Loss of primary cilia promotes inflammation and carcinogenesis.

Primary cilia (PC) are important signaling hubs, and we here explored their role in colonic pathology. In the colon, PC are mostly present on fibroblasts, and exposure of mice to either chemically induced colitis-associated colon carcinogenesis (CAC) or dextran sodium sulfate (DSS)-induced acute colitis decreases PC numbers. We generated conditional knockout mice with reduced numbers of PC on colonic fibroblasts. These mice show increased susceptibility to CAC, as well as DSS-induced colitis. Secretome and immunohistochemical analyses of DSS-treated mice display an elevated production of the proinflammatory cytokine IL-6 in PC-deficient colons. An inflammatory environment diminishes PC presence in primary fibroblast cultures, which is triggered by IL-6 as identified by RNA-seq analysis together with blocking experiments. These findings suggest an activation loop between IL-6 production and PC loss. An analysis of PC presence on biopsies of patients with ulcerative colitis or colorectal cancer (CRC) reveals decreased numbers of PC on colonic fibroblasts in pathological compared with surrounding normal tissue. Taken together, we provide evidence that a decrease in colonic PC numbers promotes colitis and CRC.

A proliferation-inducing ligand-mediated anti-inflammatory response of astrocytes in multiple sclerosis.

OBJECTIVE: The two related tumor necrosis factor members a proliferation-inducing ligand (APRIL) and B-cell activation factor (BAFF) are currently targeted in autoimmune diseases as B-cell regulators. In multiple sclerosis (MS), combined APRIL/BAFF blockade led to unexpected exacerbated inflammation in the central nervous system (CNS) of patients. Here, we investigate the role of the APRIL/BAFF axis in the CNS. METHODS: APRIL expression was analyzed in MS lesions by immunohistochemistry. The in vivo role of APRIL was assessed in the murine MS model, experimental autoimmune encephalitis (EAE). Functional in vitro studies were performed with human and mouse astrocytes. RESULTS: APRIL was expressed in lesions from EAE. In its absence, the disease was worst. Lesions from MS patients also showed APRIL expression upon infiltration of macrophages. Notably, all the APRIL secreted by these macrophages specifically targeted astrocytes. The upregulation of chondroitin sulfate proteoglycan, sometimes bearing chondroitin sulfate of type E sugar moieties, binding APRIL, in reactive astrocytes explained the latter selectivity. Astrocytes responded to APRIL by producing a sufficient amount of IL-10 to dampen antigen-specific T-cell proliferation and pathogenic cytokine secretion. Finally, an intraspinal delivery of recombinant APRIL before disease onset, shortly reduced EAE symptoms. Repeated intravenous injections of recombinant APRIL before and even at disease onset also had an effect. INTERPRETATION: Our data show that APRIL mediates an anti-inflammatory response from astrocytes in MS lesions. This protective activity is not shared with BAFF. ANN NEUROL 2019;85:406-420.

Mixed signals from the cell's antennae: primary cilia in cancer.

Primary cilia (PC) are antenna-like organelles that protrude from most mammalian cells. They are essential for the regulation of several signaling pathways such as Hedgehog and WNT It is therefore not surprising that a dysfunction of PC is frequently associated with pathologies. Originally, PC were found to be involved in a variety of diseases commonly referred to as ciliopathies including cystic kidney diseases. Evidence is accumulating that PC play also an important role in cancer formation and regulation, which is the focus of this review.

Tubulin glycylases are required for primary cilia, control of cell proliferation and tumor development in colon.

TTLL3 and TTLL8 are tubulin glycine ligases catalyzing posttranslational glycylation of microtubules. We show here for the first time that these enzymes are required for robust formation of primary cilia. We further discover the existence of primary cilia in colon and demonstrate that TTLL3 is the only glycylase in this organ. As a consequence, colon epithelium shows a reduced number of primary cilia accompanied by an increased rate of cell division in TTLL3-knockout mice. Strikingly, higher proliferation is compensated by faster tissue turnover in normal colon. In a mouse model for tumorigenesis, lack of TTLL3 strongly promotes tumor development. We further demonstrate that decreased levels of TTLL3 expression are linked to the development of human colorectal carcinomas. Thus, we have uncovered a novel role for tubulin glycylation in primary cilia maintenance, which controls cell proliferation of colon epithelial cells and plays an essential role in colon cancer development.

