Browsing by Subject "cystitis"
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Item Open Access Diabetic bladder dysfunction is associated with bladder inflammation triggered through hyperglycemia, not polyuria(Research and Reports in Urology, 2018-11-16) Inouye, BM; Hughes, FM Jr; Jin, H; Lütolf, R; Potnis, KC; Routh, JC; Rouse, dc; Foo, WC; Purves, JTPurpose
Diabetes is a grave and progressive condition characterized by debilitating complications. Diabetic bladder dysfunction (DBD) is a very common complication with no specific treatments currently available. Unlike other tissues affected by this disease, the bladder is subjected to two independent insults; 1) polyuria, created by the osmotic effects of glucose in the urine, and 2) hyperglycemia itself. Based on our understanding of inflammation as a major contributor to the underlying organ damage in several other diabetic complications, its presence in the bladder during DBD and the contribution of polyuria and hyperglycemia to its development were assessed.Methods
Awake, restrained cystometry was performed on wild type C57BL/6 mice and diabetic (Akita) mice on a C57BL/6 background at 15 weeks of age. A subgroup of the Akita mice were treated with phlorizin, an inhibitor of sodium-glucose linked transporter types 1 and 2 that prevents glucose reabsorption in the kidney. All groups were assessed for serum glucose, 4-hour voiding totals, and inflammation in the bladder (Evans blue assay).Results
Akita mice develop cystometrically-defined DBD by 15 weeks of age, as evidenced by an increase in urinary frequency, a decrease in voiding volume, and an increase in post-voiding residual volume. Phlorizin effectively normalized serum glucose in these animals while increasing the urine output. Inflammation in the bladder was present in the diabetic animals at this time point, but not detectable in animals receiving phlorizin.Conclusion
Inflammation in the bladder of diabetic mice correlates with the development of DBD and is triggered by hyperglycemia, not polyuria.Item Open Access Dynamic Compartmentalization of Persistent UPEC in the Superficial Bladder Epithelium(2016) Parekh, Viraj PankajUrinary tract infections (UTIs) are typically caused by bacteria that colonize different regions of the urinary tract, mainly the bladder and the kidney. Approximately 25% of women that suffer from UTIs experience a recurrent infection within 6 months of the initial bout, making UTIs a serious economic burden resulting in more than 10 million hospital visits and $3.5 billion in healthcare costs in the United States alone. Type-1 fimbriated Uropathogenic E. coli (UPEC) is the major causative agent of UTIs, accounting for almost 90 % of bacterial UTIs. The unique ability of UPEC to bind and invade the superficial bladder epithelium allows the bacteria to persist inside epithelial niches and survive antibiotic treatment. Persistent, intracellular UPEC are retained in the bladder epithelium for long periods, making them a source of recurrent UTIs. Hence, the ability of UPEC to persist in the bladder is a matter of major health and economic concern, making studies exploring the underlying mechanism of UPEC persistence highly relevant.
In my thesis, I will describe how intracellular Uropathogenic E.coli (UPEC) evade host defense mechanisms in the superficial bladder epithelium. I will also describe some of the unique traits of persistent UPEC and explore strategies to induce their clearance from the bladder. I have discovered that the UPEC virulence factor Alpha-hemolysin (HlyA) plays a key role in the survival and persistence of UPEC in the superficial bladder epithelium. In-vitro and in-vivo studies comparing intracellular survival of wild type (WT) and hemolysin deficient UPEC suggested that HlyA is vital for UPEC persistence in the superficial bladder epithelium. Further in-vitro studies revealed that hemolysin helped UPEC persist intracellularly by evading the bacterial expulsion actions of the bladder cells and remarkably, this virulence factor also helped bacteria avoid t degradation in lysosomes.
To elucidate the mechanistic basis for how hemolysin promotes UPEC persistence in the urothelium, we initially focused on how hemolysin facilitates the evasion of UPEC expulsion from bladder cells. We found that upon entry, UPEC were encased in “exocytic vesicles” but as a result of HlyA expression these bacteria escaped these vesicles and entered the cytosol. Consequently, these bacteria were able to avoid expulsion by the cellular export machinery.
Since bacteria found in the cytosol of host cells are typically recognized by the cellular autophagy pathway and transported to the lysosomes where they are degraded, we explored why this was not the case here. We observed that although cytosolic HlyA expressing UPEC were recognized and encased by the autophagy system and transported to lysosomes, the bacteria appeared to avoid degradation in these normally degradative compartments. A closer examination of the bacteria containing lysosomes revealed that they lacked V-ATPase. V-ATPase is a well-known proton pump essential for the acidification of mammalian intracellular degradative compartments, allowing for the proper functioning of degradative proteases. The absence of V-ATPase appeared to be due to hemolysin mediated alteration of the bladder cell F-actin network. From these studies, it is clear that UPEC hemolysin facilitates UPEC persistence in the superficial bladder epithelium by helping bacteria avoid expulsion by the exocytic machinery of the cell and at the same time enabling the bacteria avoid degradation when the bacteria are shuttled into the lysosomes.
Interestingly even though UPEC appear to avoid elimination from the bladder cell their ability to multiple in bladder cells seem limited.. Indeed, our in-vitro and in-vivo experiments reveal that UPEC survive in superficial bladder epithelium for extended periods of time without a significantly change in CFU numbers. Indeed, we observed these bacteria appeared quiescent in nature. This observation was supported by the observation that UPEC genetically unable to enter a quiescence phase exhibited limited ability to persist in bladder cells in vitro and in vivo, in the mouse bladder.
The studies elucidated in this thesis reveal how UPEC toxin, Alpha-hemolysin plays a significant role in promoting UPEC persistence via the modulation of the vesicular compartmentalization of UPEC at two different stages of the infection in the superficial bladder epithelium. These results highlight the importance of UPEC Alpha-hemolysin as an essential determinant of UPEC persistence in the urinary bladder.
Item Open Access Why Serological Responses during Cystitis are Limited.(Pathogens, 2016-02-14) Choi, Hae Woong; Abraham, Soman NThe high frequency of urinary tract infections (UTIs), some of which appear to be endogenous relapses rather than reinfections by new isolates, point to defects in the host's memory immune response. It has been known for many decades that, whereas kidney infections evoked an antibody response to the infecting bacteria, infections limited to the bladder failed to do so. We have identified the existence of a broadly immunosuppressive transcriptional program associated with the bladder, but not the kidneys, during infection of the urinary tract that is dependent on bladder mast cells. This involves the localized secretion of IL-10 and results in the suppression of humoral immune responses in the bladder. Mast cell-mediated immune suppression could suggest a role for these cells in critically balancing the needs to clear infections with the imperative to prevent harmful immune reactions in the host.