Decreased expression of response gene to complement 32 in psoriasis and its association with reduced M2 macrophage polarization

RGC-32 mediates proinflammatory and profibrotic pathways in immune-mediated kidney disease

Systemic lupus erythematosus is an autoimmune disease that results in immune-mediated damage to kidneys and other organs. We investigated the role of response gene to complement-32 (RGC-32), a proinflammatory and profibrotic mediator induced by TGFβ and C5b-9, in nephrotoxic nephritis (NTN), an experimental model that mimics human lupus nephritis. Proteinuria, loss of renal function and kidney histopathology were attenuated in RGC-32 KO NTN mice. RGC-32 KO NTN mice displayed downregulation of the CCL20/CCR6 and CXCL9/CXCR3 ligand/receptor pairs resulting in decreased renal recruitment of IL-17+ and IFNγ+ cells and subsequent decrease in the influx of innate immune cells. RGC-32 deficiency attenuated renal fibrosis as demonstrated by decreased deposition of collagen I, III and fibronectin. Thus, RGC-32 is a unique mediator shared by the Th17 and Th1 dependent proinflammatory and profibrotic pathways and a potential novel therapeutic target in the treatment of immune complex mediated glomerulonephritis such as lupus nephritis.

Macrophage Functions in Psoriasis: Lessons from Mouse Models

Psoriasis is a systemic autoimmune/autoinflammatory disease that can be well studied in established mouse models. Skin-resident macrophages are classified into epidermal Langerhans cells and dermal macrophages and are involved in innate immunity, orchestration of adaptive immunity, and maintenance of tissue homeostasis due to their ability to constantly shift their phenotype and adapt to the current microenvironment. Consequently, both macrophage populations play dual roles in psoriasis. In some circumstances, pro-inflammatory activated macrophages and Langerhans cells trigger psoriatic inflammation, while in other cases their anti-inflammatory stimulation results in amelioration of the disease. These features make macrophages interesting candidates for modern therapeutic strategies. Owing to the significant progress in knowledge, our review article summarizes current achievements and indicates future research directions to better understand the function of macrophages in psoriasis.

Exploring the polarization of M1 and M2 macrophages in the context of skin diseases

Macrophages are critical components of the immune system and play vital roles in pathogen defense, immune regulation, and tissue repair. These cells exhibit different polarization states depending on environmental signals, and the M1/M2 paradigm is a useful tool for comprehending these states. This review article comprehensively presents the underlying mechanisms of M1 and M2 macrophage polarization and examines their polarization in various skin diseases. Additionally, this paper discusses therapeutic strategies that target M1 and M2 macrophage polarization in skin diseases. A more profound understanding of macrophage polarization in skin diseases could provide valuable insights for the development of innovative therapeutic strategies.

Architecture of skin inflammation in psoriasis revealed by spatial transcriptomics

Psoriasis is a chronic inflammatory skin disease, thought to be predominantly mediated by TH17 cells. Significance of other inflammatory pathways and the innate immune system is not well understood and the spatial heterogeneity of inflammation in the skin has largely been overlooked. Our aim was to create a comprehensive map of skin inflammation in psoriasis, exploring the tissue patterning of inflammation. In situ whole transcriptome sequencing (spatial sequencing) was performed on lesional psoriatic skin in four patients with moderate-to-severe disease to quantify all expressed genes within a tissue section. Transcriptional analysis revealed three major inflammatory niches in psoriasis skin, each with distinct cytokine circuits and chemokines: the hyperplastic epidermis, upper (papillary) dermis, and reticular dermis. Interestingly, key cytokines such as IL-23, IL-17 s, and TNFα were not notably present in the skin's transcriptomic signature. Unexpectedly, IL-32 showed strong expression in the dermis. Our findings underscore the complexity of psoriatic inflammation, highlighting its architectural heterogeneity and the roles of innate cytokines. Both IL-32 and IL-1 family cytokines appear to play critical roles in the dermal and epidermal inflammation, respectively, and may provide pharmacological targets to improve the control of the inflammatory process.

Serum RGC-32 in children with systemic lupus erythematosus

Childhood-onset systemic lupus erythematosus (SLE) can be more severe than adult patients. Early diagnosis and accurate evaluation of the disease are very important for the patients. Response gene to complement-32 (RGC-32) protein is the downstream regulator of C5b-9 complex which is the terminal pathway of complement activation. Complement system plays a very important role in the pathogenesis of SLE. RGC-32 in patients with SLE has not been reported yet. We aimed to examine the clinical value of RGC-32 in children with SLE. A total of 40 children with SLE and another 40 healthy children were enrolled for this study. Clinical data were obtained prospectively. Serum RGC-32 was determined by ELISA. We found that serum RGC-32 was significantly elevated in children with SLE than that in the healthy group. Serum RGC-32 was significantly higher in the children with moderately/severely active SLE than that in the children with no/mildly active SLE. Furthermore, serum RGC-32 level correlated positively with C-reactive protein, erythrocyte sedimentation rate and ferritin and correlated negatively with white blood cell counts and C3. RGC-32 may be involved in the pathogenesis of SLE. RGC-32 might become a good biomarker in the diagnosis and evaluation of SLE.

