Researchers develop neutrophil 'nanosponges' to treat rheumatoid arthritis

Washington: Researchers have developed neutrophil "nanosponges" that can safely absorb and neutralise a variety of proteins that play a role in the progression of rheumatoid arthritis.

Nanosponges are nano-sized particles designed to look like red blood cells and protect the body.

Injections of these nanosponges are known to be effective while treating severe rheumatoid arthritis. Administering the nanosponges early on, also prevented the disease from developing.

"Nanosponges are a new paradigm of treatment to block pathological molecules from triggering disease in the body. Rather than creating treatments to block a few specific types of pathological molecules, we are developing a platform that can block a broad spectrum of them, and this way we can treat and prevent disease more effectively and efficiently," said senior author Liangfang Zhang.

The new nanosponges are nanoparticles of biodegradable polymer coated with the cell membranes of neutrophils, a type of white blood cell.

Neutrophils are among the immune system's first responders against invading pathogens. They are also known to play a role in the development of rheumatoid arthritis, a chronic autoimmune disease that causes painful inflammation in the joints and can ultimately lead to damage of cartilage and bone tissue.

When rheumatoid arthritis develops, cells in the joints produce inflammatory proteins called cytokines. The release of cytokines signals neutrophils to enter the joints. Once there, cytokines bind to receptors on the neutrophil surfaces, activating them to release more cytokines, which in turn draws more neutrophils to the joints and so on.

The nanosponges essentially nip this inflammatory cascade in the bud. By acting as tiny neutrophil decoys, they intercept cytokines and stop them from signaling even more neutrophils to the joints, reducing inflammation and joint damage.

These nanosponges offer a promising alternative to current treatments for rheumatoid arthritis. Some monoclonal antibody drugs, for example, have helped patients manage symptoms of the disease, but they work by neutralizing only specific types of cytokines. This is not sufficient to treat the disease, said Zhang, as there are many different types of cytokines and pathological molecules involved.

"Neutralising just one or two types might not be as effective. So our approach is to take neutrophil cell membranes, which naturally have receptors to bind all these different types of cytokines, and use them to manage an entire population of inflammatory molecules," explained Zhang.

To make the neutrophil nanosponges, the researchers first developed a method to separate neutrophils from whole blood. They then processed the cells in a solution that causes them to swell and burst, leaving the membranes behind. The membranes were then broken up into much smaller pieces. Mixing them with ball-shaped nanoparticles made of biodegradable polymer fused the neutrophil cell membranes onto the nanoparticle surfaces.

The nanosponges also worked as a preventive treatment when administered prior to inducing the disease.

The findings appeared in the Journal of Nature Nanotechnology.