Details for: CL4028001

Cell ID: CL4028001

Cell Name: pulmonary capillary endothelial cell

Description: Any capillary endothelial cell that is part of a lung.

Synonyms: lung capillary endothelial cell

Selected Context(s): Overall

Gene Significance Landscape

Display Options
Score:
Display
Genes

Contexts:

Cell Significance Index (CSI) is uniquely calculated to reveal cell-specific gene markers. More info here

Significant Genes List

Genes with the highest and lowest Percentile Rank Scores (PRS) for pulmonary capillary endothelial cell within the selected context(s).

Gene ID: A unique numerical identifier for this specific gene.
Symbol: Shortened abbreviation or name that represents this gene.
Ensembl Gene ID: A unique identifier assigned by Ensembl for genomic data mapping.
CSI Score: A combined effect size and statistical significance measure for pulmonary capillary endothelial cell. Higher scores indicate a stronger, more significant difference in expression.
(Previously described as "Fold Change", but now represents Cliff's Delta × –log10(p).)

Gene ID: A unique numerical identifier for this specific gene.
Symbol: Shortened abbreviation or name that represents this gene.
Ensembl Gene ID: A unique identifier assigned by Ensembl for genomic data mapping.
CSI Score: A combined effect size and statistical significance measure for pulmonary capillary endothelial cell. Higher scores indicate a stronger, more significant difference in expression.
Average CSI: csi sum / gene count
Cell network configuration

This network visualizes key genes for pulmonary capillary endothelial cell. It primarily includes:
1. Top genes highly significant for this cell (Num. Top Cell Genes - based on the 'Min. CSI' setting).
2. Any additional specific 'Context Genes' you add below.
The final network is a combined view. Choose an Interaction Source (pathways or protein interactions) and optionally compare CSI scores with a Baseline Cell Type.

Maximum number of selected genes.
Select a context for the baseline cell.
Select a context for the target cell.
Target Cell for CSI:  pulmonary capillary endothelial cell (CL4028001)

 Legend
Nodes (Genes):
 Query Gene
Node size also reflects Target Cell CSI magnitude.
Node Color (Target Cell CSI in specific network):
 Very High
 High
 Medium
 Low
 Very Low
 N/A or Not Sig.
Edges (Interactions):
 STRING (Protein-Protein)
 ONTOLOGY (Shared Pathway)
 Colors vary by pathway category; default arrow applies.

Loading network (please wait)...

