Chlamydia trachomatis plasmid-encoding Pgp3 protein induces secretion of distinct inflammatory signatures from HeLa cervical epithelial cells

BACKGROUND

Genital Chlamydia trachomatis infection is the most common bacterial sexual transmitted disease that causes severe complications including pelvic inflammatory disease, ectopic pregnancy, and infertility in females. The Pgp3 protein encoded by C. trachomatis plasmid has been speculated to be an important player in chlamydial pathogenesis. However, the precise function of this protein is unknown and thus remains to be thoroughly investigated.

METHODS

In this study, we synthesized Pgp3 protein for in vitro stimulation in the Hela cervical carcinoma cells.

RESULTS AND CONCLUSION

We showed that Pgp3 induced prominent expression of host inflammatory cytokine genes including interleukin-6 (IL-6), IL-8, tumor necrosis factor alpha-induced protein 3 (TNFAIP3), and chemokine C-X-C motif ligand 1 (CXCL1), implying a possible role of Pgp3 in modulating the inflammatory reaction in the host.

Immune Recognition versus Immune Evasion Systems in Zika Virus Infection

The reemergence of the Zika virus (ZIKV) infection in recent years has posed a serious threat to global health. Despite being asymptomatic or mildly symptomatic in a majority of infected individuals, ZIKV infection can result in severe manifestations including neurological complications in adults and congenital abnormalities in newborns. In a human host, ZIKV is primarily recognized by RIG-like receptors and Toll-like receptors that elicit anti-viral immunity through the secretion of type I interferon (IFN) to limit viral survival, replication, and pathogenesis. Intriguingly, ZIKV evades its host immune system through various immune evasion strategies, including suppressing the innate immune receptors and signaling pathways, mutation of viral structural and non-structural proteins, RNA modulation, or alteration of cellular pathways. Here, we present an overview of ZIKV recognition by the host immune system and the evasion strategies employed by ZIKV. Characterization of the host-viral interaction and viral disease mechanism provide a platform for the rational design of novel prophylactic and therapeutic strategies against ZIKV infection.

Influx of podoplanin-expressing inflammatory macrophages into the genital tract following Chlamydia infection

Genital Chlamydia trachomatis infection remains a major health issue as it causes severe complications including pelvic inflammatory disease, ectopic pregnancy and infertility in females as a result of infection-associated chronic inflammation. Podoplanin, a transmembrane receptor, has been previously reported on inflammatory macrophages. Thus, strategies that specifically target podoplanin might be able to reduce local inflammation. This study investigated the expression level and function of podoplanin in a C. trachomatis infection model. C57BL/6 mice infected with the mouse pathogen Chlamydia muridarum were examined intermittently from days 1 to 60 using flow cytometry analysis. Percentages of conventional macrophages (CD11b⁺ CD11c^- F4/80⁺ ) versus inflammatory macrophages (CD11b⁺ CD11c⁺ F4/80⁺ ), and the expression of podoplanin in these cells were investigated. Subsequently, a podoplanin-knockout RAW264.7 cell was used to evaluate the function of podoplanin in C. trachomatis infection. Our findings demonstrated an increased CD11b⁺ cell volume in the spleen at day 9 after the infection, with augmented podoplanin expression, especially among the inflammatory macrophages. A large number of podoplanin-expressing macrophages were detected in the genital tract of C. muridarum-infected mice. Furthermore, analysis of the C. trachomatis-infected patients demonstrated a higher percentage of podoplanin-expressing monocytes than that in the noninfected controls. Using an in vitro infection in a transwell migration assay, we identified that macrophages deficient in podoplanin displayed defective migratory function toward C. trachomatis-infected HeLa 229 cells. Lastly, using immunoprecipitation-mass spectrometry method, we identified two potential podoplanin interacting proteins, namely, Cofilin 1 and Talin 1 actin-binding proteins. The present study reports a role of podoplanin in directing macrophage migration to the chlamydial infection site. Our results suggest a potential for reducing inflammation in individuals with chronic chlamydial infections by targeting podoplanin.