Dissolvable hyaluronic acid microneedles loaded with β-Elemene for the treatment of psoriasis

The pathology of psoriasis involves the over-proliferation of keratinocytes, exaggerated inflammation of keratinocytes, and infiltration of inflammatory cells such as macrophages (Mø), etc. The therapeutic outcomes of current treatment targeting one single pathological process are less than satisfactory. Based on their diverse biological activities, natural products offer a potential solution to this problem. In this study, we investigated the effects of β-Elemene (ELE) on both psoriatic keratinocytes and M1-type Mø (M1-Mø) in vitro. Hyaluronic acid (HA) microneedles loaded with ELE (HA-ELE-MN) were also fabricated and tested for the treatment of psoriasis in vivo using an imiquimod (IMQ)-induced psoriatic mice model. Our data suggest that ELE induces apoptosis and inhibits inflammation of psoriatic keratinocytes. In addition, ELE attenuates the expression of inflammatory cytokines secreted from M1-Mø, thus indirectly inhibiting the inflammation of keratinocytes. Furthermore, HA-ELE-MN has been found to significantly alleviate symptoms in an IMQ-induced psoriatic mice model by inducing keratinocytes apoptosis, suppressing keratinocytes proliferation, and inhibiting M1-Mø infiltration. Taken together, this study demonstrates that ELE can be used for the treatment of psoriasis by targeting both keratinocytes and M1-Mø, which provides a potential novel reagent for psoriasis treatment.

Dendritic Cells and Macrophages in the Pathogenesis of Psoriasis

Psoriasis is a chronic inflammatory skin disease characterized by scaly indurated erythema. This disease impairs patients’ quality of life enormously. Pathological findings demonstrate proliferation and abnormal differentiation of keratinocytes and massive infiltration of inflammatory immune cells. The pathogenesis of psoriasis is complicated. Among immune cells, dendritic cells play a pivotal role in the development of psoriasis in both the initiation and the maintenance phases. In addition, it has been indicated that macrophages contribute to the pathogenesis of psoriasis especially in the initiation phase, although studies on macrophages are limited. In this article, we review the roles of dendritic cells and macrophages in the pathogenesis of psoriasis.

Single-Cell RNA-Sequencing Identifies Infrapatellar Fat Pad Macrophage Polarization in Acute Synovitis/Fat Pad Fibrosis and Cell Therapy

The pathogenesis and progression of knee inflammatory pathologies is modulated partly by residing macrophages in the infrapatellar fat pad (IFP), thus, macrophage polarization towards pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes is important in joint disease pathologies. Alteration of M1/M2 balance contributes to the initiation and progression of joint inflammation and can be potentially altered with mesenchymal stem cell (MSC) therapy. In an acute synovial/IFP inflammation rat model a single intra-articular injection of IFP-MSC was performed, having as controls (1) diseased rats not receiving IFP-MSC and (2) non-diseased rats. After 4 days, cell specific transcriptional profiling via single-cell RNA-sequencing was performed on isolated IFP tissue from each group. Eight transcriptomically distinct cell populations were identified within the IFP across all three treatment groups with a noted difference in the proportion of myeloid cells across the groups. Largely myeloid cells consisted of macrophages (>90%); one M1 sub-cluster highly expressing pro-inflammatory markers and two M2 sub-clusters with one of them expressing higher levels of canonical M2 markers. Notably, the diseased samples (11.9%) had the lowest proportion of cells expressing M2 markers relative to healthy (14.8%) and MSC treated (19.4%) samples. These results suggest a phenotypic polarization of IFP macrophages towards the pro-inflammatory M1 phenotype in an acute model of inflammation, which are alleviated by IFP-MSC therapy inducing a switch towards an alternate M2 status. Understanding the IFP cellular heterogeneity and associated transcriptional programs may offer insights into novel therapeutic strategies for disabling joint disease pathologies.

A Guttate Psoriasis That Tends to Spare Three Tattoos: A Macrophage Liaison

Induction of new psoriasis sites was reported in only a small amount of psoriasis patients undergoing tattooing, despite the intuitive belief that tattoo trauma might awaken the disease due to the isomorphic phenomenon of Koebner. In this case report, we discuss a patient who presented with a remarkable sparing of his three tattoo sites during a guttate psoriasis flare-up that was unrelated to tattooing. The spatial concordance of tattoo and psoriasis lesions was analyzed on clinical pictures of tattoo sites taken during the psoriasis episode. For the quantification of the spatial distribution of the psoriasis lesions, Voronoi diagrams were generated, and coefficients of variation and the two-sample t-test were employed to compare the distributions of Voronoi patch sizes in different settings. Compared to skin areas without tattoos, a tattoo introduced a higher variation in the sizes of the Voronoi patches centered around psoriasis lesions. Based on our findings, we would like to discuss the possible role of macrophages as the key cellular link in the complex pathophysiologic relationship between tattooing/tattoo and psoriasis. Taking into account the relationship of autophagy and psoriasis lesions, we propose the hypothesis that tattoos represent a “psoriasis-hostile” tissue environment pertained by a population of LAP active M2-polarized macrophages. Further clinical studies of the relationship of psoriasis lesions to the tattooed skin are needed and may provide important insights into the role of macrophages in the pathogenesis of psoriasis.