Table 3 Molecules related to PXS, function, and nature of association

Lysyl oxidase-like 1 (LOXL1) [28, 32, 34, 78]

Copper-dependent monoamine oxidase secreted by fibrogenic cells. Catalyzes covalent cross-linking of collagen and elastin in ECM formation

-Gene polymorphisms linked to PXS in multiple studies

-Protein present at site of pathology

Clusterin [14]

Clearance of cellular debris and apoptosis

-Clusterin deficiency associated with PXS.

-Clusterin present in PXM deposits

Homocysteine and human cell metabolic enzymes (MTHFR MTR, MTRR, MTHFD1, CBS) [46, 47]

Amino acids that participate in multiple metabolic processes.

Increased plasma levels associated with PXS

Glutathione transferase [50, 51, 56, 57]

It conjugates those toxic products with glutathione, protecting cells from oxidative damage

-Linkage of null genotype of the GST gene with PXS

CNTNAP2 (Caspr 2) [58, 60]

Regulation of potassium channels at neuron membranes. Possible role in membrane stabilization

-CNTNAP2 gene polymorphism associated with PXS

MMPs (MMP1) [15–17, 49]

Extracellular matrix maintenance

-MMP1 gene polymorphism associated with PXS

Adenosine receptors [45]

Adenosine regulates aqueous humor secretion. Intraocular pressure are regulated through adenosine receptors

-A3 receptor mRNA and protein selectively up regulated in eyes with PXS

TNF-α [65]

Has dual action depending on the type of receptor activated.

-Increased expression of TNF-α shifts the balance and activates the low affinity TNF-R1 receptor leading to cell death

High affinity TNF-R2 receptor has neuroprotective function while low affinity TNF-R1 receptors activation leads to cell death.