TGF-beta in the evolution and resolution of inflammatory and immune processes. Introduction

Cell Homing Strategies in Regenerative Endodontic Therapy

Cell homing, a process that leverages the body's natural ability to recruit cells and repair damaged tissues, presents a promising alternative to cell transplantation methods. Central to this approach is the recruitment of endogenous stem/progenitor cells-such as those from the apical papilla, bone marrow, and periapical tissues-facilitated by chemotactic biological cues. Moreover, biomaterial scaffolds embedded with signaling molecules create supportive environments, promoting cell migration, adhesion, and differentiation for the regeneration of the pulp-dentin complex. By analyzing in vivo animal studies using cell homing strategies, this review explores how biomolecules and scaffold materials enhance the recruitment of endogenous stem cells to the site of damaged dental pulp tissue, thereby promoting repair and regeneration. It also examines the key principles, recent advancements, and current limitations linked to cell homing-based regenerative endodontic therapy, highlighting the interplay of biomaterials, signaling molecules, and their broader clinical implications.

Advances in immunological research of amphioxus

Amphioxus, one of the most closely related invertebrates to vertebrates, is an important animal model for studying the origin and evolution of vertebrate immunity, especially the transition from innate immunity to adaptive immunity. The current research progresses of amphioxus in the field of immune organs, immune cells, complement system, cytokines, nuclear factor kappa B, immune-related lectins and enzymes are summarized, and some issues that remain to be understood or are in need of further clarification are highlighted. We hope to provide references for more in-depth study of the amphioxus immune system and lay a solid foundation for the construction of three-dimensional immune network in amphioxus from ontogeny to phylogeny.

Transcriptomic profiling of human dental pulp cells treated with tricalcium silicate-based cements by RNA sequencing

OBJECTIVES

Tricalcium silicate (TCS)-based biomaterials induce differentiation of human dental pulp cells (hDPCs) into odontoblasts/osteoblasts, which is regulated by the interplay between various intracellular pathways and their resultant secretome. The aim of this study was to compare the transcriptome-wide effects by next-generation RNA sequencing of custom-prepared hDPCs stimulated with TCS-based biomaterials: ProRoot white MTA (WMTA) (Dentsply, Tulsa; Tulsa, OK) and Biodentine (Septodont, Saint Maur des Fosses, France).

METHODS

Self-isolated hDPCs were seeded in a 6-well plate at a density of 5 × 10⁵ cells per well. ProRoot white MTA and Biodentine were then placed in transwell inserts with a pore size of 0.4 μm and inserted in the well plate. RNA sequencing was performed after 3 and 7 days treatment. For post-validation, RT-PCR analyses were done on some of the RNA samples used for RNA sequencing.

RESULTS

Our RNA sequencing results for the first time identified 7533 differentially expressed genes (DEGs) between different treatments and the number of DEGs in Biodentine was higher than ProRoot WMTA at both 3 and 7 days. Despite their differential gene expression, both the TCS-based biomaterial treatments showed gene expressions mainly involved in odontoblast differentiation, angiogenesis, neurogenesis, dentinogenesis, and tooth mineralization.

CONCLUSIONS

The results of the present study illustrate that several important signalling pathways are induced by hDPCs stimulated with TCS-based biomaterials.

CLINICAL RELEVANCE

The differential expression of the genes associated with odontogenesis, angiogenesis, neurogenesis, dentinogenesis, and mineralization may affect the prognosis of teeth treated with Biodentine or ProRoot white MTA.

Emerging roles of transforming growth factor β signaling in wet age-related macular degeneration

Age-related macular degeneration (AMD) is one of the major causes of irreversible blindness among aging populations in developed countries and can be classified as dry or wet according to its progression. Wet AMD, which is characterized by angiogenesis on the choroidal membrane, is uncommonly seen but more severe. Controlling or completely inhibiting the factors that contribute to the progression of events that lead to angiogenesis may be an effective strategy for treating wet AMD. Emerging evidence has shown that transforming growth factor-β (TGF-β) signaling plays a significant role in the progression of wet AMD. In this review, we described the roles of and changes in TGF-β signaling in the development of AMD and discussed the mechanisms of the TGF-β superfamily in choroidal neovascularization (CNV) and wet AMD, including the modulation of angiogenesis-related factors, inflammation, vascular fibrosis, and immune responses, as well as cross-talk with other signaling pathways. These remarkable findings indicate that TGF-β signaling is a potential target for wet AMD treatment.

