Interleukin-4 inhibits an early phase in the HIV-1 life cycle in the human colorectal cell line HT-29

Interleukin-4 Promotes Human Metapneumovirus Replication Through the JAK/STAT6 Pathway

Respiratory virus infections are the main causes of pediatric diseases. Human metapneumovirus (hMPV) is an enveloped RNA virus similar to severe acute respiratory syndrome coronavirus type 2, both of which have emerged as important new respiratory viruses. Recent studies have found that interleukin-4 (IL-4) is involved in the replication of a variety of viruses, and its role differs in different viruses. The purpose of this study was to investigate the effect of IL-4 on hMPV and to elucidate its mechanism of action. We found that hMPV infection promoted the expression of IL-4 in human bronchial epithelial cells. The replication of the virus was reduced using small interfering RNA knockdown of IL-4 expression, while the addition of exogenous recombinant human IL-4 to IL-4 knockdown cells restored viral replication ability. These results demonstrate that the expression of IL-4 is closely related to the replication of hMPV; moreover, further experiments revealed that IL-4 promotes the replication of hMPV through a mechanism dependent on the Janus kinase/signal transductor and transcription activator 6 signaling pathway. Therefore, anti-IL-4 strategies may be a promising avenue for the treatment of hMPV infection, representing an important breakthrough for children at risk from hMPV infection.

IL-17A reprograms intestinal epithelial cells to facilitate HIV-1 replication and outgrowth in CD4+ T cells

The crosstalk between intestinal epithelial cells (IECs) and Th17-polarized CD4⁺ T cells is critical for mucosal homeostasis, with HIV-1 causing significant alterations in people living with HIV (PLWH) despite antiretroviral therapy (ART). In a model of IEC and T cell co-cultures, we investigated the effects of IL-17A, the Th17 hallmark cytokine, on IEC ability to promote de novo HIV infection and viral reservoir reactivation. Our results demonstrate that IL-17A acts in synergy with TNF to boost IEC production of CCL20, a Th17-attractant chemokine, and promote HIV trans-infection of CD4⁺ T cells and viral outgrowth from reservoir cells of ART-treated PLWH. Importantly, the Illumina RNA-sequencing revealed an IL-17A-mediated pro-inflammatory and pro-viral molecular signature, including a decreased expression of type I interferon (IFN-I)-induced HIV restriction factors. These findings point to the deleterious features of IL-17A and raise awareness for caution when designing therapies aimed at restoring the paucity of mucosal Th17 cells in ART-treated PLWH.

•

IL-17A acts in synergy with TNF to enhance CCL20 production in IEC exposed to HIV

•

IL-17A/TNF-activated IEC efficiently promote HIV trans-infection of CD4⁺ T cells

•

IL-17A reprograms IEC to boost HIV outgrowth from CD4⁺ T cells of ART-treated PLWH

•

IL-17A decreases the expression of IFN-I-induced HIV restriction factors in IEC

Overt IL-32 isoform expression at intestinal level during HIV-1 infection is negatively regulated by IL-17A

OBJECTIVES

Untreated HIV infection was previously associated with IL-32 overexpression in gut/intestinal epithelial cells (IEC). Here, we explored IL-32 isoform expression in the colon of people with HIV (PWH) receiving antiretroviral therapy (ART) and IL-32 triggers/modulators in IEC.

DESIGN

Sigmoid colon biopsies (SCB) and blood were collected from ART-treated PWH (HIV + ART; n = 17; mean age: 56 years; CD4+ cell counts: 679 cells/μl; time on ART: 72 months) and age-matched HIV-uninfected controls (HIVneg; n = 5). The IEC line HT-29 was used for mechanistic studies.

METHODS

Cells from SCB and blood were isolated by enzymatic digestion and/or gradient centrifugation. HT-29 cells were exposed to TLR1-9 agonists, TNF-α, IL-17A and HIV. IL-32α/β/γ/D/ε/θ and IL-17A mRNA levels were quantified by real-time RT-PCR. IL-32 protein levels were quantified by ELISA.

