Hyperpigmentation Results in Aberrant Immune Development in Silky Fowl (Gallus gallus domesticus Brisson)

Abstract

The Silky Fowl (SF) is known for its special phenotypes and atypical distribution of melanocytes among internal organs. Although the genes associated with melanocyte migration have been investigated substantially, there is little information on the postnatal distribution of melanocytes in inner organs and the effect of hyperpigmentation on the development of SF. Here, we analyzed melanocyte distribution in 26 tissues or organs on postnatal day 1 and weeks 2, 3, 4, 6, 10, and 23. Except for the liver, pancreas, pituitary gland, and adrenal gland, melanocytes were distributed throughout the body, primarily around blood vessels. Interaction between melanocytes and the tissue cells was observed, and melanin was transported by filopodia delivery through engulfed and internalized membrane-encapsulated melanosomes. SFs less than 10 weeks old have lower indices of spleen, thymus, and bursa of Fabricius than White Leghorns (WLs). The expression levels of interferon-γ and interlukin-4 genes in the spleen, and serum antibody levels against H5N1 and infectious bursal disease virus were lower in SF than in WL. We also found immune organ developmental difference between Black-boned and non-Black- boned chickens from SFs and WLs hybrid F2 population. However, degeneration of the thymus and bursa of Fabricius occurred later in SF than in WL after sexual maturity. Analysis of apoptotic cells and apoptosis-associated Bax and Bcl-2 proteins indicated that apoptosis is involved in degeneration of the thymus and bursa of Fabricius. Therefore, these results suggest that hyperpigmentation in SF may have a close relationship with immune development in SF, which can provide an important animal model to investigate the roles of melanocyte.

Transcriptome analyses of differential gene expression in the bursa of Fabricius between Silky Fowl and White Leghorn

“…A previous report has demonstrated that the three-week age is very important for the development of B-cells and provides an opportunity for some pathogenic infection18. We also found that the development of BF was significantly weaker in SF than in WL14. In the present study, numerous melanocytes were observed in the lamina propria and bursal nodes of BF in SF.…”

“…Thus, the reduced expression of the genes associated with the metabolic pathways in the BF of SF might contribute to a relatively weaker B-cell development and lower BF indices. In addition, in our previous work, we detected low levels of antibodies in SF after vaccination14. However, in the present study, the reduced expression of genes was related to the Toll-like and NOD-like receptor pathways, which might result from the proliferation, rather than the differentiation, of B-cells in the BF.…”

“…As previously reported, the frozen sections were stained with anti-Bu-1 antibodies to label B-cells14. The optical densities of the Bu-1 + cells and the diameters of bursal nodes were identified in 10 high-power lymph nodes using the Image-Pro Plus 6.0 software, and the means were calculated.…”

Prokaryotic Expression and Anti-IBDV Activity of Chicken Interleukin-18 and Interferon-γ

“…After routine processing, the tissues were embedded in paraffin, cut into approximately 5-μm sections, and prepared for hematoxylin and eosin staining for histological examination [Han et al, 2015].…”

Effect of urea-extracted sericin on melanogenesis: potential applications in post-inflammatory hyperpigmentation

“…Unlike PIH, the association between melanoma and superficial innate immune responses is not well understood. Experiments using an interesting animal model, the silky fowl ( Gallus gallus domesticus Brisson), have suggested that hyperpigmentation may be related to inhibition of immune development and particularly to the degeneration of lymphoid organs [ 35 ]. The interaction between tyrosinase and MITF and its effect on melanogenesis has been well studied [ 17 , 36 , 37 ].…”