A New Animal Model of Gastric Lymphomagenesis: APRIL Transgenic Mice Infected by Helicobacter Species.

APRIL is a member of the tumor necrosis factor cytokine family involved in the regulation of B-cell immunity. We present a study of the infection by Helicobacter species of transgenic (Tg) C57BL6 mice, ectopically expressing the human form of APRIL. Wild-type (WT) and APRIL Tg mice were infected with Helicobacter felis and Helicobacter pylori and compared with noninfected animals. Mice were euthanized 18 months after infection, and inflammatory responses and histologic alterations were analyzed. Flow cytometry results revealed that WT-infected mice had less leukocyte infiltration than APRIL Tg-infected mice. In WT-infected mice, infiltrates in gastric tissues were predominantly composed of T cells, mainly CD4+ for H. pylori and CD8+ for H. felis. In APRIL Tg-infected mice, leukocyte infiltrates were composed of B cells with few CD4+ T cells for both species. B cells expressed B surface markers compatible with a marginal zone origin. These results were confirmed by immunohistochemistry. B cells in particular were involved in lymphoepithelial lesions, a hallmark of gastric MALT lymphoma. Monoclonality was observed in a few infiltrates in the presence of lymphoepithelial lesions. These results confirm the importance of APRIL in the development of gastric lymphoid infiltrates induced by Helicobacter species in vivo. We believe that APRIL Tg mice infected by Helicobacter species may represent a novel animal model of gastric lymphomagenesis.

A proliferation inducing ligand (APRIL) promotes IL-10 production and regulatory functions of human B cells.

B cells may have a negative regulatory role, mainly mediated by interleukin 10 (IL-10). We recently showed that regulatory B-cell functions are impaired in patients with rheumatoid arthritis (RA) and that mice transgenic for a proliferation-inducing ligand (APRIL) are protected against collagen-induced arthritis. We aimed to explore the effect of APRIL on human B-cell IL-10 production, in healthy subjects and in patients with RA. The IL-10 production of B-cell was greater with APRIL than with BLyS or control medium, in a dose dependent manner. TACI expression was greater in IL-10 producing B cells (B10) than non-IL-10-producing B cells whereas BAFF-R expression was lower. TNF-α and IFN-γ secretion of T-cells were decreased by APRIL-stimulated B cells. APRIL stimulated STAT3 and STAT3 inhibition decreased B10 cells. APRIL also promoted B10 cells in RA patients. In conclusion, APRIL but not BLyS promotes IL-10 production by CpG-activated B cells and enhances the regulatory role of B cells on T cells. B10 cells in RA patients are responsive to APRIL, which suggests a possible therapeutic application of APRIL to expand B10 cells. This could also explain the difference of clinical efficacy observed between belimumab and atacicept in RA.

Cyclin A2 modulates EMT via ß-catenin and phospholipase C pathways.

We have previously demonstrated that Cyclin A2 is involved in cytoskeletal dynamics, epithelial-mesenchymal transition (EMT) and metastasis. This phenotype was potentiated by activated oncogenic H-Ras. However, the mechanisms governing EMT in these cells have not yet been elucidated. Here, we dissected the pathways that are responsible for EMT in cells deficient for Cyclin A2. In Cyclin A2-depleted normal murine mammary gland (NMuMG) cells expressing RasV12, we found that ß-catenin was liberated from the cell membrane and cell-cell junctions and underwent nuclear translocation and activation. Components of the canonical wingless (WNT) pathway, including WNT8b, WNT10a, WNT10b, frizzled 1 and 2 and TCF4 were upregulated at the messenger RNA and protein levels following Cyclin A2 depletion. However, suppression of the WNT pathway using the acetyltransferase porcupine inhibitor C59 did not reverse EMT whereas a dominant negative form of TCF4 as well as inhibition of phospholipase C using U73122 were able to do so. This suggests that a WNT-independent mechanism of ß-catenin activation via phospholipase C is involved in the EMT induced by Cyclin A2 depletion. Our findings will broaden our knowledge on how Cyclin A2 contributes to EMT and metastasis.

