The interplay between drugs and microbiota is critical for successful treatment. An accumulating amount of evidence has identified the significant impact of intestinal microbiota composition on cancer treatment response, particularly immunotherapy. The possible molecular pathways of the interaction between immune checkpoint inhibitors (ICIs) and the microbiome can be used to reverse immunotherapy tolerance in cancer by using various kinds of interventions on the intestinal bacteria. This paper aimed to review the data available on how the antibiotic-related changes in human microbiota during colorectal cancer (CRC) treatment can affect and determine ICI treatment outcomes. We also covered the data that support the potential intimate mechanisms of both local and systemic immune responses induced by changes in the intestinal microbiota. However, further better-powered studies are needed to thoroughly assess the clinical significance of antibiotic-induced alteration of the gut microbiota and its impact on CRC treatment by direct observations of patients receiving antibiotic treatment.

In the last two decades, the vision of a unique carcinogenesis model for colorectal carcinoma (CRC) has completely changed. In addition to the adenoma to carcinoma transition, colorectal carcinogenesis can also occur via the serrated pathway. Small non-coding RNA, known as microRNAs (miRNAs), were also shown to be involved in progression towards malignancy. Furthermore, increased expression of certain miRNAs in premalignant sessile serrated lesions (SSLs) was found, emphasizing their role in the serrated pathway progression towards colon cancer. Since miRNAs function as post-transcriptional gene regulators, they have enormous potential to be used as useful biomarkers for CRC and screening in patients with SSLs particularly. In this review, we have summarized the most relevant information about the specific role of miRNAs and their relevant signaling pathways among different serrated lesions and polyps as well as in serrated adenocarcinoma. Additional focus is put on the correlation between gut immunity and miRNA expression in the serrated pathway, which remains unstudied.

The emergence of the novel SARS-CoV2 virus, proclaimed by the World Health Organization (WHO) as a culpable agent for the pandemic situation, caught the scientific and medical communities off guard. One of the most common complications following pulmonary disease is represented by gastrointestinal (GI) disorders, especially ischemic damage. Inflammation, vasculopathy, immobility, endothelial dysfunction, and a hypercoagulable condition have all been proposed as pathophysiological factors for GI ischemia in these patients. Owing to the COVID-19 effect on a variety of GI conditions, especially ischemic changes, and the high mortality rate, physicians should always keep in mind this complication. They should take a deeper look at clinical and imaging modalities in this cohort of patients so that a proper and time-saving treatment strategy can be applied. Our study aimed to elucidate the thrombogenic mechanism in different GI disorders. Moreover, we analyzed the factors related to necrotic GI changes, by summarizing the already reported data of GI ischemia in COVID-19. To the best of our knowledge, this review is the first to incorporate all GI ischemia cases reported in the literature so far.

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BACKGROUND Russell body gastritis (RBG) is very rare type of chronic inflammation of gastric mucosa. The pathologic hallmark of the disease is Russell bodies (RB) which represent accumulation of eosinophilic cytoplasmic inclusions in endoplasmic reticulum of mature plasma cells (Mott cells). Most published cases are associated with Helicobacter pylori ( H. pylori ) infection because of correlation between plasma cell activation and antigenic stimulation. There are insufficient data about H. pylori -negative RBG and very little is known about the natural course of the disease. CASE SUMMARY A 51-year-old male patient underwent endoscopic screening for mild iron deficiency anemia. Gastroscopy revealed diffuse hyperemia, edema and nodularity of the fundic and corpus mucosa. Due to non-specific endoscopic findings and iron-deficiency anemia our preliminary diagnosis was diffuse type of gastric carcinoma or gastric lymphoma. Biopsy specimens of gastric mucosa showed inflammatory infiltrate rich in Mott cells, consisting entirely of cytoplasmic RB. Absence of nuclear atypia and mitosis of the plasma cells, polyclonal pattern of the Mott cells and negative staining for cytokeratins favored diagnosis of RBG. The patient was treated with proton-pump inhibitor for 8 wk. Long-term clinical and endoscopic surveillance was scheduled. Albeit, there was no improvement in endoscopic features of the gastric mucosa in three consecutive gastroscopies, histopathological findings demonstrated that the chronic inflammatory infiltrate in the fundic mucosa is less pronounced, rich in plasma cells, with almost absent RB and Mott cells. CONCLUSION The prognosis of this entity is uncertain, that is why these patients are subjects of continuous follow up.

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The genetic and metabolomic abundance of the microbiome exemplifies that the microbiome comprises a more extensive set of genes than the entire human genome, which justifies the numerous metabolic and immunological interactions between the gut microbiota, macroorganisms and immune processes. These interactions have local and systemic impacts that can influence the pathological process of carcinogenesis. The latter can be promoted, enhanced or inhibited by the interactions between the microbiota and the host. This review aimed to present evidence that interactions between the host and the gut microbiota might be a significant exogenic factor for cancer predisposition. It is beyond doubt that the cross-talk between microbiota and the host cells in terms of epigenetic modifications can regulate gene expression patterns and influence cell fate in both beneficial and adverse directions for the host’s health. Furthermore, bacterial metabolites could shift pro- and anti-tumor processes in one direction or another. However, the exact mechanisms behind these interactions are elusive and require large-scale omics studies to better understand and possibly discover new therapeutic approaches for cancer.

In liver transplant patients, solid tumors and post-transplant lymphoproliferative disorders (PTLD) have emerged as significant long-term mortality causes. Additionally, it is assumed that de novo malignancy (DNM) after liver transplantation (LT) is the second-leading cause of death after cardiovascular complications. Well-established risk factors for PTLD and solid tumors are calcineurin inhibitors (CNIs), tacrolimus (TAC), and cyclosporine, the cornerstones of all immunosuppressive (IS) therapies used after LT. The loss of immunocompetence facilitated by the host immune system due to prolonged IS therapy leads to cancer development, including in LT patients. Hindering DNA repair mechanisms, promoting tumor cell invasiveness, and hampering apoptosis are critical events in tumorigenesis and tumor growth in LT patients resulting from IS administration. This paper aims to overview the refined mechanisms of IS-induced tumorigenesis after LT and the loss of immunocompetence facilitated by the host immune system due to prolonged IS therapy. In addition, we also discuss in detail the mechanisms of action in different types of IS regimen used after LT, and their putative effect on DNM.