Enhanced expression of IL-34 in an inflammatory cyst of the submandibular gland: a case report

Abstract

BackgroundCysts of the salivary glands are common lesions that occur in the context of various etiologies. Although the diagnostic importance of cysts in salivary gland diseases has been well studied, molecular mechanisms that control the related pathological process remain largely unknown. IL-34 is a novel cytokine that was discovered recently as a tissue-specific ligand of colony stimulating factor-1 receptor. Since its discovery, accumulating evidence has revealed emerging roles of IL-34 in various pathological conditions and has been suggested to correlate remarkably with inflammation. In this study, we report a medical case of an inflammatory cyst within the submandibular gland, through which evaluating the possible involvement of IL-34 in salivary gland disorders.Case presentationA 37-year-old male patient suffered from a sudden swelling in the right submandibular region, started initially small and had gradually increased in size to reach 3–4 cm in 1 week, accompanied by pain and local fever. Ultrasonography and MRI imaging revealed the existence of a well-defined cystic lesion with sharp borders measuring 39.8 mm × 19.7 mm within the right submandibular gland. The cyst was removed surgically, and the diagnostic decision was determined based on histopathological observations as an inflammatory cyst in the submandibular gland. Sections were generated from different regions of the surgically resected inflammatory cyst and used to examine IL-34 expression by immunohistochemistry compared to normal salivary gland tissues. Immunohistochemical staining showed enhanced expression of IL-34 in the ductal epithelial cells and endothelial cells of blood vessels, with a tendency to be accompanied with high infiltration of immune cells, which suggests a possible involvement of IL-34 in the pathogenesis of salivary gland inflammation.ConclusionsIn this report, we introduce interesting findings of enhanced IL-34 expression in a case of an inflamed submandibular gland. Our findings emphasize the pathological roles of IL-34 as an inflammation amplifier and angiogenic enhancer in inflammatory conditions, such as in salivary gland disorders.Electronic supplementary materialThe online version of this article (10.1186/s41232-018-0069-6) contains supplementary material, which is available to authorized users.

Prognostic value of IL-34 in colorectal cancer patients

“…The association of IL-34 staining in colorectal cancer tissues with patients' characteristics is summarized in Table 1. Together, these data indicate that colorectal cancers have the potential to express IL-34, consistent with previous reports [8][9][10][11][12][13][14][15][16][17][18][19].…”

“…In disease, IL-34 expression can be induced by various cells, where it plays pathological roles such as in autoimmune disease, inflammation, infection and metabolic disorders [7]. Accumulating evidence also suggests important roles for IL-34 in cancer, including tumor growth, angiogenesis, metastasis, immunosuppression, therapeutic resistance and pathological osteoclastogenesis [8][9][10][11][12][13][14][15][16][17][18][19]. In particular, IL-34 contributes to the induction of immunosuppressive tumor microenvironment.…”

Interleukin-34, a comprehensive review

“…Since NF‐κB is a master regulator of the inflammatory signaling pathway, IL‐34 is expected to be correlated with various inflammatory conditions. Consistent with this, an enhanced expression of IL‐34 has been reported in several pathological conditions accompanied by inflammation such as inflammatory bowel disease, coronary artery disease, chronic apical periodontitis, obesity, chronic liver disease in NAFLD, and lesions of the salivary glands . Importantly, IL‐34 was suggested to be involved in the pathological complications of these chronic conditions, such as renal dysfunction in chronic heart failure, liver fibrosis in NAFLD, and insulin resistance and T2DM in obesity …”

“…Since IL‐34 is expressed at mRNA level in various tissues, this expression is expected to be changed under pathological conditions. Indeed, several studies have confirmed the enhancement of IL‐34 expression at mRNA and protein levels in the context of various diseases including autoimmune disorders, inflammation, infections, metabolic diseases, neurological disorders, and cancer . At the cellular level, IL‐34‐producing cells include synovial fibroblasts, immune cells, epithelial cells, endothelial cells, adipocytes, and cancer cells.…”

“…IL‐34 has the potential to amplify the inflammatory circle by inducing the expression of several pro‐inflammatory cytokines, chemokines, and metalloproteases in a wide range of cells including monocytes, M ϕ s, microglia, fibroblasts, and epithelial cells . The existence of IL‐34 is accompanied by the expansion of pro‐inflammatory monocytes in the inflamed loci, such as in the inflamed salivary glands . Additionally, Foucher et al.…”