Immunohistochemical Analysis of Scarring Trachoma Indicates Infiltration by Natural Killer and Undefined CD45 Negative Cells

hsa_circ_0007755 competitively adsorbs miR-27b-3p to mediate CXCL2 expression and recruit Th1 cells to promote hypertrophic scars development

Background and objective

The circular RNA hsa_circ_0007755 is markedly upregulated in hypertrophic scars (HS), yet its functional roles in this fibroproliferative disorder remain to be elucidated. This investigation aims to delineate the regulatory mechanisms of hsa_circ_0007755 in HS and to decode its downstream molecular signaling pathways.

Methods

We established a murine model of HS. Tissue histopathology was assessed using Hematoxylin and Eosin and Masson's trichrome staining. Peripheral blood from the animals was collected and the ratio of T-helper 1 (Th1) to T-helper 2 (Th2) cells was quantified via flow cytometry. The proliferation and apoptosis rates of human hypertrophic scar fibroblasts (hHSFs) were evaluated using the Cell Counting Kit-8 assay and flow cytometry, respectively. The invasive capacity of hHSFs was assessed via a Transwell assay. Co-culture experiments of hHSFs with T cells were conducted, and alterations in Th1/Th2 ratios were monitored using flow cytometry. Levels of cytokines, fibrosis-associated proteins, nuclear factor-kappaB (NF-κB) pathway-related protein, and C-X-C Motif Chemokine Ligand 2 (CXCL2) were quantified using Enzyme-Linked Immunosorbent Assay or Western blot analysis. The interactions between hsa_circ_0007755, miR-27b-3p, and CXCL2 were investigated using dual-luciferase reporter assays and RNA immunoprecipitation.

Results

Both hsa_circ_0007755 and CXCL2 were highly expressed in HS, whereas miR-27b-3p was downregulated. Knockdown of hsa_circ_0007755 inhibited the proliferation and invasion of hHSFs, promoted apoptosis, and reduced the expression of fibrotic proteins α-SMA and Collagen I, as well as the phosphorylation of the inflammatory pathway protein p65. Co-culture experiments confirmed that hHSFs lowly expressing hsa_circ_0007755 showed a decreased Th1 cell proportion and an increased Th2 cell proportion, alongside lower levels of TNF-α and INF-γ and higher levels of IL-4 and IL-10. The effects of either knocking down or overexpressing hsa_circ_0007755 were reversed by knocking down either miR-27b-3p or CXCL2, respectively. hsa_circ_0007755 acted as a "molecular sponge" for miR-27b-3p, sequestering and diminishing its availability, thereby alleviating its suppression of the target gene CXCL2.

Conclusion

hsa_circ_0007755 plays a pivotal role in modulating the immune response of HS by influencing the miR-27b-3p/CXCL2 axis, regulating the function and proportion of Th1 and Th2 cells, and thereby affecting the inflammatory and fibrotic processes in scar tissue.

Insights into Pathogenesis of Trachoma

Trachoma is the most common infectious cause of blindness worldwide. This review investigates the pathogenesis of trachoma, focusing on its causative agent, transmission pathways, disease progression, and immune responses. Trachoma is caused by serovars A-C of the bacterium Chlamydia trachomatis (Ct). Transmission occurs through direct or indirect exchanges of ocular and nasal secretions, especially in regions with poor hygiene and overcrowded living conditions. The disease is initiated in early childhood by repeated infection of the ocular surface by Ct. This triggers recurrent chronic inflammatory episodes, leading to the development of conjunctival scarring and potentially to trichiasis, corneal opacity, and visual impairment. Exploring the pathogenesis of trachoma not only unveils the intricate pathways and mechanisms underlying this devastating eye disease but also underscores the multifaceted dimensions that must be considered in its management.