## Summary The **pulmonary capillary endothelial cell** ([CL4028001](/details-cell/CL4028001)) is a specialized endothelial cell type forming the critical interface for gas exchange within the lung. Based on its gene significance profile, this cell is not merely a passive barrier but an active immunological participant. The high specificity scores ([csi_z](/details-glossary/csi)) for major histocompatibility complex (MHC) components like [B2M](/details-gene/567) and [HLA E](/details-gene/3133) suggest a defining role in antigen presentation and immune surveillance. Concurrently, strong markers for angiogenesis ([TMEM100](/details-gene/55273)) and cell-cell junctions ([CLDN5](/details-gene/7122)) underscore its fundamental role in maintaining the structural integrity and vascular function of the alveolar-capillary membrane. ## Key Characteristics and Function **Overall**, the gene signature of the [pulmonary capillary endothelial cell](/details-cell/CL4028001) points to a multifaceted role integrating vascular barrier function with active immune modulation and cytoskeletal regulation. * **Immunological Sentinel Function:** A prominent feature of this cell type is the highly specific expression of genes involved in antigen processing and presentation. The top two markers, [B2M](/details-gene/567) and the non-classical MHC class I molecule [HLA E](/details-gene/3133), are critical for presenting antigens to immune cells ([Link](https://pubmed.ncbi.nlm.nih.gov/3131426/)). The presence of [HLA DPA1](/details-gene/3113), an MHC class II alpha chain, further suggests a capacity for presenting exogenous antigens. This immunological surveillance toolkit is complemented by the expression of [FCN3](/details-gene/8547), which is involved in the lectin pathway of the complement system, and [CXCL8](/details-gene/3576) (IL-8), a potent neutrophil chemoattractant, highlighting the cell's ability to initiate and shape innate immune responses at the blood-air barrier. * **Vascular Integrity and Angiogenesis:** The identity of this cell as an endothelial type is firmly established by specific markers of vascular biology. [CLDN5](/details-gene/7122), a key component of endothelial tight junctions, is crucial for maintaining barrier integrity. Additionally, genes such as [TMEM100](/details-gene/55273), [ECSCR](/details-gene/641700), and [ADGRL4](/details-gene/64123) are all associated with angiogenesis and vasculogenesis, indicating a role in the maintenance and remodeling of the pulmonary capillary network. * **Cytoskeletal Dynamics and Mechanotransduction:** A significant number of top markers are related to the cytoskeleton and calcium signaling, including multiple myosin light chains ([MYL12B](/details-gene/103910), [MYL12A](/details-gene/10627), [MYL6](/details-gene/4637)) and the calcium-binding protein [S100A6](/details-gene/6277). This suggests that these cells possess a robust system for controlling cell shape, adhesion, and contractility, which is likely essential for withstanding the shear stress of blood flow and regulating vascular tone and permeability. * **Distinct Metabolic Profile:** The anti-marker profile is strikingly enriched for genes involved in mitochondrial respiration. Numerous subunits of cytochrome c oxidase ([COX3](/details-gene/4514), [COX4I1](/details-gene/1327), [COX5B](/details-gene/1329), [COX6C](/details-gene/1345), [COX7C](/details-gene/1350)), ATP synthase ([ATP5MG](/details-gene/10632), [ATP5F1E](/details-gene/514), [ATP5MC2](/details-gene/517)), and other components of the electron transport chain show strong negative significance. This pattern strongly suggests that, relative to other cell types, the [pulmonary capillary endothelial cell](/details-cell/CL4028001) has a distinct metabolic phenotype, possibly with a lower reliance on oxidative phosphorylation. ## Clinical Significance and Contextual Roles The unique gene expression profile of [pulmonary capillary endothelial cells](/details-cell/CL4028001) positions them as central players in various pulmonary pathologies. The high expression of barrier-forming proteins like [CLDN5](/details-gene/7122) is critical for preventing fluid leakage into the alveolar space; dysfunction of this barrier is a hallmark of Acute Respiratory Distress Syndrome (ARDS). The prominent immune-related gene signature, including [HLA E](/details-gene/3133) and [CXCL8](/details-gene/3576), implicates these cells in the response to respiratory infections (e.g., influenza, SARS-CoV-2) and in inflammatory conditions like pulmonary hypertension. Their antigen presentation capabilities may also be relevant in the context of lung transplant rejection, where they could present alloantigens to circulating T-cells. The expression of pro-angiogenic factors like [TMEM100](/details-gene/55273) suggests these cells are key effectors in both physiological vascular maintenance and pathological angiogenesis, which can occur in lung cancer and other diseases. ## Potential Mechanisms and Research Directions 1. **Hypothesis:** Pulmonary capillary endothelial cells act as significant non-professional antigen-presenting cells (APCs) that continuously sample blood- and air-derived antigens, playing a critical role in local T-cell surveillance and the initiation of lung-specific immune responses. * **Surprising Findings:** While endothelial antigen presentation is a known phenomenon, the data suggest that for this specific endothelial subtype, components of both MHC class I ([B2M](/details-gene/567), [HLA E](/details-gene/3133)) and class II ([HLA DPA1](/details-gene/3113)) pathways are not just present, but are defining specific markers of the cell's identity. The high specificity of the non-classical [HLA E](/details-gene/3133) is particularly notable, suggesting a specialized role in interacting with NK cells and CD8+ T-cells. * **Testable Questions:** Using in vitro co-culture systems, can [pulmonary capillary endothelial cells](/details-cell/CL4028001) process and present viral peptide antigens via [HLA E](/details-gene/3133) to activate or inhibit lung-resident NK cells or specialized T-cell subsets? 2. **Hypothesis:** The distinct metabolic state of pulmonary capillary endothelial cells, characterized by a low signature for oxidative phosphorylation machinery, is a specialized adaptation to the high-oxygen environment of the lung. This metabolic phenotype, likely favoring glycolysis, serves to limit the production of reactive oxygen species (ROS) and prevent oxidative damage to the delicate gas-exchange barrier. * **Surprising Findings:** The anti-marker list is overwhelmingly dominated by a broad and coordinated downregulation of genes from multiple complexes of the mitochondrial electron transport chain. This is not the absence of a single subunit but a sweeping signature, suggesting a fundamental and deeply programmed metabolic state rather than a transient adaptation. * **Testable Questions:** Does metabolic flux analysis of freshly isolated [pulmonary capillary endothelial cells](/details-cell/CL4028001) confirm a lower oxygen consumption rate (OCR) and a higher extracellular acidification rate (ECAR) compared to endothelial cells from more hypoxic tissues, such as the kidney or liver? How does exposure to hyperoxia or hypoxia in vitro alter the expression of these mitochondrial genes?