Maxent as an inevitable force in cell differentiation

The maximum entropy principle applies to any thermodynamic system, including biological systems. It has been widely explored in the framework of ecology, where Shannon entropy is used as a diversity index, and it is maximized in order to find maximum entropy distributions between or within species. There is wide agreement between theoretical deductions of such distributions and real data of ecosystems. Microbial systems are also supposed to satisfy the maximum entropy principle. In particular, cell differentiation can be studied in terms of diversity, and Shannon index may be used to quantify and maximize such diversity. Cell differentiation is here considered in a wide sense, and three different examples where theory, experiments and simulations converge on accomplishing Maxent are shown. First, a simple bacterial batch culture, were biomass distribution between cells (gamma distribution) fits the maximum diversity principle with two constraints related with energetic requirements and diversity in cell division. Then, a more sophisticated system where malaria infected red blood cells in in vitro culture are studied from their infection state; in this case, the maximization of entropy requires only one constraint regarding energetic requirements, which results on an exponential distribution of infection states. Finally, and at an upper scale, a cell differentiation case in terms of spatial distribution and aggregation; this is the case of tuberculosis lesions in lungs, which also fit the exponential distribution. In all cases a transient phase is initially seen, followed by a thermodynamically stationary phase where distributions remain approximately constant and similar to those theoretically deduced with Maxent. The importance of considering diversity and its evolution in dynamic microbial systems is shown. Differentiation of cells according to individual properties or functionalities as well as their spatial organization in upper structures seem to occur according to the maximum diversity principle. In addition, microbial individual-based ecology (µIBE), that combines individual-based modelling and experimentation, is shown as an appropriate strategy to study dynamic emergent behaviours related with diversity.Postprint (published version

The origin and maintenance of tuberculosis is explained by the induction of smear-negative disease in the paleolithic

Is it possible that the origin of Mycobacterium tuberculosis (Mtb) infection was around 70,000 years before the common era? At that time Homo sapiens was just another primate species with discrete growth and a very low-density geographic occupation. Therefore, it is difficult to understand the origin of a highly virulent obligate human pathogen. We have designed a new SEIR model (TBSpectr) that allows the differentiation of smear-positive and -negative tuberculosis. The model reconciles currently accepted growth rates for the Middle Paleolithic (0.003%/year) and Neolithic (0.1%/year). The obtained data link the origin of Mtb infection in the Middle Paleolithic to the induction of smear-negative TB, and reveal that its persistence required interrelations among hunter–gatherer groups, while the risk of human extinction was negligible. It also highlights the number of people infected per case and the fast progression to disease for Mtb infection maintenance, as well as the link between poor health in the Neolithic with the increased incidence of more severe forms of TB (smear-positive). In conclusion, our data support the origin of TB as a well-tolerated, highly persistent disease, even in low-density populations, showing the difficulty of its eradication and highlighting the necessity for providing better health conditions to humans to reduce its severity.Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version

La ciència al servei de la lluita contra la Covid-19

Investigadors del Campus del Baix Llobregat de la UPC treballen amb models matemàtics per estudiar la dinàmica de la malaltia. Els científics aconsegueixen fer prediccions de com evolucionarà la infecció de tres a cinc dies i, de moment, estan funcionant.Diari El LlobregatPostprint (published version

Dades i comunicació en temps de pandèmia

Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version

Exploring lag phase and growth initiation of a yeast culture by means of an Individual-based Model

Postprint (published version

CD5L promotes M2 macrophage polarization through autophagy-mediated upregulation of ID3

CD5L (CD5 molecule-like) is a secreted glycoprotein that controls key mechanisms in inflammatory responses, with involvement in processes such as infection, atherosclerosis, and cancer. In macrophages, CD5L promotes an anti-inflammatory cytokine profile in response to TLR activation. In the present study, we questioned whether CD5L is able to influence human macrophage plasticity, and drive its polarization toward any specific phenotype. We compared CD5L-induced phenotypic and functional changes to those caused by IFN/LPS, IL4, and IL10 in human monocytes. Phenotypic markers were quantified by RT-qPCR and flow cytometry, and a mathematical algorithm was built for their analysis. Moreover, we compared ROS production, phagocytic capacity, and inflammatory responses to LPS. CD5L drove cells toward a polarization similar to that induced by IL10. Furthermore, IL10- and CD5L-treated macrophages showed increased LC3-II content and colocalization with acidic compartments, thereby pointing to the enhancement of autophagy-dependent processes. Accordingly, siRNA targeting ATG7 in THP1 cells blocked CD5L-induced CD163 and Mer tyrosine kinase mRNA and efferocytosis. In these cells, gene expression profiling and validation indicated the upregulation of the transcription factor ID3 by CD5L through ATG7. In agreement, ID3 silencing reversed polarization by CD5L. Our data point to a significant contribution of CD5L-mediated autophagy to the induction of ID3 and provide the first evidence that CD5L drives macrophage polarization.Peer ReviewedPostprint (published version

The need for detailed COVID-19 data in Spain

CP received a grant from the Catalan Government for monitoring the post-lockdown COVID-19 process in Catalonia (Spain). All other authors declare no competing interests. ST-L gratefully acknowledges funding from the European Research Council (ERC-2019-CoG-GA No 864616-HEALIN project)Postprint (published version

Transition from the old to the new viral normality: Where are we?

Background: The seasonality of respiratory diseases caused by viruses has been altered by the emergence of SARS-CoV-2. After a period of almost no bronchiolitis and influenza diagnoses, these seasonal infectious diseases are progressively recovering their pre-pandemic dynamics. We aim to describe how this process is taking place in Catalonia. Material and method: We used primary-care syndromic diagnostic data of bronchiolitis, influenza, and COVID-19 in Catalonia (Spain), which are publicly available through the new Information System for the Surveillance of Infections in Catalonia (SIVIC). We carried out a descriptive study of their dynamics from 2014 to 2023, focusing on the changes induced by the pandemic. Results: The results show that the old viral normality was significantly disrupted by SARS-CoV-2 and that we are experiencing a transition to a new viral normality where this novel infectious agent could play a role, but its precise dynamics remains unclear. Conclusions: We are slowly moving towards regular influenza and bronchiolitis seasonality. The role of SARS- CoV-2 in the viral landscape in Catalonia remains uncertain, but its effects on other pathogens are relevant and warrant further investigation.Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version

Utilización del modelo de Gompertz en forma diferencial para la modelización de la emergencia de malas hierbas

El modelo de Gompertz, en su forma integral es uno de los modelos más utilizados para describir el patrón de emergencias de malas hierbas en función de la temperatura y de la humedad del suelo. Sin embargo, la emergencia no sólo depende de la especie vegetal sino también de las características físico-químicas del suelo y de las condiciones ambientales durante la etapa de dormición de la semilla, que pueden ser muy variables de un año para el otro. Con el fin de evitar la validación previa que se requiere para cada situación específica y la ambigüedad que supone iniciar la acumulación de grados hidrotermales el día del laboreo, en este trabajo se propone la utilización de la ecuación de Gompertz en su forma diferencial para resolver estos dos aspectos.Postprint (published version