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Ferdous J, Matthew Fricke G, Moses ME. More Is Faster: Why Population Size Matters in Biological Search. J Comput Biol 2024; 31:429-444. [PMID: 38754139 DOI: 10.1089/cmb.2023.0296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024] Open
Abstract
Many biological scenarios have multiple cooperating searchers, and the timing of the initial first contact between any one of those searchers and its target is critically important. However, we are unaware of biological models that predict how long it takes for the first of many searchers to discover a target. We present a novel mathematical model that predicts initial first contact times between searchers and targets distributed at random in a volume. We compare this model with the extreme first passage time approach in physics that assumes an infinite number of searchers all initially positioned at the same location. We explore how the number of searchers, the distribution of searchers and targets, and the initial distances between searchers and targets affect initial first contact times. Given a constant density of uniformly distributed searchers and targets, the initial first contact time decreases linearly with both search volume and the number of searchers. However, given only a single target and searchers placed at the same starting location, the relationship between the initial first contact time and the number of searchers shifts from a linear decrease to a logarithmic decrease as the number of searchers grows very large. More generally, we show that initial first contact times can be dramatically faster than the average first contact times and that the initial first contact times decrease with the number of searchers, while the average search times are independent of the number of searchers. We suggest that this is an underappreciated phenomenon in biology and other collective search problems.
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Affiliation(s)
- Jannatul Ferdous
- Department of Computer Science, The University of New Mexico, Albuquerque, New Mexico, USA
| | - George Matthew Fricke
- Department of Computer Science, The University of New Mexico, Albuquerque, New Mexico, USA
- Center for Advanced Research Computing, The University of New Mexico, Albuquerque, New Mexico, USA
| | - Melanie E Moses
- Department of Computer Science, The University of New Mexico, Albuquerque, New Mexico, USA
- Department of Biology, The University of New Mexico, Albuquerque, New Mexico, USA
- Santa Fe Institute, Santa Fe, New Mexico, USA
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2
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Medzhitov R, Iwasaki A. Exploring new perspectives in immunology. Cell 2024; 187:2079-2094. [PMID: 38670066 DOI: 10.1016/j.cell.2024.03.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/11/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024]
Abstract
Several conceptual pillars form the foundation of modern immunology, including the clonal selection theory, antigen receptor diversity, immune memory, and innate control of adaptive immunity. However, some immunological phenomena cannot be explained by the current framework. Thus, we still do not know how to design vaccines that would provide long-lasting protective immunity against certain pathogens, why autoimmune responses target some antigens and not others, or why the immune response to infection sometimes does more harm than good. Understanding some of these mysteries may require that we question existing assumptions to develop and test alternative explanations. Immunology is increasingly at a point when, once again, exploring new perspectives becomes a necessity.
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Affiliation(s)
- Ruslan Medzhitov
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA; Center for Infection and Immunity, Yale School of Medicine, New Haven, CT, USA; Tananbaum Center for Theoretical and Analytical Human Biology, Yale School of Medicine, New Haven, CT, USA.
| | - Akiko Iwasaki
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA; Center for Infection and Immunity, Yale School of Medicine, New Haven, CT, USA.
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3
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Navas-Zuloaga MG, Baudier KM, Fewell JH, Ben-Asher N, Pavlic TP, Kang Y. A modeling framework for adaptive collective defense: crisis response in social-insect colonies. J Math Biol 2023; 87:87. [PMID: 37966545 DOI: 10.1007/s00285-023-01995-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 08/26/2023] [Accepted: 09/07/2023] [Indexed: 11/16/2023]
Abstract
Living systems, from cells to superorganismic insect colonies, have an organizational boundary between inside and outside and allocate resources to defend it. Whereas the micro-scale dynamics of cell walls can be difficult to study, the adaptive allocation of workers to defense in social-insect colonies is more conspicuous. This is particularly the case for Tetragonisca angustula stingless bees, which combine different defensive mechanisms found across other colonial animals: (1) morphological specialization (distinct soldiers (majors) are produced over weeks); (2) age-based polyethism (young majors transition to guarding tasks over days); and (3) task switching (small workers (minors) replace soldiers within minutes under crisis). To better understand how these timescales of reproduction, development, and behavior integrate to balance defensive demands with other colony needs, we developed a demographic Filippov ODE system to study the effect of these processes on task allocation and colony size. Our results show that colony size peaks at low proportions of majors, but colonies die if minors are too plastic or defensive demands are too high or if there is a high proportion of quickly developing majors. For fast maturation, increasing major production may decrease defenses. This model elucidates the demographic factors constraining collective defense regulation in social insects while also suggesting new explanations for variation in defensive allocation at smaller scales where the mechanisms underlying defensive processes are not easily observable. Moreover, our work helps to establish social insects as model organisms for understanding other systems where the transaction costs for component turnover are nontrivial, as in manufacturing systems and just-in-time supply chains.
