The African-centric P47S Variant of TP53 Confers Immune Dysregulation and Impaired Response to Immune Checkpoint Inhibition

The tumor suppressor TP53 is the most frequently mutated gene in cancer and is mutationally inactivated in 50% of sporadic tumors. Inactivating mutations in TP53 also occur in Li Fraumeni syndrome (LFS). In addition to germline mutations in TP53 in LFS that completely inactivate this protein, there are many more germline mutant forms of TP53 in human populations that partially inactivate this protein: we call these partially inactivating mutations "hypomorphs." One of these hypomorphs is a SNP that exists in 6%-10% of Africans and 1%-2% of African Americans, which changes proline at amino acid 47 to serine (Pro47Ser; P47S). We previously showed that the P47S variant of p53 is intrinsically impaired for tumor suppressor function, and that this SNP is associated with increased cancer risk in mice and humans. Here we show that this SNP also influences the tumor microenvironment, and the immune microenvironment profile in P47S mice is more protumorigenic. At basal levels, P47S mice show impaired memory T-cell formation and function, along with increased anti-inflammatory (so-called "M2") macrophages. We show that in tumor-bearing P47S mice, there is an increase in immunosuppressive myeloid-derived suppressor cells and decreased numbers of activated dendritic cells, macrophages, and B cells, along with evidence for increased T-cell exhaustion in the tumor microenvironment. Finally, we show that P47S mice demonstrate an incomplete response to anti-PD-L1 therapy. Our combined data suggest that the African-centric P47S variant leads to both intrinsic and extrinsic defects in tumor suppression.

Significance

Findings presented here show that the P47S variant of TP53 influences the immune microenvironment, and the immune response to cancer. This is the first time that a naturally occurring genetic variant of TP53 has been shown to negatively impact the immune microenvironment and the response to immunotherapy.

Abstract C023: A microbiome-produced metabolite drives immunostimulatory macrophages and boosts response to immune checkpoint inhibitors in pancreatic cancer

The composition of the gut microbiome controls innate and adaptive immunity and has emerged as a key regulator of tumor growth and the success of immune checkpoint blockade (ICB) therapy. However, the underlying mechanisms remain unclear. Pancreatic ductal adenocarcinoma (PDAC) tends to be refractory to therapy, including ICB. We found that the gut microbe-derived metabolite trimethylamine N-oxide (TMAO) enhances anti-tumor immunity to PDAC. Delivery of TMAO given intraperitoneally or via dietary choline supplement to PDAC-bearing mice reduces tumor growth and is associated with an immunostimulatory tumor-associated macrophage (TAM) phenotype and activated effector T cell response in the tumor microenvironment. Mechanistically, TMAO signals through potentiating type-I interferon (IFN) pathway and confers anti-tumor effects in a type-I IFN dependent manner. Notably, delivering TMAO-primed macrophages alone produced similar anti-tumor effects. Combining TMAO with ICB (anti-PD1 and/or anti-Tim3) significantly reduced tumor burden and improved survival beyond TMAO or ICB alone. Finally, the levels of trimethylamine (TMA)-producing bacteria and of CutC gene expression correlate with improved survivorship and response to anti-PD1 in cancer patients. Together, our study identifies the gut microbial metabolite TMAO as an important driver of anti-tumor immunity and lays the groundwork for new therapeutic strategies.

Citation Format: Gauri Mirji, Alison Worth, Sajad Bhat, Mohamed Sayed, Toshitha Kannan, Aaron Goldman, Hsin-Yao Tang, Qin Liu, Noam Auslander, Chi Dang, Mohamed Abdel-Mohsen, Andrew Kossenkov, Ben Stanger, Rahul Shinde. A microbiome-produced metabolite drives immunostimulatory macrophages and boosts response to immune checkpoint inhibitors in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C023.

Covid-19 Affected Workers of Micro, Small, and Medium Enterprises

Purpose: India announced the first lockdown starting from March 25, 2020, due to the outbreak of the COVID-19 pandemic. The Micro, Small and Medium Enterprises (MSMEs) have limited finances, workforce, and operations regarding products or services and do not have the resources to deal with such unexpected lockdowns. This study is to understand the impact of COVID-19 on the workers of MSMEs. Method: An e-questionnaire in the local language was circulated to 444 workers, out of which 426 participated in the study. Result: 98.6% of females earned Rs 5000 to 10000 per month. 95.6% females and 72.1% males saved less than Rs 2000 per month. 25.8% of micro 8.4% of small and 17.2% of the medium-scale workers were not aware of the updates on COVID-19. 70.55% of medium and micro-scale workers stayed at home compared to 45.1% of small-scale workers. 99.7% of micro and small and 93.8% of medium-scale workers regularly sanitized hands at the workplace. 41.9% micro, 84.2% small, and 69% of medium-scale workers said that the COVID-19 outbreak impacted their social life. The pandemic impacted 64.5% micro, 92.9% small, and 97.4% of medium-scale workers’ earnings. 80.6% micro, 97.3% small & 90.5% of medium-scale workers were provided financial assistance by their companies. 80% of medium and micro-scale workers & 94.9% of small-scale workers said they were satisfied with the response/action taken by local municipal authorities. Conclusion: The COVID-19 pandemic has impacted the socio-economic lives of MSME workers. There is an impact of information about the COVID19 outbreak shared by the Govt. of India and social media.

