The LIM-Only Protein Four and a Half LIM Domain Protein 2 Attenuates Development of Psoriatic Arthritis by Blocking Adam17-Mediated Tumor Necrosis Factor Release

Proteomic analysis reveals immune-related proteins of coelomic fluid in Urechis unicinctus

Urechis unicinctus is a marine benthic invertebrate that relies primarily on humoral immunity within the nonspecific immune system for body defense. In order to elucidate the protein components of the coelomic fluid and investigate its immune response mechanism, proteomic analysis and antimicrobial characterization of the coelomic fluid of U. unicinctus were carried out. A total of 2194 proteins were identified, with 427 showing differential expression in coelomocytes compared to those in the coelomic fluid supernatant. Of these proteins, 346 were upregulated and 81 were downregulated. Next, these identified proteins were analyzed for biological information, including GO, COG, and KEGG pathway analysis. The results from the GO analysis revealed that cytoplasm and ATP-binding were the two prominent categories of proteins found in the coelomocytes as well as the coelomic fluid supernatant of U. unicinctus. From the COG analysis, it was evident that the categories of proteins identified in the coelomocytes were essentially the same as those identified in the coelomic fluid supernatant, with only the number of proteins differing. The KEGG pathway analysis indicated that 45 pathways from the coelomic fluid supernatant and 42 from the coelomocytes were profiled, with carbon metabolism and ribosome being the two most prominent pathways. The Pfam database displayed that the immune-related proteins in U. unicinctus were neurofascin, cell adhesion molecule 4, receptor-type tyrosine-protein phosphatase F, limbic system-associated membrane protein, four and a half LIM domains protein 2, neuroglian, fasciclin-2, and neural cell adhesion molecule. Furthermore, the active substances from the coelomic fluid underwent isolation, purification, and antimicrobial characterization. The process yielded two purified components (b1 and b2), that were found to significantly inhibit the growth of Vibrio anguillarum, Aeromonas veronii, Micrococcus lysodeik, and Staphylococcus aureus. Based on the nano LC-MS/MS and homology analysis, it was concluded the two purified proteins from b1 and b2 might have been histones with a molecular weight of 11,367 Da. Our study is the first to provide proteomic information on U. unicinctus, which can extend our understanding on the roles of functional proteins in the defense mechanism of U. unicinctus and contribute to the advancement of related drug development in U. unicinctus farming.

Small Spleen Peptides (SSPs) Shape Dendritic Cell Differentiation through Modulation of Extracellular ATP Synthesis Profile

Restoring peripheral immune tolerance is crucial for addressing autoimmune diseases. An ancient mechanism in maintaining the balance between inflammation and tolerance is the ratio of extracellular ATP (exATP) and adenosine. Our previous research demonstrated the effectiveness of small spleen peptides (SSPs) in inhibiting psoriatic arthritis progression, even in the presence of the pro-inflammatory cytokine TNFα, by transforming dendritic cells (DCs) into tolerogenic cells and fostering regulatory Foxp3+ Treg cells. Here, we identified thymosins as the primary constituents of SSPs, but recombinant thymosin peptides were less efficient in inhibiting arthritis than SSPs. Since Tβ4 is an ecto-ATPase-binding protein, we hypothesized that SSPs regulate exATP profiles. Real-time investigation of exATP levels in DCs revealed that tolerogenic stimulation led to robust de novo exATP synthesis followed by significant degradation, while immunogenic stimulation resulted in a less pronounced increase in exATP and less effective degradation. These contrasting exATP profiles were crucial in determining whether DCs entered an inflammatory or tolerogenic state, highlighting the significance of SSPs as natural regulators of peripheral immunological tolerance, with potential therapeutic benefits for autoimmune diseases. Finally, we demonstrated that the tolerogenic phenotype of SSPs is mainly influenced by adenosine receptors, and in vivo administration of SSPs inhibits psoriatic skin inflammation.

