Helicobacter hepaticus

Taxonomy#

Helicobacter hepaticus—type strain ATCC 51449; first isolated from livers of mice with chronic hepatitis (Fox et al. , 1994). Family Helicobacteraceae, order Campylobacterales, class Epsilonproteobacteria.

Closely related to Helicobacter pylori, but lacks Urease—a striking divergence given urease's central role in H. pylori gastric colonization.

Metal Dependencies#

Nickel. H. hepaticus possesses a functional [NiFe] hydrogenase that oxidizes molecular H2 to generate energy.^{[1]Role of Nickel in Microbial PathogenesisRobert J. Maier, Stéphane L. Benoit · 2019Open reference 1 ↓} Unlike H. pylori, which uses hydrogenase primarily for colonization density in the stomach, H. hepaticus hydrogenase supports amino acid uptake and cell growth in the hepatobiliary environment.

Hydrogenase activity is critical for full virulence: mutants lacking hydrogenase show reduced colonization and attenuated liver lesions in mice. The nickel requirement creates a potential Achilles' heel—restricting nickel availability could limit hydrogenase activity and reduce pathogenic capacity.

Iron. Like other Helicobacter species, H. hepaticus requires iron for electron transport chain components and Oxidative Stress defense.

The hepatobiliary niche is relatively iron-rich compared to the gastric environment, which may partly explain why H. hepaticus does not require urease (no need to buffer acid for survival) but does rely heavily on iron-dependent metabolism.

Key Enzymes and Virulence Factors#

[NiFe] Hydrogenase: The central metabolic engine. Provides energy from molecular H2 to support amino acid uptake, enabling colonization of the nutrient-limited hepatobiliary niche.^{[1]Role of Nickel in Microbial PathogenesisRobert J. Maier, Stéphane L. Benoit · 2019Open reference 1 ↓}

Cytolethal distending toxin (CDT): A genotoxin that induces DNA double-strand breaks in host cells. CDT is the primary virulence factor driving hepatocellular carcinoma in chronically infected mice.

Absence of urease: A key distinction from H. pylori. H. hepaticus does not colonize the acidic stomach and does not require urease-mediated acid neutralization.

Conditions Associated#

Hepatitis and hepatocellular carcinoma (murine)—the defining disease association; chronic infection drives the Metal-Driven Inflammation-cancer cascade via CDT-mediated genotoxicity.

Inflammatory bowel disease (murine model)—H. hepaticus-induced colitis in IL-10 knockout mice is one of the most widely used IBD models in research.

Colorectal cancer (murine model)—accelerates tumorigenesis in chemically initiated models.

Interkingdom Relationships#

H. hepaticus relies on H2 produced by fermentative bacteria in the gut—a form of syntrophic cross-feeding where the metabolic waste of anaerobic fermenters becomes the energy source for hydrogenase-equipped pathogens.

This positions H. hepaticus within the same ecological framework as Helicobacter pylori: both exploit the H2 economy of the Gut Microbiome, but in different anatomical niches.

Key Studies#

^{[1]Role of Nickel in Microbial PathogenesisRobert J. Maier, Stéphane L. Benoit · 2019Open reference 1 ↓} (review)—Established the nickel-hydrogenase-virulence link across Helicobacter species, including H. hepaticus's dependence on hydrogenase for amino acid uptake and cell growth.

^{[2]Chen 2021 — Effect of Long-Term and Short-Term Imbalanced Zn Manipulation on Gut Microbiota and Screening for Microbial Markers Sensitive to Zinc StatusLingjun Chen, Zhonghang Wang, Peng Wang et al. · 2021Open reference 2 ↓} (animal model)—Showed zinc-diet-dependent enrichment of H. hepaticus in the murine gut.