Regulatory network of BLIMP1, IRF4, and XBP1 triad in plasmacytic differentiation and multiple myeloma pathogenesis

Antibody secreting plasma cell plays an indispensable role in humoral immunity. As activated B cell undergoes germinal center reaction and develops into plasma cell, it gradually loses B cell characteristics and embraces functional changes associated with immunoglobulins production. Differentiation of B cell into plasma cell involves drastic changes in cell structure, granularity, metabolism, gene expression and epigenetic regulation that couple with the mounting capacity for synthesis of a large quantity of antigen-specific antibodies. The interplay between three hallmark transcriptional regulators IRF4, BLIMP1, and XBP1, is critical for supporting the cellular reprograming activities during B to plasma cell transition. IRF4 promotes plasma cell generation by directing immunoglobulin class switching, proliferation and survival; BLIMP1 serves as a transcriptional repressor that extinguishes B cell features; whereas XBP1 controls unfolded protein response that relieves endoplasmic reticulum stress and permits antibody release during terminal differentiation. Intriguingly, high expression of IRF4, BLIMP1, and XBP1 molecules have been reported in myeloma cells derived from multiple myeloma patients, which negatively impact treatment outcome, prognosis, and relapse frequency. Despite the introduction of immunomodulatory drugs in recent years, multiple myeloma is still an incurable disease with poor survival rate. An in-depth review of IRF4, BLIMP1, and XBP1 triad molecules in plasma cell generation and multiple myeloma tumorigenesis may provide clues to the possibility of targeting these molecules in disease management.

Innate Immunity Crosstalk with Helicobacter pylori: Pattern Recognition Receptors and Cellular Responses

Helicobacter pylori is one of the most successful gastric pathogens that has co-existed with human for centuries. H. pylori is recognized by the host immune system through human pattern recognition receptors (PRRs), such as toll-like receptors (TLRs), C-type lectin like receptors (CLRs), NOD-like receptors (NLRs), and RIG-I-like receptors (RLRs), which activate downstream signaling pathways. Following bacterial recognition, the first responders of the innate immune system, including neutrophils, macrophages, and dendritic cells, eradicate the bacteria through phagocytic and inflammatory reaction. This review provides current understanding of the interaction between the innate arm of host immunity and H. pylori, by summarizing H. pylori recognition by PRRs, and the subsequent signaling pathway activation in host innate immune cells.

An Overview of Helicobacter pylori Survival Tactics in the Hostile Human Stomach Environment

Helicobacter pylori is well established as a causative agent for gastritis, peptic ulcer, and gastric cancer. Armed with various inimitable virulence factors, this Gram-negative bacterium is one of few microorganisms that is capable of circumventing the harsh environment of the stomach. The unique spiral structure, flagella, and outer membrane proteins accelerate H. pylori movement within the viscous gastric mucosal layers while facilitating its attachment to the epithelial cells. Furthermore, secretion of urease from H. pylori eases the acidic pH within the stomach, thus creating a niche for bacteria survival and replication. Upon gaining a foothold in the gastric epithelial lining, bacterial protein CagA is injected into host cells through a type IV secretion system (T4SS), which together with VacA, damage the gastric epithelial cells. H. pylori does not only establishes colonization in the stomach, but also manipulates the host immune system to permit long-term persistence. Prolonged H. pylori infection causes chronic inflammation that precedes gastric cancer. The current review provides a brief outlook on H. pylori survival tactics, bacterial-host interaction and their importance in therapeutic intervention as well as vaccine development.

Podoplanin Drives Motility of Active Macrophage via Regulating Filamin C During Helicobacter pylori Infection

Podoplanin (Pdpn) is a mucin-type transmembrane protein that has been implicated in multiple physiological settings including lymphangiogenesis, platelet aggregation, and cancer metastasis. Here, we reported an absence of Pdpn transcript expression in the resting mouse monocytic macrophages, RAW264.7 cells; intriguingly, a substantial upregulation of Pdpn was observed in activated macrophages following Helicobacter pylori or lipopolysaccharide stimulation. Pdpn-knockout macrophages demonstrated intact phagocytic and intracellular bactericidal activities comparable to wild type but exhibited impaired migration due to attenuated filopodia formation. In contrast, an ectopic expression of Pdpn augmented filopodia protrusion in activated macrophages. NanoString analysis uncovered a close dependency of Filamin C gene on the presence of Pdpn, highlighting an involvement of Filamin C in modulation of actin polymerization activity, which controls cell filopodia formation and migration. In addition, interleukin-1β production was significantly declined in the absence of Pdpn, suggesting a role of Pdpn in orchestrating inflammation during H. pylori infection besides cellular migration. Together, our findings unravel the Pdpn network that modulates movement of active macrophages.