Role of GATA transcription factor ELT-2 and p38 MAPK PMK-1 in recovery from acute P. aeruginosa infection in C. elegans

Infectious diseases caused by bacterial pathogens reduce the fitness of their associated host but are generally limited in duration. In order for the diseased host to regain any lost fitness upon recovery, a variety of molecular, cellular, and physiological processes must be employed. To better understand mechanisms underlying the recovery process, we have modeled an acute Pseudomonas aeruginosa infection in C. elegans using brief exposures to this pathogen and subsequent antibiotic treatment. To identify host genes altered during recovery from P. aeruginosa infection, we performed whole genome expression profiling. The analysis of this dataset indicated that the activity of the host immune system is down-regulated upon recovery and revealed shared and pathogen-specific host responses during recovery. We determined that the GATA transcription factor ELT-2 and the p38 MAP kinase PMK-1 are necessary for animals to successfully recover from an acute P. aeruginosa infection. In addition, we found that ELT-2 plays a more prominent and earlier role than PMK-1 during recovery. Our data sheds further light on the molecular mechanisms and transcriptional programs involved in recovery from an acute bacterial infection, which provides a better understanding of the entire infectious disease process.

Dissecting the role of transforming growth factor-β1 in topmouth culter immunobiological activity: a fundamental functional analysis

Transforming growth factor-β1 (TGF-β1) has been proven to function primarily in mammalian immunobiological activity, but information regarding the immune role of TGF-β1 in teleosts is limited. In the present study, we describe the cDNA cloning and characterization of the TGF-β1 molecule in the topmouth culter. TGF-β1 is highly expressed in immune-related tissues of the culter, including the thymus, head kidney, and spleen. The recombinant culter TGF-β1 (cTGF-β1) was successfully expressed and purified in vitro, and the effects of cTGF-β1 on the mRNA expression of pro-inflammatory cytokines, such as TNF-α and IL-1β, in the absence or presence of LPS was determined in culter peripheral blood leukocytes. cTGF-β1 was found to have bipolar properties in inflammatory reactions. Additionally, to assess the immune role of teleost TGF-β1 in vivo, the expression of TGF-β1 in the culter thymus and spleen tissues induced by poly I:C were also examined. The expression of TGF-β1 was obviously up-regulated, as shown in the cell lines. However, the peak time of cTGF-β1 expression in the cell lines occurred significantly earlier than in the organic tissues under the same inducer, suggesting that the response of the teleost TGF-β1 molecule to exogenous infection depends on a more complicated signalling pathway in vivo than in vitro.

Structural and functional characterization of a TGFβ molecule from amphioxus reveals an ancient origin of both immune-enhancing and -inhibitory functions

Transforming growth factor beta (TGFβ) is a pleiotropic cytokine with important roles in mediating inflammatory response. TGFβ has been shown to be widely present in invertebrates, but little is known about its functions in immune and inflammatory responses. Moreover, structural and functional insights into TGFβ molecules in invertebrates remain completely lacking. Here we demonstrate the presence of a single TGFβ-like gene in the amphioxus Branchiostoma japonicum, Bjtgfβ, which represents the archetype of vertebrate TGFβ proteins, and displays a higher expression in the hind-gut, hepatic caecum, ovary, and gill. We also show that amphioxus TGFβ exerts both enhancing and suppressing effects on the migration of macrophages like RAW264.7, and the motif WSTD is important for TGFβ in inducing or inhibiting the migration of macrophages. Altogether, these data suggest that amphioxus TGFβ is phylogenetically and functionally similar to vertebrate TGFβ, suggesting an ancient origin of bipolar function of TGFβ proteins.

TGF-β1 of no avail as prognostic marker in lyme disease

Background. Within the present in vivo study using the wild type mouse strains C3H/HeN and FVB/N it was intended to (1) measure TGF-β1 expression in the course of lyme disease, (2) examine the potential correlation of TGF-β1 expression with the clinical outcome of a Borrelia infection (with a focus on lyme arthritis), (3) develop a diagnostic tool based on the endogenous factor TGF-β1 to predict the progressivity of lyme disease.

Findings. In the course of lyme disease there was an increase in the serum content of active TGF-β1, which became significant 56 days post infection (p < 0.001). The serum concentration of total TGF-β1 in the course of infection initially decreased then rebounded and subsequently dropped again. Despite considerable individual variations in active TGF-β1 serum concentrations there were no identifiable dissimilarities in the clinical appearance of the mice. Likewise, no correlation could be seen between the serum content of active TGF-β1 and the severity of lyme arthritis of tibiotarsal joints of infected mice.

