Biology subjects

Altieri, A.

Publications and source records attributed to Altieri, A..

10 recordsLinked to original sources

bioRxiv2026

Pi16+ fibroblast-derived Csf1 shapes skin topography

Peptidase inhibitor 16 (Pi16)-expressing fibroblasts are found across tissues and species, but their functional role is unclear. As fibroblasts and macrophages have been proposed to exist in a reciprocal circuit, we hypothesized Pi16+ fibroblasts may regulate macrophage homeostasis. Flow cytometry revealed [~]80% of skin fibroblasts express Pi16, leading us to investigate the role of these cells in maintaining a macrophage niche in this tissue. We generated an in vivo system where fibroblast-derived Colony Stimulating Factor 1 (Csf1) was constitutively eliminated in Pi16+ fibroblasts by crossing animals with a Csf1fl/fl allele to mice in which the gene Pi16 drives an IresCre cassette. Deletion of Csf1 in Pi16+ fibroblasts resulted in significant diminishment of CD64+ and CD11c+ macrophages alongside expansion of PDPN+YFP+ fibroblasts. Alterations in cell population dynamics coincided with thickening of both the dermis and fascial compartments of the skin. Deletion of Csf1 in Pi16+ fibroblasts delayed early wound healing in a unsplinted mouse model. Loss of PI16+ fibroblasts was observed in individuals with limited (lSSc) and diffuse (dSSc) systemic Scleroderma compared to healthy controls. These findings suggest that loss of Csf1 in Pi16+ fibroblasts elicit changes in the population dynamics of skin macrophages and modifications to tissue architecture.

immunology↗

bioRxiv2025

LL-37 and citrullinated-LL-37 enhance disparate oxylipins: LL-37-mediated chemokine response is dependent on COX-2 and the P2X7 receptor in human bronchial epithelial cells

BackgroundDuring airway inflammation, chemokines, oxylipins (bioactive lipids) and cationic host defence peptides (CHDP) are enhanced in the lungs. However, the interplay of these molecules in the process of airway inflammation is not fully resolved. The human cathelicidin CHDP, LL-37, can enhance the expression of chemokines which is turn facilitates influx of leukocytes into the lungs. Moreover, LL-37 can get citrullinated during inflammation and the effect of this post-translational modification on LL-37-mediated immunomodulatory functions remains unclear. Therefore, in this study we aimed to define the impact of LL-37 and citrullinated-LL-37 (citLL-37) on oxylipins and its association with downstream chemokine production in human bronchial epithelial cells (HBEC), and its functional impact on leukocyte influx. MethodsWe used a lipidomics approach to identify oxylipins that are enhanced in response to LL-37 and citLL-37 in HBEC. We further examined the role of selected oxylipins in LL-37- and citLL-37-mediated chemokine production by ELISA, and related leukocyte migration using a transwell migration assay. ResultsWe showed that LL-37, but not citLL-37, enhances oxylipins that are known to promote inflammation such as prostaglandins regulated by the cyclooxygenase (COX pathway). Although both LL-37 and citLL-37 upregulated COX-2, LL-37-mediated increase in COX-2 expression was significantly higher than that mediated by citLL-37. We showed that upregulation of COX-2 expression was dependent on the P2X7 purinergic receptor. Our mechanistic studies revealed that LL-37-mediated increase in chemokines, GRO, IL-8 and MIP-3, was dependent on the COX-2 pathway. Our results also indicated that COX-2-induced PGE2 may act in an autocrine manner signaling through its EP receptors to facilitate LL-37-induced chemokine production. We functionally confirmed that factors secreted from HBEC in response to LL-37, but not citLL-37, promotes neutrophil migration which is COX-2 dependent. ConclusionThe results of this study indicate that pro-inflammatory responses mediated by LL-37 is alleviated by citrullination of the peptide. These findings suggest that citrullination of LL-37 may be a post-translational regulatory mechanism to control inflammation. Overall, this study underscores the role of LL-37 in influencing the enhancement of bioactive lipids and metabolic pathways such as COX-2 and its link to the peptide-mediated immunomodulatory functions in the lungs.