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Affiliation(s)
| | - Kaitlin M Baudier
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Jennifer H Fewell
- School of Life Sciences, Arizona State University, Tempe, AZ, 85281, USA
| | - Noam Ben-Asher
- Data Science Directorate, SimSpace Cooperation, Boston, MA, USA
| | - Theodore P Pavlic
- School of Life Sciences, Arizona State University, Tempe, AZ, 85281, USA
- School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ, 85281, USA
- School of Sustainability, Arizona State University, Tempe, AZ, 85281, USA
- School of Complex Adaptive Systems, Arizona State University, Tempe, AZ, 85281, USA
| | - Yun Kang
- Sciences and Mathematics Faculty, College of Integrative Sciences and Arts, Arizona State University, Tempe, AZ, 85281, USA.
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4
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Qiu J, Shi M, Li S, Ying Q, Zhang X, Mao X, Shi S, Wu S. Artificial neural network model- and response surface methodology-based optimization of Atractylodis Macrocephalae Rhizoma polysaccharide extraction, kinetic modelling and structural characterization. ULTRASONICS SONOCHEMISTRY 2023; 95:106408. [PMID: 37088027 PMCID: PMC10457599 DOI: 10.1016/j.ultsonch.2023.106408] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 03/08/2023] [Accepted: 04/13/2023] [Indexed: 05/03/2023]
Abstract
Atractylodis Macrocephalae Rhizoma (AMR) is the dried rhizome of Atractylodes macrocephala Koidz, which is widely used in the development of health products. AMR contains a large number of polysaccharides, but at present there are fewer applications for these polysaccharides. In this study, the effects of different extraction methods on the Atractylodis Macrocephalae Rhizoma polysaccharide (AMRP) yield were investigated, and the conditions for ultrasound-assisted extraction were optimized by response surface methodology (RSM) and three neural network models (BP neural network, GA-BP neural network and ACO-GA-BP neural network). The best conditions were a liquid-to-solid ratio of 17 mL/g, ultrasonic power of 400 W, extraction temperature of 72 °C, and extraction time of 40 min, which yielded 31.31% AMRP. The kinetic equation of AMRP was determined and compared with the results predicted by three neural network models. It was finally determined that the extraction conditions, kinetic processes and kinetic equation predicted by the GA-ACO-BP neural network were optimal. In addition, AMRP was characterized using SEM, FTIR, HPLC, UV, XRD, and NMR, and the structural study revealed that AMRP has a rough exterior and a porous interior; moreover, it contains high levels of glucose (5.07%), arabinose (0.80%), and galactose (0.74%). AMRP has three crystal structures, consisting of two β-type monosaccharides and one α-type monosaccharide. Additionally, the effectiveness of AMRP as an antioxidant was demonstrated in an in vitro experiment.
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Affiliation(s)
- Junjie Qiu
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Menglin Shi
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Siqi Li
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Qianyi Ying
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Xinxin Zhang
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Xinxin Mao
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Senlin Shi
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China.
| | - Suxiang Wu
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China.
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5
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Rajakaruna H, O'Connor JH, Cockburn IA, Ganusov VV. Liver Environment-Imposed Constraints Diversify Movement Strategies of Liver-Localized CD8 T Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:1292-1304. [PMID: 35131868 PMCID: PMC9250760 DOI: 10.4049/jimmunol.2100842] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 12/17/2021] [Indexed: 05/11/2023]
Abstract
Pathogen-specific CD8 T cells face the problem of finding rare cells that present their cognate Ag either in the lymph node or in infected tissue. Although quantitative details of T cell movement strategies in some tissues such as lymph nodes or skin have been relatively well characterized, we still lack quantitative understanding of T cell movement in many other important tissues, such as the spleen, lung, liver, and gut. We developed a protocol to generate stable numbers of liver-located CD8 T cells, used intravital microscopy to record movement patterns of CD8 T cells in livers of live mice, and analyzed these and previously published data using well-established statistical and computational methods. We show that, in most of our experiments, Plasmodium-specific liver-localized CD8 T cells perform correlated random walks characterized by transiently superdiffusive displacement with persistence times of 10-15 min that exceed those observed for T cells in lymph nodes. Liver-localized CD8 T cells typically crawl on the luminal side of liver sinusoids (i.e., are in the blood); simulating T cell movement in digital structures derived from the liver sinusoids illustrates that liver structure alone is sufficient to explain the relatively long superdiffusive displacement of T cells. In experiments when CD8 T cells in the liver poorly attach to the sinusoids (e.g., 1 wk after immunization with radiation-attenuated Plasmodium sporozoites), T cells also undergo Lévy flights: large displacements occurring due to cells detaching from the endothelium, floating with the blood flow, and reattaching at another location. Our analysis thus provides quantitative details of movement patterns of liver-localized CD8 T cells and illustrates how structural and physiological details of the tissue may impact T cell movement patterns.
