Multiplex tissue profiling - salivary gland

The salivary gland is a part of the gastrointestinal tract where its main function is to lubricate the oral cavity and secrete digestive enzymes. These processes involve several different cell types that form distinct histological structures. As part of the Tissue resource, we used multiplex immunohistochemistry-based fluorescence (mIHC/IF) for in-depth profiling of protein expression in salivary gland. In the current version, 121 proteins have been analyzed in 5 cell types using 1 antibody panel.

  • 5 different cell types
  • 121 profiled proteins
  • 1 antibody panel

The salivary gland panel

The antibody panel for salivary gland was generated to profile the different glandular tissues (serous and mucus glands) and ductal structures (small ducts, large ducts, and ionocytes). The mIHC/IF technique is based on the overlap between the location of the candidate protein and location of the marker proteins targeted by the panel antibodies. Figure 1 shows the different cell types/states/structures, and the corresponding marker proteins included in each panel. For more information about the multiplex panels, please visit Assays & annotations.


Figure 1. A schematic depiction of the salivary gland panel on the left with a list of cell types, representing colors and marker proteins on the right.

Protein expression in the salivary gland

Candidate proteins for in-depth profiling were selected from the Tissue resource based on cell type specific staining pattern using conventional immunohistochemistry. Multiplex immunohistochemistry has allowed us to analyze and visualize protein expression in salivary gland at a higher resolution than ever before. antibody panel. For salivary gland, the protein expression was analyzed in serous glandular cells, mucus glandular cells, small ducts, large ducts, and ionocytes.

Table 1. The number of proteins mainly located in different cell types/structures in the salivary gland based on manual annotation.

Antibody panel
Main location
# proteins
Salivary gland Ionocytes 23
Salivary gland Large ducts 46
Salivary gland Mucus acini 47
Salivary gland Serous acini 88
Salivary gland Small ducts 54


Protein expression in serous glandular cells

As shown in Table 1, 88 genes have main protein location in serous acini. Serous glandular cells produce a watery secretion containing antimicrobial proteins as well as enzymes to initiate digestion. An example of a protein found in serous acini is BPIFA2 which binds bacterial lipopolysaccharide (LPS) in the oral cavity. Other proteins found in serous acini are BHLHA15 and CD44 with functions in organelle localization and cell adhesions, respectively.



BPIFA2

BHLHA15

CD44

BPIFA2

BHLHA15

CD44


Protein expression in mucus glandular cells

As shown in Table 1, 47 genes have main protein location in mucus acini. Mucus glandular cells are crucial for creating a protective dental biofilm with mucins and lysozymes. Trefoil factor 3 (TFF3) is an example of a protein found in mucus glandular cells that is associated with mucosa maintenance and repair. Two other proteins found in mucus glandular cells are C6orf58 with an unknown function and BPIFB2 which is a member of the lipid transfer/lipopolysaccharide binding protein gene family.



TFF3

C6orf58

BPIFB2

TFF3

C6orf58

BPIFB2


Protein expression in small ducts

As shown in Table 1, 54 genes have main protein location in small ducts. Small ducts are of the intercalated duct type with a cuboidal epithelial monolayer. The main function of these ducts is to transport the produced saliva from the acini to the large ducts. DMBT1 is an example of a protein localized to only small ducts and has been hypothesized to have a function in taste regulation in saliva among other functions. Other genes localized in the small ducts are the protease inhibitor WFDC2 and the DNA binding protein Iroquois homeobox 2 (IRX2).



DMBT1

WFDC2

IRX2

DMBT1

WFDC2

IRX2


Protein expression in large ducts

As shown in Table 1, 46 genes have main protein location in large ducts. Large ducts are composed of columnar epithelia like other striated ducts. The columnar epithelial cells have a folded basement membrane facilitating active transport of ions, endocytosis, and secreting kallikrein 1 (KLK1). An example of an ion transporter found in the large ducts is SLC26A9 which functions mainly as a chloride channel. Another protein in large ducts is HSD11B2, an enzyme involved in cortisol metabolism.



KLK1

SLC26A9

HSD11B2

KLK1

SLC26A9

HSD11B2


Protein expression in ionocytes

As shown in Table 1, 23 genes have main protein location in ionocytes. The ionocyte is a columnar epithelial cell subtype present in the large ducts that is specialized in maintaining the ion concentrations in the saliva at healthy levels and has a proposed function in the repair of the salivary glands. An example of a protein found in the ionocytes is AHCYL1 which is involved in regulating ion transport. Two other examples are the sodium-glucose cotransporter transporter SLC5A5 and the transmembrane protein 213 (TMEM213) with no known function.



AHCYL1

SLC5A5

TMEM213

AHCYL1

SLC5A5

TMEM213


Relevant links and publications

Uhlén M et al., Tissue-based map of the human proteome. Science (2015)
PubMed: 25613900 DOI: 10.1126/science.1260419

Karlsson M et al., A single-cell type transcriptomics map of human tissues. Sci Adv. (2021)
PubMed: 34321199 DOI: 10.1126/sciadv.abh2169

Lewis SM et al., Spatial omics and multiplexed imaging to explore cancer biology. Nat Methods. (2021)
PubMed: 34341583 DOI: 10.1038/s41592-021-01203-6

Tan WCC et al., Overview of multiplex immunohistochemistry/immunofluorescence techniques in the era of cancer immunotherapy. Cancer Commun (Lond). (2020)
PubMed: 32301585 DOI: 10.1002/cac2.12023