APRIL promotes breast tumor growth and metastasis and is associated with aggressive basal breast cancer.

APRIL (a proliferation-inducing ligand) is a cytokine of the tumor necrosis factor family associated mainly with hematologic malignancies. APRIL is also overexpressed in breast carcinoma tissue lesions, although neither its role in breast tumorigenesis nor the underlying molecular mechanism is known. Here, we show that several breast cancer cell lines express APRIL and both its receptors, B cell maturation antigen (BCMA) and transmembrane activator and CAML-interactor (TACI), independently of luminal or basal tumor cell phenotype, and that the mitogen-activated protein kinases p38, ERK1/2, and JNK1/2 are activated in response to APRIL. The inflammatory stimulus poly I:C, a toll-like receptor (TLR) 3 ligand, enhanced APRIL secretion. Silencing experiments decreased cell proliferation, demonstrating that APRIL is a critical autocrine factor for breast tumor growth. Studies of 4T1 orthotopic breast tumors in APRIL transgenic mice showed that an APRIL-enriched environment increased tumor growth and promoted lung metastasis associated with enhanced tumor cell proliferation; BCMA and TACI expression suggests that both participate in these processes. We detected APRIL, BCMA and TACI in human luminal, triple-negative breast carcinomas and HER2 breast carcinomas, with increased levels in more aggressive basal tumors. APRIL was observed near Ki67(+) nuclei and was distributed heterogeneously in the cancer cells, in the leukocyte infiltrate, and in the myoepithelial layer adjacent to the tumor area; these results imply that APRIL provides proliferation signals to tumor cells through paracrine and autocrine signaling. Our study identifies participation of APRIL signaling in breast cancer promotion; we propose impairment of this pathway as a potential therapeutic strategy.

High levels of natural killer cells are associated with response to tocilizumab in patients with severe rheumatoid arthritis.

OBJECTIVES: We aimed to assess the effect of tocilizumab (TCZ), an IL-6 receptor inhibitor, on B, T, NK and NKT cells in patients with RA and to study the cell type predictors of remission. We also compared NK cells in patients with RA and in controls. METHODS: RA patients included in the study met the 2010 ACR/European League Against Rheumatism (EULAR) criteria, were receiving stable doses of steroids and had not received rituximab in the previous year. Different B and T cell subsets, NK cells and NKT cells were assessed by flow cytometry along with perforin A and granzyme B to estimate NK cell cytotoxicity. RESULTS: We included 92 RA patients, including 20 requiring TCZ treatment and 15 requiring anti-TNF drugs, and 25 controls. At baseline, the proportion of CD56(dim)CD16(+)CD3(-) NK cells was inversely correlated with the 28-joint DAS (DAS28). In TCZ-treated patients, the baseline proportion of CD3(-)CD56(+) NK cells was inversely correlated with the change in DAS28 at 3 months and the proportion was 3-fold greater for patients with DAS28 remission at 3 months than other patients. Change in the proportion of CD56(bri)CD16(-) NK cells was linearly correlated with change in the DAS28 at 3 months. The baseline proportion of NK cells did not predict change in disease activity at 3 months with anti-TNF therapy. The perforin content in NK cells increased with TCZ treatment. CONCLUSION: This study supports NK cell involvement in RA and in the TCZ mechanism of action. NK cells at baseline could be a predictive factor of TCZ response if results are confirmed.

Chronic lymphocytic leukemia disease progression is accelerated by APRIL-TACI interaction in the TCL1 transgenic mouse model.

Although in vitro studies pointed to the tumor necrosis factor family member APRIL (a proliferation-inducing ligand) in mediating survival of chronic lymphocytic leukemia (CLL) cells, clear evidence for a role in leukemogenesis and progression in CLL is lacking. APRIL significantly prolonged in vitro survival of CD5(+)B220(dull) leukemic cells derived from the murine Eµ-TCL1-Tg (TCL1-Tg [transgenic]) model for CLL. APRIL-TCL1 double-Tg mice showed a significantly earlier onset of leukemia and disruption of splenic architecture, and survival was significantly reduced. Interestingly, clonal evolution of CD5(+)B220(dull) cells (judged by BCR clonality) did not seem to be accelerated by APRIL; both mouse strains were oligoclonal at 4 months. Although APRIL binds different receptors, APRIL-mediated leukemic cell survival depended on tumor necrosis factor receptor superfamily member 13B (TACI) ligation. These findings indicate that APRIL has an important role in CLL and that the APRIL-TACI interaction might be a selective novel therapeutic target for human CLL.

