Paracoccidioides species present distinct fungal adherence to epithelial lung cells and promote different IL-8 secretion levels

Paracoccidioides brasiliensis Induces α3 Integrin Lysosomal Degradation in Lung Epithelial Cells

Studies on the pathogen-host interaction are crucial for the understanding of the mechanisms involved in the establishment, maintenance, and spread of infection. In recent years, our research group has observed that the P. brasiliensis species interact with integrin family receptors and increase the expression of α3 integrin in lung epithelial cells within 5 h of infection. Interestingly, α3 integrin levels were reduced by approximately 99% after 24 h of infection with P. brasiliensis compared to non-infected cells. In this work, we show that, during infection with this fungus, α3 integrin is increased in the late endosomes of A549 lung epithelial cells. We also observed that the inhibitor of the lysosomal activity bafilomycin A1 was able to inhibit the decrease in α3 integrin levels. In addition, the silencing of the charged multivesicular body protein 3 (CHMP3) inhibited the reduction in α3 integrin levels induced by P. brasiliensis in A549 cells. Thus, together, these results indicate that this fungus induces the degradation of α3 integrin in A549 lung epithelial cells by hijacking the host cell endolysosomal pathway.

Alginate-Based 3D A549 Cell Culture Model to Study Paracoccidioides Infection

A three-dimensional (3D) lung aggregate model based on sodium alginate scaffolds was developed to study the interactions between Paracoccidioides brasiliensis (Pb) and lung epithelial cells. The suitability of the 3D aggregate as an infection model was examined using cell viability (cytotoxicity), metabolic activity, and proliferation assays. Several studies exemplify the similarity between 3D cell cultures and living organisms, which can generate complementary data due to the greater complexity observed in these designed models, compared to 2D cell cultures. A 3D cell culture system of human A549 lung cell line plus sodium alginate was used to create the scaffolds that were infected with Pb18. Our results showed low cytotoxicity, evidence of increased cell density (indicative of cell proliferation), and the maintenance of cell viability for seven days. The confocal analysis revealed viable yeast within the 3D scaffold, as demonstrated in the solid BHI Agar medium cultivation. Moreover, when ECM proteins were added to the alginate scaffolds, the number of retrieved fungi was significantly higher. Our results highlight that this 3D model may be promising for in vitro studies of host-pathogen interactions.

Human Airway Epithelium Responses to Invasive Fungal Infections: A Critical Partner in Innate Immunity

The lung epithelial lining serves as the primary barrier to inhaled environmental toxins, allergens, and invading pathogens. Pulmonary fungal infections are devastating and carry high mortality rates, particularly in those with compromised immune systems. While opportunistic fungi infect primarily immunocompromised individuals, endemic fungi cause disease in immune competent and compromised individuals. Unfortunately, in the case of inhaled fungal pathogens, the airway epithelial host response is vastly understudied. Furthering our lack of understanding, very few studies utilize primary human models displaying pseudostratified layers of various epithelial cell types at air-liquid interface. In this review, we focus on the diversity of the human airway epithelium and discuss the advantages and disadvantages of oncological cell lines, immortalized epithelial cells, and primary epithelial cell models. Additionally, the responses by human respiratory epithelial cells to invading fungal pathogens will be explored. Future investigations leveraging current human in vitro model systems will enable identification of the critical pathways that will inform the development of novel vaccines and therapeutics for pulmonary fungal infections.

Cytokines help suggest aplastic anemia with pulmonary bacterial or co-fungal infection

Although aplastic anemia (AA) does not come under the category of blood malignant diseases, the infection that frequently occurs in this bone marrow failure can make it worse. Pulmonary infection is the most prevalent but limiting clinical diagnosis. To find biomarkers predicting bacterial or bacterial-combined fungal infections in the lungs, we reviewed 287 AA medical records including 151 without any infection, 87 with pure pulmonary bacterial infection, and 49 with bacterial and fungal infection were reviewed. There were substantial changes in IL-17F, IL-17A, IFN-γ, IL-6, IL-8, and IL-10 levels between the non-infected and lung bacterial infection groups (P < 0.05). Further, a significant variation in IL-17A, TNF-β, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-22, and IL-12p70, between the uninfected group and the pulmonary bacterial and fungal infection group (P < 0.05) was observed. The results further revealed significant differences in TNF-β, IL-12p70, IL-6, IL-8, and IL-10 between the pulmonary bacterial infection group and the fungal infection group (P < 0.05). Moreover, by calculating ROC and cut-off values, we determined that IL-6 (AUC = 0.98, Cut-off = 14.28 pg/ml, P = 0.0000) had a significant advantage than other cytokines, body temperature (AUC = 0.61, P = 0.0050), PCT (AUC = 0.57, P = 0.0592), and CRP (AUC = 0.60, P = 0.0147) in the detection of lungs bacterial infections. In addition, IL-6 (AUC = 1.00, Cut-off = 51.50 pg/ml, P = 0.000) and IL-8 (AUC = 0.87, Cut-off = 60.53 pg/ml, P = 0.0000) showed stronger advantages than other cytokines, body temperature (AUC = 0.60, P = 0.0324), PCT (AUC = 0.72, Cut-off = 0.63 ng/ml, P = 0.0000) and CRP (AUC = 0.79, Cut-off = 5.79 mg/l, P = 0.0000) in distinguishing bacteria from fungi. This may suggest that IL-8 may play a role in differentiating co-infected bacteria and fungi. Such advantages are repeated in severe aplastic anemia (SAA) and very severe aplastic anemia (VSAA).In conclusion, aberrant IL-6 elevations in AA patients may predict the likelihood of bacterial lung infection. The concurrent increase of IL-6 and IL-8, on the other hand, should signal bacterial and fungal infections in patients.These findings may help to suggest bacterial or fungal co-infection in patients with AA (Focus on VSAA and SAA).