Conclusions. The present study clearly shows that TGF-β1 is of no avail as prognostic marker in lyme disease. Hence, the search for an endogenous predictive factor, which can be determined in an easy and reliable manner, remains open.

Effects of growth factors on dental stem/progenitor cells

The primary goal of regenerative endodontics is to restore the vitality and functions of the dentin-pulp complex, as opposed to filing of the root canal with bioinert materials. A myriad of growth factors regulates multiple cellular functions including migration, proliferation, differentiation, and apoptosis of several cell types intimately involved in dentin-pulp regeneration. Recent work showing that growth factor delivery, without cell transplantation, can yield pulp-dentin-like tissues in vivo provides one of the tangible pathways for regenerative endodontics. This review synthesizes knowledge on many growth factors that are known or anticipated to be efficacious in dental pulp-dentin regeneration.

Identification of a novel pathway of transforming growth factor-β1 regulation by extracellular NAD+ in mouse macrophages: in vitro and in silico studies

Extracellular β-nicotinamide adenine dinucleotide (NAD(+)) is anti-inflammatory. We hypothesized that NAD(+) would modulate the anti-inflammatory cytokine Transforming Growth Factor (TGF)-β1. Indeed, NAD(+) led to increases in both active and latent cell-associated TGF-β1 in RAW 264.7 mouse macrophages as well as in primary peritoneal macrophages isolated from both C3H/HeJ (TLR4-mutant) and C3H/HeOuJ (wild-type controls for C3H/HeJ) mice. NAD(+) acts partially via cyclic ADP-ribose (cADPR) and subsequent release of Ca(2+). Treatment of macrophages with the cADPR analog 3-deaza-cADPR or Ca(2+) ionophores recapitulated the effects of NAD(+) on TGF-β1, whereas the cADPR antagonist 8-Br-cADPR, Ca(2+) chelation, and antagonism of L-type Ca(2+) channels suppressed these effects. The time and dose effects of NAD(+) on TGF-β1 were complex and could be modeled both statistically and mathematically. Model-predicted levels of TGF-β1 protein and mRNA were largely confirmed experimentally but also suggested the presence of other mechanisms of regulation of TGF-β1 by NAD(+). Thus, in vitro and in silico evidence points to NAD(+) as a novel modulator of TGF-β1.

Bipolar properties of red seabream (Pagrus major) transforming growth factor-beta in induction of the leucocytes migration

TGF-beta is one of the pleiotropic cytokines and plays a pivotal role in immune regulation and orchestrating the subsequent healing response. Recombinant red seabream TGF-beta (rTGF-beta) mature peptide was expressed and purified under native conditions in vitro. Bio-assay showed that the rTGF-beta could significantly induce head kidney (HK) and peripheral blood (PB) leucocytes migration in a dose dependent manner, whereas the rTGF-beta suppressed HK and PB leucocyte migration when the leucocytes was activated by primed with lipopolysaccharide (LPS). Both enhancing and suppressing roles of rTGF-beta on the HKL and PBL chemotactic activity indicated that the fish TGF-beta shared the similar bipolar nature with mammalian TGF-beta. Furthermore, the results indicated that the activity of TGF-beta induction of leucocyte migration appears not to be an innate feature but function by regulation the chemokines activity. This is the first time we reported that fish TGF-beta has innate bipolar property in regulation of fish immune function.

Fibrillin-1 staining anomalies are associated with increased staining for TGF-beta and elastic fibre degradation; new clues to the pathogenesis of emphysema

We recently demonstrated aberrant staining of fibrillin-1 in lung tissue specimens with emphysematous lesions. In this study, we have extended this observation by an elaborate analysis of the elastic fibre. Using domain-specific antibodies to fibrillin-1, and to other elastin fibre-associated molecules, lung tissue derived from patients without obvious clinical emphysema, but harbouring various degrees of microscopical emphysematous lesions, was analysed. In addition, the fibrillin-regulated growth factor TGF-beta was studied. Electron microscopy and biochemical analysis of desmosine (a marker for elastin) were also performed. Results were compared with lung tissue derived from patients with clinical emphysema. Domain-specific antibodies recognizing the C-terminal, N-terminal, and middle part of fibrillin-1 showed aberrant staining patterns associated with increasing degrees of microscopical emphysema. Staining for elastin, emilin-1, and fibulin-2 was, however, not aberrant. TGF-beta staining was markedly increased. On the electron microscopic, but not light microscopical, level, initial elastic fibre degradation was noticed in specimens with microscopical emphysema. Lung specimens from patients with clinical emphysema also displayed fragmented fibrillin-1 staining and, in addition, displayed extensive degradation of the elastic fibre. The results suggest that fibrillin-1 anomalies and TGF-beta overexpression are associated with initial events occurring during the emphysematous process. Based on these and other data, a mechanism for emphysematogenesis is proposed.

