Toxoplasma gondii ROP18I inhibits host innate immunity through cGAS-STING signaling.

Toxoplasma gondii is an opportunistic protozoan, which widely infects humans and other warm-blooded animals. The type I interferon (IFN) such as IFN-α/ß is involved in cGAS-STING signaling to resist T. gondii infection. We found in RAW264.7 cells, that T. gondii virulence factor TgROP18I , inhibited IFN-ß production through interacting with interferon regulatory factor 3 (IRF3). Besides, TgROP18I interacted with p62 and Tumor Necrotic Factor Receptor Associated Factor 6 (TRAF6), which resulted in the inhibition of TRAF6-p62 interaction, and phosphorylation of p62. Furthermore, TgROP18I restricted the recruitment of ubiquitin, p62 and microtubule-associated protein light chain 3 (LC3) to the parasitophorous vacuole membrane (PVM) in IFN-γ-stimulated murine cell line L929 cells. In IFN-γ-stimulated human cells, TgROP18I restricted the decoration of PVM with ubiquitin, p62, and LC3, and bound with TRAF2, TRAF6, and p62, respectively. As a result, TgROP18I led to a successful parasitic replication in murine and human cells. Collectively, our study revealed the function of TgROP18I in suppressing host type I interferon responses in T. gondii infection for parasitic immune escape.

Altered increase in STAT1 expression and phosphorylation in severe COVID-19.

The interferon pathway, a key antiviral defense mechanism, is being considered as a therapeutic target in COVID-19. Both, substitution of interferon and JAK/STAT inhibition to limit cytokine storms have been proposed. However, little is known about possible abnormalities in STAT signaling in immune cells during SARS-CoV-2 infection. We investigated downstream targets of interferon signaling, including STAT1, STAT2, pSTAT1 and 2, and IRF1, 7 and 9 by flow cytometry in 30 patients with COVID-19, 17 with mild, and 13 with severe infection. We report upregulation of STAT1 and IRF9 in mild and severe COVID-19 cases, which correlated with the IFN-signature assessed by Siglec-1 (CD169) expression on peripheral monocytes. Interestingly, Siglec-1 and STAT1 in CD14+ monocytes and plasmablasts showed lower expression among severe cases compared to mild cases. Contrary to the baseline STAT1 expression, the phosphorylation of STAT1 was enhanced in severe COVID-19 cases, indicating a dysbalanced JAK/STAT signaling that fails to induce transcription of interferon stimulated response elements (ISRE). This abnormality persisted after IFN-α and IFN-γ stimulation of PBMCs from patients with severe COVID-19. Data suggest impaired STAT1 transcriptional upregulation among severely infected patients may represent a potential predictive biomarker and would allow stratification of patients for certain interferon-pathway targeted treatments.

Exploiting the STAT3 Nexus in Cancer-Associated Fibroblasts to Improve Cancer Therapy.

The tumor microenvironment (TME) is composed of a heterogenous population of cells that exist alongside the extracellular matrix and soluble components. These components can shape an environment that is conducive to tumor growth and metastatic spread. It is well-established that stromal cancer-associated fibroblasts (CAFs) in the TME play a pivotal role in creating and maintaining a growth-permissive environment for tumor cells. A growing body of work has uncovered that tumor cells recruit and educate CAFs to remodel the TME, however, the mechanisms by which this occurs remain incompletely understood. Recent studies suggest that the signal transducer and activator of transcription 3 (STAT3) is a key transcription factor that regulates the function of CAFs, and their crosstalk with tumor and immune cells within the TME. CAF-intrinsic STAT3 activity within the TME correlates with tumor progression, immune suppression and eventually the establishment of metastases. In this review, we will focus on the roles of STAT3 in regulating CAF function and their crosstalk with other cells constituting the TME and discuss the utility of targeting STAT3 within the TME for therapeutic benefit.

Ghrelin Alleviates Endoplasmic Reticulum Stress in MC3T3E1 Cells by Inhibiting AMPK Phosphorylation.

