A mechanistic spatio-temporal framework for modelling individual-to-individual transmission—With an application to the 2014-2015 West Africa Ebola outbreak

In recent years there has been growing availability of individual-level spatio-temporal disease data, particularly due to the use of modern communicating devices with GPS tracking functionality. These detailed data have been proven useful for inferring disease transmission to a more refined level than previously. However, there remains a lack of statistically sound frameworks to model the underlying transmission dynamic in a mechanistic manner. Such a development is particularly crucial for enabling a general epidemic predictive framework at the individual level. In this paper we propose a new statistical framework for mechanistically modelling individual-to-individual disease transmission in a landscape with heterogeneous population density. Our methodology is first tested using simulated datasets, validating our inferential machinery. The methodology is subsequently applied to data that describes a regional Ebola outbreak in Western Africa (2014-2015). Our results show that the methods are able to obtain estimates of key epidemiological parameters that are broadly consistent with the literature, while revealing a significantly shorter distance of transmission. More importantly, in contrast to existing approaches, we are able to perform a more general model prediction that takes into account the susceptible population. Finally, our results show that, given reasonable scenarios, the framework can be an effective surrogate for susceptible-explicit individual models which are often computationally challenging

Expression of NF-κB p50 in Tumor Stroma Limits the Control of Tumors by Radiation Therapy

Radiation therapy aims to kill cancer cells with a minimum of normal tissue toxicity. Dying cancer cells have been proposed to be a source of tumor antigens and may release endogenous immune adjuvants into the tumor environment. For these reasons, radiation therapy may be an effective modality to initiate new anti-tumor adaptive immune responses that can target residual disease and distant metastases. However, tumors engender an environment dominated by M2 differentiated tumor macrophages that support tumor invasion, metastases and escape from immune control. In this study, we demonstrate that following radiation therapy of tumors in mice, there is an influx of tumor macrophages that ultimately polarize towards immune suppression. We demonstrate using in vitro models that this polarization is mediated by transcriptional regulation by NFκB p50, and that in mice lacking NFκB p50, radiation therapy is more effective. We propose that despite the opportunity for increased antigen-specific adaptive immune responses, the intrinsic processes of repair following radiation therapy may limit the ability to control residual disease

Tumor cytokine and growth factor levels following radiation therapy.

<p>a) Bead assay for i) GM-CSF, ii) IL-1α and iii) IL-1β in homogenates of 4T1 tumors at day 24 following injection of 4T1 left untreated (NT) or treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation to the tumor (RT) or to the uninvolved opposite limb (RT Opp). b) d24 following tumor challenge graphs show i) leg diameter ii) tumor weight and iii) splenocytes per spleen/tumor weight for mice left untreated (NT) or treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation (RT). In each graph, each symbol represents one mouse. NS = Not significant; * = p<0.05; ** = p<0.01; *** = p<0.005; **** = p<0.001. Data is representative of three replicate experiments.</p

Tumor radiation results in a myeloid contraction.

<p>a) i) Flow cytometry of fresh whole peripheral blood from naïve and 4T1 tumor-bearing BALB/c mice, showing CD11b⁺SSC^hi myeloid populations. ii) Gr1 and IA (MHC class II) staining on gated CD11b⁺SSC^hi myeloid populations from naïve and 4T1 tumor-bearing mice. b) i) Mean and standard error of leg diameter of BALB/c mice bearing 4T1 tumors left untreated (NT) or treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation (RT). Myeloid cells/µl peripheral blood of ii) mice left untreated and iii) mice treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation. iv) fitted curves from graphs ii) and iii) plotted without measurements. c) i) Clonogenic assays of lung metastases present at euthanasia in BALB/c mice bearing 4T1 tumors left untreated (empty circles – NT) or treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation (filled circles – RT). ii) Myeloid cells/µl peripheral blood of naïve mice (Naïve) and mice day 17 following injection of 4T1 i.v. (i.v.) or s.c. (s.c.) iii) Total spleen cellularity in naïve mice (NT) and mice day 24 following injection of 4T1 i.v. (i.v.) or s.c. (s.c.) d) i) Myeloid cells/µl peripheral blood of C57BL/6 mice bearing Panc02 tumor harvested at different time points. ii) day 24 leg diameter and iii) myeloid cells/µl peripheral blood of C57BL/6 mice bearing Panc02 tumor left untreated (NT) or treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation (RT). In each graph, each symbol represents one mouse. NS = Not significant; * = p<0.05; ** = p<0.01; *** = p<0.005; **** = p<0.001. Data represents multiple replicate experiments.</p

The splenic response to tumor radiation.

<p>a) Freshly excised spleens from d24 4T1 tumor-bearing BALB/c mice left untreated (NT) or treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation (RT). Boxes shown are 3 cm wide. b) i) Total spleen cellularity in naïve mice (No tumor) and mice day 24 following injection of 4T1 left untreated (Tumor NT) or treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation to the tumor (Tumor RT) or to the uninvolved opposite limb (Tumor Leg RT). ii) The number of CD11b⁺ cells per spleen in mice from the experiment shown in i). c) The number of CD11b⁺ cells in the spleen plotted against the number of CD11b⁺ cells/µl peripheral blood at harvest for each tumor and treatment group.</p

Listeria vaccination of mice during myeloid contraction.