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Affiliation(s)
| | - James H O'Connor
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra, Australia; and
- Australian National University Medical School, Acton, Australian Capital Territory, Australia
| | - Ian A Cockburn
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra, Australia; and
| | - Vitaly V Ganusov
- Department of Microbiology, University of Tennessee, Knoxville, TN;
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6
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Zenkov VS, O’Connor JH, Cockburn IA, Ganusov VV. A New Method Based on the von Mises-Fisher Distribution Shows that a Minority of Liver-Localized CD8 T Cells Display Hard-To-Detect Attraction to Plasmodium-Infected Hepatocytes. FRONTIERS IN BIOINFORMATICS 2022; 1:770448. [PMID: 36303744 PMCID: PMC9580869 DOI: 10.3389/fbinf.2021.770448] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/22/2021] [Indexed: 11/13/2022] Open
Abstract
Malaria is a disease caused by Plasmodium parasites, resulting in over 200 million infections and 400,000 deaths every year. A critical step of malaria infection is when sporozoites, injected by mosquitoes, travel to the liver and form liver stages. Malaria vaccine candidates which induce large numbers of malaria-specific CD8 T cells in mice are able to eliminate all liver stages, preventing fulminant malaria. However, how CD8 T cells find all parasites in 48 h of the liver stage lifespan is not well understood. Using intravital microscopy of murine livers, we generated unique data on T cell search for malaria liver stages within a few hours after infection. To detect attraction of T cells to an infection site, we used the von Mises-Fisher distribution in 3D, similar to the 2D von Mises distribution previously used in ecology. Our results suggest that the vast majority (70-95%) of malaria-specific and non-specific liver-localized CD8 T cells did not display attraction towards the infection site, suggesting that the search for malaria liver stages occurs randomly. However, a small fraction (15-20%) displayed weak but detectable attraction towards parasites which already had been surrounded by several T cells. We found that speeds and turning angles correlated with attraction, suggesting that understanding mechanisms that determine the speed of T cell movement in the liver may improve the efficacy of future T cell-based vaccines. Stochastic simulations suggest that a small movement bias towards the parasite dramatically reduces the number of CD8 T cells needed to eliminate all malaria liver stages, but to detect such attraction by individual cells requires data from long imaging experiments which are not currently feasible. Importantly, as far as we know this is the first demonstration of how activated/memory CD8 T cells might search for the pathogen in nonlymphoid tissues a few hours after infection. We have also established a framework for how attraction of individual T cells towards a location in 3D can be rigorously evaluated.
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Affiliation(s)
- Viktor S. Zenkov
- Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN, United States,*Correspondence: Viktor S. Zenkov, ; Vitaly V. Ganusov,
| | - James H. O’Connor
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia,The Australian National University Medical School, Australian National University, Canberra, ACT, Australia
| | - Ian A. Cockburn
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Vitaly V. Ganusov
- Department of Microbiology, University of Tennessee, Knoxville, TN, United States,Department of Mathematics, University of Tennessee, Knoxville, TN, United States,*Correspondence: Viktor S. Zenkov, ; Vitaly V. Ganusov,
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7
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Moses ME, Hofmeyr S, Cannon JL, Andrews A, Gridley R, Hinga M, Leyba K, Pribisova A, Surjadidjaja V, Tasnim H, Forrest S. Spatially distributed infection increases viral load in a computational model of SARS-CoV-2 lung infection. PLoS Comput Biol 2021; 17:e1009735. [PMID: 34941862 PMCID: PMC8740970 DOI: 10.1371/journal.pcbi.1009735] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 01/07/2022] [Accepted: 12/09/2021] [Indexed: 01/03/2023] Open
Abstract
A key question in SARS-CoV-2 infection is why viral loads and patient outcomes vary dramatically across individuals. Because spatial-temporal dynamics of viral spread and immune response are challenging to study in vivo, we developed Spatial Immune Model of Coronavirus (SIMCoV), a scalable computational model that simulates hundreds of millions of lung cells, including respiratory epithelial cells and T cells. SIMCoV replicates viral growth dynamics observed in patients and shows how spatially dispersed infections can lead to increased viral loads. The model also shows how the timing and strength of the T cell response can affect viral persistence, oscillations, and control. By incorporating spatial interactions, SIMCoV provides a parsimonious explanation for the dramatically different viral load trajectories among patients by varying only the number of initial sites of infection and the magnitude and timing of the T cell immune response. When the branching airway structure of the lung is explicitly represented, we find that virus spreads faster than in a 2D layer of epithelial cells, but much more slowly than in an undifferentiated 3D grid or in a well-mixed differential equation model. These results illustrate how realistic, spatially explicit computational models can improve understanding of within-host dynamics of SARS-CoV-2 infection.
