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Tag: inflammation (Page 1 of 2)

Conventional type 1 dendritic cells protect against age-related adipose tissue dysfunction and obesity

Elena Hernández-García, Francisco J. Cueto, Emma C. L. Cook, Ana Redondo-Urzainqui, Sara Charro-Zanca, Iñaki Robles-Vera, Ruth Conde-Garrosa, Ivana Nikolić, Guadalupe Sabio, David Sancho & Salvador Iborra.

Conventional dendritic cells (cDCs) scan and integrate environmental cues in almost every tissue, including exogenous metabolic signals. While cDCs are critical in maintaining immune balance, their role in preserving energy homeostasis is unclear.

Body composition by MRI.

Here, we showed that Batf3-deficient mice lacking conventional type 1 DCs (cDC1s) had increased body weight and adiposity during aging. This led to impaired energy expenditure and glucose tolerance, insulin resistance, dyslipidemia, and liver steatosis. cDC1 deficiency caused adipose tissue inflammation that was preceded by a paucity of NK1.1+ invariant NKT (iNKT) cells. Accordingly, among antigen-presenting cells, cDC1s exhibited notable induction of IFN-γ production by iNKT cells, which plays a metabolically protective role in lean adipose tissue. Flt3L treatment, which expands the dendritic cell (DC) compartment, mitigated diet-induced obesity and hyperlipidemia in a Batf3-dependent manner. This effect was partially mediated by NK1.1+ cells.

These results reveal a new critical role for the cDC1-iNKT cell axis in the regulation of adipose tissue homeostasis.

Resident macrophage-dependent immune cell scaffolds drive anti-bacterial defense in the peritoneal cavity

Adrián Vega-Pérez, Laura H. Villarrubia, Cristina Godio, Alejandra Gutiérrez-González, Lidia Feo-Lucas, Margarita Ferriz, Natalia Martínez-Puente, Julieta Alcaín, Alfonso Mora, Guadalupe Sabio, María López-Bravo, Carlos Ardavín.

Peritoneal immune cells reside unanchored within the peritoneal fluid in homeostasis. Here, we examined the mechanisms that control bacterial infection in the peritoneum using a mouse model of abdominal sepsis following intraperitoneal Escherichia coli infection.

Whole-mount immunofluorescence and confocal microscopy of the peritoneal wall and omentum revealed that large peritoneal macrophages (LPMs) rapidly cleared bacteria and adhered to the mesothelium, forming multilayered cellular aggregates composed by sequentially recruited LPMs, B1 cells, neutrophils, and monocyte-derived cells (moCs). The formation of resident macrophage aggregates (resMφ-aggregates) required LPMs and thrombin-dependent fibrin polymerization. E. coli infection triggered LPM pyroptosis and release of inflammatory mediators. Resolution of these potentially inflammatory aggregates required LPM-mediated recruitment of moCs, which were essential for fibrinolysis-mediated resMφ-aggregate disaggregation and the prevention of peritoneal overt inflammation.

Thus, resMφ-aggregates provide a physical scaffold that enables the efficient control of peritoneal infection, with implications for antimicrobial immunity in other body cavities, such as the pleural cavity or brain ventricles

p38γ and p38δ reprogram liver metabolism by modulating neutrophil infiltration

Bárbara González‐Terán, Nuria Matesanz, Ivana Nikolic, María Angeles Verdugo, Vinatha Sreeramkumar, Lourdes Hernández‐Cosido, Alfonso Mora, Georgiana Crainiciuc, María Laura Sáiz, Edgar Bernardo, Luis Leiva‐Vega, Elena Rodríguez, Victor Bondía, Jorge L Torres, Sonia Perez‐Sieira, Luis Ortega, Ana Cuenda, Francisco Sanchez‐Madrid, Rubén Nogueiras, Andrés Hidalgo, Miguel Marcos & Guadalupe Sabio.

Non‐alcoholic fatty liver disease (NAFLD) is a major health problem and the main cause of liver disease in Western countries. Although NAFLD is strongly associated with obesity and insulin resistance, its pathogenesis remains poorly understood.

The disease begins with an excessive accumulation of triglycerides in the liver, which stimulates an inflammatory response. Alternative p38 mitogen‐activated kinases (p38γ and p38δ) have been shown to contribute to inflammation in different diseases. Here we demonstrate that p38δ is elevated in livers of obese patients with NAFLD and that mice lacking p38γ/δ in myeloid cells are resistant to diet‐induced fatty liver, hepatic triglyceride accumulation and glucose intolerance. This protective effect is due to defective migration of p38γ/δ‐deficient neutrophils to the damaged liver.

We further show that neutrophil infiltration in wild‐type mice contributes to steatosis development by means of inflammation and liver metabolic changes. Therefore, p38γ and p38δ in myeloid cells provide a potential target for NAFLD therapy.

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