43 kDa Glycoprotein (gp43) fromParacoccidioides brasiliensisInduced IL-17A and PGE2 Production by Human Polymorphonuclear Neutrophils: Involvement of TLR2 and TLR4

Abstract

The glycoprotein gp43 is the major antigenic/diagnostic component of Paracoccidioides brasiliensis, one of the etiologic agents of paracoccidioidomycosis (PCM). Gp43 has protective roles in mice, but due to adhesive properties, this glycoprotein has also been associated with immune evasion mechanisms. The present study evaluated gp43 interaction in vitro with Toll-like receptors 2 and 4 (TLR2 and TLR4) present in polymorphonuclear neutrophils (PMNs) from healthy human individuals and the consequent modulation of the immune response through the expression and release of cytokines and eicosanoids. PMNs were incubated in the absence or presence of monoclonal antibodies anti-TLR2 and anti-TLR4 (individually or in combination) before gp43 stimulation. Then, PMNs were analyzed for the expression of both surface receptors and the detection of intracytoplasmic IL-17A and IL-4 using flow cytometry, while the production of PGE2, LTB4, IL-6, IL-10, IL-12, IFN-γ, and TNF-α was evaluated in the supernatants by enzyme-linked immunosorbent assay (ELISA). Our results showed that gp43 increased TLR2 and TLR4 expression by PMNs and induced PGE2 and IL-17A via TLR4 and TLR2, respectively. Thus, our data suggest that gp43 from P. brasiliensis might modulate host susceptibility to the fungal infection by affecting PGE2 and IL-17A production.

Paracoccidioidomycosis Protective Immunity

“…A decreased expression of TLR2, TLR4 and TLR1 on monocytes and increased expression on neutrophils was also found [ 32 ]. The interaction of the immunodominant Paracoccidioides antigen gp43 with TLR2 and TLR4 neutrophils from healthy human individuals resulted in an upregulated expression of these receptors, followed by production of the inflammatory cytokine IL-17A and of the eicosanoids PGE2 and LTB4 [ 33 ]. This finding is different from that of Balderramas [ 34 ] who showed that the release of LTB4 by neutrophils did not involve TLR2 or TLR4.…”

“…The production of all Th17-associated cytokines increased in the lung and that of IL-17A increased in vitro, suggesting that Th17-associated cytokines are involved in the modulation of the immune response to Paracoccidioides [ 37 ]. Gardizan et al [ 33 ] reported that gp43-stimulated human PMNs produced IL-17. This cytokine was also produced by human monocytes from healthy individuals IL-17A after incubation with Paracoccidioides via activation of the Dectin-1 receptor [ 45 ].…”

The Role of the Interleukin-17 Axis and Neutrophils in the Pathogenesis of Endemic and Systemic Mycoses

“…On the other hand, other studies have reported that neutrophils recognize P. brasiliensis yeasts via Dectin-1, MR, TLR2, and TLR4 (Acorci-Valeŕo et al, 2010;Balderramas et al, 2014;Gardizani et al, 2019) and produce cytokines including IL-12, IL-10, PGE2, and LTB4 (Balderramas et al, 2014). Additionally, these interactions were able to induce NETs formation by either dependent or independent reactive oxygen species production, correlating with the fungal morphotype used for stimulation (conidia or yeast, respectively); however, the killing of the fungus by NETs was dependent on the fungal strain and previous activation by cytokines, including TNF-a, IFN-g, and GM-CSF.…”

“…Conversely, in vitro studies showed that neutrophils primed with the 43kDa glycoprotein (gp43) from P. brasiliensis express higher levels of TLR2 and IL-17 (Gardizani et al, 2019). It is noteworthy that MyD88 (the adaptor molecule used by TLRs) is required to mount an efficient innate and adaptive immune response; thus, MyD88 deficient mice showed an association between disease severity and reduced Th17 response and IL-1b production (Loures et al, 2011).…”

“…• IL-8 production inhibits apoptosis and allows fungal replication • Paracoccin induces: IL-8, IL-1b, ROS production, DNA release and inhibit apoptosis • Phagocytic cells primed with IFN-g, IL-1b, GM-CSF, TNF-a, and IL-15 exhibit antifungal activity and trigger respiratory burst • Host genetic background influences their immunoregulatory functions • Puerta-Arias et al, 2018• Mejıá et al, 2015Della-Coletta et al, 2015;Bachiega et al, 2016• Acorci-Valeŕio et al, 2010Balderramas et al, 2014;Gardizani et al, 2019• Balderramas et al, 2014• Acorci et al, 2008• Ricci-Azevedo et al, 2018• Kurita et al, 2000Tavian et al, 2007;Rodrigues et al, 2007• Pina et al, 2006Sperandio et al, 2015 dermatitidis has been demonstrated (Brummer and Stevens, 1984;Brummer et al, 1986;Morrison et al, 1989), some reports have shown that neutrophils enhance and allow the replication of this fungal pathogen, a fact that was associated with an exacerbation of the infection by accumulation and death of neutrophils in the tissue lesions (Brummer and Stevens, 1983). In this sense, the presence of a fungal chemotactic factor in serum-free culture filtrated of B. dermatitidis has been demonstrated (Sixbey et al, 1979;Thurmond and Mitchell, 1984).…”