Helicobacter pylori infection in children: an overview of diagnostic methods.

Children differ from adults regarding Helicobacter pylori (H. pylori) infection in many terms. H. pylori infection represents a key factor in the pathogenesis of duodenal ulcer and chronic gastritis in children. H. pylori infection causes some extraintestinal diseases as well as gastrointestinal diseases. Although, among these illnesses in children, symptoms like recurrent abdominal pain are not specific. Moreover, the role of the pathogen in the growth faltering, iron deficiency anemia, and asthma still remains controversial. A reliable method to detect H. pylori infection is a crucial issue, sand is still a matter of active debate. The tests applied for H. pylori diagnosis are grouped as either invasive or non-invasive methods. Invasive methods consist of endoscopic evaluation, the rapid urease test (RUT), histology, and bacterial culture. Non-invasive tests include the urea breath test (UBT), stool antigen test (SAT), serology, and molecular diagnostic approaches. Use of endoscopy is a pre-requisite for all invasive methods and poses difficulties in children as it is a difficult procedure and requires patient's cooperation. For this reason, the non-invasive tests have been commonly used in children, although their accuracy is not very reliable in some cases. Invasive tests may be opted to confirm the diagnosis as and when needed. This review presents the diagnostic tests used to detect H. pylori infection in children.

Diagnostic methods for Helicobacter pylori infection: ideals, options, and limitations.

Helicobacter pylori (H. pylori) resides in the stomach, colonizes gastric epithelium, and causes several digestive system diseases. Several diagnostic methods utilizing invasive or non-invasive techniques with varying levels of sensitivity and specificity are developed to detect H. pylori infection. Selection of one or more diagnostic tests will depend on the clinical conditions, the experience of the clinician, cost, sensitivity, and specificity. Invasive methods require endoscopy with biopsies of gastric tissues for the histology, culture, and rapid urease test. Among non-invasive tests, urea breath test and fecal antigen tests are a quick diagnostic procedure with comparable accuracy to biopsy-based techniques and are methods of choice in the test and treatment setting. Other techniques such as serological methods to detect immunoglobulin G antibodies to H. pylori can show high accuracy as other non-invasive and invasive biopsies, but do not differentiate between current or past H. pylori infections. Polymerase chain reaction (PCR) is an emerging option that can be categorized as invasive and non-invasive tests. PCR method is beneficial to detect H. pylori from gastric biopsies without the need for the cultures. There is no other chronic gastrointestinal infection such as H. pylori with a set of comparable diagnostic methodologies. Despite the availability of multiple diagnostic methods, it remains unclear on the choice of any one method as the gold standard for detecting H. pylori infection, especially in epidemiological studies. In this work, we review the principal diagnostic methods used to detect H. pylori infection and their advantages and disadvantages, and applications in clinical practice.

Helicobacter pylori evasion strategies of the host innate and adaptive immune responses to survive and develop gastrointestinal diseases.

Helicobacter pylori (H. pylori) is a bacterial pathogen that resides in more than half of the human population and has co-evolved with humans for more than 58,000 years. This bacterium is orally transmitted during childhood and is a key cause of chronic gastritis, peptic ulcers and two malignant cancers including MALT (mucosa-associated lymphoid tissue) lymphoma and adenocarcinoma. Despite the strong innate and adaptive immune responses, H. pylori has a long-term survival in the gastric mucosa. In addition to the virulence factors, survival of H. pylori is strongly influenced by the ability of bacteria to escape, disrupt and manipulate the host immune system. This bacterium can escape from recognition by innate immune receptors via altering its surface molecules. Moreover, H. pylori subverts adaptive immune response by modulation of effector T cell. In this review, we discuss the immune-pathogenicity of H. pylori by focusing on its ability to manipulate the innate and acquired immune responses to increase its survival in the gastric mucosa, leading up to gastrointestinal disorders. We also highlight the mechanisms that resulted to the persistence of H. pylori in gastric mucosa.

Checkpoint immunotherapy by nivolumab for treatment of metastatic melanoma.

Clinical management of metastatic melanoma suffered historically from a lack of effective targeted and immunotherapies due to short-lived clinical responses. Recent advances in our understanding of tumor-immune signaling pathways, discovery of immunosuppressive checkpoints, and subsequent development of antibodies that target these checkpoints reverses the situation to some extent. Two antibodies ipilimumab and nivolumab gained Food and Drug administration approval for the treatment of metastatic melanoma and target two major immunosuppressive checkpoints cytotoxic T lymphocyte antigen and programmed cell death protein 1 (PD-1), respectively. Nivolumab binds to PD-1, prevents PD-1 interaction with ligand Programmed death ligand 1 (PD-L1), and thus releases the T-cell exhaustion events (such as T cell apoptosis, decrease in T cell proliferation, etc.) leading to buildup of potent tumor-specific immune response. Successful Phase I-III results with remarkable antitumor activity and safety led to approval of nivolumab against ipilimumab refractory metastatic melanoma. Nivolumab therapy is exciting in that it not only provides substantial benefit but also provides durable responses. This review focuses on the evolution of immunotherapy leading to nivolumab approval and its potential in treating melanoma either alone or in combination with other therapies.