Process-based diagnostics of extreme pollution trail using numerical modelling during fatal second COVID-19 wave in the Indian capital

The world's worst outbreak, the second COVID-19 wave, not only unleashed unprecedented devastation of human life, but also made an impact of lockdown in the Indian capital, New Delhi, in particulate matter (PM: PM_2.5 and PM₁₀) virtually ineffective during April to May 2021. The air quality remained not only unabated but also was marred by some unusual extreme pollution events. SAFAR-framework model simulations with different sensitivity experiments were conducted using the newly developed lockdown emission inventory to understand various processes responsible for these anomalies in PM. Model results well captured the magnitude and variations of the observed PM before and after the lockdown but significantly underestimated their levels in the initial period of lockdown followed by the first high pollution event when the mortality counts were at their peak (∼400 deaths/day). It is believed that an unaccounted emission source was playing a leading role after balancing off the impact of curtailed lockdown emissions. The model suggests that the unprecedented surge in PM₁₀ (690 μg/m³) on May 23, 2021, though Delhi was still under lockdown, was associated with large-scale dust transport originating from the north west part of India combined with the thunderstorm. The rainfall and local dust lifting played decisive roles in other unusual events. Obtained results and the proposed interpretation are likely to enhance our understanding and envisaged to help policymakers to frame suitable strategies in such kinds of emergencies in the future.

Abstract 5610: Targeting Rb1 in experimental pancreatic cancer remodels immune cell landscape and suppresses tumor progression

Background: Pancreatic ductal adenocarcinoma (PDA) remains among the cancers with the poorest prognosis. Currently, no effective treatment available for PDA. Immunotherapy that has been shown effective for several cancer types is not successful for PDA treatment overall. The possible reasons of this PDA immunotherapy resistance include lack of neoantigen mutations, low T cell responses and overall immunosuppression state in the tumor microenvironment mediated by myeloid cells and tumor stroma. Recent studies suggest that targeting tumor microenvironment can overcome this immunotherapy resistance and significantly improve the disease outcome. Retinoblastoma (Rb1) protein is a known tumor suppressor protein. In addition, there is accumulating evidence for its role in immune cell response as well, including regulation of apoptosis in myeloid cells. However, the mechanisms of this phenomenon remain not clear. Here we show that targeting Rb1 with a novel molecule AP-3-84 developed in our lab causes apoptosis of tumor-associated macrophages (TAMs) in the model of PDA, induces T cell infiltration of the tumor and decreases tumor burden.

Results: Recently our lab has developed the new small molecule AP-3-84 that is able to bind Rb1 and modulate its activity. Originally, we found that this Rb1 modulator can induce cell death of TAMs and thioglycolate-induced macrophages, but not of the other cell types (neither tumor nor T cells). Gene expression changes upon AP-3-84 treatment showed the induction of oxidative and ER stress programs with a clear activation of p53-dependent genes and caspases. We tested the use of AP-3-84 as immunotherapy against PDA cancer growth using 2 PDA cell lines intrinsically characterized by low T cell and high T cell infiltration (T-low-PDA and T-high-PDA, respectively, originally generated and characterized by J. Li et al., Immunity 2018). In accordance with our in vitro observation, AP-3-84 was able to reshape immune cell landscape in mice with T-high-PDA by depleting macrophages and inducing T cell infiltration. Importantly, those changes were accompanied by significant reduction of tumor growth. Addition of AP-3-84 to immunotherapy (anti-CD40/PD1/CTL4) was also able to decrease tumor burden in T-low-PDA model, which is otherwise resistant to this immunotherapy. Thus, AP-3-84 treatment was able to significantly improve the outcome of experimental PDA by altering immune cell subsets and represent a prospective clinical approach for the clinic.

Statistical analysis of the data was conducted using unpaired Student t-test with additional false discovery rate adjustment for multiple comparisons for gene expression analysis.

Conclusions: Modulation of Rb1 in myeloid cells is a novel promising target for PDA treatment. This approach reduces PDA tumor burden by shifting the immune cell landscape towards greater T cell infiltration upon tumor macrophage depletion.

Citation Format: Evgenii N. Tcyganov, Taekyoung Kwak, Adi Narayana Reddy Poli, Laxminarasimha Donthireddy, Joel Cassel, Andrew Kossenkov, Rahul Shinde, Ben Z. Stanger, Joseph Salvino, Luis J. Montaner. Targeting Rb1 in experimental pancreatic cancer remodels immune cell landscape and suppresses tumor progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5610.

