS function. Information regarding the clinical presentation and magnetic resonance imaging (MRI) findings in cases of aspergillosis with CNS involvement is lacking, resulting in a need for better understanding of this disease.

Hypothesis/Objectives

The primary objectives were to describe the clinical features and MRI findings in dogs with CNS aspergillosis. The secondary objectives were to describe clinicopathologic findings and case outcome.

Animals

Seven dogs with CNS aspergillosis.

Methods

Archived records from 6 institutions were reviewed to identify cases with MRI of CNS aspergillosis confirmed with serum galactomannan enzyme immunoassay (EIA) testing, culture, or supported by histopathology. Signalment, clinical, MRI, clinicopathologic, histopathologic, and microbiologic findings were recorded and evaluated.

Results

Aspergillosis of the CNS was identified in 7 dogs from 3 institutions. The median age was 3 years and six were German Shepherd dogs. Five dogs had signs of vestibular dysfunction as a component of multifocal neurological abnormalities. The MRI findings ranged from normal to abnormal, including hemorrhagic infarction and mass lesions.

Conclusions and Clinical Importance

Until now, all reported MRI findings in dogs with CNS aspergillosis have been abnormal. We document that CNS aspergillosis in dogs, particularly German Shepherd dogs, can be suspected based on neurologic signs, whether MRI findings are normal or abnormal. Confirmatory testing with galactomannan EIA, urine, cerebrospinal fluid (CSF) or tissue culture should be performed in cases where aspergillosis is a differential diagnosis.

Immune modulatory mechanisms of lanthionine synthetase C-like protein 2 (IRM12P.656)

Lanthionine synthetase C-like protein 2 (LANCL2) has emerged as a novel therapeutic target for metabolic, infectious and immune-mediated diseases. We previously demonstrated that directly targeting LANCL2 through treatment with abscisic acid or 61610 results in efficacious anti-inflammatory responses during DSS-induced colitis however molecular mechanisms underlying this immunomodulatory function remain elusive. Here we report for the first time the use of LANCL2-deficient mice to investigate the mechanism of action and cell specificity of the protein. At the cellular level, bone marrow derived macrophages (BMDM), RAW cells, and gastric epithelial cells express comparable levels of basal LANCL2 mRNA. LPS-mediated inflammation in BMDM increased both mRNA and protein levels of LANCL2 that peaked 6 hours post-challenge and subsequently returned to normal levels after 12 hours. Similarly, DSS-induced colitis induced expression of LANCL2 in the colons of wild-type (WT) mice and correlated with elevated levels of proinflammatory cytokines. Interestingly, the absence of LANCL2 did not cause significant alterations in infiltrating cellular phenotypes however LANCL2-deficiency permitted exaggerated IL17 and IFNγ expression in colonic tissue when compared to WT counterparts at day 7 post-challenge. In conclusion, our findings indicate that LANCL2 is a novel regulator of inflammation that functions predominantly at the molecular level to down-regulate excessive inflammatory responses.

Macrophages modulate bacterial persistence and gastric pathology during Helicobacter pylori infection (INC4P.346)

Based on preliminary data suggesting that macrophages are critical regulators of Helicobacter pylori colonization and gastric pathology, we investigated how macrophage phenotypes shape the outcome of infection and persistence. The loss of PPARγ in the myeloid compartment favors a 5 to 10-fold decrease in bacterial loads at the expense of more severe gastric lesions. PPARγ-deficient macrophages present altered control of transcription factors such as NFκB, which results in a pro-inflammatory phenotype. Stomach lamina propria analyses at weeks 0 to 4 post-infection revealed increased levels of CD11b+ F4/80hi CD64+ CR3CR1+ macrophages in WT mice, while PPARγKO mice failed to expand and maintain such population. Macrophage depletion using clodronate liposomes resulted in a significant reduction of gastric H. pylori in WT mice, thus abrogating the differences in bacterial loads observed between WT and PPARγKO mice. In vitro co-culture of H. pylori with bone marrow derived macrophages showed that either PPARγ loss or pharmacological blockade enhances bactericidal activity, which is associated to significant differential expression of chil1, etv5, iigp1, ptger4, sqle, osm, hspa2 and rptoros levels as revealed by global transcriptome analyses. Hence, macrophages facilitate H. pylori infection by 1) serving as bacterial reservoirs and allowing intracellular replication, and 2) favoring a gastric regulatory response that favors persistence.

