Details for: CL0000890

Cell ID: CL0000890

Cell Name: alternatively activated macrophage

Description: Role or process: tissue remodeling.

Synonyms: anti-inflammatory macrophage, alternatively activated macrophage

Selected Context(s): Overall

Gene Significance Landscape

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Score:
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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 alternatively activated macrophage 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 alternatively activated macrophage. 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 alternatively activated macrophage. 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 alternatively activated macrophage. 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:  alternatively activated macrophage (CL0000890)

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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.

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## Summary The [alternatively activated macrophage](/details-cell/CL0000890), also known as an anti-inflammatory or M2 macrophage, is a myeloid cell subtype primarily associated with tissue remodeling, immune suppression, and the resolution of inflammation. **Overall**, the gene significance profile strongly underscores its specialization in iron homeostasis, marked by the exceptional specificity of the ferritin light and heavy chain genes, [FTL](/details-gene/2512) and [FTH1](/details-gene/2495). This, combined with high specificity for genes involved in polyamine metabolism and complement-mediated clearance, paints a picture of a cell centrally involved in managing the metabolic and cellular debris of the tissue microenvironment to promote healing and restore homeostasis. ## Key Characteristics and Function Analysis of top marker genes, ranked by expression specificity (`csi_z`), reveals several core functional clusters that define the [alternatively activated macrophage](/details-cell/CL0000890). * **Iron Sequestration and Metabolism:** The most defining characteristic is an intense involvement in iron metabolism. [FTL](/details-gene/2512) (CSI: 96.12) and [FTH1](/details-gene/2495) (CSI: 86.13) are the top two markers, indicating that the ferritin complex, responsible for sequestering intracellular iron, is a uniquely active system in these cells. This function is critical for tissue repair, as it limits iron availability for pathogens and prevents iron-driven oxidative damage (Fenton reactions), while recycling essential iron from phagocytosed cells. * **Tissue Remodeling and Resolution:** A key role in tissue repair is supported by the high specificity of genes related to polyamine metabolism, such as [SAT1](/details-gene/6303) and [OAZ1](/details-gene/4946). Polyamines are downstream products of the Arginase-1 pathway (a classical M2 pathway) and are essential for cell proliferation and tissue regeneration. Furthermore, the high expression specificity of complement component [C1QB](/details-gene/713) suggests a critical role in efferocytosis (the clearance of apoptotic cells), a primary mechanism for resolving inflammation and preventing secondary necrosis. This is physically supported by the specificity of cytoskeletal components like [CFL1](/details-gene/1072), which are necessary for cell motility and phagocytosis. * **Immunomodulation and Antigen Presentation:** These macrophages appear equipped to actively communicate with the adaptive immune system. The high significance of [B2M](/details-gene/567) (a component of MHC class I) and [HLA DPA1](/details-gene/3113) (MHC class II) suggests they are capable of presenting antigens to both CD8+ and CD4+ T cells. The presence of [FCER1G](/details-gene/2207), a common signaling adaptor for Fc receptors, further points to their ability to respond to antibody-opsonized targets. This suggests a role in shaping the T cell response, likely towards a regulatory or anti-inflammatory phenotype consistent with their overall function. * **Bioenergetics and Stress Response:** A distinct cluster of highly specific mitochondrial genes, including [COX1](/details-gene/4512), [COX2](/details-gene/4513), and [ATP5F1E](/details-gene/514), indicates a reliance on oxidative phosphorylation for energy. This metabolic profile is a hallmark of M2 macrophages, providing sustained energy for long-term functions like tissue repair, in contrast to the glycolytic switch seen in pro-inflammatory M1 macrophages. Concurrently, genes like [GSTP1](/details-gene/2950) and [PRDX1](/details-gene/5052) suggest a robust system for managing oxidative stress, befitting a cell that operates within sites of injury