Neonatal Multisystem Inflammatory Syndrome (MIS-N) Associated with Prenatal Maternal SARS-CoV-2: A Case Series

Multisystem inflammatory syndrome in children (MIS-C) is a post-infectious immune-mediated condition, seen 3-5 weeks after COVID-19. Maternal SARS-CoV-2 may potentially cause a similar hyperinflammatory syndrome in neonates due to transplacental transfer of antibodies. We reviewed the perinatal history, clinical features, and outcomes of 20 neonates with features consistent with MIS-C related to maternal SARS-CoV-2 in Kolhapur, India, from 1 September 2020 to 30 April 2021. Anti-SARS-CoV-2 IgG and IgM antibodies were tested in all neonates. Fifteen singletons and five twins born to eighteen mothers with a history of COVID-19 disease or exposure during pregnancy presented with features consistent with MIS-C during the first 5 days after birth. Nineteen were positive for anti-SARS-CoV-2 IgG and all were negative for IgM antibodies. All mothers were asymptomatic and therefore not tested by RTPCR-SARS-CoV-2 at delivery. Eighteen neonates (90%) had cardiac involvement with prolonged QTc, 2:1 AV block, cardiogenic shock, or coronary dilatation. Other findings included respiratory failure (40%), fever (10%), feeding intolerance (30%), melena (10%), and renal failure (5%). All infants had elevated inflammatory biomarkers and received steroids and IVIG. Two infants died. We speculate that maternal SARS-CoV-2 and transplacental antibodies cause multisystem inflammatory syndrome in neonates (MIS-N). Immunomodulation may be beneficial in some cases, but further studies are needed.

Nuclear receptors, the aryl hydrocarbon receptor, and macrophage function

Nuclear receptors (NRs) are key regulators of innate immune responses and tissue homeostasis. Evidence indicates that NRs significantly impact steady-state immune regulation, uptake and processing of apoptotic cells, tolerance induction, and control of inflammatory immunity. In this review, we describe our current understanding of the NR activity for balancing inflammation and tolerance, the signaling cascade inducing the NR activation and functional responses, and different mechanisms of the NR-driven immune effects in the context of autoimmune diseases. We further describe the ligand-activated transcription factor the aryl hydrocarbon receptor (AhR) that exhibits analogous functionality. Moreover, we will discuss the putative role of NRs and AhR in immune regulation and disease pathogenesis providing a rationale for therapeutic targeting as a unique opportunities in the clinical management of autoimmune diseases.

COVID-19 and environmental -weather markers: Unfolding baseline levels and veracity of linkages in tropical India

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is rapidly spreading across the globe due to its contagion nature. We hereby report the baseline permanent levels of two most toxic air pollutants in top ranked mega cities of India. This could be made possible for the first time due to the unprecedented COVID-19 lockdown emission scenario. The study also unfolds the association of COVID-19 with different environmental and weather markers. Although there are numerous confounding factors for the pandemic, we find a strong association of COVID-19 mortality with baseline PM_2.5 levels (80% correlation) to which the population is chronically exposed and may be considered as one of the critical factors. The COVID-19 morbidity is found to be moderately anti-correlated with maximum temperature during the pandemic period (-56%). Findings although preliminary but provide a first line of information for epidemiologists and may be useful for the development of effective health risk management policies.

The Aryl Hydrocarbon Receptor: Connecting Immunity to the Microenvironment

The aryl hydrocarbon receptor (AhR) is a cytoplasmic receptor and transcription factor activated through cognate ligand binding. It is an important factor in immunity and tissue homeostasis, and structurally diverse compounds from the environment, diet, microbiome, and host metabolism can induce AhR activity. Emerging evidence suggests that AhR is a key sensor allowing immune cells to adapt to environmental conditions and changes in AhR activity have been associated with autoimmune disorders and cancer. Furthermore, AhR agonists or antagonists can impact immune disease outcomes identifying AhR as a potentially actionable target for immunotherapy. In this review, we describe known ligands stimulating AhR activity, downstream proinflammatory and suppressive mechanisms potentiated by AhR, and how this understanding is being applied to immunopathology to help control disease outcomes.

Apoptotic cell-induced AhR activity is required for immunological tolerance and suppression of systemic lupus erythematosus in mice and humans

The transcription factor AhR modulates immunity at multiple levels. Here we report phagocytes exposed to apoptotic cells exhibited rapid activation of AhR, which drove production of interleukin 10. Activation of AhR was dependent on interactions between apoptotic-cell DNA and the pattern-recognition receptor TLR9 that was required for prevention of immune responses to DNA and histones in vivo. Moreover, disease progression in murine systemic lupus erythematosus (SLE) correlated with strength of the AhR signal, and disease course could be altered by modulation of AhR activity. Deletion of AhR in the myeloid lineage caused systemic autoimmunity in mice and an increased AhR transcriptional signature correlated with disease in patients with SLE. Thus, AhR activity induced by apoptotic cell phagocytes maintains peripheral tolerance.

Real-world treatment patterns and outcomes among metastatic cutaneous melanoma patients treated with ipilimumab

BACKGROUND

There is a scarcity of real-world data on treatment patterns and outcomes among advanced melanoma patients treated with immunotherapies including ipilimumab, an anti-CTLA-4 antibody approved since 2011.

OBJECTIVE

To evaluate ipilimumab and postipilimumab treatment patterns and outcomes among patients with advanced melanoma in Australia, Germany, Italy and Spain, following regulatory approval.

METHODS

Retrospective multicentre, multinational, observational chart review study. Data were extracted from the start of ipilimumab therapy until the end of at least 40 weeks of follow-up, or death.

