Osteoimmunology: A Link between Gastrointestinal Diseases and Skeletal Health in Chickens

Abstract

Bone serves as a multifunctional organ in avian species, giving structural integrity to the body, aiding locomotion and flight, regulating mineral homeostasis, and supplementing calcium for eggshell formation. Furthermore, immune cells originate and reside in the bone marrow, sharing a milieu with bone cells, indicating a potential interaction in functions. In avian species, the prevalence of gastrointestinal diseases can alter the growth and the immune response, which costs a great fortune to the poultry industry. Previous studies have shown that coccidiosis and necrotic enteritis can dramatically reduce bone quality as well. However, possible mechanisms on how bone quality is influenced by these disease conditions have not yet been completely understood, other than the reduced feed intake. On the other hand, several mediators of the immune response, such as chemokines and cytokines, play a vital role in the differentiation and activation of osteoclasts responsible for bone resorption and osteoblasts for bone formation. In the case of Eimeria spp./Clostridium perfringens coinfection, these mediators are upregulated. One possible mechanism for accelerated bone loss after gastrointestinal illnesses might be immune-mediated osteoclastogenesis via cytokines-RANKL-mediated pathways. This review article thus focuses on osteoimmunological pathways and the interaction between host immune responses and bone biology in gastrointestinal diseases like coccidiosis and necrotic enteritis affecting skeletal health.

Akkermansia muciniphila Promotes Bone Development and Improves Eggshell Quality during the Sexual Maturity Period of Laying Hens by Increasing Osteogenesis

“…The receptor activator of NF-κB ligand (RANKL) plays an important role in osteoclastogenesis, primarily sourced from osteoblasts and activated T cells, effectively bridging these two systems [52]. The term "osteoimmunology" underscores the reciprocal interactions between the skeletal and immune systems [23,24,53]. Specifically, CD4 + T cells serve as one of the sources of RANKL in the bone marrow, and an increase in CD4 + T cells has been observed in osteoporosis associated with inflammatory bowel disease [54].…”

Aflatoxin B1 Impairs Bone Mineralization in Broiler Chickens

“…This further reduces the number of available receptors for vitamin D, compounding the impairment of VDR signaling. Vitamin D deficiency is also linked with an impaired immune system which might further impair the bone remodeling process [ 51 , 52 ]. Therefore, AFB1 may affect the bone microstructure of broiler chickens by disrupting vitamin D synthesis, calcium and phosphorus homeostasis and the bone remodeling process.…”

The Functional Roles of Methionine and Arginine in Intestinal and Bone Health of Poultry: Review

“…In essence, it triggers the apoptosis of osteoblasts and osteocytes, while promoting osteoclast formation through upregulating RANKL [ 159 ]. Consequently, this disruption generates an imbalance within the bone remodeling process, impeding mineralization and osteogenesis, and increasing bone resorption, ultimately leading to increased bone loss [ 11 , 157 , 160 ]. A recent study investigating the impact of hydrogen peroxide-induced oxidative stress on chicken compact bone-derived MSCs revealed that oxidative stress significantly increased apoptosis and decreased osteogenic differentiation of the cells, and this was accompanied by a universal decrease in osteogenesis-related gene expression and a decline in vitro mineralization [ 161 ].…”

“…Although appearing distinct, the intestinal health and bone health are intricately interconnected and the immune system emerges as a significant factor that bridges the gap between them [ 11 ]. On one hand, the bone marrow serves as the hemopoietic organ, offering a specialized environment for the development of hematopoietic stem cells, which are the shared origin of various immune cell types [ 169 ].…”

“…Likewise, bone health is also a significant contributor to the overall well-being of the birds [ 10 , 11 ]. The skeletal system serves as the foundation for the structure of the birds, providing support and enabling efficient movement [ 12 ].…”