FHL2 regulates microglia M1/M2 polarization after spinal cord injury via PARP14-depended STAT1/6 pathway

Neuronal apoptosis and inflammation exacerbate the secondary injury after spinal cord injury (SCI). Four and a half domains 2 (FHL2) is a multifunctional scaffold protein with tissue- and cell-type specific effects on the regulation of inflammation, but its role in SCI remains unclear. The T10 mouse spinal cord contusion model was established, and the mice were immediately injected with lentiviruses carrying FHL2 shRNA after SCI. The results showed that FHL2 expression was increased following SCI, and then gradually decreased. Moreover, FHL2 depletion aggravated functional impairment, neuronal necrosis, and enlarged lesion cavity areas in the injured spinal cord. FHL2 deficiency facilitated neuronal apoptosis by elevating cleaved caspase 3/9 expression, neuroinflammation by regulating microglia polarization, and bone loss. Indeed, FHL2 deficiency increased the secretion of TNF-α and IL-6, M1 microglia polarization, and the activation of STAT1 pathway but decreased the secretion of IL-10 and IL-4, M2 microglia polarization, and the activation of the STAT6 pathway in the spinal cord. In vitro, FHL2 silencing promoted LPS + IFN-γ-induced microglia M1 polarization through activating the STAT1 pathway and alleviated IL-4-induced microglia M2 polarization via inhibiting the STAT6 pathway. FHL2 positively regulated the expression of poly (ADP-ribose) polymerase family member 14 (PARP14) by promoting its transcription. PARP14 overexpression inhibited FHL2 silencing-induced microglia M1 polarization and relieved the inhibitory effect of FHL2 silencing on microglia M2 polarization. Collectively, the study suggests that FHL2 reduces the microglia M1/M2 polarization-mediated inflammation via PARP14-dependent STAT1/6 pathway and thereby improves functional recovery after SCI.

Small spleen peptides prevent development of psoriatic arthritis via restoration of peripheral tolerance

The major challenge in the treatment of autoimmune diseases is the restoration of the impaired peripheral immune tolerance that always accompanies the development of such diseases. Here, we show that small splenic peptides (SSPs) of whole spleen extract efficiently suppress the development of psoriatic arthritis in vivo, even in the presence of sustained levels of pro-inflammatory cytokines. SSPs target dendritic cells (DCs) and convert them into tolerogenic cells, which in turn differentiate naive CD4⁺ cells into Foxp3-expressing T regulatory cells (Tregs). The latter requires direct contact between SSP-activated DCs and naive CD4⁺ T cells via PD-1 and CTLA4 immune checkpoint receptors of T cells. Finally, depletion of Foxp3⁺ Tregs in vivo abrogated the protective effect of SSPs on psoriatic arthritis development. We hypothesize that SSPs represent an intrinsic component of the adaptive immune system responsible for the physiological maintenance of peripheral tolerance and that therapeutically administered SSPs are able to restore imbalanced peripheral tolerance in autoimmune diseases.

Four and a Half LIM Domains Protein 2 Mediates Bortezomib-Induced Osteogenic Differentiation of Mesenchymal Stem Cells in Multiple Myeloma Through p53 Signaling and β-Catenin Nuclear Enrichment

Myeloma bone disease (MBD), caused by the inhibition of osteoblast activity and the activation of osteoclast in the bone marrow environment, is the most frequent and life-threatening complication in multiple myeloma (MM) patients. Bortezomib (Bzb) was shown to promote MM-derived mesenchymal stem cells (MM-MSCs) differentiation to osteoblast in vitro and in animal models, promoting the bone formation and regeneration, may be mediated via β-catenin/T-cell factor (TCF) pathway. Further defining molecular mechanism of Bzb-enhanced bone formation in MM will be beneficial for the treatment of myeloma patients. The present study has identified for the first time four and a half LIM domains protein 2 (FHL2), a tissue-specific coregulator that interacts with many osteogenic marker molecules, as a therapeutic target to ameliorate MM bone disease. First, increased messenger RNA (mRNA) and protein levels of FHL2, and the mRNA level of main osteoblast markers (including Runx2, ALP, and Col1A1), were found in MM-patients-derived MSCs after Bzb treatment. FHL2 KD with short hairpin RNA (shRNA) reduced the expression of osteoblast marker genes and blocked the osteogenic differentiation of MM-MSCs regardless of the presence or absence of Bzb, implying that FHL2 is an important activator of the osteogenic differentiation of human MSCs under a proteasome inhibition condition. Molecular analysis showed that the enhanced expression of FHL2 was associated with the Bzb-induced upregulation of p53. No significant change at protein level of total β-catenin was observed with or without Bzb treatment. However, it was mostly enriched to nuclei in MSCs after Bzb treatment. Moreover, β-catenin was restricted to the perinuclear region in FHL2 KD cells. These data provide evidence that FHL2 is essential for promoting β-catenin nuclear enrichment in MM-MSCs. In conclusion, FHL2 is critical for Bzb-induced osteoblast differentiation of MM-MSCs and promotes the osteogenesis, through p53 signaling and β-catenin activation. Targeting FHL2 in MM may provide a new therapeutic strategy for treating MBD.