Topical Delivery of Silver Nanoparticles Promotes Wound Healing

Wound healing is a complex process and has been the subject of intense research for a long time. The recent emergence of nanotechnology has provided a new therapeutic modality in silver nanoparticles for use in burn wounds. Nonetheless, the beneficial effects of silver nanoparticles on wound healing remain unknown. We investigated the wound-healing properties of silver nanoparticles in an animal model and found that rapid healing and improved cosmetic appearance occur in a dose-dependent manner. Furthermore, through quantitative PCR, immunohistochemistry, and proteomic studies, we showed that silver nanoparticles exert positive effects through their antimicrobial properties, reduction in wound inflammation, and modulation of fibrogenic cytokines. These results have given insight into the actions of silver and have provided a novel therapeutic direction for wound treatment in clinical practice.

Cytokine production following experimental implantation of xenogenic dermal collagen and polypropylene grafts in mice

AIM

We earlier showed that xenogenic Pelvicol (Bard, Olen, Belgium) implants induce a lesser inflammatory response than Prolene (Johnson and Johnson, Dilbeek, Belgium). The purpose of this study was to determine cytokine profiles in the host immune responses to Pelvicol in a mouse model. The hypothesis was that Pelvicol would induce a "T-helper2" (Th2) rather than T-helper1 (Th1) type of inflammatory response.

METHODS

Mice were implanted subcutaneously with Pelvicol or Prolene and the graft sites were harvested at 3 to 28 days. Histopathology was done and cytokine levels were determined by immunohistochemistry and RT-PCR. Flow cytometry was used to identify which cell population contributed to the observed cytokine production profiles.

RESULTS

Pelvicol induced a decreased inflammation and displayed an increase in IL-10 and TGF-beta, but reduce of TNF-alpha and IFN-gamma, indicating a Th2 type dominated response as examined by immunohistochemistry and RT-PCR. Flow cytometry showed that the monocytes/maceophages were the main cell population responsible for production of these cytokines. Monocytes/maceophages from Pelvicol explants showed upregulated expression of IL-10 while Prolene explants expressed TNF-alpha.

CONCLUSION

Pelvicol induced a Th2 type cytokine-dominated immune response after subcutaneous implantation in mice.

Release of PMN elastase, TGF-β1 and neopterin during blood storage; unfiltered versus filtered blood

Release of inflammatory mediators from blood cells during prestorage leukocyte filtration may result in recipient immune suppression. To investigate the effects of prestorage leukocyte filtration on the quality of blood components, twenty-four blood units were collected from healthy donors and randomised into 3 groups. Eight units were stored as whole blood, eight units were separated into plasma, red blood cells (RBC) and buffy coat and eight units were collected and filtered through the ASAHI RZ 2000 leukocyte filter and separated into plasma and RBC. The units were stored for 35 days. Samples were collected weekly for analyses of polymorphonuclear elastase (PMN elastase), transforming growth factor-beta1 (TGF-beta1) and neopterin. PMN elastase and neopterin increased during storage of whole blood and RBC. From the beginning and throughout storage, PMN elastase was increased in filtered plasma as compared with unfiltered plasma. Filtration per se did not influence the neopterin concentration in plasma or RBC. TGF-beta1 increased in plasma and RBC during storage. In filtered plasma, an elevation of the TGF-beta1 concentration was observed from the start of storage. The TGF-beta1 levels were higher in filtered plasma compared with unfiltered plasma. Prestorage leukocyte filtration increased the release of PMN elastase and TGF-beta1 in plasma and RBC.

