Pattern of cytokine and chemokine production by THP-1 derived macrophages in response to live or heat-killed Mycobacterium bovis bacillus Calmette-Guérin Moreau strain

Novel human STING activation by hydrated-prenylated xanthones from Garcinia cowa

OBJECTIVES

We investigate the anticancer activity and human stimulator of interferon genes pathway activation by a new hydrated-prenylated tetraoxygenated xanthone, garcicowanone I (1) and two known xanthones (2 and 3) that were isolated from the root bark of Garcinia cowa Roxb. ex Choisy.

METHODS

The anticancer activity of each compound was evaluated by sulforhodamine B assay in immortalized cancer cell lines. Stimulator of interferon genes pathway activation was assessed by western blot analysis using human THP-1-derived macrophages. The production of pro-inflammatory cytokines from these macrophages was also evaluated via enzyme-linked immunosorbent assay.

KEY FINDINGS

Both compounds 1 and 3 displayed moderate inhibitory effects on the cancer cells, including a cisplatin-resistant cell line, with IC50 values in the range of 10-20 µM. All three xanthones activated the stimulator of interferon genes, as evidenced by phosphorylation of tank-binding kinase 1, the stimulator of interferon genes protein and interferon regulatory factor 3. Furthermore, treatment of these macrophages with compounds 1-3 led to the production of pro-inflammatory cytokines, including interleukin 6, tumour necrosis factor α and interleukin 1β.

CONCLUSIONS

In conclusion, the isolated xanthones, including the novel garcicowanone I, displayed promising anticancer and immunomodulatory activity that warrants further research.

Tyndallized Bacteria Preferentially Induce Human Macrophage M1 Polarization: An Effect Useful to Balance Allergic Immune Responses and to Control Infections

Macrophage polarization is a dynamic process through which macrophages acquire specific features whose extremes are represented by M1 and M2 polarization. Interleukin (IL)-6, IL-1β, IL-12 and IL-8 belong to M1 macrophages while transforming growth factor-beta (TGF-β belongs to M2 cytokines. M2 polarization prevalence is observed in allergic diseases. Tyndallization is a thermal process able to inactivate microorganisms and to allow their use for chronic respiratory disease treatment via immune response modulation. The present study explores the effects of a blend of tyndallized bacteria (TB) on macrophage polarization. THP-1-derived macrophages were exposed to different concentrations of TB (106, 5 × 106, 107, 5 × 107, 108 CFU/mL) and then cell viability and TB phagocytosis, and IL-8, IL-1β, IL-6, IL-12 and TGF-β1 gene expression and release were assessed. TB were tolerated, phagocyted and able to increase IL-8, IL-1β and IL-6 gene expression and release IL-12 gene expression, as well as decrease TGF-β1 gene expression and release. The effects on IL-8, IL-6 and TGF-β1 release were confirmed in human monocyte-derived macrophages (hMDMs) exposed to TB. In conclusion, TB promote M1 polarization, and this mechanism might have valuable potential in controlling allergic diseases and infections, possibly preventing disease exacerbations.

In vitro response of THP-1 derived macrophages to antimicrobially effective PHMB-coated Ti6Al4V alloy implant material with and without contamination with S. epidermidis and P. aeruginosa

AIM

Periprosthetic joint infections are a devastating complication after arthroplasty, leading to rejection of the prosthesis. The prevention of septic loosening may be possible by an antimicrobial coating of the implant surface. Poly (hexamethylene) biguanide hydrochloride [PHMB] seems to be a suitable antiseptic agent for this purpose since previous studies revealed a low cytotoxicity and a long-lasting microbicidal effect of Ti6Al4V alloy coated with PHMB. To preclude an excessive activation of the immune system, possible inflammatory effects on macrophages upon contact with PHMB-coated surfaces alone and after killing of S. epidermidis and P. aeruginosa are analyzed.

METHODS

THP-1 monocytes were differentiated to M0 macrophages by phorbol 12-myristate 13-acetate and seeded onto Ti6Al4V surfaces coated with various amounts of PHMB. Next to microscopic immunofluorescence analysis of labeled macrophages after adhesion on the coated surface, measurement of intracellular reactive oxygen species and analysis of cytokine secretion at different time points without and with previous bacterial contamination were conducted.

RESULTS

No influence on morphology of macrophages and only slight increases in iROS generation were detected. The cytokine secretion pattern depends on the surface treatment procedure and the amount of adsorbed PHMB. The PHMB coating resulted in a high reduction of viable bacteria, resulting in no significant differences in cytokine secretion as reaction to coated surfaces with and without bacterial burden.

CONCLUSION

Ti6Al4V specimens after alkaline treatment followed by coating with 5-7 μg PHMB and specimens treated with H2O2 before PHMB-coating (4 μg) had the smallest influence on the macrophage phienotype and thus are considered as the surface with the best cytocompatibility to macrophages tested in the present study.