Ghrelin is a gastric endocrine peptide that has been found to be involved in the process of energy homeostasis and bone physiology in recent years. To explore the effects of ghrelin on endoplasmic reticulum stress (ERS) in MC3T3E1 cells and its possible mechanism, an ERS model was induced by tunicamycin (TM) in the osteoblast line MC3T3E1. TM at 1.5 µg/mL was selected as the experimental concentration found by CCK8 assay. Through the determination of apoptosis, reactive oxygen species production, and endoplasmic reticulum stress-related gene expression, we found that ERS induced by TM can be relieved by ghrelin in a concentration-dependent manner (P < 0.001). Compared with the TM group, ghrelin reduced the expression of ERS-related marker genes induced by TM. Compared with the GSK621 + TM group without ghrelin pretreatment, the mRNA expression of genes in the ghrelin pretreatment group decreased significantly (P < 0.001). The results of protein analysis showed that the levels of BIP, p-AMPK, and cleaved-caspase3 in the TM group increased significantly, while the levels decreased after ghrelin pretreatment. In group GSK621 + TM compared with group GSK621 + ghrelin+TM, ghrelin pretreatment significantly reduced the level of p-AMPK, which is consistent with the trend of the ERS-related proteins BIP and cleaved-caspase3. In conclusion, ghrelin alleviates the ERS induced by TM in a concentration-dependent manner and may or at least partly alleviate the apoptosis induced by ERS in MC3T3E1 cells by inhibiting the phosphorylation of AMPK.

TNFAIP3-upregulated RIP3 exacerbates acute pancreatitis via activating NLRP3 inflammasome.

Acute pancreatitis (AP) is an inflammatory disease of the pancreas. Accumulating studies have revealed the involvement of tumor necrosis factor alpha-induced protein 3 (TNFAIP3) in the progression of AP. Here, the current study was conducted to elucidate the role of TNFAIP3 and the underlying molecular mechanisms on the progression of AP. The in vivo animal model and in vitro cell model of AP were generated by retrograde injection of sodium taurocholate and stimulation of cerulein into AR42J cells, respectively. Relationships among TNFAIP3, receptor interacting protein 3 (RIP3) and nod-like receptor protein 3 (NLRP3) were predicted on bioinformatics websites and verified by co-immunoprecipitation. AR42J cells were transfected with overexpressing plasmid or shRNA to study the effects of TNFAIP3/RIP3/NLRP3 axis on cell proliferation and apoptosis, secretion of inflammatory cytokines and production of ROS. The effect of TNFAIP3/RIP3/NLRP3 axis in AP was further confirmed in vivo. High expression of TNFAIP3 was observed in AP pancreatic tissues and AP cell model. TNFAIP3 increased RIP phosphorylation through deubiquitination. RIP activated the NLRP3 inflammasome. Silencing of TNFAIP3 or RIP3T led to elevated proliferation and inhibited apoptosis in AR42J cells, accompanied by decreased inflammatory cytokine levels and ROS production. The protective role of inhibited TNFAIP3 in AP was confirmed evidenced by reduced levels of AMY, LIPA, and ROS in vivo. Collectively, overexpressed TNFAIP3 could contribute to the progression of AP by activating RIP3/NLRP3 axis, providing a potential therapeutic target for AP treatment.

The MAPK dual specific phosphatase (DUSP) proteins: A versatile wrestler in T cell functionality.

The functional state of T cells is diverse and under dynamic control for adapting to the changes of microenvironment. Reversible protein phosphorylation represents an important post-translational modification that not only involves in the immediate early response of T cells, but also affects their functionality in the long run. Perturbation of global phosphorylation profile and/or phosphorylation of specific signaling nodes result in aberrant T cell activity. Dual specific phosphatases (DUSPs), which target MAPKs and beyond, have increasingly been emerged as a versatile regulator in T cell biology. Herein in this mini review, we sought to summarize and discuss the impact of DUSP proteins on the regulation of effector T cell activity, T cell polarization, regulatory T cell development and T cell senescence/exhaustion. Given the distinctive engagement of each DUSP member under various disease settings such as chronic infection, autoimmune disorders, cancer and age-related diseases, DUSP proteins likely hold the promise to become a druggable target other than the existing therapeutics that are predominantly by manipulating protein kinase activity.

The Migration of Human Follicular Dendritic Cell-Like Cell Is Facilitated by Matrix Metalloproteinase 3 Expression That Is Mediated through TNFα-ERK1/2-AP1 Signaling.

