Trichomonas vaginalis (T. vaginalis) infection leads to the synthesis of specific antibodies in the serum and local secretions. The profile of T. vaginalis-specific antibodies and T cell-mediated immune responses may influence the outcome of infection, towards parasite elimination, persistence or pathological reactions. Studies have indicated that Th1-, Th17- and Th22 cell-related cytokines may be protective or pathogenic, whereas Th2- and Treg cell-related cytokines can exert anti-inflammatory effects during T. vaginalis infection. A number of T. vaginalis-related components such as lipophosphoglycan (TvLPG), α-actinin, migration inhibitory factor (TvMIF), pyruvate:ferredoxin oxidoreductase (PFO), legumain-1 (TvLEGU-1), adhesins and cysteine proteases lead to the induction of specific antibodies. T. vaginalis has acquired several strategies to evade the humoral immune responses such as degradation of immunoglobulins by cysteine proteases, antigenic variation and killing of antibody-producing B cells. The characterization of the T. vaginalis-specific antibodies to significant immunogenic molecules and formulation of strategies to promote their induction in vaginal mucosa may reveal their potential protective effects against trichomoniasis. In this review, we discuss the current understanding of antibody and T cell-mediated immune responses to T. vaginalis and highlight novel insights into the possible role of immune responses in protection against parasite.

Infection with Trichomonas vaginalis may be asymptomatic or with symptoms suggestive of vaginitis. Because cysteine proteinase 30 (CP30) of T. vaginalis is known to be a virulence marker that plays a role in cytoadherence, the aim of this study was to analyse the presence of CP30 and antibody to CP30 in clinical samples of symptomatic and asymptomatic infected women. CP30 was detected in all the serum and vaginal washes (VWs) of symptomatic women and in 65% of the serum and 80% of the VWs of asymptomatic women. This suggested that the majority of asymptomatic women also exhibit CP30 in the serum and VWs. Antibody to CP30 was detected in all the serum samples of symptomatic and asymptomatic women and in the VWs of only 54.5% of the symptomatic and 35% of the asymptomatic women. Antibody to CP30 was also detected in 3/20 of the serum samples and in none of the VWs from uninfected women. Significantly higher amounts of antibody (mean OD values) were observed in serum and VWs of symptomatic as compared to asymptomatic and healthy women (P<0.001). These results indicate that besides CP30, other factors may also be playing a role in leading to symptomatic infection, because CP30 was detected in clinical samples from all the symptomatic and the majority of the asymptomatic women. Although anti-CP30 antibodies do not appear to be protective, detection of antibody to CP30 antigen in serum samples may be used as a diagnostic tool.

Innate and adaptive immunity play a significant role in urogenital infections. Innate immunity is provided by the epithelial cells and mucus lining along with acidic pH, which forms a strong physical barrier against the pathogens in female reproductive tract. Cells of innate immune system, antimicrobial peptides, cytokines, chemokines and adaptive immunity in the reproductive tract are evolved during infection, and a pro-inflammatory response is generated to fight against the invading pathogen Trichomonas vaginalis, a primary urogenital protozoa, the etiological agent of human trichomoniasis, a curable sexually transmitted infection. The involvement of the urogenital tract by other protozoal infections such as P. falciparum, Trypanosoma, Leishmania, Toxoplasma, Entamoeba histolytica and Acanthamoeba infection is rarely reported. Trichomonas induce pro-inflammatory and immunosuppressive responses in infected subjects. Multifactorial pathogenic mechanisms including parasite adherence, cysteine proteases, lipophosphoglycan, free radical, cytokine generation and Toll-like receptors appear to interplay with the induction of local and systemic immune responses that ultimately determine the outcome of the infection. However, the involvement of urogenital pathogen-specific immune mechanisms and effect of normal local resident flora on the outcome (symptomatic vs. asymptomatic) of infection are poorly understood. Moreover, immune interactions in trichomoniasis subjects co-infected with bacterial and viral pathogens need to be elucidated.