immunology↗

bioRxiv2025

Bigh3 is essential for pulmonary fibrosis

Transforming growth factor beta (TGF-{beta})-induced gene-human, clone 3 (BIGH3) has been implicated as a biomarker of lung fibrosis. However, it is unknown if BIGH3 plays a functional role in fibrosis pathogenesis. To address this question, we used in silico, in vitro and in vivo approaches. We found that BIGH3/Bigh3 is upregulated in human lung fibrosis and mouse models of pulmonary fibrosis. We next generated a novel Bigh3 knockout (Bigh3-/-) mouse and found that while these animals exhibited lung architecture and immune cellularity that is broadly equivalent to wild-type mice, they were protected from lung fibrosis in response to bleomycin administration. In silico modeling suggested that BIGH3 can bind to integrin alpha v (ITGAV). In vitro co-culture systems revealed that activated human lung fibroblasts can elicit BIGH3 expression from human monocyte-derived macrophages. Last, macrophages elicited collagen expression from lung fibroblasts in a manner that is Bigh3-dependent. Collectively, these data suggest that Bigh3 is a product of fibroblast-macrophage interactions that is essential for the pathogenesis of lung fibrosis, possibly via interactions with ITGAV.

immunology↗

bioRxiv2024

Dermatopontin-expressing fibroblasts mediate an essential skin macrophage niche

Fibroblasts are present in all tissues and are crucial for maintaining tissue homeostasis. We previously identified fibroblasts marked by Dermatopontin (Dpt) but their role in supporting macrophage homeostasis remains unclear. Here, we generated novel mesenchymal lineage-restricted genetic tools to target Dpt expressing fibroblasts and elucidate their role in supporting skin macrophages. Transcriptional profiling, flow cytometry, and in situ hybridization uncovered two broad populations of F4/80-expressing skin macrophages, denoted by high expression of CD206 and CD64 (CD206hiCD64+), or CD11c. Targeted depletion of Dpt+ fibroblasts resulted in a profound loss of both macrophage populations. Conditional deletion of colony-stimulating factor-1 (Csf1) in Dpt+ fibroblasts revealed that CD206hiCD64+, and not CD11c+, macrophages are acutely dependent on fibroblast-derived Csf1, consistent with their higher expression of the Csf1 receptor. Following Csf1 deletion in Dpt+ fibroblasts, loss of CD206hiCD64+ macrophages were observed across the dermis, dermal white adipose tissue (dWAT), and adventitia, accompanied by a modest upregulation of fibroblast-related and extracellular matrix (ECM) genes and structural changes to the skin. Alterations to the skin network upon loss of fibroblast-derived Csf1 and CD206hiCD64+ macrophages led to a significant delay in wound healing. We also demonstrate the CSF1-CSF1R signaling pathway is functionally relevant in human systemic sclerosis, or scleroderma, as elevated levels of CSF1 produced by fibroblasts and an increased abundance of macrophages both correlate with disease severity. Our findings demonstrate the role of Dpt+ fibroblasts in regulating a Csf1-dependent macrophage niche in skin and orchestrating responses in injury and disease.

immunology↗

bioRxiv2024

LL-37 modulates IL-17A/F-mediated airway inflammation by selectively suppressing Lipocalin-2.

