Table 2.

Overview of Toll-like receptors (TLRs).

TLR	Primary Location	Principal Ligand	Signaling Pathway	Functions and Application Examples
TLR1/2	Cell Surface	Triacylated lipopeptides (Pam3CSK4)	MyD88-dependent	Involved in immune response activation, potential applications in cancer and infectious disease treatments [1]
TLR2/6	Cell Surface	Lipopeptides	MyD88-dependent	Regulates inflammation and immune responses, potential treatments for allergic and autoimmune diseases [30]
TLR3	Endosomes	Double-stranded RNA (dsRNA)	TRIF-dependent	Antiviral immune responses, applications as vaccine adjuvants and in tumor treatments [31]
TLR4	Cell Surface	Lipopolysaccharide (LPS)	MyD88-dependent and TRIF-dependent	Regulates inflammatory responses, potential treatments for infectious diseases and cancer [32]
TLR7	Endosomes	Single-stranded RNA (ssRNA)	MyD88-dependent	Antiviral responses and regulation of autoimmune diseases such as SLE [13]
TLR8	Endosomes	Single-stranded RNA (ssRNA)	MyD88-dependent	Antiviral and anti-tumor therapeutic applications [13]
TLR9	Endosomes	CpG DNA	MyD88-dependent	Applications in antiviral vaccine adjuvants, treatments for infectious diseases and tumors [30]
TLR10	Cell Surface	Double-stranded RNA (dsRNA) (presumed)	MyD88-dependent	Potential roles in antiviral responses and immune regulation, further research needed to clarify specific functions [33]