Extragastric Diseases and Helicobacter pylori

The Infectious Etiology of Alzheimer's Disease

BACKGROUND

Inflammation is a part of the first line of defense of the body against invasive pathogens, and plays a crucial role in tissue regeneration and repair. A proper inflammatory response ensures the suitable resolution of inflammation and elimination of harmful stimuli, but when the inflammatory reactions are inappropriate it can lead to damage of the surrounding normal cells. The relationship between infections and Alzheimer's Disease (AD) etiology, especially lateonset AD (LOAD) has been continuously debated over the past three decades.

METHODS

This review discusses whether infections could be a causative factor that promotes the progression of AD and summarizes recent investigations associating infectious agents and chronic inflammation with AD. Preventive and therapeutic approaches to AD in the context of an infectious etiology of the disease are also discussed.

RESULTS

Emerging evidence supports the hypothesis of the role of neurotropic viruses from the Herpesviridae family, especially Human herpesvirus 1 (HHV-1), Cytomegalovirus (CMV), and Human herpesvirus 2 (HHV-2), in AD neuropathology. Recent investigations also indicate the association between Hepatitis C virus (HCV) infection and dementia. Among bacteria special attention is focused on spirochetes family and on periodontal pathogens such as Porphyromonas gingivalis or Treponema denticola that could cause chronic periodontitis and possibly contribute to the clinical onset of AD.

CONCLUSION

Chronic viral, bacterial and fungal infections might be causative factors for the inflammatory pathway in AD.

Role of Helicobacter pylori Infection in Body Height of Adult Dyspeptic Patients

INTRODUCTION

The prevalence of H. pylori infection is high in underdeveloped countries and is associated with growth retardation. In the first half of the 20th century, Sardinia was an underdeveloped region; however, more recent development resulted in a decline in H. pylori infection. Because body height is correlated with health and nutritional status in childhood, the association among H. pylori infection and height was explored.

MATERIALS AND METHODS

A retrospective observational study was conducted involving patients undergoing endoscopy for dyspepsia from 2002 to 2012. H. pylori status was assessed by histology plus the rapid urease test or 13Carbon-urea breath test.

RESULTS

Body height and H. pylori status were assessed in 5045 adult patients: 3257 (64.6%) were women. Patients born after 1950 showed a significant increase in height (average 3.22 cm) compared to patients born before 1950 (163.93 vs 160 cm; 95% confidence interval, CI = 2.74-3.70 cm) (p < .0001). H. pylori-infected patients were nearly 1 cm shorter than uninfected patients (95% CI = -1.35 to·-0.09 cm) (p = .012). The multivariate linear regression analysis showed male gender, birth cohort, and occupational categories to be strongly associated with height, while the weak effect of H. pylori infection disappeared.

CONCLUSIONS

Our results demonstrate a strong secular trend related to body height in Sardinia with a minimal influence of H. pylori infection.

Structural Basis of the Heterodimer Formation between Cell Shape-Determining Proteins Csd1 and Csd2 from Helicobacter pylori

Colonization of the human gastric mucosa by Helicobacter pylori requires its high motility, which depends on the helical cell shape. In H. pylori, several genes (csd1, csd2, csd3/hdpA, ccmA, csd4, csd5, and csd6) play key roles in determining the cell shape by alteration of cross-linking or by trimming of peptidoglycan stem peptides. H. pylori Csd1, Csd2, and Csd3/HdpA are M23B metallopeptidase family members and may act as d,d-endopeptidases to cleave the d-Ala4-mDAP3 peptide bond of cross-linked dimer muropeptides. Csd3 functions also as the d,d-carboxypeptidase to cleave the d-Ala4-d-Ala5 bond of the muramyl pentapeptide. To provide a basis for understanding molecular functions of Csd1 and Csd2, we have carried out their structural characterizations. We have discovered that (i) Csd2 exists in monomer-dimer equilibrium and (ii) Csd1 and Csd2 form a heterodimer. We have determined crystal structures of the Csd2121-308 homodimer and the heterodimer between Csd1125-312 and Csd2121-308. Overall structures of Csd1125-312 and Csd2121-308 monomers are similar to each other, consisting of a helical domain and a LytM domain. The helical domains of both Csd1 and Csd2 play a key role in the formation of homodimers or heterodimers. The Csd1 LytM domain contains a catalytic site with a Zn2+ ion, which is coordinated by three conserved ligands and two water molecules, whereas the Csd2 LytM domain has incomplete metal ligands and no metal ion is bound. Structural knowledge of these proteins sheds light on the events that regulate the cell wall in H. pylori.