Follicular dendritic cells are important stromal components of the germinal center (GC) and have pivotal roles in maintaining the GC microenvironment for high-affinity antibody production. Tumor necrosis factor-α (TNFα) is essential for the development and functions of follicular dendritic cells. Despite the importance of follicular dendritic cells in humoral immunity, their molecular control mechanisms have yet to be fully elucidated due to the lack of an adequate investigation system. Here, we have used a unique human primary follicular dendritic cell-like cell (FDCLC) to demonstrate that the migration of these cells is enhanced by TNFα-mediated metalloproteinase 3 (MMP3) expression. MMP3 was found to be highly expressed in normal human GCs and markedly upregulated in human primary FDCLCs by TNFα. TNFα induced ERK1/2 phosphorylation and the transcription of MMP3 through AP1. TNFα treatment increased FDCLC migration, and a knockdown of MMP3 significantly reduced the TNFα-induced migration of FDCLCs. Overall, we have newly identified a control mechanism for the expression of MMP3 in FDCLCs that modulates their migration and may indicate an important role in GC biology. Since GCs are observed in the lesions of autoimmune diseases and lymphomas, targeting the MMP3/TNFα-mediated migration of stromal cells in the B cell follicle may have great potential as a future therapeutic modality against aberrant GC-associated disorders.

Central Nervous System-Infecting Pathogens Escherichia coli and Cryptococcus neoformans Exploit the Host Pdlim2 for Intracellular Traversal and Exocytosis in the Blood-Brain Barrier.

Microbial penetration of the blood-brain barrier, a prerequisite for the development of central nervous system (CNS) infection, involves microbial invasion, intracellular traversal, and exocytosis. Microbial invasion of the blood-brain barrier has been investigated, but the molecular basis for microbial traversal and exit from the blood-brain barrier remains unknown. We performed transcriptome analysis of human brain microvascular endothelial cells (HBMEC) infected with Escherichia coli and Cryptococcus neoformans, representative bacterial and fungal pathogens common in CNS infections. Among the targets upregulated in response to E. coli and C. neoformans infection, PDLIM2 was knocked down by small hairpin RNA (shRNA) in HBMEC for further investigation. We demonstrated that Pdlim2 specifically regulated microbial traversal and exit from HBMEC by assessing microbial invasion, transcytosis, intracellular multiplication, and egression. Additionally, the defective exocytosis of internalized E. coli cells from the PDLIM2 shRNA knockdown cells was restored by treatment with a calcium ionophore (ionomycin). Moreover, we performed proximity-dependent biotin labeling with the biotin ligase BioID2 and identified 210 potential Pdlim2 interactors. Among the nine Pdlim2 interactors enriched in response to both E. coli and C. neoformans infection, we selected MPRIP and showed that HBMEC with knockdown of MPRIP mimicked the phenotype of PDLIM2 knockdown cells. These results suggest that the CNS-infecting microbes hijack Pdlim2 and Mprip for intracellular traversal and exocytosis in the blood-brain barrier.

Protectin D1 reduces imiquimod-induced psoriasiform skin inflammation.

Specialized proresolving mediators are enzymatically oxygenated natural molecules derived from polyunsaturated fatty acids and are considered novel. These novel mediators include lipoxins from arachidonic acid, resolvins and protectins from omega-3 essential fatty acids, and new maresins. These mediators harbor potent dual proresolving and anti-inflammatory properties. Resolvins and protectins are known to be potent when administered to various inflammation-associated animal models of human diseases. Although psoriasis' etiology remains unknown, there is accumulating evidence indicating that cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-23, and IL-17, play pivotal roles in its development. Experimentally, resolvins, maresins, and lipoxins downregulate the cytokine expression of the IL-23/IL-17 axis and inhibition of mitogen-activated protein kinases and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) cell signaling transduction pathways. Here, we assessed the effects of protectin D1 (PD1) on imiquimod (IMQ)-induced psoriasiform skin inflammation and keratinocytes. PD1 showed clinical improvement in skin thickness, redness, and scaling in psoriasis mouse models. Moreover, PD1 decreased IL-1ß, IL-6, IL-17, and CXCL1 mRNA expressions and reduced STAT1 and NF-κB signaling pathway activation in lesions. Serum myeloperoxidase, IgG2a, IL-1ß, IL-6, IL-17, and TNF-α and spleen CD4+IFN-γ+IL-17+ T lymphocytes were reduced after PD1 treatment in IMQ-induced psoriasiform mouse models. In addition, IL-1ß, IL-6, IL-8, and IL-18BP gene expressions were decreased in PD1-treated keratinocytes. Moreover, a decrease in the expression levels of CCL17 and IL-6 and an inhibition of the STAT1 and NF-κB signaling transduction pathways was observed in keratinocytes. These PD1 anti-inflammatory effects suggest that it is a good therapeutic candidate for psoriasis.