RESULTS

IL-32β/γ/ε isoform transcripts were detectable in the blood and SCB, with IL-32β mRNA levels being predominantly expressed in both compartments and at significantly higher levels in HIV + ART compared to HIVneg. IL-17A transcripts were only detectable in SCB, with increased IL-17A levels in HIVneg compared with HIV + ART and negatively correlated with IL-32β mRNA levels. IL-32β/γ/ε isoform mRNA were detected in HT-29 cells upon exposure to TNF-α, Poly I:C (TLR3 agonist), Flagellin (TLR-5 agonist) and HIV. IL-17A significantly decreased both IL-32 β/γ/ε mRNA and cell-associated IL-32 protein levels induced upon TNF-α and Poly I:C triggering.

CONCLUSION

We document IL-32 isoforms abundant in the colon of ART-treated PWH and reveal the capacity of the Th17 hallmark cytokine IL-17A to attenuate IL-32 overexpression in a model of inflamed IEC.

Differential levels of soluble inflammatory markers by human immunodeficiency virus controller status and demographics

Background. Human immunodeficiency virus (HIV)-1 elite controllers (ECs) represent an ideal population to study the effects of HIV persistence on chronic inflammation in the absence of antiretroviral therapy (ART).

Methods. Twenty inflammatory markers measured in cohorts of ECs, HIV suppressed noncontrollers, and HIV-uninfected controls were compared using rank-based tests and partial least squares discriminant analysis (PLSDA). Spearman correlations were determined among the inflammatory markers, residual viremia by the single-copy assay, and CD4⁺ T cell slope.

Results. Significant differences were seen between cohorts in 15 of the soluble inflammatory markers. Human immunodeficiency virus-1 ECs were found to have the highest levels for all of the markers with the exception of RANTES. In particular, median levels of 7 inflammatory markers (soluble CD14 [sCD14], interferon [IFN]-γ, IFN-γ-inducible protein [IP]-10, interleukin [IL]-4, IL-10, sCD40L, and granulocyte-macrophage colony-stimulating factor) were twice as high in the HIV-1 ECs compared with either of the HIV-suppressed or uninfected groups. Multivariate PLSDA analysis of inflammatory markers improved differentiation between the patient cohorts, discerning gender differences in inflammatory profile amongst individuals on suppressive ART. Soluble markers of inflammation in ECs were not associated with either levels of residual HIV-1 viremia or CD4⁺ T cell decline.

Conclusions. Despite maintaining relatively low levels of viremia, HIV-1 ECs had elevated levels of a set of key inflammatory markers. Additional studies are needed to determine whether ECs may benefit from ART and to further evaluate the observed gender differences.

Cholera toxin inhibits HIV-1 replication in human colorectal epithelial HT-29 cells through adenylate cyclase activation

Mixed feeding, combining breast milk and nonhuman milk and/or solid food, is a common practice in developing countries that increases the risk of vertical HIV-1 transmission. It also enhances the risk of infection by waterborne microorganisms such as Vibrio cholerae, a diarrhoea-causing pathogen that frequently infects children below 18 months of age. Although both HIV-1 and V. cholerae affect young children and target intestinal epithelial cells, no information is currently available on possible interactions between these two pathogens. In this study, we show for the first time that cholera toxin (CTx), at a concentration as low as 100 pg/ml, inhibits HIV-1 infection of HT-29, a human colorectal epithelial cell line. The CTx-mediated inhibitory effect does not result from a down-regulation of receptor/co-receptor expression or a modulation of viral transcription. Nevertheless, additional experiments indicate that a yet to be identified early step in the virus life cycle is targeted by CTx since the enterotoxin similarly reduces infection of HT-29 cells with AMLV-I, HTLV-I and HIV-1 pseudotyped viruses while exerting no effect on infection with VSV-G pseudotypes. Furthermore, our results indicate that the CTx-dependent suppression is not due to the cholera toxin subunit B but linked instead to the action of cholera toxin subunit A (CTA). Altogether our data indicate that the CTA subunit of CTx is negatively affecting an early event in HIV-1 replication in human colon cancer HT-29 cells.