Exploring How Adipose Tissue, Obesity, and Gender Influence the Immune Response to Vaccines: A Comprehensive Narrative Review

Abstract

Vaccines represent an essential tool for the prevention of infectious diseases. Upon administration, a complex interaction occurs between the vaccine formulation and the recipient's immune system, ultimately resulting in protection against disease. Significant variability exists in individual and population responses to vaccination, and these differences remain the focus of the ongoing research. Notably, well-documented factors, such as age, gender, and genetic predisposition, influence immune responses. In contrast, the effects of overweight and obesity have not been as thoroughly investigated. The evidence indicates that a high body mass index (BMI) constitutes a significant risk factor for infections in general, with adipose tissue playing a crucial role in modulating the immune response. Furthermore, suboptimal levels of vaccine seroconversion have been observed among individuals with obesity. This review provides a plausible examination of the immunity and protection conferred by various vaccines in individuals with an overweight status, offering a comprehensive analysis of the mechanisms to enhance vaccination efficiency.

Keywords: adipokines; gender; immune response; inactivated vaccine; mRNA vaccines; obesity; recombinant vaccines; thyroid hormones; vaccine response.

Figure 1

The figure represents the characteristics of the different adipose cells. The white adipose cells contain the highest amount of stored lipids and are low responders to stimuli; the brown adipose cells are involved in thermogenesis to control body temperature; and the beige adipose cells also serve as lipid deposits, but control temperature upon stimulation. Beige adipose cells are found along white adipose cells in the adipose tissue. Cell comp refers to organelle cell composition. The white circles refer to lipid deposits, the blue circles refer to mitochondria, and the black circles refer to the nucleus.

Figure 2

The distinct differences between lean and obese adipose tissue. The obese tissue is characterized by the loss of a tolerogenic environment and the infiltration of immune cells. In adipose tissue, the inflammatory cytokines are more prevalent than the tolerogenic cytokines present in lean adipose tissue. The inflammatory response also involves pro-inflammatory cells as described in obese tissue as compared to the tolerogenic cells in normal adipose tissue. The scheme also presents the general impact of testosterone and estrogen depending on the site in which adipose tissue is located. Subcutaneous adipose tissue, controlled mainly by female hormones, differs from abdominal tissue in the low involvement in insulin resistance and local and peripheral inflammation. An increase in abdominal adipose tissue has been linked to cardiovascular diseases and diabetes.

Figure 3

A summary of the points analyzed in this review. The description of immune cells involved in brown and lean adipose tissue, the process that induces the formation of white adipose tissue, and the effect of exercise and bariatric surgery. On the right is the process related to inflammation, which involves significant metabolic and immune response-related changes, including autoimmunity. Subclinical inflammation has been described in overweight and obesity (metabolic syndrome) and has been involved in several diseases.