Loss of transforming growth factor-beta type II receptor promotes metastatic head-and-neck squamous cell carcinoma

The prognosis of head-and-neck squamous cell carcinoma (HNSCC) has not been improved in the past 20 years. Validation of HNSCC biomarkers for targeted therapy has been hindered by a lack of animal models mimicking human HNSCC at both the pathological and molecular levels. Here we report that overexpression of K-ras or H-ras and loss of transforming growth factor-beta type II receptor (TGFbetaRII) are common events in human HNSCC. Activation of either K-ras or H-ras in combination with TGFbetaRII deletion from mouse head-and-neck epithelia caused HNSCC with complete penetrance, some of which progressed to metastases. These tumors displayed pathology indistinguishable from human HNSCCs and exhibited multiple molecular alterations commonly found in human HNSCCs. Additionally, elevated endogenous TGFbeta1 in these lesions contributed to inflammation and angiogenesis. Our data suggest that targeting common oncogenic pathways in tumor epithelia together with blocking the effect of TGFbeta1 on tumor stroma may provide a novel therapeutic strategy for HNSCC.

Current view of the role of transforming growth factor beta 1 in skin carcinogenesis

Previously, we have shown that transforming growth factor beta 1 (TGFbeta1) overexpression in suprabasal epidermis suppresses skin carcinogenesis at early stages, but promotes tumor invasion at later stages. To elucidate the role of TGFbeta1 overexpression in naturally occurring human squamous cell carcinomas (SCC), we screened TGFbeta1 expression patterns in human skin SCC samples and found that TGFbeta1 was overexpressed with two distinct patterns: either predominantly in suprabasal layers or throughout tumor epithelia including basal proliferative cells. To determine the effect of TGFbeta1 overexpression in basal keratinocytes, we generated transgenic mice expressing wild-type TGFbeta1 in basal keratinocytes and hair follicles using the K5 promoter (K5.TGFbeta1(wt)). Surprisingly, these mice developed a severe inflammatory skin disorder. Inflammation was also observed in head and neck tissue when TGFbeta1 transgene expression was inducibly expressed in head and neck epithelia in our gene-switch-TGFbeta1 transgenic mice. Given the importance of inflammation in cancer development, our data suggest that TGFbeta1-induced inflammation may override its tumor-suppressive effect even at early stages of skin carcinogenesis. This notion is further suggested by our recent study that Smad3 knockout mice were resistant to skin chemical carcinogenesis at least in part via abrogation of endogenous TGFbeta1-induced inflammation.

Molecular circuits of resolution: formation and actions of resolvins and protectins

The cellular events underlying the resolution of acute inflammation are not known in molecular terms. To identify anti-inflammatory and proresolving circuits, we investigated the temporal and differential changes in self-resolving murine exudates using mass spectrometry-based proteomics and lipidomics. Key resolution components were defined as resolution indices including Psi(max), the maximal neutrophil numbers that are present during the inflammatory response; T(max), the time when Psi(max) occurs; and the resolution interval (R(i)) from T(max) to T(50) when neutrophil numbers reach half Psi(max). The onset of resolution was at approximately 12 h with proteomic analysis showing both haptoglobin and S100A9 levels were maximal and other exudate proteins were dynamically regulated. Eicosanoids and polyunsaturated fatty acids first appeared within 4 h. Interestingly, the docosahexaenoic acid-derived anti-inflammatory lipid mediator 10,17S-docosatriene was generated during the R(i). Administration of aspirin-triggered lipoxin A(4) analog, resolvin E1, or 10,17S-docosatriene each either activated and/or accelerated resolution. For example, aspirin-triggered lipoxin A(4) analog reduced Psi(max), resolvin E1 decreased both Psi(max) and T(max), whereas 10,17S-docosatriene reduced Psi(max), T(max), and shortened R(i). Also, aspirin-triggered lipoxin A(4) analog markedly inhibited proinflammatory cytokines and chemokines at 4 h (20-50% inhibition), whereas resolvin E1 and 10,17S-docosatriene's inhibitory actions were maximal at 12 h (30-80% inhibition). Moreover, aspirin-triggered lipoxin A(4) analog evoked release of the antiphlogistic cytokine TGF-beta. These results characterize the first molecular resolution circuits and their major components activated by specific novel lipid mediators (i.e., resolvin E1 and 10,17S-docosatriene) to promote resolution.

