Helicobacter pylori Dormant States Are Affected by Vitamin C

Helicobacter pylori colonizes human gastric mucosa, overcoming stressful conditions and entering in a dormant state. This study evaluated: (i) H. pylori's physiological changes from active to viable-but-non-culturable (VBNC) and persister (AP) states, establishing times/conditions; (ii) the ability of vitamin C to interfere with dormancy generation/resuscitation. A dormant state was induced in clinical MDR H. pylori 10A/13 by: nutrient starvation (for VBNC generation), incubating in an unenriched medium (Brucella broth) or saline solution (SS), and (for AP generation) treatment with 10xMIC amoxicillin (AMX). The samples were monitored after 24, 48, and 72 h, 8-14 days by OD₆₀₀, CFUs/mL, Live/Dead staining, and an MTT viability test. Afterwards, vitamin C was added to the H. pylori suspension before/after the generation of dormant states, and monitoring took place at 24, 48, and 72 h. The VBNC state was generated after 8 days in SS, and the AP state in AMX for 48 h. Vitamin C reduced its entry into a VBNC state. In AP cells, Vitamin C delayed entry, decreasing viable coccal cells and increasing bacillary/U-shaped bacteria. Vitamin C increased resuscitation (60%) in the VBNC state and reduced the aggregates of the AP state. Vitamin C reduced the incidence of dormant states, promoting the resuscitation rate. Pretreatment with Vitamin C could favor the selection of microbial vegetative forms that are more susceptible to H. pylori therapeutical schemes.

Ultrastructure and Morphological Variability of Non-Culturable Forms of Yersinia pseudotuberculosis Bacteria

One of the mechanisms underlying the appearance of chronic infections is transition of pathogens into a non-culturable state, which is largely associated with the use of antibiotics. We studied ultrastructure of dormant bacteria Yersinia pseudotuberculosis obtained from the vegetative form of strain 512 by inhibition with kanamycin. On the model of the causative agent of pseudotuberculosis we showed that transition of prokaryotes to a dormant state occurs through apoptosis of bacteria. Fragmentation and condensation of chromatin with the formation of electron-dense fibrils, clumps and large conglomerates characteristic of apoptosis were found in the nucleoid zone of the cytoplasm of inhibited bacterial cells. These results are of great importance for understanding the mechanisms of the existence of pathogens in different conditions, as well as for identifying the causative agents of infectious diseases.

The Genetic Basis of Dormancy and Awakening in Cutaneous Metastatic Melanoma

Immune dysregulation, in combination with genetic and epigenetic alterations, induces an excessive proliferation of uncontrolled melanoma cells followed by dissemination of the tumor cells to distant sites, invading organs and creating metastasis. Although immunotherapy, checkpoint inhibitors and molecular targeted therapies have been developed as treatment options for advanced melanoma, there are specific mechanisms by which cancer cells can escape treatment. One of the main factors associated with reduced response to therapy is the ability of residual tumor cells to persist in a dormant state, without proliferation. This comprehensive review aimed at understanding the genetic basis of dormancy/awakening phenomenon in metastatic melanoma will help identify the possible therapeutical strategies that might eliminate melanoma circulating tumor cells (CTCs) or keep them in the dormant state forever, thereby repressing tumor relapse and metastatic spread.

Potential of Immunotherapies in Treating Hematological Cancer-Infection Comorbidities-A Mathematical Modelling Approach

BACKGROUND

The immune system attacks threats like an emerging cancer or infections like COVID-19 but it also plays a role in dealing with autoimmune disease, e.g., inflammatory bowel diseases, and aging. Malignant cells may tend to be eradicated, to appraoch a dormant state or escape the immune system resulting in uncontrolled growth leading to cancer progression. If the immune system is busy fighting a cancer, a severe infection on top of it may compromise the immunoediting and the comorbidity may be too taxing for the immune system to control.

METHOD

A novel mechanism based computational model coupling a cancer-infection development to the adaptive immune system is presented and analyzed. The model maps the outcome to the underlying physiological mechanisms and agree with numerous evidence based medical observations.

RESULTS AND CONCLUSIONS

Progression of a cancer and the effect of treatments depend on the cancer size, the level of infection, and on the efficiency of the adaptive immune system. The model exhibits bi-stability, i.e., virtual patient trajectories gravitate towards one of two stable steady states: a dormant state or a full-blown cancer-infection disease state. An infectious threshold curve exists and if infection exceed this separatrix for sufficiently long time the cancer escapes. Thus, early treatment is vital for remission and severe infections may instigate cancer progression. CAR T-cell Immunotherapy may sufficiently control cancer progression back into a dormant state but the therapy significantly gains efficiency in combination with antibiotics or immunomodulation.

Ultrastructural Changes of Bacteria in Static Cultures of Yersinia pseudotuberculosis under Long Storage under Conditions of Low Temperature

Electron microscopy study revealed changes in the ultrastructure of bacteria of Yersinia pseudotuberculosis strains characterized by significantly reduced reproductive ability and virulence potential after long-term storage at low temperature of 4-8°C. Most bacterial cells contained dark cytosol with reduced cellular material or empty cytosol, while the cell wall was preserved. The revealed ultrastructural changes in the bacterial cells of the static culture of Y. pseudotuberculosis suggest that storage of strains under low positive temperatures could induce the transition of the majority of bacterial cell population to a dormant, non-cultivated state with a decrease in their virulence. This fact is of great scientific and applied importance in studies of causative agents of saprozoonoses, including pseudotuberculosis, which has the etiopathogenetic background of persistent infection.