Spontaneous onset of TNFα-triggered colonic inflammation depends on functional T lymphocytes, S100A8/A9 alarmins, and MHC H-2 haplotype

Recently, we established a doxycycline-inducible human tumor necrosis factor alpha (TNFα)-transgenic mouse line, ihTNFtg. Non-induced young and elderly mice showed low but constitutive expression of hTNFα due to promoter leakiness. The persistently present hTNFα stimulated endogenous pro-inflammatory mouse mS100A8/A9 alarmins. Secreted mS100A8/A9 in turn induced the expression and release of mouse mTNFα. The continuous upregulation of pro-inflammatory mTNFα and mS100A8/A9 proteins, due to their mutual expression dependency, gradually led to increased levels in colon tissue and blood. This finally exceeded the threshold levels tolerated by the healthy organism, leading to the onset of intestinal inflammation. Here, recombinant hTNFα functioned as an initial trigger for the development of chronic inflammation. Crossing ihTNFtg mice with S100A9^KO mice lacking active S100A8/A9 alarmins or with Rag1^KO mice lacking T and B lymphocytes completely abrogated the development of colonic inflammation, despite the still leaky hTNFα promoter. Furthermore, both the intensity of the immune response and the strength of immunosuppressive Treg induction was found to depend on the major histocompatibility complex (MHC) genetic composition. In summary, the onset of intestinal inflammation in elderly mice depends on at least four factors that have to be present simultaneously: TNFα upregulation, S100A8/A9 protein expression, functional T lymphocytes and genetic composition, with the MHC haplotype being of central importance. Only joint action of these factors leads to chronic intestinal inflammation, while absence of any of these determinants abrogates the development of the autoimmune disorder. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

PD-1 IC Inhibition Synergistically Improves Influenza A Virus-Mediated Oncolysis of Metastatic Pulmonary Melanoma

Recently, we showed that infection of primary lung tumor-bearing mice with oncolytic influenza A viruses (IAVs) led to strong virus-induced tumor cell lysis but also to restoration of immune competence of innate immune cells. Murine B16-F10 melanoma cells are known for their high lung tropism and progressive growth. As these cells are also highly permissive for IAVs, we analyzed their oncolytic and immunomodulatory efficiency against pulmonary B16-F10 lung metastases in vivo. IAV infection abrogated the melanoma-mediated immune suppression in the lung and induced a more than 50% cancer cell lysis. The oncolytic effect reached maximal efficacy 3 days post-infection, but it was not sustained over time. In order to maintain the virus-induced anti-tumor effect, mice with melanoma-derived lung cancers were treated in addition to influenza virus infection with an immune checkpoint inhibitor against programmed death-1 receptor (PD-1). The combined IAV and immune checkpoint inhibition (ICI) therapy resulted in a sustained anti-tumor efficacy, keeping the lung melanoma mass at day 12 of IAV infection still reduced by 50% over the control mice. In conclusion, ICI treatment strongly enhanced the oncolytic effect of influenza virus infection, suggesting that combined treatment is a promising approach against metastatic pulmonary melanoma.

