Rodrigues, P. F. | Search bioRxiv

bioRxiv2025

Plasmacytoid dendritic cells in the intestine preferentially produce interferon lambda at homeostasis contributing to tonic localized innate immune responses

The healthy intestine maintains homeostasis in part via immune responses to microbiota, which includes basal production of interferon cytokines. Previous work showed that Type III Interferon (IFN-{lambda}) stimulates localized pockets of interferon-stimulated genes (ISGs) in the adult mouse intestinal epithelium at homeostasis that provide preemptive protection from viral pathogens. Here, we demonstrate that a major source of homeostatic IFN-{lambda} production in the intestine is a population of epithelium-associated plasmacytoid dendritic cells (pDC). Depletion of bacterial microbiota in the intestine also reduces pDC abundance, and pDC depletion or bone marrow reconstitution with IFN-{lambda}-deficient pDC results in reduced expression of homeostatic ISGs in the intestinal epithelium. Notably, intestinal pDC preferentially produce IFN-{lambda} over Type I IFNs whereas splenic pDC produce more Type I IFNs. Comparison of intestinal and splenic pDC reveal tissue-specific changes in gene expression and genomic accessibility, including evidence of responses to transforming growth factor beta (TGF-{beta}) in the intestine. Isolated gut pDC produce more IFN-{lambda} than splenic pDC upon stimulation, and pre-treatment of a human pDC cell line with TGF-{beta} results in enhanced production of IFN-{lambda} upon stimulation. This study demonstrates that pDC are an important source of homeostatic IFN-{lambda} in the intestine and defines the role of barrier cytokine TGF-{beta} in regulating IFN types produced by pDC upon stimulation. Reprogramming of recruited pDC by tissue cytokines may have important implications for balancing effective antimicrobial responses with damaging inflammation at barrier tissues. One sentence summaryThis study demonstrates that pDC are an important source of homeostatic IFN-{lambda} in the intestine and defines the role of barrier cytokine TGF-{beta} in regulating IFN types produced by pDC upon stimulation.

immunology↗

bioRxiv2021

Climate trends and behavior of an avian forest specialist in central Amazonia indicate thermal stress during the dry season

Rainforest loss threatens terrestrial insectivorous birds throughout the worlds tropics. Recent evidence shows these birds to be declining in undisturbed Amazonian rainforest, possibly due to climate change. Here, we first addressed whether Amazonian terrestrial insectivores were exposed to climate change using 38 years of climate data. We found that climate has changed in central Amazonia, especially in the dry season, which was [~]1.3{degrees}C hotter and 21% drier in 2019 than in 1981. Second, to test whether birds actively avoided hot and dry conditions, we used field sensors to identify ambient extremes and prospective microclimate refugia within undisturbed rainforest from 2017 - 2019. Simultaneously, we examined how tagged Black-faced Anthrushes (Formicarius analis) used this space. We collected 1.4 million field measurements quantifying ambient conditions in the forest understory, including along elevation gradients. For 11 birds, we obtained GPS locations to test whether birds adjusted their shelter use (n = 2,724) or elevation (n = 640) across seasonal and daily cycles. For four additional birds, we collected >180,000 light and temperature readings to assess exposure. Field measurements in the modern landscape revealed that temperature was higher in the dry season and highest on plateaus. Thus, low-lying areas were relatively buffered, providing microclimate refugia during hot afternoons in the dry season. At those times, birds entered shelters and shifted downslope, reducing their thermal exposure by 50%. Because climate change intensifies the hot, dry conditions that antthrushes avoid, our results are consistent with the hypothesis that climate change lowers habitat quality for terrestrial insectivores. This sensitivity may be related to their declines within undisturbed Amazonian rainforest.

ecology↗