Testing in Mice the Hypothesis That Melanin Is Protective in Malaria Infections

Malaria has had the largest impact of any infectious disease on shaping the human genome, exerting enormous selective pressure on genes that improve survival in severe malaria infections. Modern humans originated in Africa and lost skin melanization as they migrated to temperate regions of the globe. Although it is well documented that loss of melanization improved cutaneous Vitamin D synthesis, melanin plays an evolutionary ancient role in insect immunity to malaria and in some instances melanin has been implicated to play an immunoregulatory role in vertebrates. Thus, we tested the hypothesis that melanization may be protective in malaria infections using mouse models. Congenic C57BL/6 mice that differed only in the gene encoding tyrosinase, a key enzyme in the synthesis of melanin, showed no difference in the clinical course of infection by Plasmodium yoelii 17XL, that causes severe anemia, Plasmodium berghei ANKA, that causes severe cerebral malaria or Plasmodium chabaudi AS that causes uncomplicated chronic disease. Moreover, neither genetic deficiencies in vitamin D synthesis nor vitamin D supplementation had an effect on survival in cerebral malaria. Taken together, these results indicate that neither melanin nor vitamin D production improve survival in severe malaria

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

The role of Adiponectin in acute Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), consisting of Crohn’s Disease and Ulcerative Colitis, are highly multifactorial, comprising a complex relationship between genetics, immunity, the microbiota and environmental influences. Although treatment options have vastly improved over the last decade, patients may still be unresponsive to treatments and thus require surgical intervention. Homeostasis within the colonic environment is of paramount importance in curtailing exaggerated immune responses. A breakdown in the balance between proliferation and apoptosis in the colonic environment, alongside excessive immune cell infiltrate has been implicated in disease progression. Conflicting studies with respect to the hormone adiponectin are published in IBD, and are yet to properly define its role in IBD pathogenesis. In the studies outlined, adiponectin knockout mice were administered dextran sulfate sodium (DSS) to induce colitis, and suffered severe disease activity compared with wild type mice. This was characterised by significant colonic epithelial cell architectural distortion, accompanied by a reduction in colonic crypt length, and a notable immune cell infiltrate. To investigate the processes underlying this pathology, further studies were undertaken at both the in vitro and in vivo level. The results reported in this thesis revealed that a disruption between proliferative and apoptotic pathways were prominent in the adiponectin knockout colitic mice, alongside the activation of signal transducer and activator of transcription factor 3 (STAT3) and nuclear factor kappa B (NFκB) signalling, compared with wild type mice. Analysis of signalling pathways in vitro suggested that the addition of adiponectin in the presence of the colitis causing agent, DSS, ameliorated disease activity with respect to the balance between proliferation, apoptosis and stress signals, mediated by the receptor AdipoR1. An interesting phenotype yet to be reported in adiponectin null colitic mice was brought to light, where excessive B cell infiltration was noted in the colon, compared with wild type mice. Moreover, adiponectin knockout mice had a highly inflammatory cytokine profile characteristic of B cell proliferation and stimulation, compared with wild type mice. To date, no studies have reported an association between adiponectin and B cell infiltration in acute IBD. The adiponectin knockout model may provide a vehicle to assess immune mediated colitis, and may thus contribute to understanding the multifaceted complexity underlying the cross talk between the immune system and the colonic environment in the development of colitis

Role of adiponectin and its receptors in cancer

Adiponectin (APN), a novel hormone/cytokine derived from adipocyte tissue, is involved in various physiological functions. Genetics, nutrition, and adiposity are factors contributing to circulating plasma concentrations of APN. Clinical correlation studies have shown that lower levels of serum APN are associated with increased malignancy of various cancers, such as breast and colon cancers, suggesting that APN has a role in tumorigenesis. APN affects insulin resistance, thus further influencing cancer development. Tumor cells may express receptors for APN. Cellular signaling is the mechanism by which APN exerts its host-protective responses. These factors suggest that serum APN levels and downstream signaling targets of APN may serve as potential diagnostic markers for malignancies. Further research is necessary to clarify the exact role of APN in cancer diagnosis and therapy

