Malondialdehyde (MDA) is a compound that is derived from the peroxidation of polyunsaturated fatty acids. It has been used as a biomarker to measure oxidative stress in various biological samples in patients who are affected by a wide range of diseases. The aim of our work is to provide an updated overview of the role of MDA as a marker of oxidative stress in allergy-related diseases. We considered studies involving both paediatric and adult patients affected by rhinitis, asthma, urticaria and atopic dermatitis. The measurement of MDA was performed on different types of samples. The reported data highlight the role of serum MDA in inflammatory airway diseases. According to the literature review, the oxidative stress status in asthmatic patients, assessed via MDA determination, appears to worsen in the presence of other allergic airway diseases and in relation to the disease severity. This suggests that MDA can be a suitable marker for monitoring the disease status. However, there are several limitations in the considered studies due to the different samples used and the lack of phenotyping and description of the clinical period of patients examined. In cutaneous allergic diseases, the role of MDA is controversial because of the smallness of the studies and the heterogeneity of the samples and patients.

Longevity and aging are two sides of the same coin, as they both derive from the interaction between genetic and environmental factors. Aging is a complex, dynamic biological process characterized by continuous remodeling. One of the most recent theories on aging focuses on immune response, and takes into consideration the activation of subclinical, chronic low-grade inflammation which occurs with aging, named “inflammaging”. Long-lived people, especially centenarians, seem to cope with chronic subclinical inflammation through an anti-inflammatory response, called therefore “anti-inflammaging”. In the present review, we have focused our attention on the contrast between inflammaging and anti-inflammaging systems, by evaluating the role of cytokines and their impact on extreme longevity. Cytokines are the expression of a network involving genes, polymorphisms and environment, and are involved both in inflammation and anti-inflammation. We have described the role of IL-1, IL-2, IL-6, IL-12, IL-15, IL-18, IL-22, IL-23, TNF-α, IFN-γ as pro-inflammatory cytokines, of IL-1Ra, IL-4, IL-10, TGF-β1 as anti-inflammatory cytokines, and of lipoxin A4 and heat shock proteins as mediators of cytokines. We believe that if inflammaging is a key to understand aging, anti-inflammaging may be one of the secrets of longevity.

The immunosenescence is a relatively recent chapter, correlated with the linear extension of the average life began in the nineteenth century and still in progress. The most important feature of immunosenescence is the accumulation in the “immunological space” of memory and effector cells as a result of the stimulation caused by repeated clinical and subclinical infections and by continuous exposure to antigens (inhalant allergens, food, etc.). This state of chronic inflammation that characterizes senescence has a significant impact on survival and fragility. In fact, the condition of frail elderly occurs less frequently in situations characterized by poor contact with viral infections and parasitic diseases. Furthermore the immunosenescence is characterized by a particular “remodelling” of the immune system, induced by oxidative stress. Apoptosis plays a central role in old age, a period in which the ability of apoptosis can change. The remodelling of apoptosis, together with the Inflammaging and the up-regulation of the immune response with the consequent secretion of pro-inflammatory lymphokines represents the major determinant of the rate of aging and longevity, as well as of the most common diseases related with age and with tumors. Other changes occur in the innate immunity, the first line of defence providing rapid, but unspecific and incomplete protection, consisting mostly of monocytes, natural killer cells and dendritic cells, acting up to the establishment of a adaptive immune response, which is slower, but highly specific, which cellular substrate consists of T and B lymphocytes. The markers of “Inflammaging” in adaptive immunity in centenarians are characterized by a decrease in T cells “naive.” The reduction of CD8 virgins may be related to the risk of morbidity and death, as well as the combination of the increase of CD8+ cells and reduction of CD4+ T cells and the reduction of CD19+ B cells. The immune function of the elderly is weakened to due to the exhaustion of T cell-virgin (CD95−), which are replaced with the clonal expansion of CD28-T cells. The increase of pro-inflammatory cytokines is associated with dementia, Parkinson’s disease, atherosclerosis, diabetes type 2, sarcopenia and a high risk of morbidity and mortality. A correct modulation of immune responses and apoptotic phenomena can be useful to reduce age-related degenerative diseases, as well as inflammatory and neoplastic diseases.

Atopic dermatitis is a common chronic/chronically relapsing inflammatory skin disease, with increasing worldwide prevalence. Etiopathogenesis is complex and multifactorial, with a mix of genetic, immunological and environmental aspects. Like in other chronic inflammatory diseases, oxidative stress plays an important pathogenetic role. We reviewed in vivo research studies on humans about oxidative stress and atopic dermatitis. Although sometimes contrasting, overall, they suggest that oxidative stress may have a significant role in atopic dermatitis, but our understanding is still incomplete, at least concerning in vivo data, because of limitations of available literature. Research consists of 33 papers published in 28 years, was not always performed on large study populations, represents a limited number of countries and ethnicities—not always in proportion to their size—and is scattered over multiple papers that, in the majority of cases, cannot be pooled and/or compared because many biomarkers were studied, in different tissues and with different methods. Further, larger studies appear warranted and necessary to shed more light on this aspect of atopic dermatitis, which is important not only to improve our understanding of this disease, but also for potential clinical and therapeutic implications.