BackgroundLevels of the human cationic host defence peptide (CHDP) LL-37 is enhanced in the lungs during neutrophilic airway inflammation. LL-37 drives Th17 differentiation, and Th17 cells produce IL-17A and IL-17F which forms the biologically active heterodimer IL-17A/F. While IL-17 is a critical mediator of neutrophilic airway inflammation, LL-37 exhibits contradictory functions; LL-37 can both promote and mitigate neutrophil recruitment depending on the inflammatory milieu. The impact of LL-37 on IL-17-induced responses in the context of airway inflammation remains largely unknown. Therefore, we examined signaling intermediates and downstream responses mediated by the interplay of IL-17A/F and LL-37, in human bronchial epithelial cells (HBEC). As LL-37 can get citrullinated during airway inflammation, we also examined LL-37-mediated downstream response compared to that with citrullinated LL-37 (citLL- 37), in HBEC. ResultsUsing an aptamer-based proteomics approach, we identified proteins that are altered in response to IL-17A/F in HBEC. Proteins enhanced in response to IL-17A/F were primarily neutrophil chemoattractants, including chemokines and proteins associated with neutrophil migration such as lipocalin-2 (LCN-2) and Elafin. We showed that selective depletion of LCN-2 mitigated neutrophil migration, thus functionally demonstrating LCN-2 as a critical neutrophil chemoattractant. We further demonstrated that LL-37 and citLL-37 selectively suppresses IL- 17A/F-induced LCN-2 production, in bronchial epithelial cells. Mechanistic studies revealed that LL-37 and citLL-37 suppressed IL-17A/F-mediated C/EBP{beta}, a transcription factor required for LCN-2 production. In contrast, LL-37 and citLL-37 enhanced the ribonuclease Regnase-1, which is a negative regulator of IL-17 and LCN-2. In an animal model of neutrophilic airway inflammation with elevated IL-17A/F in the lungs, we demonstrated that CRAMP (mouse ortholog of LL-37) negatively correlates with LCN-2. ConclusionsOverall, our findings showed that LL-37 and citLL-37 can selectively suppress the abundance of IL-17A/F-mediated LCN-2, a protein that is critical for neutrophil migration, in bronchial epithelial cells. These results suggest that LL-37, and its modified citrullinated form, has the potential to negatively regulate IL-17-mediated neutrophil migration to control airway inflammation. To our knowledge, this is the first study to report that the immunomodulatory function of LL-37 engages an RNA binding protein, Regnase-1, indicating post-transcriptional regulation of airway inflammation by the peptide.

immunology↗

bioRxiv2024

Temperature drives seagrass recovery across the Western North Atlantic

Climate-driven shifts in herbivores, temperature and nutrient runoff threaten coastal ecosystem resilience. However, our understanding of ecological resilience, particularly for foundation species, remains limited due to a rarity of field experiments that are conducted across appropriate spatial and temporal scales and that investigate multiple stressors. This study aimed to evaluate the resilience of a widespread tropical marine plant (turtlegrass) to disturbances across its geographic range and how this is impacted by environmental gradients in (a)biotic factors. We assessed the resilience (i.e. recovery) of turtlegrass to a simulated disturbance (complete above- and belowground biomass removal) over a year. Contrary to temperate studies, higher temperature generally enhanced seagrass recovery. While nutrients and light availability had minimal impact, combined high levels of nutrients and herbivore grazing (meso and megaherbivore) reduced aboveground recovery. Our results suggest that the resilience of some tropical species, especially in cooler subtropical waters, may initially increase with warming.

ecology↗

bioRxiv2023

Shifts in the coral microbiome in response to in situ experimental deoxygenation

Global climate change impacts ocean communities through rising surface temperatures, ocean acidification, and deoxygenation. While the response of the coral holobiont to the first two effects has been relatively well studied, little is known about the response of the coral microbiome to deoxygenation. In this study, we investigated the response of the microbiome to hypoxia in two coral species that differ in their relative tolerance to hypoxia. We conducted in situ oxygen manipulations on a coral reef in Bahia Almirante, Panama, which has previously experienced episodes of low dissolved oxygen concentrations. Naive coral colonies (previously unexposed to hypoxia) of massive starlet coral (Siderastrea siderea) and Lamarcks sheet coral (Agaricia lamarcki) were transplanted to a reef and either enclosed in chambers that created hypoxic conditions or left at ambient oxygen levels. We collected samples of surface mucus and tissue after 48 hours of exposure and characterized the microbiome by sequencing 16S rRNA genes. We found that the microbiomes of the two coral species were distinct from one another and remained so after exhibiting similar shifts in microbiome composition in response to hypoxia. There was an increase in both abundance and number of taxa of anaerobic microbes after exposure to hypoxia. Some of these taxa may play beneficial roles in the coral holobiont by detoxifying the surrounding environment during hypoxic stress. This work describes the first characterization of the coral microbiome under hypoxia and is an initial step toward identifying potential beneficial bacteria for corals facing this environmental stressor. ImportanceMarine hypoxia is a threat for corals but has remained understudied in tropical regions where coral reefs are abundant. Deoxygenation on coral reefs will worsen with ongoing climate change, acidification, and eutrophication. We do not yet understand the response of the coral microbiome to hypoxia, and whether this reaction may have a beneficial or harmful role in the coral holobiont. To understand how the coral microbial community structure responds during hypoxic stress, we experimentally lowered the oxygen levels around corals in the field to observe changes in the composition of the coral microbiome. We documented the increase of anaerobic and pathogenic bacteria in the microbiomes of the massive starlet coral (Siderastrea siderea) and Lamarcks sheet coral (Agaricia lamarcki) in 48 hours. This work provides fundamental knowledge of the microbial response in the coral holobiont during hypoxia and may provide insight to holobiont function during stress.