Insights into innate immune cell evasion by Chlamydia trachomatis

Chlamydia trachomatis, is a kind of obligate intracellular pathogen. The removal of C. trachomatis relies primarily on specific cellular immunity. It is currently considered that CD4+ Th1 cytokine responses are the major protective immunity against C. trachomatis infection and reinfection rather than CD8+ T cells. The non-specific immunity (innate immunity) also plays an important role in the infection process. To survive inside the cells, the first process that C. trachomatis faces is the innate immune response. As the "sentry" of the body, mast cells attempt to engulf and remove C. trachomatis. Dendritic cells present antigen of C. trachomatis to the "commanders" (T cells) through MHC-I and MHC-II. IFN-γ produced by activated T cells and natural killer cells (NK) further activates macrophages. They form the body's "combat troops" and produce immunity against C. trachomatis in the tissues and blood. In addition, the role of eosinophils, basophils, innate lymphoid cells (ILCs), natural killer T (NKT) cells, γδT cells and B-1 cells should not be underestimated in the infection of C. trachomatis. The protective role of innate immunity is insufficient, and sexually transmitted diseases (STDs) caused by C. trachomatis infections tend to be insidious and recalcitrant. As a consequence, C. trachomatis has developed a unique evasion mechanism that triggers inflammatory immunopathology and acts as a bridge to protective to pathological adaptive immunity. This review focuses on the recent advances in how C. trachomatis evades various innate immune cells, which contributes to vaccine development and our understanding of the pathophysiologic consequences of C. trachomatis infection.

Injectable Hydrogels of Amphiphilic Vitamin E Derivatives for Locoregional Chemotherapy

Vitamin E derivatives are particularly effective in chemotherapy drug development because they are nontoxic, biocompatible, and selective. Among them, α-tocopheryl succinate (α-TOS) can act synergistically with some chemotherapeutic agents. However, its hydrophobicity limits its systemic administration, and localized formulations are not available. Herein, we developed an injectable hydrogel based on self-assembled micelles of a triblock amphiphilic derivative of α-TOS (PEG-2VES), in which doxorubicin (DOX) was encapsulated in the core of the micelles for combined chemotherapy. A molecule of α-TOS was grafted onto each end of poly(ethylene glycols) (PEGs) of different lengths. Hydrogels were prepared by dissolving the polymers or the DOX-loaded micelles in water at room temperature. The subcutaneously injected hydrogels kept their shape and sustainably released the payloads over 7 days without any noticeable inflammatory response. In vitro and in vivo results confirmed the synergistic antitumor effects of the hydrogel and loaded drug. Furthermore, DOX-loaded hydrogels showed greater therapeutic efficiency and fewer toxic side effects than DOX alone. Overall, this hydrogel acts as a multifunctional system that can deliver drug, improve the therapeutic effect, and minimize drug toxicity.

The conjunctival transcriptome in Ethiopians after trichiasis surgery: associations with the development of eyelid contour abnormalities and the effect of oral doxycycline treatment

Background: Surgery to correct trichiasis is a key component of the World Health Organisation trachoma control strategy, however unfavourable outcomes such as eyelid contour abnormalities (ECA) following surgery are relatively common. This study aimed to understand the transcriptional changes associated with the early development of ECA and the impact of doxycycline, which has anti-inflammatory and anti-fibrotic properties, upon these transcription patterns. Methods: One thousand Ethiopians undergoing trichiasis surgery were enrolled in a randomised controlled trial following informed consent. Equal groups of randomly assigned individuals were orally administered with 100mg/day of doxycycline (n=499) or placebo (n=501) for 28 days. Conjunctival swabs were collected immediately prior to surgery and at one- and six-months post-surgery. 3' mRNA sequencing was performed on paired baseline and one-month samples from 48 individuals; 12 in each treatment/outcome group (Placebo-Good outcome, Placebo-Poor outcome, Doxycycline-Good outcome, Doxycycline-Poor outcome). qPCR validation was then performed for 46 genes of interest in 145 individuals who developed ECA at one month and 145 matched controls, using samples from baseline, one and six months. Results: All treatment/outcome groups upregulated genes associated with wound healing pathways at one month relative to baseline, however no individual differences were detected between groups. The summed expression of a highly coexpressed cluster of pro-fibrotic genes was higher in patients that developed ECA in the placebo group relative to controls. qPCR validation revealed that all genes in this cluster and a number of other pro-inflammatory genes were strongly associated with ECA, however these associations were not modulated by trial arm. Conclusions: The development of post-operative ECA is associated with overexpression of pro-inflammatory and pro-fibrotic genes including growth factors, matrix metalloproteinases, collagens and extracellular matrix proteins. There was no evidence that doxycycline modulated the association between gene expression and ECA.