Trichomoniasis, the most common nonviral sexually transmitted disease, is caused by infection with the protist Trichomonas vaginalis. The clinical spectrum varies from an asymptomatic state to mild, moderate or severe symptoms. However, the exact factors leading to varied symptomatology have not been well elucidated. The mouse is a useful experimental model for intravaginal trichomoniasis, for understanding the role of local immune responses in the pathogenesis and varied symptomatology of this disease. The present study reports anti-Trichomonas IgG, IgM, IgA and IgG subclass antibody responses on different post-infection days (3rd, 7th, 14th, 21st and 28th) in serum and vaginal washes of mice infected intravaginally with T. vaginalis isolates from 15 symptomatic and 15 asymptomatic women. Successful intravaginal infection was established by inoculating T. vaginalis in BALB/c mice pre-inoculated with Lactobacillus acidophilus and pretreated with oestradiol. A significant increase in parasite load was observed on the 14th post-infection day (p.i.d.) in mice inoculated with T. vaginalis isolates from symptomatic women as compared to asymptomatic women (P < 0.001), followed by reduction until the 28th p.i.d. (P < 0.05). A significant increase in specific IgG (P < 0.001) and in particular IgG1 (P < 0.001) and IgM (P < 0.01) responses was observed on the 14th p.i.d. in serum and vaginal washes of mice infected with T. vaginalis isolates from symptomatic women as compared to asymptomatic women. Significant increases in specific IgG, IgM and IgG1 responses was observed on the 14th p.i.d. in serum samples as compared with vaginal washes of mice infected with T. vaginalis isolates from symptomatic and asymptomatic women (P < 0.01), whereas no significant difference was observed in IgA, IgG2a, IgG2b and IgG3 antibody responses. The study indicates that specific IgG, particularly IgG1 and IgM, may be playing a role in establishing symptomatic infection.

Trichomoniasis, the most common non-viral sexually transmitted disease, is caused by infection with the protist Trichomonas vaginalis. The clinical spectrum varies from an asymptomatic to a severe symptomatic state. However, the exact factors leading to varied symptomatology have not been well elucidated. The role of cytokines in the pathogenesis of many microbial diseases has been reported. The present study reports the cytokine levels (IL-2, IL-4, IFN-gamma) on different days post infection (3rd, 7th, 14th, 21st and 28th d.p.i.) in serum and vaginal washes (VWs) of mice infected intravaginally with T. vaginalis isolates from 15 symptomatic and 15 asymptomatic women. Significantly higher production of IL-2 and IFN-gamma was observed on the 3rd to 28th d.p.i., and IL-4 on the 7th to 21st d.p.i., in infected as compared to uninfected mice. A significant increase in cytokine IL-2 and IFN-gamma was observed on the 3rd to 28th d.p.i. in serum and VWs of mice infected with T. vaginalis isolates from asymptomatic as compared to symptomatic women. IL-2 (P < 0.001) and IFN-gamma (P < 0.05) concentrations were significantly higher on the 14th d.p.i. in serum samples as compared to VWs of mice infected with T. vaginalis isolates from asymptomatic and symptomatic women, while no significant difference was observed in IL-4 concentration between the two groups of mice. The study indicates the involvement of a Th-1 (IL-2 and IFN-gamma) like response in mice infected with isolates from asymptomatic women as compared to symptomatic women and suggests that Th-1 type cytokines might be playing a role in maintaining low levels of infection.

Human nucleic acid-binding protein 1 and 2 (hNABP1 and hNABP2, also known as hSSB2 and hSSB1 respectively) form two separate and independent complexes with two identical proteins, integrator complex subunit 3 (INTS3) and C9ORF80. We and other groups have demonstrated that hNABP1 and 2 are single-stranded (ss) DNA- and RNA-binding proteins, and function in DNA repair; however, the function of INTS3 and C9OFR80 remains elusive. In the present study, we purified recombinant proteins INTS3 and C9ORF80 to near homogeneity. Both proteins exist as a monomer in solution; however, C9ORF80 exhibits anomalous behavior on SDS–PAGE and gel filtration because of 48% random coil present in the protein. Using electrophoretic mobility shift assay (EMSA), INTS3 displays higher affinity toward ssRNA than ssDNA, and C9ORF80 binds ssDNA but not ssRNA. Neither of them binds dsDNA, dsRNA, or RNA : DNA hybrid. INTS3 requires minimum of 30 nucleotides, whereas C9OFR80 requires 20 nucleotides for its binding, which increased with the increasing length of ssDNA. Interestingly, our GST pulldown results suggest that the N-terminus of INTS3 is involved in protein–protein interaction, while EMSA implies that the C-terminus is required for nucleic acid binding. Furthermore, we purified the INTS3–hNABP1/2–C9ORF80 heterotrimeric complex. It exhibits weaker binding compared with the individual hNABP1/2; interestingly, the hNABP1 complex prefers ssDNA, whereas hNABP2 complex prefers ssRNA. Using reconstituted heterotrimeric complex from individual proteins, EMSA demonstrates that INTS3, but not C9ORF80, affects the nucleic acid-binding ability of hNABP1 and hNABP2, indicating that INTS3 might regulate hNABP1/2's biological function, while the role of C9ORF80 remains unknown.

