COVID-19 pandemic:Pathophysiology and manifestations from the gastrointestinal tract

The pandemic of coronavirus disease 2019(COVID-19),caused by a newly identifiedβ-coronavirus(SARS-CoV-2)has emerged as a dire health problem,causing a massive crisis for global health.Primary method of transmission was firstly thought to be animal to human transmission.However,it has been observed that the virus is transmitted from human to human via respiratory droplets.Interestingly,SARS-CoV-2 ribonucleic acid(RNA)has been isolated from patient stools,suggesting a possible gastrointestinal(GI)involvement.Most commonly reported clinical manifestations are fever,fatigue and dry cough.Interestingly,a small percentage of patients experience GI symptoms with the most common being anorexia,diarrhea,nausea and vomiting.The presence of viral RNA in stools is also common and fecal tests can be positive even after negative respiratory samples.The exact incidence of digestive symptoms is a matter of debate.The distribution of Angiotensin converting enzyme type 2 receptors in multiple organs in the body provides a possible explanation for the digestive symptoms’mechanism.Cases with solely GI symptoms have been reported in both adults and children.Viral RNA has also been detected in stool and blood samples,indicating the possibility of liver damage,which has been reported in COVID-19 patients.The presence of chronic liver disease appears to be a risk factor for severe complications and a poorer prognosis,however data from these cases is lacking.The aim of this review is firstly,to briefly update what is known about the origin and the transmission of SARS-CoV-2,but mainly to focus on the manifestations of the GI tract and their pathophysiological background,so that physicians on the one hand,not to underestimate or disregard digestive symptoms due to the small number of patients exhibiting exclusively this symptomatology and on the other,to have SARS-CoV-2 on their mind when the“gastroenteritis”type symptoms predominate.

Helicobacter pylori,gastric microbiota and gastric cancer relationship:Unrolling the tangle

Helicobacter pylori infection(Hp-I)represents a typical microbial agent intervening in the complex mechanisms of gastric homeostasis by disturbing the balance between the host gastric microbiota and mucosa-related factors,leading to inflammatory changes,dysbiosis and eventually gastric cancer.The normal gastric microbiota shows diversity,with Proteobacteria[Helicobacter pylori(H.pylori)belongs to this family],Firmicutes,Actinobacteria,Bacteroides and Fusobacteria being the most abundant phyla.Most studies indicate that H.pylori has inhibitory effects on the colonization of other bacteria,harboring a lower diversity of them in the stomach.When comparing the healthy with the diseased stomach,there is a change in the composition of the gastric microbiome with increasing abundance of H.pylori(where present)in the gastritis stage,while as the gastric carcinogenesis cascade progresses to gastric cancer,the oral and intestinal-type pathogenic microbial strains predominate.Hp-I creates a premalignant environment of atrophy and intestinal metaplasia and the subsequent alteration in gastric microbiota seems to play a crucial role in gastric tumorigenesis itself.Successful H.pylori eradication is suggested to restore gastric microbiota,at least in primary stages.It is more than clear that Hp-I,gastric microbiota and gastric cancer constitute a challenging tangle and the strong interaction between them makes it difficult to unroll.Future studies are considered of crucial importance to test the complex interaction on the modulation of the gastric microbiota by H.pylori as well as on the relationships between the gastric microbiota and gastric carcinogenesis.

Room for improvement in the treatment of pancreatic cancer: Novel opportunities from gene targeted therapy

Pancreatic cancer is one of the highest and in fact,unchanged mortality-associated tumor,with an exceptionally low survival rate due to its challenging diagnostic approach.So far,its treatment is based on a combination of approaches(such as surgical resection with or rarely without chemotherapeutic agents),but with finite limits.Thus,looking for additional space to improve pancreatic tumorigenesis therapeutic approach,research has focused on gene therapy with unexpectedly growing horizons not only for the treatment of inoperable pancreatic disease,but also for its early stages.In vivo gene delivery viral vectors,despite few disadvantages(possible immunogenicity,toxicity,mutagenicity,or high cost),could be one of the most efficient cancer gene therapeutic strategies for clinical application due to their superiority compared with other systems(ex vivo delivery strategies).Their dominance consists of simple preparation,easy operation and a wide range of functions.Adenoviruses are one of the most common used vectors,inducing strong immune as well as inflammatory reactions.Oncolytic virotherapy,using the above mentioned in vivo viral vectors,is one of the most promising nonpathogenic,highly-selective cytotoxic anti-cancer therapy using anti-cancer agents with high anti-tumor potency and strong oncolytic effect.There have been a variety of targeted therapeutic and pre-clinical strategies tested for gene therapy in pancreatic cancer such as gene-editing systems(e.g.,clustered regularly interspaced palindromic repeats-Cas9),RNA interference technology(e.g.,microRNAs,short hairpin RNA or small interfering RNA),adoptive immunotherapy and vaccination(e.g.,chimeric antigen receptor T-cell therapy)with encouraging results.