Trachoma

Trachoma is a neglected tropical disease caused by infection with conjunctival strains of Chlamydia trachomatis. It can result in blindness. Pathophysiologically, trachoma is a disease complex composed of two linked chronic processes: a recurrent, generally subclinical infectious-inflammatory disease that mostly affects children, and a non-communicable, cicatricial and, owing to trichiasis, eventually blinding disease that supervenes in some individuals later in life. At least 150 infection episodes over an individual's lifetime are needed to precipitate trichiasis; thus, opportunity exists for a just global health system to intervene to prevent trachomatous blindness. Trachoma is found at highest prevalence in the poorest communities of low-income countries, particularly in sub-Saharan Africa; in June 2021, 1.8 million people worldwide were going blind from the disease. Blindness attributable to trachoma can appear in communities many years after conjunctival C. trachomatis transmission has waned or ceased; therefore, the two linked disease processes require distinct clinical and public health responses. Surgery is offered to individuals with trichiasis and antibiotic mass drug administration and interventions to stimulate facial cleanliness and environmental improvement are designed to reduce infection prevalence and transmission. Together, these interventions comprise the SAFE strategy, which is achieving considerable success. Although much work remains, a continuing public health problem from trachoma in the year 2030 will be difficult for the world to excuse.

Immunological mechanisms of scarring and their psychological impact on patients

A scar is a local symptom, which results from severe physical, biological and chemical damage to human skin and soft tissue. Scars can affect both skin appearance and function. The affected skin or soft tissue cannot be completely repaired normally by itself and is replaced by formed fibrous tissue. Patients with scars can develop physical pain and mental conditions, especially those with scars left after burns, scalds and severe traumas. The scar proliferation phase can be up to several years which could be almost unbearable for patients. Also, the atrophic period afterwards makes the patient's face unrecognizable and dysfunctional, causing great physical and mental impairment. Therefore, scar repair is of great clinical importance for patients, and understanding the immunological mechanisms of scar repair is an important prerequisite for the effective treatment of scars. This study is a systematic review of current research advances about the immunological mechanisms of scar repair, so as to provide a reference for the selection of regimens in clinical treatment.

Comparative analysis of the tumor immune-microenvironment of primary and brain metastases of non-small-cell lung cancer reveals organ-specific and EGFR mutation-dependent unique immune landscape

BACKGROUND

To evaluate the characteristics of the tumor immune-microenvironment in brain metastases of non-small-cell lung cancer (NSCLC), we investigated the immunophenotype of primary NSCLC and its brain metastasis.

METHODS

Expression profiling of 770 immune-related genes in 28 tissues from primary and brain metastases of NSCLC was performed using the NanoString nCounter PanCancer Immune Profiling Panel. The immune cell profiles were validated by immunohistochemistry of 42 matched samples.

RESULTS

Based on unsupervised clustering and principal component analysis of the immune-related gene expression profile, tumors were primarily clustered according to the involved organ and further grouped according to the EGFR mutation status. Fifty-four genes were significantly differentially expressed between primary and brain metastatic tumors. Clustering using these genes showed that tumors harboring mutated EGFR tended to be grouped together in the brain. Pathway analysis revealed that various immune-related functions involving immune regulation, T cell activity, and chemokines were enriched in primary tumors compared to brain metastases. Diverse immune-related pathways were upregulated in brain metastases of EGFR-mutated compared to EGFR-wild-type adenocarcinoma, but not in primary tumors. The interferon-γ-related gene signature was significantly decreased in brain metastases. The anti-inflammatory markers TOLLIP and HLA-G were upregulated in brain metastases. The proportions of most immune cell subsets were decreased in brain metastases, but those of macrophages and CD56dim-NK-cells were increased, as was the ratios of CD163+M2- to iNOS+M1-macrophages and NCR1+NK-cells to CD3+T cells.

CONCLUSIONS

Our findings illustrate the immune landscape of brain metastases from NSCLC and reveal potential therapeutic strategies targeting cellular and non-cellular components of the tumor immune-microenvironment.

