Liposomal-lipopolysaccharide vaccine extracted from Proteus mirabilis induces moderate TLR4 and CD14 production

Abstract

Proteus mirabilis is a common cause of recurrent urinary tract infections in individuals with functional or structural abnormalities. It also forms bladder and kidney stones. Lipopolysaccharide (LPS) is a potential Proteus virulence factor that plays a key role in pathogenesis, as well as in stimulating innate immune response. Therefore, this study aimed to extract LPS from a highly resistant isolate and incorporate it in a delivery system (liposome) to stimulate an immune response against virulent pathogens. In the work, 50 isolates of P. mirabilis were taken from 200 urine specimens obtained from recurrent-urinary tract infections (UTI) of patients of AL-Sadar Hospital. Specimens were cultured on specific media, and then bacterial isolates were identified via morphological, biochemical and Vitek-2 systems. The results showed that P. mirabilis was expressed in 11 (22%), 30 (60%) and 9 (18%) recurrent UTI, kidney stone and catheter samples, respectively. All isolates were assessed through antibiogram testing, with the results revealing that most isolates were multidrug resistant to more than 3 classes of antibiotics. Herein, P. mirabilis NO 50 revealed particularly high resistance, so it was chosen for LPS extraction. Lethal dose 50 (LD50) observations indicated that a live suspension of P. mirabilis was at 4.5×107 CFU/ml, while LPS was at 270 μg/ml. LPS was used as an immunogenic to stimulate the immune system through injecting Rats intraperitoneally (I.P.) with 1 ml of LD50%. Subsequently, the efficiency of immunogenes in stimulating the immune response was evaluated by determining the Toll-like receptor and CD14 levels. The results indicate that LPS incorporated in the Liposome released moderate levels of Toll-like receptors-4 (TLR4) that enabled the immune system to clear pathogens. The LPS+ complete Freund’s adjuvant (CFA) and LPS vaccinated groups recorded hyper production for TLR4 (52.2 and 40.9 pg/ml, respectively), this was followed by liposome (LIP) and bacterial suspension (11 and 20.5 pg/ml, respectively) in ranking effectiveness. This study reveals a mean of CD14 that was higher in both LPS and LPS+CFA and moderate in LPS+LIP, in comparison with control and liposome groups.

Keywords

• lipopolysaccharide
• liposome(lip)
• proteus mirabilis
• immunomodulater activity
• cytokine