The role of FHL2 in wound healing and inflammation

The 4-and-a-half LIM domain protein 2 (FHL2) is a multifunctional adaptor protein that can interact with cell surface receptors, cytosolic adaptor and structural proteins, kinases, and nuclear transcription factors. It is involved in numerous functional activities, including the epithelial-mesenchymal transition, cell proliferation, apoptosis, adhesion, migration, structural stability, and gene expression. Despite this, FHL2-knockout (KO) mice are viable and fertile with no obvious abnormalities, rather suggesting a high capacity for fine-tuning adjustment and functional redundancy of FHL2. Indeed, challenging FHL2-KO cells or mice provided numerous evidences for the great functional significance of FHL2. In recent years, several reviews have been published describing the high capacity of FHL2 to bind diverse proteins as well as the versatile functions of FHL2, emphasizing in particular its role in cardiovascular diseases and carcinogenesis. Here, we view the function of FHL2 from a different perspective. We summarize the published data demonstrating the impact of FHL2 on wound healing and inflammation. FHL2 seems to be involved in numerous steps of these extremely complex and multidirectional but tightly regulated tissue remodeling processes, supporting tissue repair and coordinating inflammation. Deficiency of FHL2 not only slows down ongoing wound healing but also often turns it into a chronic condition.-Wixler, V. The role of FHL2 in wound healing and inflammation.

Protective or deleterious role of Wnt/beta-catenin signaling in diabetic nephropathy: An unresolved issue

In recent years, the Wnt/β-catenin signaling has gained tremendous attention due to its ability to modulate a number of diseases including diabetic nephropathy. Studies have shown that there is decrease in the secretion of Wnt proteins including Wnt4, 5a and Wnt 6 during high glucose concentration or diabetic conditions, which leads to decreased translocation of β-catenin to nucleus. The down-regulation of Wnt/β-catenin signaling leads to detrimental effects on kidney including increased apoptosis of mesangial cells and increased deposition of fibrous tissue in mesangium. The pharmacological modulators such as spironolactone, NO donor and antioxidant are shown to produce beneficial effects in diabetic nephropathy by up regulating the expression of Wnt proteins and activation of diabetes-induced suppressed Wnt/β-catenin signaling. On the other hand, it is documented that diabetes leads to overactivation of Wnt1/β-catenin signaling, which promotes podocyte injury, induce epithelial-mesenchymal transition of podocytes along with renal injury and fibrosis. Accordingly, different interventions aimed to suppress overactivated Wnt/β-catenin signaling are reported to improve the condition and symptoms associated with diabetic nephropathy. The present review discusses the dual role of Wnt/beta-catenin signaling in the pathogenesis of diabetic nephropathy.

Deficiency of Fhl2 leads to delayed neuronal cell migration and premature astrocyte differentiation

The four and a half LIM domains protein 2 (Fhl2) is an adaptor protein capable of mediating protein-protein interactions. Here, we report for the first time phenotypic changes in the brain of Fhl2-deficient mice. We showed that Fhl2 is expressed in neural stem cells, precursors and mature cells of neuronal lineage. Moreover, Fhl2 deficiency leads to delayed neuroblast migration in vivo, premature astroglial differentiation of neural stem cells (NSCs) in vitro, and a gliosis-like accumulation of glial fibrillary acidic protein (GFAP)-positive astrocytes in vivo that substantially increases with age. Collectively, Fhl2-deficiency in the brain interrupts the maintenance and the balanced differentiation of adult NSCs, resulting in preferentially glial differentiation and early exhaustion of the NSC pool required for adult neurogenesis.

The Four-and-a-Half LIM Domain Protein 2 Supports Influenza A Virus-Induced Lung Inflammation by Restricting the Host Adaptive Immune Response

Four-and-a-half LIM domain protein 2 (FHL2) is a multifunctional adaptor protein with fine-tuning adjustment properties. It acts as a regulator of signaling cascades but also as a cofactor of transcription and controls several anti-inflammatory immune responses. Recently, we described FHL2 as a novel regulator of influenza A virus propagation. We have shown that in vitro FHL2 restricts viral replication by accelerating the interferon regulatory factor 3-dependent transcription of the Ifnb1 gene. In this work, we unraveled an ambiguous role of FHL2 during influenza A virus infection in vivo. Although FHL2 restrained viral replication during the first 24 hours of infection, it significantly delayed viral clearance afterward. Comparison of lung immune status of wild-type and FHL2 knockout mice during influenza virus infection did not acknowledge significant differences in the innate host immune response but revealed an improved migration of dendritic cells from infected lungs into draining lymph nodes as well as increased levels of activated CD8⁺ T lymphocytes accumulated in the lungs of FHL2 knockout mice.