Isolation and molecular identification of Aeromonas species from the tank water of ornamental fishes

Aeromonads are recognised as important pathogens of fishes. In this study, ten water samples were randomly collected from pet shops' fish tanks and home aquaria inhabited by several fish species (silver arowana, koi, goldfish, catfish, pictus fish, silver shark and silver dollar fish). Altogether 298 colonies were isolated using Aeromonas selective agar. A total of 154 isolates were then confirmed as belonging to the genus Aeromonas using the GCAT gene. Using ERIC-PCR, a total of 40 duplicate isolates were excluded from the study and 114 isolates were subjected to PCR-RFLP targeting the RNA polymerase sigma factor (rpoD) gene using lab-on-chip. A total of 13 different Aeromonas species were identified. The most prevalent species were A. veronii (27%, 31/114), followed by A. dhakensis (17%, 19/114), A. finlandiensis (9%, 10/114), A. caviae (8%, 9/114), A. hydrophila (4%, 4/114), A. jandaei (4%, 4/114), A. rivuli (3%, 3/114), A. enteropelogens (2%, 2/114), A. tecta (2%, 2/114), A. allosaccharophila (1%, 1/114), A. eucrenophila (1%, 1/114), A. media (1%, 1/114) and A. diversa (1%, 1/114). Twenty-six isolates (23%) were unidentifiable at species level. The present study demonstrates that Aeromonas species are highly diverse in freshwater fish tanks, and suggests the potential risks posed by the isolated bacteria to the health of ornamental fish species.

Chronic Inflammatory Diseases at Secondary Sites Ensuing Urogenital or Pulmonary Chlamydia Infections

Chlamydia trachomatis and C. pneumoniae are members of the Chlamydiaceae family of obligate intracellular bacteria. The former causes diseases predominantly at the mucosal epithelial layer of the urogenital or eye, leading to pelvic inflammatory diseases or blindness; while the latter is a major causative agent for pulmonary infection. On top of these well-described diseases at the respective primary infection sites, Chlamydia are notoriously known to migrate and cause pathologies at remote sites of a host. One such example is the sexually acquired reactive arthritis that often occurs at few weeks after genital C. trachomatis infection. C. pneumoniae, on the other hand, has been implicated in an extensive list of chronic inflammatory diseases which include atherosclerosis, multiple sclerosis, Alzheimer’s disease, asthma, and primary biliary cirrhosis. This review summarizes the Chlamydia infection associated diseases at the secondary sites of infection, and describes the potential mechanisms involved in the disease migration and pathogenesis.

In vitro evaluation of novel low-pressure spark plasma sintered HA–BG composite scaffolds for bone tissue engineering

The low-pressure spark plasma sintering (SPS) technique is adopted to fabricate hydroxyapatite–bioglass (HA–BG) scaffolds while maintaining the physical properties of both components, including their bulk and relative density and hardness. However, prior to their orthopaedic and dental applications, these scaffolds must be validated via pre-clinical assessments. In the present study, scaffolds with different ratios of HA : BG, namely, 100 : 0 (HB 0 S), 90 : 10 (HB 10 S), 80 : 20 (HB 20 S) and 70 : 30 (HB 30 S) were fabricated. These scaffolds were characterized by investigating their physicochemical properties (X-ray diffraction (XRD) and surface wettability), bioactivity in a simulated body fluid (SBF) (field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR) and calcium dissolution), antimicrobial properties, biocompatibility and osteoinduction of human bone marrow-derived mesenchymal stromal cells (hBMSCs) and human monocyte immune cell response. The XRD and surface wettability results confirmed no formation of undesirable phases and the enhanced surface hydrophilicity of the scaffolds, respectively. The bioactivity in SBF indicated the formation of bone-like apatite on the surface of the scaffolds, corresponding to an increase in BG%, which was confirmed through FTIR spectra and the increasing trend of calcium release in SBF. The scaffolds showed inhibition properties against Staphylococcus aureus and Staphylococcus epidermidis. The scanning electron microscopy (SEM) micrographs and Alamar Blue proliferation assay indicated the good attachment and significant proliferation, respectively, of hBMSCs on the scaffolds. Alizarin Red S staining confirmed that the scaffolds supported the mineralisation of hBMSCs. The osteogenic protein secretion (bone morphogenetic protein-2 (BMP2), type-I collagen (COL1) and osterix (OSX)) was significant on the HB 30 S-seeded hBMSCs when compared with that of HB 0 S. The monocyte migration was significantly halted in response to HA–BG-conditioned media when compared with the positive control (monocyte chemoattractant protein-1: MCP-1). In conclusion, the HB 30 S composite scaffold has a greater potential to substitute bone grafts in orthopaedic and dental applications.

