Helicobacter pylori infection causes chronic gastritis and systemic inflammation.

Helicobacter pylori (H. pylori) is a globally recognized infectious pathogen that acts as the primary driver of chronic gastric inflammation and a significant contributor to low-grade systemic inflammation.

Clinical evidence for chronic gastritis

H. pylori infection is the definitive cause of chronic active gastritis in nearly all infected individuals. The medical community has formally reclassified H. pylori-associated gastritis as an infectious disease, moving beyond its previous categorization as a precursor to functional dyspepsia.

• Disease Progression: Histological evidence, often staged using the OLGA (Operative Link for Gastritis Assessment) system, shows a predictable progression from superficial mucosal inflammation to chronic atrophic gastritis and intestinal metaplasia.
• Risk Metrics: Individuals with persistent H. pylori infection have a 2.4-fold higher risk of developing chronic atrophic gastritis compared to uninfected controls.
• Eradication Impact: Clinical trials consistently show that successful eradication of the bacteria via antibiotic therapy resolves mucosal inflammation and can halt or even partially reverse atrophic changes.

Systemic inflammation and inflammatory markers

Beyond the stomach, H. pylori triggers a systemic immune response characterized by elevated inflammatory markers, most notably C-reactive protein (CRP).

• Inflammatory Indicators: Infected individuals typically exhibit higher baseline levels of CRP and high-sensitivity CRP (hs-CRP) compared to those who are uninfected.
• Reduction Post-Treatment: Meta-analyses of clinical studies demonstrate a significant reduction in hs-CRP levels following successful eradication therapy, confirming the causal relationship between the infection and systemic inflammatory status.

Mechanistic explanations

The transition from a localized gastric infection to systemic inflammation occurs through specific molecular pathways:

• Cytokine Cascade: The infection stimulates the activation of the NLRP3 inflammasome in gastric macrophages, leading to the localized production of pro-inflammatory cytokines such as Tumor Necrosis Factor-alpha (TNF-α) and Interleukin-1β (IL-1β).
• Hepatic Response: These cytokines, particularly Interleukin-6 (IL-6), enter the systemic circulation and act on hepatocytes (liver cells), stimulating the synthesis and secretion of CRP.
• Virulence Factors: Bacterial proteins like CagA and VacA contribute to this process by damaging the gastric epithelium and directly modulating the host immune response to favor persistent inflammation.

Bottom line

H. pylori infection is a primary cause of chronic gastritis and induces a measurable state of systemic inflammation characterized by elevated CRP. Eradication of the bacteria is the established clinical standard for resolving both gastric and systemic inflammatory markers.