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Affiliation(s)
- Melanie E. Moses
- Department of Computer Science, University of New Mexico, Albuquerque, New Mexico, United States of America
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
- * E-mail:
| | - Steven Hofmeyr
- Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Judy L. Cannon
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Akil Andrews
- Department of Computer Science, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Rebekah Gridley
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Monica Hinga
- Department of Computer Science, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Kirtus Leyba
- Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Abigail Pribisova
- Department of Computer Science, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Vanessa Surjadidjaja
- Department of Computer Science, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Humayra Tasnim
- Department of Computer Science, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Stephanie Forrest
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
- Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
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8
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Fowell DJ, Kim M. The spatio-temporal control of effector T cell migration. Nat Rev Immunol 2021; 21:582-596. [PMID: 33627851 PMCID: PMC9380693 DOI: 10.1038/s41577-021-00507-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2021] [Indexed: 02/08/2023]
Abstract
Effector T cells leave the lymph nodes armed with specialized functional attributes. Their antigenic targets may be located anywhere in the body, posing the ultimate challenge: how to efficiently identify the target tissue, navigate through a complex tissue matrix and, ultimately, locate the immunological insult. Recent advances in real-time in situ imaging of effector T cell migratory behaviour have revealed a great degree of mechanistic plasticity that enables effector T cells to push and squeeze their way through inflamed tissues. This process is shaped by an array of 'stop' and 'go' guidance signals including target antigens, chemokines, integrin ligands and the mechanical cues of the inflamed microenvironment. Effector T cells must sense and interpret these competing signals to correctly position themselves to mediate their effector functions for complete and durable responses in infectious disease and malignancy. Tuning T cell migration therapeutically will require a new understanding of this complex decision-making process.
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Affiliation(s)
- Deborah J. Fowell
- David H. Smith Center for Vaccine Biology and Immunology, Aab Institute for Biomedical Sciences, Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY.,Department of Microbiology and Immunology, Cornell University, Ithaca, NY
| | - Minsoo Kim
- David H. Smith Center for Vaccine Biology and Immunology, Aab Institute for Biomedical Sciences, Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY
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9
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Friedman DA, Tschantz A, Ramstead MJD, Friston K, Constant A. Active Inferants: An Active Inference Framework for Ant Colony Behavior. Front Behav Neurosci 2021; 15:647732. [PMID: 34248515 PMCID: PMC8264549 DOI: 10.3389/fnbeh.2021.647732] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 05/18/2021] [Indexed: 11/13/2022] Open
Abstract
In this paper, we introduce an active inference model of ant colony foraging behavior, and implement the model in a series of in silico experiments. Active inference is a multiscale approach to behavioral modeling that is being applied across settings in theoretical biology and ethology. The ant colony is a classic case system in the function of distributed systems in terms of stigmergic decision-making and information sharing. Here we specify and simulate a Markov decision process (MDP) model for ant colony foraging. We investigate a well-known paradigm from laboratory ant colony behavioral experiments, the alternating T-maze paradigm, to illustrate the ability of the model to recover basic colony phenomena such as trail formation after food location discovery. We conclude by outlining how the active inference ant colony foraging behavioral model can be extended and situated within a nested multiscale framework and systems approaches to biology more generally.