Loss of NLRX1 results in increased intestinal pathology and T cell responses in mice with inflammatory bowel disease (HUM1P.312)

NLRX1 is a mitochondrial-associated NOD-like receptor that modulates antiviral immunity, cellular stress, autophagy, and reactive oxygen species (ROS). The role of NLRX1 in inflammatory bowel disease remains unknown. This study aimed to characterize NLRX1-mediated mechanisms of protection from IBD. We investigated the ability of NLRX1 to modulate gut pathology, inflammation and immunity by using DSS and CD4+CD45RBhigh transfer colitis models. Colons, spleens, and mesenteric lymph nodes were excised for characterizing immune cell subsets, histological analyses, cytokine and autophagy expression, NF-κB activity, and ROS production. The loss of NLRX1 increased severity of disease and colonic histopathology in both models of IBD. Colons of NLRX1-/- mice had significantly increased epithelial ulceration and leukocyte infiltration in the DSS model, while recipients of NLRX1-/- CD4+ T cells had increased leukocytic infiltration, proliferation, fibrosis, and crypt abscessation in both colon and ileum. The loss of NLRX1 increased numbers of Th1, Th17, and Treg in the spleen, increased colonic NF-κB activity, upregulation of IL-17, IFNγ and TNF-α production, and increased ROS production. NLRX1 ameliorates intestinal pathology during IBD by acting as an internal thermostat that modulates the balance of effector versus regulatory CD4+ T cell responses, and suppressing colonic NF-κB activity, inflammatory cytokine expression, ROS production, and autophagy.

Computational modeling of heterogeneity and function of CD4+ T cells

The immune system is composed of many different cell types and hundreds of intersecting molecular pathways and signals. This large biological complexity requires coordination between distinct pro-inflammatory and regulatory cell subsets to respond to infection while maintaining tissue homeostasis. CD4+ T cells play a central role in orchestrating immune responses and in maintaining a balance between pro- and anti- inflammatory responses. This tight balance between regulatory and effector reactions depends on the ability of CD4+ T cells to modulate distinct pathways within large molecular networks, since dysregulated CD4+ T cell responses may result in chronic inflammatory and autoimmune diseases. The CD4+ T cell differentiation process comprises an intricate interplay between cytokines, their receptors, adaptor molecules, signaling cascades and transcription factors that help delineate cell fate and function. Computational modeling can help to describe, simulate, analyze, and predict some of the behaviors in this complicated differentiation network. This review provides a comprehensive overview of existing computational immunology methods as well as novel strategies used to model immune responses with a particular focus on CD4+ T cell differentiation.

Immune modulatory mechanisms of Oncostemum bojerianum extracts during Clostridium difficile infection in mice (MUC4P.845)

Activation of Peroxisome Proliferator-Activated Receptor γ has proven beneficial for the treatment of several inflammatory diseases. However, current drugs targeting PPAR result in significant side effects. Therefore, the development of safer anti-inflammatory therapies is important. This project aimed to discover new natural constituents from ethnomedicinal plants that target PPARγ and elucidate the mechanisms of action underlying their anti-inflammatory activities. From a screen of 200 plant extracts, we identified more than 50 that activate PPARγ, with a high predominance in Oncostenum species. The anti-inflammatory properties of two O. bojerianum extracts were further tested in a mouse model of Clostridium difficile infection, which resulted in a detectable improvement in disease activity, weight loss, colonic inflammatory lesions, and increased levels of colonic IL-10-producing CD4+ T cells. Oral treatment with Oncostemum extracts increased PPARγ and PPARα activity and elevated transcriptional expression of their responsive genes. Bioassay-guided fractionation studies in combination with in silico molecular screening, identified the resorcinol family as the PPARγ-activating compounds contained in the extracts. Characterizing the modulation of cellular and molecular signatures by resorcinols at the sites of inflammation will translate natural products discovery into the development of safer and more efficacious therapeutics for infectious and immune-mediated diseases.