Role of IL-6-IL-27 Complex in Host Antiviral Immune Response.

The IL family of cytokines participates in immune response and regulation. We previously found that soluble IL-6 receptor plays an important role in the host antiviral response. In this study, we detected the IL-6-IL-27 complex in serum and throat swab samples from patients infected with influenza A virus. A plasmid expressing the IL-6-IL-27 complex was constructed to explore its biological function. The results indicated that the IL-6-IL-27 complex has a stronger antiviral effect than the individual subunits of IL-6, IL-27A, and EBV-induced gene 3. Furthermore, the activity of the IL-6-IL-27 complex is mainly mediated by the IL-27A subunit and the IL-27 receptor α. The IL-6-IL-27 complex can positively regulate virus-triggered expression of IFN and IFN-stimulated genes by interacting with adaptor protein mitochondrial antiviral signaling protein, potentiating the ubiquitination of TNF receptor-associated factors 3 and 6 and NF-κB nuclear translocation. The secreted IL-6-IL-27 complex can induce the phosphorylation of STAT1 and STAT3 and shows antiviral activity. Our results demonstrate a previously unrecognized mechanism by which IL-6, IL-27A, and EBV-induced gene 3 form a large complex both intracellularly and extracellularly, and this complex acts in the host antiviral response.

CD45 pre-exclusion from the tips of T cell microvilli prior to antigen recognition.

The tyrosine phosphatase CD45 is a major gatekeeper for restraining T cell activation. Its exclusion from the immunological synapse (IS) is crucial for T cell receptor (TCR) signal transduction. Here, we use expansion super-resolution microscopy to reveal that CD45 is mostly pre-excluded from the tips of microvilli (MV) on primary T cells prior to antigen encounter. This pre-exclusion is diminished by depleting cholesterol or by engineering the transmembrane domain of CD45 to increase its membrane integration length, but is independent of the CD45 extracellular domain. We further show that brief MV-mediated contacts can induce Ca2+ influx in mouse antigen-specific T cells engaged by antigen-pulsed antigen presenting cells (APC). We propose that the scarcity of CD45 phosphatase activity at the tips of MV enables or facilitates TCR triggering from brief T cell-APC contacts before formation of a stable IS, and that these MV-mediated contacts represent the earliest step in the initiation of a T cell adaptive immune response.

SARS-CoV-2 viral proteins NSP1 and NSP13 inhibit interferon activation through distinct mechanisms.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a devastating global pandemic, infecting over 43 million people and claiming over 1 million lives, with these numbers increasing daily. Therefore, there is urgent need to understand the molecular mechanisms governing SARS-CoV-2 pathogenesis, immune evasion, and disease progression. Here, we show that SARS-CoV-2 can block IRF3 and NF-κB activation early during virus infection. We also identify that the SARS-CoV-2 viral proteins NSP1 and NSP13 can block interferon activation via distinct mechanisms. NSP1 antagonizes interferon signaling by suppressing host mRNA translation, while NSP13 downregulates interferon and NF-κB promoter signaling by limiting TBK1 and IRF3 activation, as phospho-TBK1 and phospho-IRF3 protein levels are reduced with increasing levels of NSP13 protein expression. NSP13 can also reduce NF-κB activation by both limiting NF-κB phosphorylation and nuclear translocation. Last, we also show that NSP13 binds to TBK1 and downregulates IFIT1 protein expression. Collectively, these data illustrate that SARS-CoV-2 bypasses multiple innate immune activation pathways through distinct mechanisms.

Uncovering a novel role of PLCß4 in selectively mediating TCR signaling in CD8+ but not CD4+ T cells.