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Affiliation(s)
- Daniel Ari Friedman
- Department of Entomology and Nematology, University of California, Davis, Davis, CA, United States
- Active Inference Lab, University of California, Davis, Davis, CA, United States
| | - Alec Tschantz
- Sackler Centre for Consciousness Science, University of Sussex, Brighton, United Kingdom
- Department of Informatics, University of Sussex, Brighton, United Kingdom
| | - Maxwell J. D. Ramstead
- Division of Social and Transcultural Psychiatry, Department of Psychiatry, McGill University, Montreal, QC, Canada
- Culture, Mind, and Brain Program, McGill University, Montreal, QC, Canada
- Wellcome Centre for Human Neuroimaging, University College London, London, United Kingdom
- Spatial Web Foundation, Los Angeles, CA, United States
| | - Karl Friston
- Wellcome Centre for Human Neuroimaging, University College London, London, United Kingdom
| | - Axel Constant
- Theory and Method in Biosciences, The University of Sydney, Sydney, NSW, Australia
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10
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Sadjadi Z, Zhao R, Hoth M, Qu B, Rieger H. Migration of Cytotoxic T Lymphocytes in 3D Collagen Matrices. Biophys J 2020; 119:2141-2152. [PMID: 33264597 PMCID: PMC7732778 DOI: 10.1016/j.bpj.2020.10.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 10/15/2020] [Accepted: 10/19/2020] [Indexed: 12/27/2022] Open
Abstract
CD8+ cytotoxic T lymphocytes (CTL) and natural killer cells are the main cytotoxic killer cells of the human body to eliminate pathogen-infected or tumorigenic cells (also known as target cells). To find their targets, they have to navigate and migrate through complex biological microenvironments, a key component of which is the extracellular matrix (ECM). The mechanisms underlying killer cell's navigation are not well understood. To mimic an ECM, we use a matrix formed by different collagen concentrations and analyze migration trajectories of primary human CTLs. Different migration patterns are observed and can be grouped into three motility types: slow, fast, and mixed. The dynamics are well described by a two-state persistent random walk model, which allows cells to switch between slow motion with low persistence and fast motion with high persistence. We hypothesize that the slow motility mode describes CTLs creating channels through the collagen matrix by deforming and tearing apart collagen fibers and that the fast motility mode describes CTLs moving within these channels. Experimental evidence supporting this scenario is presented by visualizing migrating T cells following each other on exactly the same track and showing cells moving quickly in channel-like cavities within the surrounding collagen matrix. Consequently, the efficiency of the stochastic search process of CTLs in the ECM should strongly be influenced by a dynamically changing channel network produced by the killer cells themselves.
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Affiliation(s)
- Zeinab Sadjadi
- Department of Theoretical Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Saarland, Germany.
| | - Renping Zhao
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Universität des Saarlandes, Homburg, Saarland, Germany
| | - Markus Hoth
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Universität des Saarlandes, Homburg, Saarland, Germany
| | - Bin Qu
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Universität des Saarlandes, Homburg, Saarland, Germany; Leibniz Institute for New Materials, Saarbrücken, Germany
| | - Heiko Rieger
- Department of Theoretical Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Saarland, Germany
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11
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Schrom EC, Levin SA, Graham AL. Quorum sensing via dynamic cytokine signaling comprehensively explains divergent patterns of effector choice among helper T cells. PLoS Comput Biol 2020; 16:e1008051. [PMID: 32730250 PMCID: PMC7392205 DOI: 10.1371/journal.pcbi.1008051] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 06/13/2020] [Indexed: 12/13/2022] Open
Abstract
In the animal kingdom, various forms of swarming enable groups of autonomous individuals to transform uncertain information into unified decisions which are probabilistically beneficial. Crossing scales from individual to group decisions requires dynamically accumulating signals among individuals. In striking parallel, the mammalian immune system is also a group of decentralized autonomous units (i.e. cells) which collectively navigate uncertainty with the help of dynamically accumulating signals (i.e. cytokines). Therefore, we apply techniques of understanding swarm behavior to a decision-making problem in the mammalian immune system, namely effector choice among CD4+ T helper (Th) cells. We find that incorporating dynamic cytokine signaling into a simple model of Th differentiation comprehensively explains divergent observations of this process. The plasticity and heterogeneity of individual Th cells, the tunable mixtures of effector types that can be generated in vitro, and the polarized yet updateable group effector commitment often observed in vivo are all explained by the same set of underlying molecular rules. These rules reveal that Th cells harness dynamic cytokine signaling to implement a system of quorum sensing. Quorum sensing, in turn, may confer adaptive advantages on the mammalian immune system, especially during coinfection and during coevolution with manipulative parasites. This highlights a new way of understanding the mammalian immune system as a cellular swarm, and it underscores the power of collectives throughout nature.
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Affiliation(s)
- Edward C. Schrom
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- * E-mail:
| | - Simon A. Levin
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Andrea L. Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
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12
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Pull CD, McMahon DP. Superorganism Immunity: A Major Transition in Immune System Evolution. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00186] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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