RESULTS

Data from 371 patients (Australia, 103; Germany, 152; Italy, 76; Spain, 40) were analysed. Mean age was 65 years; 62% were male. Eastern Cooperative Oncology Group performance status (ECOG PS) was 0 or 1 for 94%. In 67%, ipilimumab was initially received as second-line or later therapy. Patients received on average 3.4 ipilimumab doses. The ipilimumab-refractory cohort comprised of 226 patients. Of these, 17% in Australia, 47% in Germany, 29% in Italy and 14% in Spain received another antimelanoma treatment after ipilimumab including chemotherapy in 26% and BRAF/other kinase inhibitors in 11%. Ipilimumab-refractory patients who received postipilimumab treatment showed a 40% reduced hazard of dying than those not receiving treatment after ipilimumab (HR 0.60; 95% CI 0.43-0.83), after adjustment for potential confounders.

CONCLUSION

During the time observed, ipilimumab was mainly used as second-line or later therapy. A significant proportion of patients received postipilimumab therapy, most of which was chemotherapy. Nevertheless, overall survival following progression on ipilimumab treatment remained poor, highlighting the need for research to develop more effective end-of-life treatment options.

Selective Memory to Apoptotic Cell-Derived Self-Antigens with Implications for Systemic Lupus Erythematosus Development

Autoimmune diseases are characterized by pathogenic immune responses to self-antigens. In systemic lupus erythematosus (SLE), many self-antigens are found in apoptotic cells (ACs), and defects in removal of ACs from the body are linked to a risk for developing SLE. This includes pathological memory that gives rise to disease flares. In this study, we investigated how memory to AC-derived self-antigens develops and the contribution of self-memory to the development of lupus-related pathology. Multiple injections of ACs without adjuvant into wild-type mice induce a transient primary autoimmune response without apparent anti-nuclear Ab reactivity or kidney pathology. Interestingly, as the transient Ab response reached baseline, a single boost injection fully recalled the immune response to ACs, and this memory response was furthermore transferable into naive mice. Additionally, the memory response contains elements of pathogenicity, accompanied by selective memory to selective Ags. Thus, we provide evidence for a selective self-memory that underlies progression of the response to self-antigens with implications for SLE development therapy.

Deregulation of arginase induces bone complications in high-fat/high-sucrose diet diabetic mouse model

A balanced diet is crucial for healthy development and prevention of musculoskeletal related diseases. Diets high in fat content are known to cause obesity, diabetes and a number of other disease states. Our group and others have previously reported that activity of the urea cycle enzyme arginase is involved in diabetes-induced dysregulation of vascular function due to decreases in nitric oxide formation. We hypothesized that diabetes may also elevate arginase activity in bone and bone marrow, which could lead to bone-related complications. To test this we determined the effects of diabetes on expression and activity of arginase, in bone and bone marrow stromal cells (BMSCs). We demonstrated that arginase 1 is abundantly present in the bone and BMSCs. We also demonstrated that arginase activity and expression in bone and bone marrow is up-regulated in models of diabetes induced by HFHS diet and streptozotocin (STZ). HFHS diet down-regulated expression of healthy bone metabolism markers (BMP2, COL-1, ALP, and RUNX2) and reduced bone mineral density, bone volume and trabecular thickness. However, treatment with an arginase inhibitor (ABH) prevented these bone-related complications of diabetes. In-vitro study of BMSCs showed that high glucose treatment increased arginase activity and decreased nitric oxide production. These effects were reversed by treatment with an arginase inhibitor (ABH). Our study provides evidence that deregulation of l-arginine metabolism plays a vital role in HFHS diet-induced diabetic complications and that these complications can be prevented by treatment with arginase inhibitors. The modulation of l-arginine metabolism in disease could offer a novel therapeutic approach for osteoporosis and other musculoskeletal related diseases.

The PTEN pathway in Tregs is a critical driver of the suppressive tumor microenvironment

The tumor microenvironment is profoundly immunosuppressive. We show that multiple tumor types create intratumoral immune suppression driven by a specialized form of regulatory T cell (Treg) activation dependent on the PTEN (phosphatase and tensin homolog) lipid phosphatase. PTEN acted to stabilize Tregs in tumors, preventing them from reprogramming into inflammatory effector cells. In mice with a Treg-specific deletion of PTEN, tumors grew slowly, were inflamed, and could not create an immunosuppressive tumor microenvironment. In normal mice, exposure to apoptotic tumor cells rapidly elicited PTEN-expressing Tregs, and PTEN-deficient mice were unable to maintain tolerance to apoptotic cells. In wild-type mice with large established tumors, pharmacologic inhibition of PTEN after chemotherapy or immunotherapy profoundly reconfigured the tumor microenvironment, changing it from a suppressive to an inflammatory milieu, and tumors underwent rapid regression. Thus, the immunosuppressive milieu in tumors must be actively maintained, and tumors become susceptible to immune attack if the PTEN pathway in Tregs is disrupted.

