About inflammation and infection

Dear Editor,The review recently published by Autio et al. entitled ‘Nuclear imaging of inflammation: homing-associated molecules as targets’ [1] contains some statement that may be misleading and requires some clarification.In particular, I think it is important to correctly define the terms ‘inflammation’ and ‘infection.’ Just by reading the definition of inflammation in the Wikipedia, we learn that ‘inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The classical signs of acute inflammation are pain (dolor), heat (calor), redness (rubor), swelling (tumor), and loss of function (functio laesa). Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process. Inflammation is not a synonym for infection, even in cases where inflammation is caused by infection. Although infection is caused by a microorganism, inflammation is one of the responses of the organism to the pathogen. However, inflammation is a stereotyped response, and therefore it is considered as a mechanism of innate immunity, as compared to adaptive immunity, which is specific for each pathogen’ [2].Similarly, we can find a definition for infection as ‘the invasion of a host organism's bodily tissues by disease-causing organisms, their multiplication, and the reaction of host tissues to these organisms and the toxins they produce. Infections are caused by microorganisms such as viruses, prions, bacteria, and viroids, and larger organisms like parasites and fungi. Hosts can fight infections using their immune system. Mammalian hosts react to infections with an innate response, often involving inflammation, followed by an adaptive response’. Therefore, we usually always have an inflammation associated with an infection, but not always we have an infection if there is an inflammation [3].This is not just an exercise of semantics, but it is very relevant, part