Christine Winterbourn

Neutrophil Function and Myeloperoxidase Activity

Winterbourn’s study “Inside the Neutrophil Phagosome: Oxidants, Myeloperoxidase, and Bacterial Killing” (1998) investigated the biochemical environment within neutrophil phagosomes and how oxidants can contribute to microbial killing. Neutrophils, white blood cells, neutralise invading bacteria and microorganisms through ingestion into intracellular compartments called phagosomes – a highly oxidative environment, where reactive oxygen species (ROS) are formed through the NADPH oxidase system. The NADPH oxidase enzyme system produces superoxide radicals (O₂^-) and hydrogen peroxide (H₂O₂) from molecular oxygen. Myeloperoxidase (MPO), an enzyme in neutrophil granules, converts H₂O₂ and chloride ions into hypochlorous acid (HOCl; the same chemical as found in common household bleach) –an antimicrobial agent that chlorinates and oxidises bacterial components, leading to cell damage. Winterbourn’s study confirmed that neutrophils generate high levels of ROS, particularly O2- and H2O2 through the NADPH oxidase system. She also found that HOCl is key to bacterial destruction. Winterbourn’s work reinforced the role of MPO and oxidative mechanisms in neutrophil-mediated bacterial killing while providing insight into how pathogens can resist these, allowing further research and understanding into immune deficiencies and therapeutic strategies targeting oxidative pathways in the human system. 

Oxidative Reactions of Haemoglobin  

Winterbourn's 1990 study on “Oxidative Reactions of Haemoglobin” investigated how haemoglobin interacts with ROS and the resulting oxidative damage. Haemoglobin, a protein found in red blood cells that binds to oxygen, allows for oxygen transportation throughout the body. Due to this, haemoglobin can readily undergo oxidation and reduction, acting as a source of free radicals. When haemoglobin autoxidises, it converts oxyhaemoglobin (Fe²⁺-O₂) to methemoglobin (Fe³⁺), releasing superoxide. Superoxide can then become H₂O₂, which reacts with haemoglobin to form ferryl haemoglobin (Fe⁴⁺=O). H₂O₂ can also react with other radicals and oxidant species, resulting in the denaturation of haemoglobin.  Winterbourn’s work showed that haemoglobin acts not only as an oxygen transporter but also as a pro-oxidant molecule that is prone to generate and react with ROS, leading to oxidative damage in red blood cells, and contributing to anaemia and various pathological conditions.

Professor Winterbourn’s work has established her in a leading position in her field, reflected through prestigious awards both in New Zealand and worldwide. She was elected a Fellow of the Royal Society Te Apārangi in 1988 and appointed an Officer of the New Zealand Order of Merit in 1997, which was elevated to Companion in 2012. In 2007, Winterbourn received the University of Otago Distinguished Research Medal, the highest research honour from the University of Otago, followed by the Marsden Medal in 2010 by the New Zealand Association of Scientists (NZAS) for her achievements in radicals, oxidative stress, and haemoglobin. In 2011, she became the first woman to be awarded the Royal Society Te Aparangi’s Rutherford Medal. In 2024, at the Society for Redox Biology and Medicine’s (SfRBM) 31st annual conference, she won the prestigious Lifetime Achievement Award, making her the first researcher in Australasia and third outside of North and South America to win this award.

With over 53,000 citations and 250 scientific papers, Professor Christine Winterbourn is one of New Zealand’s most influential researchers, leading the world in understanding reactive oxidation, the biochemistry of biological damage, and the consequences of disease pathology.