and repair. The anti-marker profile does not show strong negative regulation of genes from other specific lineages, but the relatively low significance of key RNA processing factors like [HNRNPC](/details-gene/3183) may point towards a distinct, perhaps more stable, post-transcriptional regulatory program compared to other immune cells. ## Clinical Significance and Contextual Roles The distinct functional profile of the [alternatively activated macrophage](/details-cell/CL0000890) positions it as a critical player in both health and disease. Its profound capacity for iron sequestration via [FTL](/details-gene/2512) and [FTH1](/details-gene/2495) is a double-edged sword. In normal wound healing, this is protective. However, in the context of cancer, tumor-associated macrophages (TAMs) often display an M2-like phenotype. Their ability to manage iron may contribute to the tumor microenvironment by shielding cancer cells from iron-induced ferroptosis and supporting their growth. The cell's central role in tissue remodeling and efferocytosis, highlighted by markers like [C1QB](/details-gene/713) and [SAT1](/details-gene/6303), is crucial for resolving acute injury. Dysregulation of this function, however, can lead to pathology. Insufficient activity can result in chronic inflammation and autoimmunity due to the persistence of apoptotic debris. Conversely, excessive or prolonged activity can drive pathological fibrosis in organs like the lung, liver, and kidney, where these macrophages are known to orchestrate the deposition of extracellular matrix. Finally, their immunomodulatory functions, suggested by the expression of [B2M](/details-gene/567) and MHC class II genes, are critical for dampening immune responses. This is beneficial for preventing excessive tissue damage during infection but can be co-opted by tumors to create an immunosuppressive shield that prevents effective anti-cancer immunity. Therefore, understanding the signals that maintain this cell's phenotype is a key goal for both regenerative medicine and oncology. ## Potential Mechanisms and Research Directions 1. **Hypothesis: Ferritin acts as a central immunometabolic checkpoint in alternatively activated macrophages, directly shaping the T cell microenvironment.** The unparalleled expression specificity of [FTL](/details-gene/2512) and [FTH1](/details-gene/2495) suggests their function extends beyond simple iron storage. We hypothesize that by aggressively sequestering intracellular free iron, these macrophages create a localized iron-deficient state that preferentially inhibits the proliferation of highly metabolic, pro-inflammatory effector T cells, while facilitating their own sustained, pro-resolving functions. * **Surprising Findings:** The dominance of ferritin complex genes as the most specific markers, even over canonical M2-associated surface receptors or enzymes, suggests that iron handling is a more fundamental and defining feature of this cell state across diverse tissues than previously recognized. * **Testable Questions:** Does selective inhibition of ferritin function in alternatively activated macrophages, for instance via siRNA targeting [FTH1](/details-gene/2495), alter their ability to suppress T cell proliferation in a co-culture system, even when their polarization state is maintained? 2. **Hypothesis: The polyamine pathway is a key effector mechanism for the direct modulation of stromal cells during M2-mediated tissue repair.** The co-enrichment of genes controlling polyamine synthesis and catabolism ([SAT1](/details-gene/6303), [OAZ1](/details-gene/4946)) implies that the dynamic regulation of polyamine levels is a critical output of this cell type. We propose that these macrophages actively secrete or transport polyamines to directly stimulate the proliferation and matrix-producing activity of local fibroblasts and endothelial cells, thereby actively driving wound closure. * **Surprising Findings:** The high specificity of both a biosynthetic regulator ([OAZ1](/details-gene/4946), an antizyme that promotes ubiquitin-independent degradation of ODC) and a catabolic enzyme ([SAT1](/details-gene/6303)) points to a finely tuned, dynamic control of the polyamine pool. This suggests that the *flux* through the pathway, rather than just simple overproduction, is the critical regulated variable. * **Testable Questions:** Does conditioned media from [alternatively activated macrophages](/details-cell/CL0000890) promote fibroblast migration and collagen expression in vitro, and is this effect specifically blocked by inhibiting spermidine/spermine N1-acetyltransferase ([SAT1](/details-gene/6303)) activity in the macrophages prior to media collection?