The Associations Between Helicobacter pylori Infection, Serum Vitamin D, and Metabolic Syndrome: A Community-Based Study

The associations between Helicobacter pylori infection, serum vitamin D level, and metabolic syndrome (MS) are controversial. The present community-based study aimed to investigate the effect of H pylori infection and serum vitamin D deficiency on MS development.Individuals from the northeastern region of Taiwan were enrolled in a community-based study from March, 2014 to August, 2015. All participants completed a demographic survey and underwent the urea breath test (UBT) to detect H pylori infection as well as blood tests to determine levels of vitamin D, adiponectin, leptin, and high-sensitivity C-reactive protein. The ATP III criteria for MS were used in this study.A total of 792 men and 1321 women were enrolled. The mean age was 56.4 ± 13.0 years. After adjusting for age and sex, the estimated odds of MS development for a UBT-positive subject were 1.503 (95% confidence interval [CI]: 1.206-1.872, P < 0.001) when compared to a UBT-negative subject. For participants with vitamin D deficiency (<20 ng/mL), the odds of MS development were 1.423 (95% CI: 1.029-1.967, P = 0.033) when compared to those with sufficient vitamin D level (>30 ng/mL). For participants with both H pylori infection and vitamin D deficiency, the odds of MS development were 2.140 (95% CI: 1.348-3.398, P = 0.001) when compared to subjects without H pylori infection and with sufficient vitamin D levels.H pylori infection and vitamin D deficiency could be predictors of MS. For individuals with both H pylori infection and vitamin D deficiency, the odds of MS development were 2.140 when compared to individuals without H pylori infection and with sufficient vitamin D levels.

A Systematic Review and Meta-Analysis of the Association between Helicobacterpylori Infection and Dementia

BACKGROUND

A positive association between Helicobacter pylori infection and dementia has been reported, yet findings are inconsistent.

OBJECTIVE

To examine the association between H. pylori infection and dementia.

METHODS

A literature search was performed using the databases OVID-Medline, Institute of Scientific Information Web of Science, and EMBASE. The meta-analysis was conducted using the random effects model. The primary analysis included studies in which the exposure variable was presence of H. pylori infection (yes versus no) and the outcome was incident dementia (yes versus no), which was pre-selected as the end-result of gradual cognitive decline overtime. Publication bias was explored using funnel plot and the Egger regression intercept.

RESULTS

A total of 260 records were identified; 13 addressed cognition and/or dementia in relation to H. pylori infection, of which only seven were included in the meta-analysis. The primary analysis showed a significant positive association between H. pylori infection and dementia; pooled odds ratio 1.71 (95% CI 1.17-2.49) (pv = 0.01). No significant evidence of publication bias was found.

CONCLUSIONS

H. pylori may play a role in the etiology of dementia. Identification of the biological mechanisms of such association is needed, as well as assessment of the impact of H. pylori therapy on the risk and progression of dementia.

Correlation between coronary atherosclerotic heart disease and Helicobacter pylori infection

AIM: To investigate the relationship between Helicobacter pylori (H. pylori) infection and coronary atherosclerotic heart disease (CAHD).

METHODS: A total of 1030 patients with CAHD and 1116 patients with non-coronary atherosclerotic heart disease underwent ¹⁴C-urea breath test. H. pylori positive rate were compared between the two groups. The CAHD group was further divided into two groups according to the test results for H. pylori: an H. pylori positive group and an H. pylori negative group. According to SYNTAX score, CAHD patients were divided into a low risk group, a moderate risk group, and a high risk group, and the difference in H. pylori positive rates was analyzed.

RESULTS: The positive rate of H. pylori in patients with CAHD was higher than that of the control group. Serum homocysteine level in H. pylori positive CAHD patients was significantly higher than that in the negative group (P < 0.01). The positive rate of H. pylori in the high risk group was the highest, followed by moderate and low risk groups, but the difference was not statistically significant (P > 0.05). Serum homocysteine level increased with the increasing of the CAHD risk degree in H. pylori positive CAHD patients (P < 0.01).

CONCLUSION: H. pylori infection is an important risk factor for CAHD. H. pylori infection may increase the degree of CAHD by elevating serum homocysteine levels, thereby promoting the development of coronary atherosclerosis.

Association between Helicobacter pylori infection and carotid atherosclerosis in patients with vascular dementia

BACKGROUND AND PURPOSE

Accumulating evidence indicates that various infections contribute to the pathogenesis of atherosclerosis. Helicobacter pylori (Hp) has been implicated as a risk factor of atherosclerosis for stroke and other cardiovascular disease, but limited data exist regarding vascular dementia (VD). This study aimed to investigate the relationship between Hp infection and carotid atherosclerosis in patients with VD.

METHODS

A total of 354 patients who were diagnosed with VD were enrolled. Patients were divided into Hp positive VD group (n=208) and Hp negative VD group (n=156) using the (13)C-urea breath test ((13)C-UBT). Serum YKL-40, a marker for inflammation, were analyzed by ELISA. Traditional atherosclerotic risk factors including age, gender, body mass index (BMI), total cholesterol (TC), low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), triglycerides (TG), systolic blood pressure (SBP), diastolic blood pressure (DBP) and fasting blood glucose (FBG) were collected or detected. Carotid intima-media thickness (CIMT) was determined by color Doppler ultrasound.

RESULTS

CIMT values and serum YKL-40 significantly increased in Hp positive VD group in comparison with Hp negative VD group (p<0.05). In Hp positive VD group, serum YKL-40 was positively correlated with CIMT (r=0.412, p<0.05), and the association was independent of traditional atherosclerotic risk factors (β=0.381, p<0.001).

CONCLUSIONS

CIMT and serum YKL-4 were significantly higher in Hp positive patients than Hp negative patients. Hp-induced inflammation may be a risk factor for atherosclerosis in patients with VD.