<p>Flow cytometry of intracellular IFNγ production in response to a) LLO91 or b) AH1 peptide, from mouse spleens 7 days following Listeria vaccination of i) naïve mice, ii) tumor bearing mice left untreated, iii) tumor bearing mice with their tumor irradiated prior to vaccination, iv) control tumor-bearing mice not receiving vaccination. c) Summary of intracellular IFNγ production in response to each peptide, each symbol represents one mouse. Data represents combined data from 3 replicate experiments. d) representative staining showing i) dual IFNγ-CD40L, ii) dual IFNγ-TNFα or iii) triple IFNγ-CD40L-TNFα positive cells from vaccinated mice in response to LLO91 peptide. Summary of single, dual and triple positive IFNγ⁺ cells from each vaccinated group stimulated with iv) LLO91 and v) AH1 peptides. NS = Not significant; * = p<0.05; ** = p<0.01; *** = p<0.005; **** = p<0.001.</p

Myeloid subpopulations responding to tumor radiation.

<p>a) Flow cytometry of fresh whole peripheral blood from i) naïve mice or mice bearing 4T1 tumors ii) left untreated or iii) irradiated, showing Ly6C and Ly6G within gated CD11b⁺Gr1^hi myeloid populations. iv) Histograms of Ly6C expression in gated CD11b⁺Gr1^hiLy6G⁺ cells, including negative control staining (FMO) and showing the percentage Ly6C⁻ in mice irradiated in the tumor (Tumor RT) or the opposite limb (Tumor Leg RT). v) The percentage of CD11b⁺Gr1^hiLy6G⁺ cells that are Ly6C⁻ from naïve mice (No tumor) and mice day 24 following injection of 4T1 left untreated (Tumor NT) or treated beginning on day 14 with 3 daily doses of 20Gy focal radiation to the tumor (Tumor RT) or to the uninvolved opposite limb (Tumor Leg RT). Each symbol represents one mouse. b) Cytospins of sorted CD11b⁺Gr1^hi cells from untreated mice that are i) Ly6C⁺Ly6G⁻, ii) Ly6C⁺Ly6G⁺, or iii) Ly6C⁻Ly6G⁺. Each cytospin is shown next to the sort purity plot with increased magnification on the inset box. c) Wright-Giemsa stain of d24 blood smears from i) naïve mice (No tumor) and mice day 24 following injection of 4T1 ii) left untreated (Tumor NT) or iii) treated beginning on day 14 with 3 daily doses of 20 Gy focal radiation to the tumor (Tumor RT). The inset box is rotated and shown at increased magnification. NS = Not significant; * = p<0.05; ** = p<0.01; *** = p<0.005; **** = p<0.001. Data represents multiple replicated experiments; each subfigure includes data from a different replicate experiment.</p

Altered SOD1 maturation and post-translational modification in amyotrophic lateral sclerosis spinal cord

International audienceAberrant self-assembly and toxicity of wild-type and mutant superoxide dismutase 1 (SOD1) has been widely examined in silico, in vitro and in transgenic animal models of amyotrophic lateral sclerosis. Detailed examination of the protein in disease-affected tissues from amyotrophic lateral sclerosis patients, however, remains scarce.We used histological, biochemical and analytical techniques to profile alterations to SOD1 protein deposition, subcellular localization, maturation and post-translational modification in post-mortem spinal cord tissues from amyotrophic lateral sclerosis cases and controls. Tissues were dissected into ventral and dorsal spinal cord grey matter to assess the specificity of alterations within regions of motor neuron degeneration.We provide evidence of the mislocalization and accumulation of structurally disordered, immature SOD1 protein conformers in spinal cord motor neurons of SOD1-linked and non-SOD1-linked familial amyotrophic lateral sclerosis cases, and sporadic amyotrophic lateral sclerosis cases, compared with control motor neurons. These changes were collectively associated with instability and mismetallation of enzymatically active SOD1 dimers, as well as alterations to SOD1 post-translational modifications and molecular chaperones governing SOD1 maturation. Atypical changes to SOD1 protein were largely restricted to regions of neurodegeneration in amyotrophic lateral sclerosis cases, and clearly differentiated all forms of amyotrophic lateral sclerosis from controls. Substantial heterogeneity in the presence of these changes was also observed between amyotrophic lateral sclerosis cases.Our data demonstrate that varying forms of SOD1 proteinopathy are a common feature of all forms of amyotrophic lateral sclerosis, and support the presence of one or more convergent biochemical pathways leading to SOD1 proteinopathy in amyotrophic lateral sclerosis. Most of these alterations are specific to regions of neurodegeneration, and may therefore constitute valid targets for therapeutic development