Association of IFN-gamma and IL-10 gene variants with the risk of extrapulmonary tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) is a chronic infectious disease. Interferon-gamma (IFN-γ) is an important cytokine imparting resistance to mycobacterial diseases. It is believed that IFN-γ and Interleukin-10 (IL-10) play divergent roles in the host immune system against MTB infection. IL-10 is an important inhibitory cytokine and helps balancing the inflammatory and immune responses. IL-10 is involved in down regulation of Th1 cytokines, MHC class II antigen and co-stimulatory molecular expression on macrophages, while IFN-γ results in macrophage activation allowing them to exert the microbicidal role. The objectives were to find out the association of IL-10 (-1082 A/G) and IFN-γ (+874 A/T) single nucleotide polymorphisms (SNPs) with extrapulmonary tuberculosis in ethnic Kashmiri population. A total of 100 extrapulmonary tuberculosis cases and 102 healthy controls were analyzed for IL-10 (-1082 A/G) and IFN- γ (+874 A/T) SNPs using Allele-Specific PCR. We found a significant association of IFN-γ + 874 'TT' genotype with extrapulmonary tuberculosis (p = 0.006) and in case of IL-10 (-1082 A/G) we found a significant association with extrapulmonary tuberculosis under recessive model (GG vs GA + AA) (p = 0.03) in Kashmiri population. IL-10 (-1082 A/G) and IFN-γ (+874 A/T) have a significant association with extrapulmonary tuberculosis in ethnic Kashmiri population.

Identification and evaluation of immunogenic MHC-I and MHC-II binding peptides from Mycobacterium tuberculosis

Due to several limitations of the only available BCG vaccine, to generate adequate protective immune responses, it is important to develop potent and cost-effective vaccines against tuberculosis (TB). In this study, we have used an immune-informatics approach to identify potential peptide based vaccine targets against TB. The proteome of Mycobacterium tuberculosis (Mtb), the causative agent of TB, was analyzed for secretory or surface localized antigenic proteins as potential vaccine candidates. The T- and B-cell epitopes as well as MHC molecule binding efficiency were identified and mapped in the modelled structures of the selected proteins. Based on antigenicity score and molecular dynamic simulation (MD) studies two peptides namely Pep-9 and Pep-15 were analyzed, modelled and docked with MHC-I and MHC-II structures. Both peptides exhibited no cytotoxicity and were able to induce proinflammatory cytokine secretion in stimulated macrophages. The molecular docking, MD and in-vitro studies of the predicted B and T-cell epitopes of Pep-9 and Pep-15 peptides with the modelled MHC structures exhibited strong binding affinity and antigenic properties, suggesting that the complex is stable, and that these peptides can be considered as a potential candidates for the development of vaccine against TB.

Posttranslational Regulation of IL-23 Production Distinguishes the Innate Immune Responses to Live Toxigenic versus Heat-Inactivated Vibrio cholerae

Vibrio cholerae infection provides long-lasting protective immunity, while oral, inactivated cholera vaccines (OCV) result in more-limited protection. To identify characteristics of the innate immune response that may distinguish natural V. cholerae infection from OCV, we stimulated differentiated, macrophage-like THP-1 cells with live versus heat-inactivated V. cholerae with and without endogenous or exogenous cholera holotoxin (CT). Interleukin 23A gene (IL23A) expression was higher in cells exposed to live V. cholerae than in cells exposed to inactivated organisms (mean change, 38-fold; 95% confidence interval [95% CI], 4.0 to 42; P < 0.01). IL-23 secretion was also higher in cells exposed to live V. cholerae than in cells exposed to inactivated V. cholerae (mean change, 5.6-fold; 95% CI, 4.4 to 11; P < 0.001). This increase in IL-23 secretion was more marked than for other key innate immune cytokines (e.g., IL-1β and IL-6) and dependent on exposure to the combination of both live V. cholerae and CT. While IL-23 secretion was reduced following stimulation with either heat-inactivated wild-type V. cholerae or a live isogenic ctxAB mutant of V. cholerae, the addition of exogenous CT restored IL-23 secretion in combination with the live isogenic ctxAB mutant V. cholerae, but not when it was paired with stimulation by heat-inactivated V. cholerae The posttranslational regulation of IL-23 under these conditions was dependent on the activity of the cysteine protease cathepsin B. In humans, IL-23 promotes the differentiation of Th17 cells to T follicular helper cells, which maintain and support long-term memory B cell generation after infection. Based on these findings, the stimulation of IL-23 production may be a determinant of protective immunity following V. cholerae infection.IMPORTANCE An episode of cholera provides better protection against reinfection than oral cholera vaccines, and the reasons for this are still under study. To better understand this, we compared the immune responses of human cells exposed to live Vibrio cholerae with those of cells exposed to heat-killed V. cholerae (similar to the contents of oral cholera vaccines). We also compared the effects of active cholera toxin and the inactive cholera toxin B subunit (which is included in some cholera vaccines). One key immune signaling molecule, IL-23, was uniquely produced in response to the combination of live bacteria and active cholera holotoxin. Stimulation with V. cholerae that did not produce the active toxin or was killed did not produce an IL-23 response. The stimulation of IL-23 production by cholera toxin-producing V. cholerae may be important in conferring long-term immunity after cholera.