BackgroundInflammatory response during urinary tract infection (UTI) is mediated by innate immune defense. Nod like receptors (NLRs) have been proposed to work simultaneously beside TLR pathways to mediate pro-inflammatory response and maintain tissue homeostasis. Some in vitro reports have showed the involvement of NLRP3 inflammasome during uropathogenic Escherichia coli (UPEC) mediated UTI. So we have sought to determine the status of various inflammasomes and their components in UPEC mediated UTI.MethodsA total of 186 females experiencing the first episode of UTI were recruited for the study and forty were found to be positive for UPEC (≥105 CFU/ml) in their urine (N = 40). Further, we analyzed the expression of NLRP3, NLRC4, NAIP, AIM2, ASC, CASPASE-4, and CASPASE-1 gene at mRNA and protein level in the blood of UPEC confirmed study subjects through real time qPCR and immunoblotting. Healthy females (N = 40) visiting the OPD for health checkups, family planning advice and subjects undergoing routine medical examinations, were recruited as healthy control subjects. Pro-inflammatory cytokines (IL-6, IL-8, IFN-γ, TNF-α and MCP-1) were measured in the plasma of patients and controls through ELISA. For investigation of the involvement of NLRC4 and NLRP3 inflammasome, in vitro studies were performed using co-immunoprecipitation and confocal microscopy.ResultsMost of the inflammatory regulators studied (i.e., NLRP3, NAIP, NLRC4, ASC, and CASPASE-1) were found to be up-regulated at both mRNA and protein levels in the UPEC infected UTI patients. Also, pro-inflammatory cytokines (IL-6, IL-8, IFN-γ, TNF-α, and MCP-1) were found to be up-regulated in the patients group. However, no significant difference was observed in the expression of AIM2 and CASPASE-4 genes at both mRNA and protein levels. Further, in vitro studies have shown the involvement of NLRC4 inflammasome in UPEC infected THP1 derived macrophages.ConclusionInvolvement of NLRP3 and NLRC4 inflammasomes in UPEC infected UTI is evident from our findings. This is the first report showing levels of inflammasome and its components in UTI patients suggesting a possible role during UPEC mediated UTI. We have also reported the involvement of NLRC4 inflammasome for the first time during UTI infection.

Inflammasomes are multiprotein complexes present in the cytosol as pattern recognition receptors or as sensors of damage-associated molecular patterns. After recognition of microbe-associated molecular patterns or host-derived danger signals, nucleotide oligomerization domain-like receptors oligomerize to form inflammasomes. The activation of inflammasomes results in an alarm, which is raised to alert adjacent cells through the processing and release of a number of other substrates present in the cytosol. A wide array of inflammasomes and their adapter molecules have been identified in the host’s innate immune system in response to various pathogens. Components of specific pathogens activate different inflammasomes, which once activated in response to pathogen-induced infection, induce the activation of caspases, and the release of mature forms of interleukin-1β (IL-1β) and IL-18. Identifying the mechanisms underlying pathogen-induced inflammasome activation is important if we are to develop novel therapeutic strategies to target sexually transmitted infections (STIs) related pathogens. This information is currently lacking in literature. In this review, we have discussed the role of various inflammasomes in sensing different STIs, as well as the beneficial or detrimental effects of inflammasome signaling in host resistance. Additionally, we have discussed both canonical and non-canonical processing of IL-1β induced with respect to particular infections. Overall, these findings transform our understanding of both the basic biology and clinical relevance of inflammasomes.