B Cell-Intrinsic IDO1 Regulates Humoral Immunity to T Cell-Independent Antigens

Humoral responses to nonproteinaceous Ags (i.e., T cell independent [TI]) are a key component of the early response to bacterial and viral infection and a critical driver of systemic autoimmunity. However, mechanisms that regulate TI humoral immunity are poorly defined. In this study, we report that B cell-intrinsic induction of the tryptophan-catabolizing enzyme IDO1 is a key mechanism limiting TI Ab responses. When Ido1(-/-) mice were immunized with TI Ags, there was a significant increase in Ab titers and formation of extrafollicular Ab-secreting cells compared with controls. This effect was specific to TI Ags, as Ido1 disruption did not affect Ig production after immunization with protein Ags. The effect of IDO1 abrogation was confined to the B cell compartment, as adoptive transfer of Ido1(-/-) B cells to B cell-deficient mice was sufficient to replicate increased TI responses observed in Ido1(-/-) mice. Moreover, in vitro activation with TLR ligands or BCR crosslinking rapidly induced Ido1 expression and activity in purified B cells, and Ido1(-/-) B cells displayed enhanced proliferation and cell survival associated with increased Ig and cytokine production compared with wild-type B cells. Thus, our results demonstrate a novel, B cell-intrinsic, role for IDO1 as a regulator of humoral immunity that has implications for both vaccine design and prevention of autoimmunity.

Amino acid metabolism inhibits antibody-driven kidney injury by inducing autophagy

Inflammatory kidney disease is a major clinical problem that can result in end-stage renal failure. In this article, we show that Ab-mediated inflammatory kidney injury and renal disease in a mouse nephrotoxic serum nephritis model was inhibited by amino acid metabolism and a protective autophagic response. The metabolic signal was driven by IFN-γ-mediated induction of indoleamine 2,3-dioxygenase 1 (IDO1) enzyme activity with subsequent activation of a stress response dependent on the eIF2α kinase general control nonderepressible 2 (GCN2). Activation of GCN2 suppressed proinflammatory cytokine production in glomeruli and reduced macrophage recruitment to the kidney during the incipient stage of Ab-induced glomerular inflammation. Further, inhibition of autophagy or genetic ablation of Ido1 or Gcn2 converted Ab-induced, self-limiting nephritis to fatal end-stage renal disease. Conversely, increasing kidney IDO1 activity or treating mice with a GCN2 agonist induced autophagy and protected mice from nephritic kidney damage. Finally, kidney tissue from patients with Ab-driven nephropathy showed increased IDO1 abundance and stress gene expression. Thus, these findings support the hypothesis that the IDO-GCN2 pathway in glomerular stromal cells is a critical negative feedback mechanism that limits inflammatory renal pathologic changes by inducing autophagy.

Indoleamine 2,3-dioxygenase inhibits B cell immune response to T independent antigens (IRM8P.710)

T cell independent (TI) antibody responses are crucial for humoral immunity to viruses and encapsulated bacteria. Here we report a novel mechanism where the tryptophan catabolizing enzyme indoleamine 2,3-dioxygenase (IDO) 1 regulates the B cell response to TI antigens. Immunization with NP-Ficoll led to rapid splenic induction of IDO, primarily in the extra-follicular space. When IDO1KO mice were immunized there was a significant increase in humoral responses with increased formation of extra-follicular IgM and IgG3 foci, antibody secreting cells (ASCs), and increased antibody titers. This was not associated with an alteration in affinity maturation suggesting the primary impact of IDO1 deficiency was increased B cell proliferation and plasma cell formation. IDO1 did not affect immune responses to protein antigens as immunization with NP-OVA elicited similar antibody titers regardless of IDO1 function. In addition, adoptive transfer of IDO1 deficient B cells to µMT-/- (B cell deficient) mice was sufficient to replicate increased TI responses observed in IDOKO mice. Moreover, in vitro LPS rapidly induced IDO1 in MACS-purified B cells and IDO deficient B cells display enhanced LPS and CpG-driven proliferation associated with increased production of IgM, IgG3, and IL10. Thus, our results demonstrate a novel role of IDO in suppressing T cell independent antibody response that provides insight into the understanding of B cell immune responses in autoimmunity and vaccine biology.

Innate and adaptive tolerance to apoptotic cells is controlled by an IDO- dependent mechanism. (123.49)

Marginal zone macrophages (MZMs) play a crucial role in generation of systemic tolerance to apoptotic cell (AC)-associated antigens. However, the mechanism(s) by which MZMs drive tolerogenic responses is not understood. In this report, we show that systemic administration of ACs induces splenic expression of the immunosuppressive enzyme indoleamine 2-3 dioxygenase (IDO) in Marco+SignR1+ MZMs. Moreover, we found abrogation of IDO activity altered immunity to ACs resulting in decreased TGF-β synthesis and increased pro-inflammatory cytokine production associated with a reduction in Treg function and a loss of T cell tolerance towards AC antigens. When pre-symptomatic, lupus-prone MRLlpr/lpr mice were examined we found significant IDO expression in the splenic MZ analogous to the observations in AC challenged mice. When IDO was inhibited, autoimmunity was rapidly accelerated in MRLlpr/lpr mice with a >10-fold increase in anti-dsDNA IgG titers and increased renal pathology. Finally, IDO-/- mice, which do not show signs of autoimmunity, were challenged chronically with ACs. The mice developed high titer serum IgG autoreactivity, kidney inflammation, and increased mortality compared to B6 mice, which did not develop autoimmunity. Thus, the data demonstrate that a novel IDO-dependent regulatory circuit is induced in MZMs upon apoptotic cell phagocytosis providing clues to future therapeutic targets to re-establish tolerance in systemic autoimmune disease.