IL-4 Inhibits Expression of the Formyl Peptide Receptor Gene in Mouse Peritoneal Macrophages

Regulation of leukocyte recruitment is an important determinant of the host response to microbial infection. Because tissue infiltration by inflammatory cells represents a potential source of unnecessary tissue damage, the process may be controlled by modulating the expression of chemoattractants and the receptors through which they promote directed leukocyte migration. In the present report, we show that expression of the receptor for chemotactic formylated peptides (FPR1)is negatively regulated in both macrophages and neutrophils by interleukin-4 (IL-4). The reduction of FPR1 mRNA occurs rapidly in response to both IL-4 and IL-13 but endures for <4 h after the removal of IL-4. As with many other responses to IL-4 and IL-13, suppression of FPR1 expression is dependent on the activation of Stat6. The inhibitory effect exhibits relative stimulus specificity in that other Stat-activating cytokines, such as interferon-gamma (IFN-gamma), IFN-beta, and IL-10, have no effect. Using nuclear run-on analysis, the rate of FPR1 gene transcription is high but is not suppressed by IL-4. Moreover, IL-4 does not appear to alter the rate of FPR mRNA decay. Nevertheless, FPR mRNA exhibits a short half-life (< or =2 h), and this appears to be a critical feature of the ability of IL-4 to reduce expression. Taken together, the data suggest that IL-4 and IL-13 suppress the expression of FPR1 mRNA via a mechanism that operates to eliminate primary transcripts prior to maturation and depends on the constitutive instability of preexisiting mRNA.

Overexpression of Transforming Growth Factor β1 in Head and Neck Epithelia Results in Inflammation, Angiogenesis, and Epithelial Hyperproliferation

In the present study, we show that transforming growth factor beta1 (TGF-beta1) was frequently overexpressed in human head and neck squamous cell carcinomas (HNSCCs) and adjacent tissues in comparison with normal head and neck tissues. To determine the role of TGF-beta1 overexpression in HNSCC carcinogenesis, we generated transgenic mice in which TGF-beta1 transgene expression can be induced in head and neck epithelia. TGF-beta1 transgene induction in head and neck epithelia, at levels similar to those in human HNSCCs, caused severe inflammation and angiogenesis. Consequently, TGF-beta1-transgenic epithelia exhibited hyperproliferation. These phenotypes correlated with enhanced Smad signaling in transgenic epithelia and stroma. Our study suggests that TGF-beta1 overexpression at early stages of HNSCC formation provides a tumor promoting microenvironment.

Burn Injury Initiates a Shift in Superantigen-Induced T Cell Responses and Host Survival

Severe injury induces a temporal shift in immune reactivity that can cause serious complications or even death. We previously reported that mice exposed to bacterial superantigen (SAg) early after injury undergo a strong SAg response with lethal consequences. This study compares the early and late effects of burn injury on SAg reactivity in vivo to establish how injury influences adaptive immune responses. We found that mice challenged with ordinarily sublethal doses of staphylococcal enterotoxin A or staphylococcal enterotoxin B at 1 day after burn injury exhibited high mortality, whereas no mortality occurred at 7 days after injury. This shift in mortality correlated with higher Th2-type cytokines (IL-4 and IL-10) being expressed by CD4(+) and CD8(+) T cells from burn as opposed to sham mice at 7 days after injury. Lymph node cells from burn-injured mice also produced higher levels of Th2-type cytokines at 7 days after injury. The results of cell-mixing studies using CD4(+) and CD8(+) T cells mixed with APCs from sham or burn mice suggested that changes in both T cells and APCs are involved in the altered SAg response. Finally, the biological significance of altered SAg reactivity following injury was shown by demonstrating that blocking IL-10 activity in vivo caused higher SAg-induced mortality at 7 days after injury. These findings support the idea that injury promotes a Th2-type shift in adaptive immune reactivity. Although prior studies link this counterinflammatory-type response to lowered resistance to infection, the present results suggest it may sometimes benefit the injured host.

Latent TGFbeta1 overexpression in keratinocytes results in a severe psoriasis-like skin disorder

Transforming growth factor beta1 (TGFbeta1), a potent keratinocyte growth inhibitor, has been shown to be overexpressed in keratinocytes in certain inflammatory skin diseases and has been thought to counteract the effects of other growth factors at the site of inflammation. Surprisingly, our transgenic mice expressing wild-type TGFbeta1 in the epidermis using a keratin 5 promoter (K5.TGFbeta1(wt)) developed inflammatory skin lesions, with gross appearance of psoriasis-like plaques, generalized scaly erythema, and Koebner's phenomenon. These lesions were characterized by epidermal hyperproliferation, massive infiltration of neutrophils, T lymphocytes, and macrophages to the epidermis and superficial dermis, subcorneal microabscesses, basement membrane degradation, and angiogenesis. K5.TGFbeta1(wt) skin exhibited multiple molecular changes that typically occur in human Th1 inflammatory skin disorders, such as psoriasis. Further analyses revealed enhanced Smad signaling in transgenic epidermis and dermis. Our study suggests that certain pathological condition-induced TGFbeta1 overexpression in the skin may synergize with or induce molecules required for the development of Th1 inflammatory skin disorders.