ecology↗

bioRxiv2022

Simulated green turtle grazing reduces seagrass productivity and alters benthic community structure while triggering further disturbance by feeding stingrays

While green turtles (Chelonia mydas) were once abundant throughout the Caribbean, overexploitation has dramatically reduced their numbers. We conducted a 168-day simulated grazing experiment to determine how loss of this once-abundant mega-herbivore could have affected the productivity and community composition of Thalassia testudinum-dominated seagrass beds in Bocas del Toro, Panama. Simulated grazing reduced both percent cover and productivity of T. testudinum. High runoff and local pollution from industrial farming may limit light availability and reduce seagrass photosynthetic performance to replace biomass lost to simulated grazing. Other seagrass species and algae failed to colonize space opened by reductions in T. testudinum percent cover. Many plots subjected to simulated grazing were also bioturbated by stingrays. Relevance of these findings to balancing sea turtle and seagrass conservation efforts are discussed.

ecology↗

bioRxiv2021

Discovery of highly potent pancoronavirus fusion inhibitors that also effectively inhibit COVID-19 variants from the UK and South Africa

We report here the discovery of several highly potent small molecules that showed low nM potency against SARS-CoV (IC50: as low as 13 nM), SARS-CoV-2 (IC50: as low as 23 nM), and MERS-CoV (IC50: as low as 76 nM) in pseudovirus based assays with excellent selectivity indices (SI: as high as > 5000) demonstrating their pancoronavirus inhibition. Some compounds also show 100% inhibition of CPE (IC100) at 1.25 {micro}M against an authentic SARS-CoV-2 (US_WA-1/2020). Furthermore, the most active inhibitors also potently inhibited variants of concerns (VOCs), such as the UK (B.1.1.7), South Africa (B.1.351), and Delta variant (B.1.617.2), originated in India. We confirmed that one of the potent inhibitors binds to the prefusion spike protein trimer of SARS-CoV-2 by SPR. Besides, we showed that they inhibit virus-mediated cell-cell fusion. The ADME data of one of the most active inhibitors, NBCoV1, show drug-like properties. In vivo PK of NBCoV1 in rats demonstrated excellent half-life (t1/2) of 11.3 h, mean resident time (MRT) of 14.2 h, and oral bioavailability. We expect the lead inhibitors to pave the way for further development to preclinical and clinical candidates.

pharmacology and toxicology↗

bioRxiv2019

Defining variation in pre-human ecosystems can guide conservation: An example from a Caribbean coral reef

There is a consensus that Caribbean coral reefs are a pale shadow of what they once were, yet a reef’s pre-human state is typically assumed or estimated using space-for-time substitution approaches. These approaches may fail to account for past variation before human impact which could mislead conservation priorities and actions. In this study we use a suite of fossilised mid-Holocene (7.2-5.6 ka) fringing reefs in Caribbean Panama to define the Historical Range of Variation (HRV) in coral community structure before human-impact to provide context for the states of modern reefs in the same area. Using the abundances of coral taxa to quantify communities, we found that most of the modern coral communities exist in novel ecosystem states with no fossil precedence. We do however identify one modern reef that is indistinguishable in coral community structure from the mid-Holocene reefs. Reef-matrix cores show that the community on this reef has remained in a stable state for over 760 years, suggesting long-term resistance to the region-wide shift to novel states. Without historical context this robust and stable reef would be overlooked since it does not fulfil expectations of what a “pristine” coral reef should look like. This example illustrates how defining past variation using the fossil record can place modern degradation in historical context and improve conservation recommendations.View Full Text

paleontology↗