Because of their common signaling molecules, the main T cell receptor (TCR) signaling cascades in CD4+ and CD8+ T cells are considered qualitatively identical. Herein, we show that TCR signaling in CD8+ T cells is qualitatively different from that in CD4+ T cells, since CD8α ignites another cardinal signaling cascade involving phospholipase C ß4 (PLCß4). TCR-mediated responses were severely impaired in PLCß4-deficient CD8+ T cells, whereas those in CD4+ T cells were intact. PLCß4-deficient CD8+ T cells showed perturbed activation of peripheral TCR signaling pathways downstream of IP3 generation. Binding of PLCß4 to the cytoplasmic tail of CD8α was important for CD8+ T cell activation. Furthermore, GNAQ interacted with PLCß4, mediated double phosphorylation on threonine 886 and serine 890 positions of PLCß4, and activated CD8+ T cells in a PLCß4-dependent fashion. PLCß4-deficient mice exhibited defective antiparasitic host defense and antitumor immune responses. Altogether, PLCß4 differentiates TCR signaling in CD4+ and CD8+ T cells and selectively promotes CD8+ T cell-dependent adaptive immunity.

MiT Family Transcriptional Factors in Immune Cell Functions.

The microphthalmia-associated transcription factor family (MiT family) proteins are evolutionarily conserved transcription factors that perform many essential biological functions. In mammals, the MiT family consists of MITF (microphthalmia-associated transcription factor or melanocyte-inducing transcription factor), TFEB (transcription factor EB), TFE3 (transcription factor E3), and TFEC (transcription factor EC). These transcriptional factors belong to the basic helix-loop-helix-leucine zipper (bHLH-LZ) transcription factor family and bind the E-box DNA motifs in the promoter regions of target genes to enhance transcription. The best studied functions of MiT proteins include lysosome biogenesis and autophagy induction. In addition, they modulate cellular metabolism, mitochondria dynamics, and various stress responses. The control of nuclear localization via phosphorylation and dephosphorylation serves as the primary regulatory mechanism for MiT family proteins, and several kinases and phosphatases have been identified to directly determine the transcriptional activities of MiT proteins. In different immune cell types, each MiT family member is shown to play distinct or redundant roles and we expect that there is far more to learn about their functions and regulatory mechanisms in host defense and inflammatory responses.

Cytosolic d-type CpG-oligonucleotides induce a type I interferon response by activating the cGAS-STING signaling pathway.

Cytosolic DNA receptor cyclic GMP-AMP (cGAMP) synthase (cGAS) has been shown to be critically involved in the detection of cytosolic, self- and non-self-DNA, initiating a type I IFN response through the adaptor protein Stimulator of Interferon Genes (STING) and interferon regulatory factor 3 (IRF3). Current studies propose that canonical binding of dsDNA by cGAS depends on DNA length, but not on base sequence. In contrast, activation of TLR9 is sequence dependent. It requires unmethylated CpG dinucleotides in microbial DNA, which is mimicked by synthetic oligodeoxynucleotides (ODN). Here, we provide evidence that d-type ODN (D-ODN), but not K-type ODN (K-ODN), bind to human cGAS and activate downstream signaling. Transfection of D-ODN into a TLR9-deficient, human monocytic cell line (THP-1) induced phosphorylation of IRF3 and secretion of IFN. This response was absent in cells with CRISPR/Cas9-mediated cGAS- or STING-deficiency. Utilizing a protein pulldown approach, we further demonstrate direct binding of D-ODN to cGAS. Induction of a type I IFN response by D-ODN was confirmed in human primary monocytes and monocyte-derived macrophages. These results are relevant to our understanding of self-nonself-discrimination by cGAS and to the pharmacologic effects of ODN, which currently are investigated in clinical studies.

Functional monovalency amplifies the pathogenicity of anti-MuSK IgG4 in myasthenia gravis.

Human immunoglobulin (Ig) G4 usually displays antiinflammatory activity, and observations of IgG4 autoantibodies causing severe autoimmune disorders are therefore poorly understood. In blood, IgG4 naturally engages in a stochastic process termed "Fab-arm exchange" in which unrelated IgG4s exchange half-molecules continuously. The resulting IgG4 antibodies are composed of two different binding sites, thereby acquiring monovalent binding and inability to cross-link for each antigen recognized. Here, we demonstrate that this process amplifies autoantibody pathogenicity in a classic IgG4-mediated autoimmune disease: muscle-specific kinase (MuSK) myasthenia gravis. In mice, monovalent anti-MuSK IgG4s caused rapid and severe myasthenic muscle weakness, whereas the same antibodies in their parental bivalent form were less potent or did not induce a phenotype. Mechanistically this could be explained by opposing effects on MuSK signaling. Isotype switching to IgG4 in an autoimmune response thereby may be a critical step in the development of disease. Our study establishes functional monovalency as a pathogenic mechanism in IgG4-mediated autoimmune disease and potentially other disorders.

cAbl Kinase Regulates Inflammasome Activation and Pyroptosis via ASC Phosphorylation.