HB 30 S composite scaffold inhibits Staphylococcus spp., supports the biocompatibility and osteogenic differentiation of hBMSCs and resists monocyte migration.

Diversity of endocervical microbiota associated with genital Chlamydia trachomatis infection and infertility among women visiting obstetrics and gynecology clinics in Malaysia

The cervical microbiota constitutes an important protective barrier against the invasion of pathogenic microorganisms. A disruption of microbiota within the cervical milieu has been suggested to be a driving factor of sexually transmitted infections. These include Chlamydia trachomatis which frequently causes serious reproductive sequelae such as infertility in women. In this study, we profiled the cervical microbial composition of a population of 70 reproductive-age Malaysian women; among which 40 (57.1%) were diagnosed with genital C. trachomatis infection, and 30 (42.8%) without C. trachomatis infection. Our findings showed a distinct compositional difference between the cervical microbiota of C. trachomatis-infected subjects and subjects without C. trachomatis infection. Specifically, significant elevations of mostly strict and facultative anaerobes such as Streptococcus, Megasphaera, Prevotella, and Veillonella in the cervical microbiota of C. trachomatis-positive women were detected. The results from the current study highlights an interaction of C. trachomatis with the environmental microbiome in the endocervical region.

T-Cell Exhaustion in Chronic Infections: Reversing the State of Exhaustion and Reinvigorating Optimal Protective Immune Responses

T-cell exhaustion is a phenomenon of dysfunction or physical elimination of antigen-specific T cells reported in human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) infections as well as cancer. Exhaustion appears to be often restricted to CD8+ T cells responses in the literature, although CD4+ T cells have also been reported to be functionally exhausted in certain chronic infections. Although our understanding of the molecular mechanisms associated with the transcriptional regulation of T-cell exhaustion is advancing, it is imperative to also explore the central mechanisms that control the altered expression patterns. Targeting metabolic dysfunctions with mitochondrion-targeted antioxidants are also expected to improve the antiviral functions of exhausted virus-specific CD8+ T cells. In addition, it is crucial to consider the contributions of mitochondrial biogenesis on T-cell exhaustion and how mitochondrial metabolism of T cells could be targeted whilst treating chronic viral infections. Here, we review the current understanding of cardinal features of T-cell exhaustion in chronic infections, and have attempted to focus on recent discoveries, potential strategies to reverse exhaustion and reinvigorate optimal protective immune responses in the host.

Lung-infiltrating T helper 17 cells as the major source of interleukin-17A production during pulmonary Cryptococcus neoformans infection

Background

IL-17A has emerged as a key player in the pathologies of inflammation, autoimmune disease, and immunity to microbes since its discovery two decades ago. In this study, we aim to elucidate the activity of IL-17A in the protection against Cryptococcus neoformans, an opportunistic fungus that causes fatal meningoencephalitis among AIDS patients. For this purpose, we examined if C. neoformans infection triggers IL-17A secretion in vivo using wildtype C57BL/6 mice. In addition, an enhanced green fluorescence protein (EGFP) reporter and a knockout (KO) mouse models were used to track the source of IL-17A secretion and explore the protective function of IL-17A, respectively.

Results

Our findings showed that in vivo model of C. neoformans infection demonstrated induction of abundant IL-17A secretion. By examining the lung bronchoalveolar lavage fluid (BALF), mediastinal lymph node (mLN) and spleen of the IL-17A–EGFP reporter mice, we showed that intranasal inoculation with C. neoformans promoted leukocytes lung infiltration. A large proportion (~ 50%) of the infiltrated CD4⁺ helper T cell population secreted EGFP, indicating vigorous T_H17 activity in the C. neoformans–infected lung. The infection study in IL-17A–KO mice, on the other hand, revealed that absence of IL-17A marginally boosted fungal burden in the lung and accelerated the mouse death.

Conclusion

Therefore, our data suggest that IL-17A is released predominantly from T_H17 cells in vivo, which plays a supporting role in the protective immunity against C. neoformans infection.

Electronic supplementary material

The online version of this article (10.1186/s12865-018-0269-5) contains supplementary material, which is available to authorized users.