Burn injury promotes antigen-driven Th2-type responses in vivo

Severe injury induces detrimental changes in immune function, often leaving the host highly susceptible to developing life-threatening opportunistic infections. Advances in our understanding of how injury influences host immune responses suggest that injury causes a phenotypic imbalance in the regulation of Th1- and Th2-type immune responses. We report in this study, using a TCR transgenic CD4(+) T cell adoptive transfer approach, that injury skews T cell responses toward increased Th2-type reactivity in vivo without substantially limiting Ag-driven CD4(+) T cell expansion. The increased Th2-type response did not occur unless injured mice were immunized with specific Ag, suggesting that the phenotypic switch is Ag dependent. These findings establish that severe injury induces fundamental changes in the induction of Ag-specific CD4(+) Th cell responses favoring the development of Th2-type immune reactivity in vivo.

Reciprocal functions of hepatocyte growth factor and transforming growth factor-beta1 in the progression of renal diseases: a role for CD44?

Progressive renal fibrosis occurs via common pathophysiologic mechanisms, regardless of the primary underlying disease. This cascade includes release of cytokines/chemokines and toxic molecules, interstitial inflammation, tubular cell damage, accumulation of myofibroblasts, and finally, fibrosis. Hepatocyte growth factor (HGF) and transforming growth factor-beta1 (TGF-beta1) are key molecules in this cascade that, in general, exert opposite actions. Hepatocyte growth factor promotes, to some extent, inflammation, protects tubular epithelial cells, blocks myofibroblast transition, and contributes to tissue remodeling. In contrast, TGF-beta1 has powerful anti-inflammatory actions, promotes apoptosis, induces myofibroblast transition, and is a strong pro-fibrotic agent. The mechanisms which orchestrate the reciprocal actions of HGF and TGF-beta1 are still largely unknown and are probably multiple. One of these mechanisms involves the selective up-regulation of CD44 in damaged kidney. The glomerular and tubular expression of CD44 closely correlates with the degree of renal damage, and CD44 has been shown to facilitate the action of both HGF and TGF-beta1. Moreover, during chronic obstructive nephropathy CD44 knock-out mice display much more tubular damage but develop less fibrosis in the course of the renal disease. These histologic findings are associated with impairment of signaling pathways of both HGF and TGF-beta1. The development of new therapeutic strategies aimed at preventing progression of renal diseases that are based on HGF and/or TGF-beta1 may take in account the pivotal role of CD44 expression in the functions of both molecules.

CC Chemokine Ligand 2 and Its Receptor Regulate Mucosal Production of IL-12 and TGF-β in High Dose Oral Tolerance

Oral tolerance is the result of a complex immunoregulatory strategy used by the gut and its associated lymphoid tissues to render the peripheral immune system unresponsive to nonpathogenic proteins, such as food or commensal bacteria. The mechanism of oral tolerance induction and maintenance is not well understood. We have previously shown that the chemokine, CC chemokine ligand 2 (CCL2), is important for the induction and maintenance of oral tolerance. To address the role CCL2 plays in oral tolerance, we used both CCL2(-/-) and CCR2(-/-) mice. Cells from the spleen, mesenteric lymph nodes, and peripheral lymph nodes of CCL2(-/-) and CCR2(-/-) mice fed high doses of OVA showed robust proliferative responses compared with cells from Ag-fed wild-type mice. CCL2(-/-) and CCR2(-/-) mice also produced high amounts of Th1 cytokines such as IL-2 and IFN-gamma and very low amounts of IL-4 and IL-10. The ability of APCs from the gut of CCL2(-/-) and CCR2(-/-) OVA-fed mice to stimulate an indicator T cell line was evaluated. APCs from the Peyer's patch of OVA-fed knockout animals could induce a T cell response measured by an increase in proliferation and generation of IL-12 and IFN-gamma with a concomitant reduction of TGF-beta compared with wild-type controls that did not induce a Th1 response. These data indicate that CCL2 and signaling through its receptor CCR2 is critical for the induction of oral tolerance by regulating Ag presentation leading to a disruption in the balance of inflammatory and regulatory cytokines.