The role of zinc in antiviral immunity

Zinc is an essential trace element that is crucial for growth, development, and the maintenance of immune function. Its influence reaches all organs and cell types, representing an integral component of approximately 10% of the human proteome, and encompassing hundreds of key enzymes and transcription factors. Zinc deficiency is strikingly common, affecting up to a quarter of the population in developing countries, but also affecting distinct populations in the developed world as a result of lifestyle, age, and disease-mediated factors. Consequently, zinc status is a critical factor that can influence antiviral immunity, particularly as zinc-deficient populations are often most at risk of acquiring viral infections such as HIV or hepatitis C virus. This review summarizes current basic science and clinical evidence examining zinc as a direct antiviral, as well as a stimulant of antiviral immunity. An abundance of evidence has accumulated over the past 50 y to demonstrate the antiviral activity of zinc against a variety of viruses, and via numerous mechanisms. The therapeutic use of zinc for viral infections such as herpes simplex virus and the common cold has stemmed from these findings; however, there remains much to be learned regarding the antiviral mechanisms and clinical benefit of zinc supplementation as a preventative and therapeutic treatment for viral infections

Lack of MERS Coronavirus Neutralizing Antibodies in Humans, Eastern Province, Saudi Arabia

We used a lentiviral vector bearing the viral spike protein to detect neutralizing antibodies against Middle East respiratory syndrome coronavirus (MERS-CoV) in persons from the Eastern Province of Saudi Arabia. None of the 268 samples tested displayed neutralizing activity, which suggests that MERS-CoV infections in humans are infrequent in this province

HBEC take up fluorescently labelled antigen via actin-dependent mechanisms and form conjugates with T cells.

<p>Flow cytometry histograms depicting level of uptake of FITC-OVA (<i>A</i>) and Lucifer yellow (<i>C</i>) by HBEC at 37°C (blue line) vs background uptake at 4°C (red line). Data are representative of three independent experiments. Inhibition of FITC-OVA (<i>B</i>) and Lucifer yellow (<i>D</i>) uptake by HBEC cells pre-incubated with 10 mM Cytochalasin D (CCD). <i>C</i>, Flow cytometry histogram depicting level of uptake of Lucifer yellow by HBEC at 37°C (blue line) vs background uptake at 4°C (red line). Data are representative of three independent experiments Percentage increase in mean fluorescence intensity (MFI) is calculated as follows: (MFI following uptake at 37°C/MFI following uptake at 4°C)×100. Data are pooled from three independent experiments (n = 3 per experiment) and are expressed as mean +/− SD. ** and *** indicates statistically significant differences between control and CCD treatment as assessed by Student t test (p, 0.001, p<0.001 respectively). Representative flow cytometry plots indicating the levels of conjugation between HBEC and CD4⁺<i>(E)</i> and CD8⁺<i>(F)</i> cells. HBEC were labeled with PKH67 and isolated T cells labeled with PKH26 and equal numbers of cells were co-cultured for 30 min prior to flow cytometric analysis.</p

Expression of markers relevant to antigen presentation and T cell activation on HBEC.

<p>Histograms represent flow cytometry results from unstimulated and cytokine stimulated HBEC cells 18 h following stimulation. HBEC were stimulated with either 10 ng/ml TNF (blue line), 50 ng/ml IFNg (green line), or 10 ng/ml TNF+50 ng/ml IFNg (orange line) and compared to unstimulated cells (red line). Cells were stained with mAbs against CD54 (ICAM-1), Endoglin (CD105), MHC II (HLA-DR), ICOSL (CD275), CD40, CD80 and CD86 as per manufacturers instructions. Data are representative of four independent experiments.</p