Innate Lymphoid Cells Are Required for Endometrial Resistance to Chlamydia trachomatis Infection

In some women, sexually transmitted Chlamydia trachomatis may ascend to infect the endometrium, leading to pelvic inflammatory disease. To identify endometrial innate immune components that interact with Chlamydia, we introduced C. trachomatis into mouse endometrium via transcervical inoculation and compared the infectious yields in mice with and without immunodeficiency. Live C. trachomatis recovered from vaginal swabs or endometrial tissues peaked on day 3 and then declined in all mice with or without deficiency in adaptive immunity, indicating a critical role for innate immunity in endometrial control of C. trachomatis infection. Additional knockout of interleukin 2 receptor common gamma chain (IL-2Rγc) from adaptive immunity-deficient mice significantly compromised the endometrial innate immunity, demonstrating an important role for innate lymphoid cells (ILCs). Consistently, deficiency in IL-7 receptor alone, a common gamma chain-containing receptor required for ILC development, significantly reduced endometrial innate immunity. Furthermore, mice deficient in RORγt or T-bet became more susceptible to endometrial infection with C. trachomatis, suggesting a role for group 3-like ILCs in endometrial innate immunity. Furthermore, genetic deletion of gamma interferon (IFN-γ) but not IL-22 or antibody-mediated depletion of IFN-γ from adaptive immunity-deficient mice significantly compromised the endometrial innate immunity. Finally, depletion of NK1.1⁺ cells from adaptive immunity-deficient mice both significantly reduced IFN-γ and increased C. trachomatis burden in the endometrial tissue, confirming that mouse ILCs contribute significantly to endometrial innate immunity via an IFN-γ-dependent effector mechanism. It will be worth investigating whether IFN-γ-producing ILCs also improve endometrial resistance to sexually transmitted C. trachomatis infection in women.

Immunopathogenesis of Progressive Scarring Trachoma: Results of a 4-Year Longitudinal Study in Tanzanian Children

Trachoma is initiated during childhood following repeated conjunctival infection with Chlamydia trachomatis, which causes a chronic inflammatory response in some individuals that leads to scarring and in-turning of the eyelids in later life. There is currently no treatment to halt the progression of scarring trachoma due to an incomplete understanding of disease pathogenesis. A cohort study was performed in northern Tanzania in 616 children aged 6 to 10 years at enrollment. Every 3 months for 4 years, children were examined for clinical signs of trachoma, and conjunctival swabs were collected for C. trachomatis detection and to analyze the expression of 46 immunofibrogenic genes.

Trachoma is initiated during childhood following repeated conjunctival infection with Chlamydia trachomatis, which causes a chronic inflammatory response in some individuals that leads to scarring and in-turning of the eyelids in later life. There is currently no treatment to halt the progression of scarring trachoma due to an incomplete understanding of disease pathogenesis. A cohort study was performed in northern Tanzania in 616 children aged 6 to 10 years at enrollment. Every 3 months for 4 years, children were examined for clinical signs of trachoma, and conjunctival swabs were collected for C. trachomatis detection and to analyze the expression of 46 immunofibrogenic genes. Data were analyzed in relation to progressive scarring status between baseline and the final time point. Genes that were significantly associated with scarring progression included those encoding proinflammatory chemokines (CXCL5, CCL20, CXCL13, and CCL18), cytokines (IL23A, IL19, and IL1B), matrix modifiers (MMP12 and SPARCL1), immune regulators (IDO1, SOCS3, and IL10), and a proinflammatory antimicrobial peptide (S100A7). In response to C. trachomatis infection, IL23A and PDGF were significantly upregulated in scarring progressors relative to in nonprogressors. Our findings highlight the importance of innate proinflammatory signals from the epithelium and implicate interleukin 23A (IL-23A)-responsive cells in driving trachomatous scarring, with potential key mechanistic roles for PDGFB, MMP12, and SPARCL1 in orchestrating fibrosis.