TGFbeta inhibits LPS-induced chemokine mRNA stabilization

The mechanisms involved in anti-inflammatory action of transforming growth factor beta (TGFbeta) have been examined by evaluating its effect on chemokine gene expression in mouse macrophages. Lipopolysaccharide (LPS)-stimulated expression of the CXC chemokines KC and MIP-2 was selectively reduced by TGFbeta in a time- and protein synthesis-dependent process. While TGFbeta had a modest effect on transcription of the KC and MIP-2 mRNAs as measured by nuclear run-on, it had no effect on LPS-stimulated luciferase expression driven by the KC promoter nor on the activation of nuclear factor kappaB (NFkappaB) DNA-binding activity and transactivation function. Interestingly, KC mRNA levels were markedly reduced by TGFbeta treatment in cells transfected with KC genomic or cDNA constructs driven from either the KC or cytomegalovirus (CMV) promoters, demonstrating the importance of sequences within the mature mRNA and suggesting that suppression may involve a posttranscriptional mechanism. In support of this possibility, LPS stimulation prolonged the half-life of KC mRNA and this stabilization response was blocked in cells treated with TGFbeta. Examination of KC mRNA expressed under control of a tetracycline-responsive promoter demonstrated that TGFbeta prevented stabilization of KC mRNA, in response to LPS but did not alter KC mRNA half-life directly. KC mRNA stabilization by LPS was dependent on activation of p38 mitogen-activated protein kinase (MAPK) activity, and TGFbeta treatment inhibited p38 MAPK activation. These findings support the hypothesis that TGFbeta-mediated suppression of chemokine gene expression involves antagonism of LPS-stimulated KC mRNA stabilization via inhibition of p38 MAPK.

Activin A stimulates type IV collagenase (matrix metalloproteinase-2) production in mouse peritoneal macrophages

The role of activin, a dimer of inhibin beta subunit, in mouse peritoneal macrophages was evaluated. Activin activity in the cultured macrophages was augmented in response to activation by LPS. In Western blot analysis, immunoreactive activin A was detected in the culture medium only when the macrophages were stimulated by LPS. Although mRNA expression of betaA subunit was detected, that of alpha and betaB subunit was not found in macrophages by reverse RT-PCR. The activin betaA mRNA level was increased in macrophages by LPS, suggesting that the activin production augmented by LPS is regulated at the mRNA level of the betaA gene. The mRNAs of four activin receptors (ActRI, ActRIB, ActRII, and ActRIIB) were also detected in the peritoneal macrophages, and the mRNA levels, except for ActRIB, were decreased during the LPS treatment. Exogenous activin A stimulated the mRNA expression and gelatinolytic activity of matrix metalloproteinase-2 (MMP-2) in macrophages in both the presence and the absence of LPS. In contrast, activin did not affect the production of MMP-9 in macrophages. These results suggested that 1) mouse peritoneal macrophages produced activin A; 2) expression of activin A was enhanced with activation of the macrophages; 3) the macrophages also expressed activin receptors; and 4) exogenous activin A stimulated MMP-2 expression and activity, implicating activin A as an positive regulator of MMP-2 expression. Considering that MMP-2 constitutes the rate-limiting proteinase governing the degradation of basement membrane collagens, activin A may be involved in migration and infiltration of macrophages through the basement membrane in an inflammatory state.

Photopheresis: clinical applications and mechanism of action

Photopheresis is a leukapheresis-based therapy that utilizes 8-methoxypsoralen and ultraviolet A irradiation. Photopheresis is currently available at approximately 150 medical centers worldwide. Recent evidence suggests that this therapy used as a single agent may significantly prolong life, as well as induce a 50%-75% response rate among individuals with advanced cutaneous T cell lymphoma (CTCL). Furthermore, a 20%-25% complete response rate with photopheresis alone, or in combination with other biologic response modifiers, has been obtained at our institution among patients with Sezary syndrome. These complete responses have been characterized by the complete disappearance of morphologically atypical cells from the skin and blood. The use of sensitive molecular techniques has also confirmed the sustained disappearance of the malignant T cell clone from the blood of patients with complete responses. In addition to the treatment of CTCL, numerous reports indicate that photopheresis is a potent agent in the therapy of acute allograft rejection among cardiac, lung, and renal transplant recipients. Chronic graft versus host disease also appears to be quite responsive to photopheresis therapy. Likewise, there may also be a potential role for photopheresis in the therapy of certain autoimmune diseases that are poorly responsive to conventional therapy. The immunologic basis for the responses of patients with these conditions is likely due to the induction of anticlonotypic immunity directed against pathogenic clones of T lymphocytes. Treatment-induced apoptotic death of pathogenic T cells and activation of antigen presenting cells are postulated to have important effects in this therapeutic process.