Potential of cranberry powder for management of hyperglycemia using in vitro models

Aqueous solutions of two different cranberry powders (CP and CP-SAB) were evaluated for organic acids, sugars, total phenolics, antioxidant activity based on the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay, and functionality such as in vitro inhibition of α-amylase, α-glucosidase, and angiotensin I-converting enzyme (ACE) relevant for potential management of hyperglycemia and hypertension linked to type 2 diabetes. The total phenolics content was 11 and 51 mg/g of sample dry weight for CP and CP-SAB, respectively. p-Coumaric acid and quercetin derivatives were the main phenolic compounds identified in the cranberry powders. CP-SAB had α-glucosidase inhibitory activity that increased with increased dose (1-5 mg/mL) from 60% to 100% inhibition. There was limited amount of α-amylase inhibitory activity that reached a maximum of 40% inhibition at 5 mg/mL treatment. Significant ACE inhibitory activity was detected for CP-SAB at 100 and 200 mg/mL sample concentrations. These in vitro results indicate the potential of cranberry powders as dietary supplement and food-based strategies for potential hyperglycemia management. This biochemical rationale provides the basis for further design of animal and clinical studies using standardized extracts.

Platelet Na,K-adenosine triphosphatase as a tissue marker of hyperthyroidism

Platelet Na(+),K(+)-adenosine triphosphatase (ATPase) activity was measured in 34 (15 males, 19 females) healthy subjects, 89 (35 males, 54 females) hyperthyroid patients, and 34 (7 males, 27 females) treated hyperthyroid patients to assess the potential of this measurement as a tissue marker and diagnostic test for hyperthyroidism. Platelet Na(+),K(+)-ATPase activity was measured in platelet lysates by the rate of release of phosphate from adenosine triphosphate (ATP) in the presence and absence of ouabain. Platelet Na(+),K(+)-ATPase activity (median and range) in the hyperthyroid group (271, 169 to 821 pmol/h/g protein) was significantly higher compared with the healthy group (125, 74 to 185 micromol/h/g protein, P <.001 by Mann-Whitney U test). The treated hyperthyroid group had slightly, but significantly higher, free triiodothyronine (FT3) and free thyroxine (FT4), as well as platelet Na(+),K(+)-ATPase activity (147, 98 to 246 micromol/h/g protein, P <.05). If a platelet Na(+),K(+)-ATPase activity of 190 micromol/h/g protein was used as a cut off value, the specificity and sensitivity were 90% and 93%, respectively. We conclude that platelet Na(+),K(+)-ATPase may be a useful tissue marker of hyperthyroidism.

Probing Static Structure of Colloid-Polymer Suspensions with Multiply Scattered Light

Time-dependent measurements of light propagation were conducted in aqueous dispersions of 523 nm diameter polystyrene at concentrations between 0.1 and 0.4 solids volume fraction in order to assess how particle correlation is influenced by depletion interactions arising from the addition of soluble polyethyleneoxide (PEO). In the absence of polymer, the transport scattering length can be predicted from Mie scattering theory and the Percus-Yevick (P-Y) model for static structure of a dense hard-sphere colloidal solution. Depletion forces arising from the addition of PEO of varying molecular weights influenced the spatial ordering of the dispersion and caused a further increase in the transport scattering length beyond that predicted by hard-sphere static structure factor but similar to that predicted by the mean sphere approximation (MSA) to the P-Y model described by Ye et al. (1996). Onset of flocculation occurred with increased PEO addition and correlated with PEO molecular weight. Phase separation was noted by no further change in the transport scattering length, except when flocculation was induced by the highest molecular weight PEO. The use of time-dependent measurements of light propagation in dense systems provides an alternative to small-angle light, neutron, and X-ray scattering characterization of interaction potentials in dense, multiply scattering samples and promises further fruitful investigation of colloidal particle interactions in suspensions. Copyright 1999 Academic Press.

Investigation of static structure factor in dense suspensions by use of multiply scattered light

Near-infrared, frequency-domain photon migration measurements of phase shift are used to derive accurate values of isotropic scattering coefficients in concentrated, interacting suspensions of aqueous polystyrene microspheres with volume concentrations ranging from 1% to 45% by solids and mean diameters ranging from 135 to 500 nm. Under conditions of high ionic strength, the isotropic scattering coefficient can be quantitatively predicted by the Percus-Yevick model for hard-sphere interactions and Mie theory. In addition, the attractive interactions between scatterers arising from the addition of soluble poly(ethylene glycol) with molecular weights of 100 and 600 K cause hindered scattering. The increases in static structure and decreases in isotropic scattering coefficient agree with that predicted by Mie theory and the depletion interaction model developed by Asakura and Oosawa [J. Chem. Phys. 22, 1255 (1954)]. These results demonstrate the success of monitoring interaction between particles by use of multiple-scattered light and the necessity of incorporating models for these interactions when predicting scattering of dense, concentrated suspensions.

