Osteoporosis is one of the most frequent forms of metabolic bone disease that makes bones brittle. It happens due to the loss in the mineral density of the bone making it more susceptible to fractures. Traditionally, this has been attributed to issues in endocrine functions like vitamin D deficiency or low levels of estrogen. However, exciting new insights into the mechanisms that contribute to the onset of osteoporosis have been uncovered by research in the last few decades. In this article, we will look into some of the pathophysiology of osteoporosis.
What Is Osteoporosis?
Osteoporosis is a metabolic bone disease that develops when the reabsorption of bone by osteoclasts is not being compensated by osteoblastic bone formation. As a result of this, bones become weak, and it affects the whole skeletal structure. Typically, this is an age-related disorder that more frequently affects women than men. That said, it can affect individuals belonging to any age group and both genders.
The Biology Of Bone
Evidence from years of research has revealed the multiple roles of bone in human biology. Some of its classical roles are locomotion, regulating mineral homeostasis, and protecting internal organs. Apart from this, it influences glucose metabolism, male fertility, energy expenditure, and cognitive functions. These are due to osteocalcin, which is a protein hormone secreted by osteoblasts.
Research over the years shows that along with osteoblasts and osteoclasts, osteocytes also play a key role in bone metabolism. Osteocytes have a significant influence on mineral homeostasis, and this is important regarding osteoporosis. They release effector proteins that influence the activity of osteoblasts and osteoclasts on bones.
The Pathophysiology Of Osteoporosis
Osteoporosis is a multifactorial disease that develops due to the interplay of intrinsic, genetic, exogenous, and lifestyle factors. Their combination increases the risk of an individual developing this metabolic bone disease. This is a deviation from the traditional pathophysiologic models that focused primarily on endocrine mechanisms like estrogen levels, reduced dietary intake of vitamin D, and hyperparathyroidism in elderly people. Due to this, there has been a shift in the treatment strategies for osteoporosis.
Osteoimmunology is an emerging field that deals with the interaction between bone and the immune system. You must know that the cells responsible for bone reabsorption, i.e., osteoclasts are regarded as the prototype for an osteoimmune cell. Studies have shown that there is crosstalk between osteoclasts and the immune cells. Also, a subclass of T-cells called regulatory T cells acts as the interface between the immune system and the skeletal system.
On a final note, to come up with better treatments for this bone disease, more research is required to better understand the pathophysiology of osteoporosis.