Mucosal antimicrobial protection toward enteroaggregative Escherichia coli infection is modulated by dietary tryptophan through an IL17-dependent mechanism (MUC4P.846)

Enteroaggregative E. coli (EAEC) is a predominant extracellular pathogen that causes inflammatory diarrhea in individuals worldwide, especially in persons suffering from malnutrition. We previously reported that protein-energy malnutrition abrogates protective Th17-dependent antimicrobial immunity in a murine model of EAEC infection. However, mechanisms whereby malnutrition enhances host-susceptibility to EAEC colonization remain unreported. This study presents evidence that tryptophan is crucial for antibacterial protection against EAEC infection. Mice fed tryptophan-free diet had reduced antimicrobial peptide production coinciding with significantly high pathogen levels. Likewise, bacterial burden occurred in a dose dependent manner when mice were supplemented with glycly-L-tryptophan dipeptide. Low serum tryptophan directly correlated with hampered gene expression levels of cytokines regulating effector IL-17A responses (e.g. IL-23 and IL-6). Mechanistically, orally administered tryptophan enhanced IL-17A and IL-17C production at the colonic and ileal mucosa facilitating antimicrobial defense and protection against EAEC colonization. IL17a-/- and IL17ra-/- mice receiving nourished diets or tryptophan supplements were unable to recover from disease due to impaired intestinal epithelial barrier function. Thus, our data suggests that tryptophan modulates IL17-dependent antimicrobial responses and is required for preventing EAEC colonization and pathogenic disease.

Screening high-risk populations for thyroid cancer

BACKGROUND

Children treated with radiotherapy to the neck or exposed to environmental radiation are at risk for developing thyroid cancer later in life. The best method for screening these high-risk patients is unclear. We systematically reviewed evidence on the accuracy of ultrasound and palpation to detect thyroid nodules and of fine needle aspiration (FNA), a confirmatory test, to diagnose thyroid cancer.

PROCEDURE

We searched the MEDLINE database for papers published since 1966, using the MeSH term thyroid neoplasms and terms related to diagnostic test performance. To supplement our MEDLINE searches, we searched reference lists from recent reviews and articles recommended by thyroid cancer experts. We recorded the tests used, the gold standard determination of disease, the test performance results, and the presence of biases that could affect the reported results. We also abstracted the number of patients who underwent surgery and the final diagnoses. We created two decision models: one for screening 10,000 medically irradiated patients, and one for screening 10,000 environmentally irradiated patients.

RESULTS

Using ultrasound as the gold standard determination of the presence of a nodule, the sensitivity of palpation for all sized nodules was 10-41 percent, indicating that a high proportion of nodules detected by ultrasound are too small to be palpated. Sensitivity of palpation increased with nodule size. The specificity of palpation ranged from 95 to 100%. In studies from referral centers, the reported sensitivity and specificity of FNA were 71-95 and 52-99%, respectively. However, most authors excluded the proportion of patients (6-33%) who had inadequate or nondiagnostic FNA results when calculating sensitivity and specificity, even though 6-100% of these patients went on to have a diagnostic lobectomy. When each study was reanalyzed so that patients with nondiagnostic FNA results who went directly to surgery were reclassified as positive tests, sensitivity increased slightly, but specificity dropped by 4-20 percentage points per study. The decision model for screening 10,000 medically irradiated patients revealed that if ultrasound were used as an initial screen, 2,741 patients would have nodules at least 1 cm in size; assuming no patients with smaller nodules had surgery, 1,964 patients would have surgery; 275 patients would have a diagnosis of thyroid cancer. Screening with ultrasound as an initial test would detect an additional 150 cases of thyroid cancer compared to those screened with palpation. However, an additional 1,689 patients would have surgery for nonmalignant nodules (compared to 480 patients with nonmalignant nodules screened with palpation). The yield for screening 10,000 environmentally irradiated patients was several times smaller than for screening 10,000 medically irradiated patients. If 10,000 environmentally irradiated patients were screened initially with ultrasound, approximately 708 patients would have nodules at least 1 cm in size; 89 patients would have surgery; and 38 patients would be diagnosed with thyroid cancer.

CONCLUSIONS

Regardless of type of exposure, testing initially with ultrasound detects several times more cases of thyroid cancer than palpation. However, when ultrasound is the initial test, many more patients also have surgery for nonmalignant nodules. Screening with palpation is not very reassuring, particularly to medically irradiated patients with negative tests, since almost half (46%) of these patients may have undetected nodules.