Antibody repertoire development in fetal and neonatal piglets. I. Four VH genes account for 80 percent of VH usage during 84 days of fetal life

VDJ rearrangement and VH gene usage during fetal development in 35 outbred piglets was examined by PCR amplification of VDJs; VDJs were subsequently characterized by hybridization with VH-specific gene probes and by sequencing. VDJ rearrangement was first seen in the fetal liver on day 30 of a 114-day gestation. Four VH genes (V(H)A, V(H)B, V(H)C, and V(H)E) accounted for approximately 80% of all VH gene usage regardless of gestational age, choice of piglet, or lymphoid tissue tested; D(H)A and D(H)B were used in >90% of the fetal VDJs examined. Evidence of somatic hypermutation during fetal development was not found. The proportion of the four prominent fetal VH genes did not differ significantly between cDNA and DNA, suggesting the absence of selective B cell differentiation. A comparison of recombination signal sequences, flanking sequences, and framework sequences of these fetal genes with other germline VH genes of swine offered no clue as to their selective usage. N-region additions were prominent on day 40 but not on day 30, suggesting that the onset of terminal deoxynucleotidyltransferase activity occurs after 30 days of fetal development. These collective findings indicate that the preimmune, "natural Ab" repertoire of the fetal piglet is largely restricted to the use of four nonpolymorphic and nonmutated VH genes and two nonmutated DH segments. This suggests that the preimmune repertoire of swine is either highly restricted or almost entirely determined by junctional diversity in complementarity-determining region-3.

Antibody Repertoire Development in Fetal and Neonatal Piglets. I. Four VH Genes Account for 80 Percent of VH Usage During 84 Days of Fetal Life

VDJ rearrangement and VH gene usage during fetal development in 35 outbred piglets was examined by PCR amplification of VDJs; VDJs were subsequently characterized by hybridization with VH-specific gene probes and by sequencing. VDJ rearrangement was first seen in the fetal liver on day 30 of a 114-day gestation. Four VH genes (VHA, VHB, VHC, and VHE) accounted for ~80% of all VH gene usage regardless of gestational age, choice of piglet, or lymphoid tissue tested; DHA and DHB were used in &gt;90% of the fetal VDJs examined. Evidence of somatic hypermutation during fetal development was not found. The proportion of the four prominent fetal VH genes did not differ significantly between cDNA and DNA, suggesting the absence of selective B cell differentiation. A comparison of recombination signal sequences, flanking sequences, and framework sequences of these fetal genes with other germline VH genes of swine offered no clue as to their selective usage. N-region additions were prominent on day 40 but not on day 30, suggesting that the onset of terminal deoxynucleotidyltransferase activity occurs after 30 days of fetal development. These collective findings indicate that the preimmune, “natural Ab” repertoire of the fetal piglet is largely restricted to the use of four nonpolymorphic and nonmutated VH genes and two nonmutated DH segments. This suggests that the preimmune repertoire of swine is either highly restricted or almost entirely determined by junctional diversity in complementarity-determining region-3.

The hinge deletion allelic variant of porcine IgA results from a mutation at the splice acceptor site in the first C alpha intron

Recently published genomic and cDNA sequences for porcine IgA suggested that the splice acceptor site in the C alpha 1-C alpha 2 intron was an AA rather than an AG dinucleotide. This possibility was tested in an in vitro HeLa cell splicing system using an RNA substrate corresponding to the genomic DNA with the putative AA splice site. Data indicated that splicing occurred at a cryptic AG site 12 nucleotides into the C alpha 2 domain rather than at the AA site. The possibility that swine B cells could use either site was tested by preparing the cDNAs from 13 different samples representing nine animals and amplifying the segment from the first C alpha 1 nucleotide to nucleotide 532 in C alpha 2 (genomic DNA numbering system). Analysis on a 6% polyacrylamide sequencing gel revealed two polynucleotide products in most samples that differed by the expected 12 nucleotides, suggesting that swine could use both splice sites. Sequence analysis confirmed that the shorter form was spliced at the downstream site and the larger form at the apparent upstream AA site. However, when the genomic DNA from an animal expressing only the longer polynucleotide was cloned and sequenced, the upstream splice acceptor site was AG not AA. Thus the data suggested that porcine IgA occurred in two allelic forms, designated IgAa and IgAb, which differ by an apparent G to A mutation in the last nucleotide of intron 1 resulting in a short-hinged (two amino acids, IgAb) variant, in which the downstream cryptic splice site is used, as well as a "normal-hinged" (six amino acids, IgAa) variant. Evidence that IgAa and IgAb are allelic was confirmed by genotypic analyses of progeny from matings of IgAa/IgAb heterozygotes. Evidence that both transcripts are functional was confirmed by showing that serum IgA levels were similar in animals homozygous for each variant.

