The metabolic-immune interface of obesity in Covid-19: a role for angiotensin ii and inflammatory cytokines

Figures

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  Figure 1. Representative diagram of how obesity and SARS-CoV-2 infection interact. Imbalance of the Renin–Angiotensin–Aldosterone System (RAAS), increased angiotensin II, release of pro-inflammatory cytokines, and reduced IL-10, resulting in worse clinical prognosis and mortality exclusively in obese patients. Image created with BioRender, 2025.

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  Figure 2. Interleukin 1β concentration. (A) IL-1β stratified by BMI, between controls and mild cases with flu-like illness; (B) IL-1β stratified by BMI, between controls and severe cases with severe acute respiratory syndrome; (C) IL-1β comparison between flu-like illness and severe acute respiratory syndrome. Source: Author (2025). (A–C) were calculated using the Two-Way ANOVA test with Tukey’s post-hoc test. * Indicates significant differences in intergroup comparisons (positives versus negatives) to assess the effect of viral infection. LN- with LN+, OB- with OB+. # Denotes significant intragroup difference (positives only) to assess the effect of BMI, LN+ with OB+ p < 0.05. LN-, negative lean (control); OB-, negative obese (control). LN+, lean positive COVID-19; OB+, obese positive COVID-19. SG, Flu-Like Syndrome (mild/moderate manifestations); SARS, Severe Acute Respiratory Syndrome (severe manifestations).

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  Figure 3. Interleukin-6 concentration. (A) IL-6 stratified by BMI, between controls and mild cases with flu-like illness; (B) IL-6 stratified by BMI, between controls and severe cases with severe acute respiratory syndrome; (C) IL-6 comparison between flu-like illness and severe acute respiratory syndrome. Source: Author (2025). (A–C) were calculated using the Two-Way ANOVA test with Tukey’s post-hoc test. * Indicates significant differences in intergroup comparisons (positives versus negatives) to assess the effect of viral infection. LN- with LN+, OB- with OB+. # Denotes significant intragroup difference (positives only) to assess the effect of BMI, LN+ with OB+ p < 0.05. LN-, negative lean (control); OB-, negative obese (control). LN+, lean positive COVID-19; OB+, obese positive COVID-19. SG, Flu-Like Syndrome (mild/moderate manifestations); SARS, Severe Acute Respiratory Syndrome (severe manifestations).

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  Figure 4. Tumor necrosis factor (TNF) concentration. (A) TNF stratified by BMI, between controls and mild cases with flu-like illness; (B) TNF stratified by BMI, between controls and severe cases with severe acute respiratory syndrome; (C) TNF comparison between flu-like illness and severe acute respiratory syndrome. Source: Author (2025). (A–C) were calculated using the Two-Way ANOVA test with Tukey’s post-hoc test. * Indicates significant differences in intergroup comparisons (positives versus negatives) to assess the effect of viral infection. LN- with LN+, OB- with OB+. # Denotes significant intragroup difference (positives only) to assess the effect of BMI, LN+ with OB+ p < 0.05. LN-, negative lean (control); OB-, negative obese (control). LN+, lean positive COVID-19; OB+, obese positive COVID-19. SG, Flu-Like Syndrome (mild/moderate manifestations); SARS, Severe Acute Respiratory Syndrome (severe manifestations).

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  Figure 5. Interleukin - 10 concentration. (A) IL-10 stratified by BMI, between controls and mild cases with flu-like illness; (B) IL-10 stratified by BMI, between controls and severe cases with severe acute respiratory syndrome; (C) IL-10 comparison between flu-like illness and severe acute respiratory syndrome. Source: Author (2025). (A–C) were calculated using the Two-Way ANOVA test with Tukey’s post-hoc test. * Indicates significant differences in intergroup comparisons (positives versus negatives) to assess the effect of viral infection. LN- with LN+, OB- with OB+. # Denotes significant intragroup difference (positives only) to assess the effect of BMI, LN+ with OB+ p < 0.05. LN-, negative lean (control); OB-, negative obese (control). LN+, lean positive COVID-19; OB+, obese positive COVID-19. SG, Flu-Like Syndrome (mild/moderate manifestations); SARS, Severe Acute Respiratory Syndrome (severe manifestations).

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  Figure 6. Plasma angiotensin II levels. (A) Lean and stratified by BMI, between controls and mild cases with flu-like illness; (B) Lean and obese individuals with SARS, stratified by BMI, between controls and severe cases with severe acute respiratory syndrome; (C) Comparison of Angiotensin II levels between obese individuals (control and COVID-19), in both severity levels. (D) Correlation between BMI and Angiotensin II concentration. Source: Author (2025). (A–C) were calculated using two-way ANOVA with Tukey’s post-hoc test. (D) was calculated using Pearson’s correlation. * Indicates significant differences in intergroup comparisons (positive versus negative) to assess the effect of viral infection. LN- with LN+, OB- with OB+. # Denotes significant intragroup difference (positives only) to assess the effect of BMI, LN+ with OB+ p < 0.05. LN-, lean negative (control); OB-, obese negative (control). LN+, lean positive for COVID-19; OB+, obese positive for COVID-19. SG, Influenza-like syndrome (mild/moderate manifestations); SARS, Severe acute respiratory syndrome (severe manifestations).