Evasion of Innate Lymphoid Cell-Regulated Gamma Interferon Responses by Chlamydia muridarum To Achieve Long-Lasting Colonization in Mouse Colon

Revealing the mechanisms by which bacteria establish long-lasting colonization in the gastrointestinal tract is an area of intensive investigation. The obligate intracellular bacterium Chlamydia is known to colonize mouse colon for long periods. A colonization-deficient mutant strain of this intracellular bacterium is able to regain long-lasting colonization in gamma interferon (IFN-γ) knockout mice following intracolon inoculation. We now report that mice deficient in conventional T lymphocytes or recombination-activating gene (Rag) failed to show rescue of mutant colonization. Nevertheless, antibody depletion of IFN-γ or genetic deletion of interleukin 2 (IL-2) receptor common gamma chain in Rag-deficient mice did rescue mutant colonization. These observations suggest that colonic IFN-γ, responsible for inhibiting the intracellular bacterial mutant, is produced by innate lymphoid cells (ILCs). Consistently, depletion of NK1.1⁺ cells in Rag-deficient mice both prevented IFN-γ production and rescued mutant colonization. Furthermore, mice deficient in transcriptional factor RORγt, but not chemokine receptor CCR6, showed full rescue of the long-lasting colonization of the mutant, indicating a role for group 3-like ILCs. However, the inhibitory function of the responsible group 3-like ILCs was not dependent on the natural killer cell receptor (NCR1), since NCR1-deficient mice still inhibited mutant colonization. Consistently, mice deficient in the transcriptional factor T-bet only delayed the clearance of the bacterial mutant without fully rescuing the long-lasting colonization of the mutant. Thus, we have demonstrated that the obligate intracellular bacterium Chlamydia maintains its long-lasting colonization in the colon by evading IFN-γ from group 3-like ILCs.

The conjunctival transcriptome in Ethiopians after trichiasis surgery: associations with the development of eyelid contour abnormalities and the effect of oral doxycycline treatment

Background: Surgery to correct trichiasis is a key component of the World Health Organisation trachoma control strategy, however unfavourable outcomes such as eyelid contour abnormalities (ECA) following surgery are relatively common. This study aimed to understand the transcriptional changes associated with the early development of ECA and the impact of doxycycline, which has anti-inflammatory and anti-fibrotic properties, upon these transcription patterns. Methods: One thousand Ethiopians undergoing trichiasis surgery were enrolled in a randomised controlled trial following informed consent. Equal groups of randomly assigned individuals were orally administered with 100mg/day of doxycycline (n=499) or placebo (n=501) for 28 days. Conjunctival swabs were collected immediately prior to surgery and at one- and six-months post-surgery. 3’ mRNA sequencing was performed on paired baseline and one-month samples from 48 individuals; 12 in each treatment/ECA outcome group. qPCR validation was then performed for 46 genes of interest in 145 individuals who developed ECA at one month and 145 matched controls, using samples from baseline, one and six months. Results: All treatment/outcome groups upregulated genes associated with wound healing pathways at one month relative to baseline, however no individual differences were detected between groups. The summed expression of a highly coexpressed cluster of pro-fibrotic genes was higher in patients that developed ECA in the placebo group relative to controls. qPCR validation revealed that all genes in this cluster and a number of other pro-inflammatory genes were strongly associated with ECA, however these associations were not modulated by trial arm. Conclusions: The development of post-operative ECA is associated with overexpression of pro-inflammatory and pro-fibrotic genes including growth factors, matrix metalloproteinases, collagens and extracellular matrix proteins. There was no evidence that doxycycline modulated the association between gene expression and ECA.

Immunofibrogenic Gene Expression Patterns in Tanzanian Children with Ocular Chlamydia trachomatis Infection, Active Trachoma and Scarring: Baseline Results of a 4-Year Longitudinal Study