The hinge deletion allelic variant of porcine IgA results from a mutation at the splice acceptor site in the first C alpha intron

Recently published genomic and cDNA sequences for porcine IgA suggested that the splice acceptor site in the C alpha 1-C alpha 2 intron was an AA rather than an AG dinucleotide. This possibility was tested in an in vitro HeLa cell splicing system using an RNA substrate corresponding to the genomic DNA with the putative AA splice site. Data indicated that splicing occurred at a cryptic AG site 12 nucleotides into the C alpha 2 domain rather than at the AA site. The possibility that swine B cells could use either site was tested by preparing the cDNAs from 13 different samples representing nine animals and amplifying the segment from the first C alpha 1 nucleotide to nucleotide 532 in C alpha 2 (genomic DNA numbering system). Analysis on a 6% polyacrylamide sequencing gel revealed two polynucleotide products in most samples that differed by the expected 12 nucleotides, suggesting that swine could use both splice sites. Sequence analysis confirmed that the shorter form was spliced at the downstream site and the larger form at the apparent upstream AA site. However, when the genomic DNA from an animal expressing only the longer polynucleotide was cloned and sequenced, the upstream splice acceptor site was AG not AA. Thus the data suggested that porcine IgA occurred in two allelic forms, designated IgAa and IgAb, which differ by an apparent G to A mutation in the last nucleotide of intron 1 resulting in a short-hinged (two amino acids, IgAb) variant, in which the downstream cryptic splice site is used, as well as a "normal-hinged" (six amino acids, IgAa) variant. Evidence that IgAa and IgAb are allelic was confirmed by genotypic analyses of progeny from matings of IgAa/IgAb heterozygotes. Evidence that both transcripts are functional was confirmed by showing that serum IgA levels were similar in animals homozygous for each variant.

Hyperinsulinaemia and Na+, K(+)-ATPase activity in thyrotoxic periodic paralysis

OBJECTIVE

Thyrotoxic periodic paralysis (TPP) usually follows a heavy carbohydrate meal and this may be explained by hyperinsulinaemia stimulating Na+, K(+)-ATPase activity. To clarify this the effect of glucose load on serum insulin concentration and platelet Na+, K(+)-ATPase activity in thyrotoxic periodic paralysis (TPP) was examined.

DESIGN

In all subjects a standard 75-g glucose tolerance test was done and blood samples were taken at 0, 1 and 2 hours.

SUBJECTS

Twenty-five healthy controls (8 M and 17 F), 17 uncomplicated thyrotoxic patients (7 M and 10 F), 15 TPP patients who presented with paralysis and 4 TPP patients after treatment with antithyroid drugs.

MEASUREMENTS

Plasma glucose was measured by the glucose oxidase method, serum insulin by radioimmunoassay and platelet Na+, K(+)-ATPase by the release of phosphate from ATP.

RESULTS

TPP patients showed glucose intolerance (area under the curve (AUC) 16.5 +/- 4.4 (mean +/- SD) in TPP compared to 12.9 +/- 4.5 in controls (P < 0.01)) and hyperinsulinaemia (AUC 189.6 +/- 100.6 vs 98.5 +/- 53.4, P < 0.001). In uncomplicated thyrotoxicosis the results were similar to that in healthy controls. Platelet Na+, K(+)-ATPase were significantly higher in thyrotoxic patients compared to controls and in TPP patients were even higher. Ingestion of glucose increased platelet Na+, K(+)-ATPase in all groups. AUC for platelet Na+, K(+)-ATPase in TPP patients were significantly higher than in uncomplicated thyrotoxicosis (601 +/- 99.3 vs 482 +/- 109.4, P < 0.01) or healthy controls (320 +/- 107.3). In the 4 TPP patients studied after antithyroid treatment the results were similar to healthy controls.

CONCLUSION

Patients with thyrotoxic periodic paralysis have hyperinsulinaemia and this is accompanied by higher Na+, K(+)-ATPase activity.

In vivo and in vitro sodium pump activity in subjects with thyrotoxic periodic paralysis

OBJECTIVE

To examine whether sodium pump activity plays a part in the pathogenesis of thyrotoxic periodic paralysis.

DESIGN

Measurement of platelet sodium-potassium ATPase and in vivo sodium pump activities in healthy subjects and thyrotoxic subjects with and without paralysis.

SETTING

University hospital in Hong Kong.

SUBJECTS

21 healthy subjects, 23 untreated thyrotoxic subjects, 13 untreated men with periodic paralysis, seven treated thyrotoxic subjects, and six treated men with periodic paralysis.

MAIN OUTCOME MEASURES

Platelet Na+, K(+)-ATPase activity and plasma rubidium concentration after oral loading.

RESULTS

Median (range) platelet Na+, K(+)-ATPase activity in thyrotoxic subjects was 253 (169-821) mumol inorganic phosphate/h/g protein--significantly higher than that in healthy subjects (134 (81-180) mumol/h/g protein; p less than 0.001). Na+, K(+)-ATPase activity in those with periodic paralysis was 374 (195-1196) mumol/h/g protein, again significantly higher than that in healthy subjects (p less than 0.001) and that in other thyrotoxic subjects (p less than 0.01) despite similar degrees of hyperthyroidism. Activities in treated thyrotoxic subjects with and without periodic paralysis were 148 (110-234) and 131 (86-173) mumol/h/g protein respectively. Mean (95% confidence interval) plasma rubidium concentration five hours after oral administration in thyrotoxic subjects (7.0 (6.6 to 7.5) mumol/l) was significantly lower than in healthy subjects (10.2 (9.5 to 10.9) mumol/l; p less than 0.001) and higher than in those with periodic paralysis (6.0 (5.7 to 6.3) mumol/l; p less than 0.01).

CONCLUSIONS

Sodium pump activity in untreated subjects with periodic paralysis is higher than in other thyrotoxic subjects, and this may be responsible for the hypokalaemia.