Inflammasome activation is regulated in part by the posttranslational modification of inflammasome proteins. Tyrosine phosphorylation is one possible modification. Having previously shown that the protein tyrosine kinase (PTK) inhibitor AG126 greatly inhibits inflammasome activation, we sought to uncover the target kinase. To do this, we screened a commercial tyrosine kinase library for inhibition of inflammasome-dependent IL-18/IL-1ß release and pyroptosis. THP-1 cells (human monocyte cell line) were incubated with PTK inhibitors (0.1, 1, and 10 µM) before stimulation with LPS followed by ATP. The PTK inhibitors DCC-2036 (Rebastinib) and GZD824, specific for Bcr-Abl kinase, showed the most severe reduction of IL-18 and lactate dehydrogenase release at all concentrations used. The suggested kinase target, cAbl kinase, was then deleted in THP-1 cells by CRISPR/Cas9 editing and then tested for its role in inflammasome function and potential to phosphorylate the inflammasome adaptor ASC. The cABL knockout not only significantly inhibited inflammasome function but also decreased release of phosphorylated ASC after LPS/ATP stimulation. One predicted target of cAbl kinase is tyrosine 146 in ASC. Complementation of ASC knockout THP-1 cells with mutated Y146A ASC significantly abrogated inflammasome activation and ASC oligomerization as compared with wild-type ASC complementation. Thus, these findings support cAbl kinase as a positive regulator of inflammasome activity and pyroptosis, likely via phosphorylation of ASC.

Commensal fungi and their cell-wall ß-glucans direct differential responses in human intestinal epithelial cells.

Intestinal epithelial cells (IECs) are the first to encounter luminal antigens and play an active role in intestinal immune responses. We previously reported that ß-glucans, major fungal cell-wall glycans, induced chemokine secretion by IEC lines in a Dectin-1- and Syk-dependent manner. Here, we show that in contrast to ß-glucans, stimulation of IEC lines with Candida albicans and Saccharomyces cerevisiae did not induce secretion of any of the proinflammatory cytokines IL-8, CCL2, CXCL1, and GM-CSF. Commensal fungi and ß-glucans activated Syk and ERK in IEC lines. However, only ß-glucans activated p38, JNK, and the transcription factors NF-κB p65 and c-JUN, which were necessary for cytokine secretion. Furthermore, costimulation of IEC lines with ß-glucans and C. albicans yielded decreased cytokine secretion compared to stimulation with ß-glucans alone. Finally, ex vivo stimulation of human colonic mucosal explants with zymosan and C. albicans, leads to epithelial Syk and ERK phosphorylation, implying recognition of fungi and similar initial signaling pathways as in IEC lines. Lack of cytokine secretion in response to commensal fungi may reflect IECs' response to fungal glycans, other than ß-glucans, that contribute to mucosal tolerance. Skewed epithelial response to commensal fungi may impair homeostasis and contribute to intestinal inflammation.

Cardiolipin-mediated PPARγ S112 phosphorylation impairs IL-10 production and inflammation resolution during bacterial pneumonia.

Bacterial pneumonia is a global healthcare burden, and unwarranted inflammation is suggested as an important cause of mortality. Optimum levels of the anti-inflammatory cytokine IL-10 are essential to reduce inflammation and improve survival in pneumonia. Elevated levels of the mitochondrial-DAMP cardiolipin (CL), reported in tracheal aspirates of pneumonia patients, have been shown to block IL-10 production from lung MDSCs. Although CL-mediated K107 SUMOylation of PPARγ has been suggested to impair this IL-10 production, the mechanism remains elusive. We identify PIAS2 to be the specific E3-SUMOligase responsible for this SUMOylation. Moreover, we identify a concomitant CL-mediated PPARγ S112 phosphorylation, mediated by JNK-MAPK, to be essential for PIAS2 recruitment. Furthermore, using a clinically tested peptide inhibitor targeting JNK-MAPK, we blocked these post-translational modifications (PTMs) of PPARγ and rescued IL-10 expression, improving survival in murine pneumonia models. Thus, we explore the mechanism of mito-DAMP-mediated impaired lung inflammation resolution and propose a therapeutic strategy targeting PPARγ PTMs.