Respiratory Epithelial Cells: More Than Just a Physical Barrier to Fungal Infections

The respiratory epithelium is highly complex, and its composition varies along the conducting airways and alveoli. In addition to their primary function in maintaining the respiratory barrier and lung homeostasis for gas exchange, epithelial cells interact with inhaled pathogens, which can manipulate cell signaling pathways, promoting adhesion to these cells or hosting tissue invasion. Moreover, pathogens (or their products) can induce the secretion of chemokines and cytokines by epithelial cells, and in this way, these host cells communicate with the immune system, modulating host defenses and inflammatory outcomes. This review will focus on the response of respiratory epithelial cells to two human fungal pathogens that cause systemic mycoses: Aspergillus and Paracoccidioides. Some of the host epithelial cell receptors and signaling pathways, in addition to fungal adhesins or other molecules that are responsible for fungal adhesion, invasion, or induction of cytokine secretion will be addressed in this review.

Paracoccidioides brasiliensis downmodulates α3 integrin levels in human lung epithelial cells in a TLR2-dependent manner

Paracoccidioidomycosis (PCM) is the most prevalent systemic mycosis in Latin America and may be caused by the species Paracoccidioides brasiliensis. In the lungs, this fungus interacts with epithelial cells, activating host cell signalling pathways, resulting in the production of inflammatory mediators. This event may be initiated through the activation of Pattern-Recognition Receptors such as Toll-like Receptors (TLRs). By interacting with cell wall components, TLR2 is frequently related to fungal infections. In this work, we show that, after 24 h post-infection with P. brasiliensis, A549 lung epithelial cells presented higher TLR2 levels, which is important for IL-8 secretion. Besides, integrins may also participate in pathogen recognition by host cells. We verified that P. brasiliensis increased α3 integrin levels in A549 cells after 5 h of infection and promoted interaction between this receptor and TLR2. However, after 24 h, surprisingly, we verified a decrease of α3 integrin levels, which was dependent on direct contact between fungi and epithelial cells. Likewise, we observed that TLR2 is important to downmodulate α3 integrin levels after 24 h of infection. Thus, P. brasiliensis can modulate the host inflammatory response by exploiting host cell receptors and cell signalling pathways.

Time-series clustering of cytokine expression after transarterial chemoembolization in patients with hepatocellular carcinoma

Cytokines play an important role in the development of tumors. The purpose of the present study was to evaluate the mechanisms and cytokine level changes after transarterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC). The Short Time-series Expression Miner (STEM) program was utilized to cluster cytokine expression profiles from the day before TACE to day 21 post-TACE. Based on the identified significant signatures, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed. Cytokines were serially monitored in 60 evaluable patients to identify the results of the STEM program. Examination of the significant signatures identified 6 significant time-varied expression patterns for 507 cytokines (profiles 16, 18, 28, 41, 42 and 43). GO analysis was enriched in 'cytokine receptor-binding' and 'cytokine receptor activity', and the identified signaling pathways included 'cytokine-cytokine receptor interaction' and the 'JAK-STAT signaling pathway'. Ciliary neurotrophic factor (CNTF) level was increased early after TACE, reaching a peak on day 7 before finally decreasing from day 14 onwards, and was significantly positively correlated with aminotransferase level. Serum levels of pre-TACE IL-10 predicted the local tumor response and overall survival (OS) of the patients, while serum levels of post-TACE IL-1β only indicated the local tumor response of the patient. Overall, the present study identified cytokine time-series expression profiles of patients with HCC undergoing TACE. Early phase increases in CNTF after TACE were associated with post-treatment hepatic injury. IL-1β may reflect an objective response after TACE, while IL-10 may represent a biomarker for OS and the objective response pre-TACE, which may help patients with HCC to benefit from TACE.