Trachoma, caused by Chlamydia trachomatis, is the world's leading infectious cause of blindness and remains a significant public health problem. Much of trachomatous disease pathology is thought to be caused indirectly by host cellular and immune responses, however the immune response during active trachoma and how this initiates progressive scarring is not clearly understood. Defining protective vs. pathogenic immune response to C. trachomatis is important for vaccine design and evaluation. This study reports the baseline results of a longitudinal cohort of Tanzanian children, who were monitored for 4 years in order to determine the immunofibrogenic and infectious correlates of progressive scarring trachoma. In this cohort baseline, 506 children aged 6-10 years were assessed for clinical signs, infection status and the expression of 91 genes of interest prior to mass azithromycin administration for trachoma control. C. trachomatis was detected using droplet digital PCR and gene expression was measured using quantitative real-time PCR. The prevalence of follicles, papillary inflammation and scarring were 33.6, 31.6, and 28.5%, respectively. C. trachomatis was detected in 78/506 (15.4%) individuals, 62/78 of whom also had follicles. C. trachomatis infection was associated with a strong upregulation of IFNG and IL22, the enrichment of Th1 and NK cell pathways and Th17 cell-associated cytokines. In individuals with inflammation in the absence of infection the IFNG/IL22 and NK cell response was reduced, however, pro-inflammatory, growth and matrix factors remained upregulated and mucins were downregulated. Our data suggest that, strong IFNG/IL22 responses, probably related to Th1 and NK cell involvement, is important for clearance of C. trachomatis and that the residual pro-inflammatory and pro-fibrotic phenotype that persists after infection might contribute to pathological scarring. Interestingly, females appear more susceptible to developing papillary inflammation and scarring than males, even at this young age, despite comparable levels of C. trachomatis infection. Females also had increased expression of a number of IFNγ pathway related genes relative to males, suggesting that overexpression of this pathway in response to infection might contribute to more severe scarring. Longitudinal investigation of these factors will reveal their relative contributions to protection from C. trachomatis infection and development of scarring complications.

Maternal Milk T Cells Drive Development of Transgenerational Th1 Immunity in Offspring Thymus

Using multiple murine foster-nursing protocols, thereby eliminating placental transfer and allowing a distinction between dam- and pup-derived cells, we show that foster nursing by an immunized dam results in development of CD8(+) T cells in nonimmunized foster pups that are specific for Ags against which the foster dam was immunized (Mycobacterium tuberculosis or Candida albicans). We have dubbed this process "maternal educational immunity" to distinguish it from passive cellular immunity. Of the variety of maternal immune cells present in milk, only T cells were detected in pup tissues. Maternal T cells, a substantial percentage of which were CD4(+)MHC class II(+), accumulated in the pup thymus and spleen during the nursing period. Further analysis of maternal cells in the pup thymus showed that a proportion was positive for maternal immunogen-specific MHC class II tetramers. To determine the outcome of Ag presentation in the thymus, the maternal or foster pup origin of immunogen-responding CD8(+) cells in foster pup spleens was assessed. Whereas ∼10% were maternally derived in the first few weeks after weaning, all immunogen-responding CD8(+) T cells were pup derived by 12 wk of age. Pup-derived immunogen-responsive CD8(+) cells persisted until at least 1 y of age. Passive cellular immunity is well accepted and has been demonstrated in the human population. In this study, we show an arguably more important role for transferred immune cells: the direction of offspring T cell development. Harnessing maternal educational immunity through prepregnancy immunization programs has potential for improvement of infant immunity.

Differential frequency of NKG2C/KLRC2 deletion in distinct African populations and susceptibility to Trachoma: a new method for imputation of KLRC2 genotypes from SNP genotyping data

NKG2C is an activating receptor that is preferentially expressed on natural killer (NK) cells. The gene encoding NKG2C (killer cell lectin-like receptor C2, KLRC2) is present at different copy numbers in the genomes of different individuals. Deletion at the NKG2C locus was investigated in a case-control study of 1522 individuals indigenous to East- and West-Africa and the association with the ocular Chlamydia trachomatis infection and its sequelae was explored. The frequency of homozygous KLRC2 deletion was 13.7 % in Gambians and 4.7 % in Tanzanians. A significantly higher frequency of the deletion allele was found in West-Africans from the Gambia and Guinea-Bissau (36.2 % p = 2.105 × 10(-8), 26.8 % p = 0.050; respectively) in comparison to East-African Tanzanians where the frequency of the deletion is comparable to other human populations (20.9 %). We found no evidence for an association between the numbers of KLRC2 gene copies and the clinical manifestations of trachoma (follicular trachoma or conjunctival scarring). A new method for imputation of KLRC2 genotypes from single nucleotide polymorphism (SNP) data in 2621 individuals from the Gambia further confirmed these results. Our data suggest that NKG2C does not play a major role in trachomatous disease. We found that the deletion allele is present at different frequencies in different populations but the reason behind these differences is currently not understood. The new method offers the potential to use SNP arrays from genome wide association studies to study the frequency of KLRC2 deletion in other populations and its association with other diseases.