Mycobacterium bovis BCG promotes IL-10 expression by establishing a SYK/PKCα/β positive autoregulatory loop that sustains STAT3 activation

Mycobacterium ensures its survival inside macrophages and long-term infection by subverting the innate and adaptive immune response through the modulation of cytokine gene expression profiles. Different Mycobacterium species promote the expression of TGFβ and IL-10, which, at the early stages of infection, block the formation of the phagolysosome, thereby securing mycobacterial survival upon phagocytosis, and at later stages, antagonize IFNγ production and functions. Despite the key role of IL-10 in mycobacterium infection, the signal transduction pathways leading to IL-10 expression in infected macrophages are poorly understood. Here, we report that Mycobacterium bovis BCG promotes IL-10 expression and cytokine production by establishing a SYK/PKCα/β positive feedback loop that leads to STAT3 activation.

Microchip Cytometry for Multiplexed Single-Cell Protein Detection in a Low-Resource Setting toward Point of Care Diagnosis

Multiplex measurement of protein expression with the single-cell resolution has been challenging. Although a few conventional approaches including flow cytometry and immunofluorescence-based methods have been developed to detect proteins in individual cells, they are either dependent on bulky instrument or not multiplexed and high-throughput enough. Here we present a portable single-cell analysis system that is operable in a resource-limited environment. A stand-sit microchip housed in a clamp enables simple and instrument-free operation of all necessary steps, and the detection based on immunogold enhancement exonerates the reliance on fluorescence optics and electronics. The quantified sensitivity was found comparable to the conventional fluorescence approaches. We used this system to analyze five immune effector proteins and found the system is equally effective to detect those proteins in hundreds of single cells. Significant increase of cytokine protein production by THP1 monocytes was observed upon stimulation by lipopolysaccharide. Further study showed that a low-end imaging setup with low resolution can also detect signals without much loss of sensitivity. Taken together, this portable multiplex single-cell system may find broad biomedical applications in a field setting.

Gain of function in Mycobacterium bovis BCG Moreau due to loss of a transcriptional repressor

The Bacille Calmette-Guérin (BCG) vaccine comprises a family of genetically different strains derived by the loss of genomic regions (RDs) and other mutations. In BCG Moreau, loss of RD16 inactivates rv3405c^* , encoding a transcriptional repressor that negatively regulates the expression of Rv3406, an alkyl sulfatase. To evaluate the impact of this loss on the BCG and host cell viability and the cytokine profile, THP-1 cells were infected with BCG Moreau (harbouring the empty vector) and a complemented strain carrying a functional copy of rv3405c. Viability of the host cells and bacteria as well as the pattern of cytokine secretion were evaluated. Our results show that the viability of BCG Moreau is higher than that of the complemented strain in an axenic medium, suggesting a possible functional gain associated with the constitutive expression of Rv3406. Viability of the host cells did not vary significantly between recombinant strains, but differences in the profiles of the cytokine secretion (IL-1β and IL-6) were observed. Our results suggest an example of a functional gain due to gene loss contributing to the elucidation of the impact of RD16 on the physiology of BCG Moreau.

Cytokine Biomarkers Associated with Human Extra-Pulmonary Tuberculosis Clinical Strains and Symptoms

Background: The primary site of infection for Mycobacterium tuberculosis (Mtb) is the alveolar macrophages. However, Mtb can disseminate into other organs and causes extrapulmonary tuberculosis (EPTB). The diagnosis of EPTB is challenging due to relatively inaccessible infectious sites that may be paucibacillary and with clinical symptoms varying by site that are similar to those seen in other diseases. Hence, we sought to identify the expression patterns of a variety of cytokines that may be specific to EPTB from in vitro infections and in the plasma of TB patients. Methods: To define those cytokine secretions associated with EPTB, human THP-1 derived macrophages were first infected with Mtb clinical isolates from pulmonary and EPTB. Infected macrophages supernatants were harvested at different time points and cytokines known to play key roles in TB immune responses including TNF-α, IL-6, IL-10, IFN-γ, and VEGF-A were measured by ELISA. Those cytokines that were in vitro associated to EPTB were also measured in the plasma from patients with PTB, EPTB, non-EPTB-confirmed-like symptoms and healthy controls. Results: While all of the studied cytokine secretions varied after in vitro infection, higher levels of TNF-α and VEGF secretions were observed in vitro in the infected macrophages respectively in the PTB and EPTB infecting clinical isolates. Similar trends were observed from the plasma of patients where patients with PTB showed significantly higher level of TNF-α compared to EPTB and healthy control groups. The patients with EPTB showed higher plasma level of VEGF compared to those patients with the non-EPTB (p < 0.01) and to healthy controls group (p < 0.0001). Using Receiver Operating Curves (ROC), we showed that TNF-α and VEGF concentrations could distinguish EPTB from non-confirmed EPTB with high sensitivity and specificity. Conclusion: Pulmonary and extrapulmonary Mtb clinical isolates showed different cytokine induction pattern in human macrophages that is also found in the plasma level of the EPTB patients. Further investigations are needed to define cytokine secretions that can lead to the definition of bio-signatures to differentiate EPTB from other pathologies with confusing symptoms that hampered the diagnosis of TB.