Macrophages can be categorized into different subtypes depending on their physical appearance, role, and surface markers. M1 and M2 are particularly noteworthy among these subtypes due to their distinct roles in both physiological and pathological conditions.

Creative Biolabs provides our customers with knowledge sharing related to M1 and M2 macrophages, and also offers a wide range of products and services in the field of macrophage research.

What are M1 and M2 Macrophages?

M1 and M2 are two distinct subtypes that exhibit different functional properties and cytokine profiles.

• Pro-inflammatory signals activate M1 macrophages, which exhibit a profile that is important in safeguarding the host from bacterial and viral infections. Additionally, this profile initiates and maintains the inflammatory response.
• M2 macrophages, which exhibit an anti-inflammatory and tissue repair phenotype, are stimulated by anti-inflammatory factors. This activation is critical for resolving inflammation, remodeling tissues, and promoting wound healing.

Fig 1 Schematic representation of the functions of M1 and M2-like macrophages in tumor development.¹

M1 VS M2 Macrophages

The roles of M1 and M2 can be context-dependent and vary between different tissues and diseases.

• In acute infections, M1 macrophages are important for the initial response to pathogens and the recruitment of other immune cells to the site of infection. However, if the M1 response is prolonged or excessive, it can lead to tissue damage and chronic inflammation.
• In contrast, in chronic infections and tumors, M2 macrophages are often associated with immunosuppression and tumor-promoting functions.

Thus, targeting the M1/M2 balance may be a potential therapeutic strategy for certain diseases.

M1/M2 Macrophage Markers

Macrophage phenotypes exhibit distinct expression patterns of surface markers and cytokines, enabling their identification and isolation from complex tissues or cultures. Some examples of markers are listed below.

M1 markers:

• CD86
• CD80
• iNOS
• IL-1β
• IL-6
• TNF-α

M2 markers:

• CD206 (mannose receptor)
• Arg1
• Ym1/2
• IL-10
• TGF-β
• CCL17

The expression of these markers is regulated by transcription factors such as STAT1 and STAT6, which are activated by pro- and anti-inflammatory cytokines, respectively. The M1/M2 phenotype is not fixed and can be dynamically regulated.

Different Types of Macrophages

There are many other subtypes of macrophages in addition to M1 and M2, that have been identified based on their tissue localization, developmental origin, and functional properties. Some examples include:

• Kupffer cells in the liver
• Alveolar macrophages in the lungs
• Microglia in the brain
• Osteoclasts in bone
• Peritoneal macrophages in the abdominal cavity
• Monocyte-derived macrophages in the circulation

Each of these macrophage subtypes has unique functions and interactions with other cells in their respective microenvironments.

In conclusion, the M1/M2 balance is critical for maintaining immune homeostasis and preventing chronic inflammation and tissue damage. Understanding the molecular mechanisms that regulate macrophage activation and polarization may provide new insights into the pathogenesis of many diseases and potential therapeutic targets.

Creative Biolabs is dedicated to providing total solutions for macrophage research. Professional scientists, a comprehensive powerful platform, and abundant experience make us a perfect partner to help our clients with macrophage reprogramming. For more products and services, please feel free to contact us or send us your inquiries or questions.

Reference

1. Van Dalen, Floris J., et al. "Molecular repolarisation of tumour-associated macrophages." Molecules 24.1 (2018): 9.