Targeting the Fas/FasL system in Rheumatoid Arthritis therapy: Promising or risky?

Rheumatoid Arthritis (RA) is a chronic inflammatory disease affecting synovial joints. Tumor necrosis factor (TNF) α is a key component of RA pathogenesis and blocking this cytokine is the most common strategy to treat the disease. Though TNFα blockers are very efficient, one third of the RA patients are unresponsive or present side effects. Therefore, the development of novel therapeutic approaches is required. RA pathogenesis is characterized by the hyperplasia of the synovium, closely associated to the pseudo-tumoral expansion of fibroblast-like synoviocytes (FLS), which invade and destroy the joint structure. Hence, depletion of RA FLS has been proposed as an alternative therapeutic strategy. The TNF family member Fas ligand (FasL) was reported to trigger apoptosis in FLS of arthritic joints by binding to its receptor Fas and therefore suggested as a promising candidate for targeting the hyperplastic synovial tissue. However, this cytokine is pleiotropic and recent data from the literature indicate that Fas activation might have a disease-promoting role in RA by promoting cell proliferation. Therefore, a FasL-based therapy for RA requires careful evaluation before being applied. In this review we aim to overview what is known about the apoptotic and non-apoptotic effects of Fas/FasL system and discuss its relevance in RA.

Anti-inflammatory role of APRIL by modulating regulatory B cells in antigen-induced arthritis.

APRIL (A Proliferation-Inducing Ligand), a member of the TNF superfamily, was initially described for its ability to promote proliferation of tumor cells in vitro. Moreover, this cytokine has been related to the pathogenesis of different chronic inflammatory diseases, such as rheumatoid arthritis. This study aimed to evaluate the ability of APRIL in regulating B cell-mediated immune response in the antigen-induced arthritis (AIA) model in mice. AIA was induced in previously immunized APRIL-transgenic (Tg) mice and their littermates by administration of antigen (mBSA) into the knee joints. Different inflammatory cell populations in spleen and draining lymph nodes were analyzed using flow cytometry and the assay was performed in the acute and chronic phases of the disease, while cytokine levels were assessed by ELISA. In the acute AIA, APRIL-Tg mice developed a less severe condition and a smaller inflammatory infiltrate in articular tissues when compared with their littermates. We also observed that the total cellularity of draining lymph nodes was decreased in APRIL-Tg mice. Flow cytometry analysis revealed an increase of CD19+IgM+CD5+ cell population in draining lymph nodes and an increase of CD19+CD21hiCD23hi (B regulatory) cells in APRIL-Tg mice with arthritis as well as an increase of IL-10 and CXCL13 production in vitro.

The TNF family member APRIL dampens collagen-induced arthritis.

BACKGROUND: The tumour necrosis factor (TNF)-family members B cell activating factor (BAFF) and A PRoliferation-Inducing Ligand (APRIL) play important roles in B cell biology, and share binding to B cell maturation antigen and transmembrane activator and cyclophilin ligand interactor, both receptors of the TNF-family. However, while it is reported that BAFF can break B cell tolerance, the role of APRIL in autoimmunity remains elusive. OBJECTIVE: To evaluate the role of APRIL on collagen-induced arthritis (CIA). METHODS: CIA was induced in APRIL-transgenic (Tg) DBA/1 mice and littermates. Disease progression was evaluated by clinical and histological signs of arthritis. In another experimental setting mice were exposed to the collagen antibody-induced arthritis. In addition, we tested T cell dependent humoral responses in APRIL-Tg mice. RESULTS: We found that APRIL-Tg displayed a strongly reduced incidence and severity of CIA compared with littermates, with decreases in collagen-specific autoantibody titres, immune complex deposition and downstream mast cell activation in joints. Notably, ectopic APRIL-expression was also found to negatively regulate T cell dependent humoral responses. The lower autoantibody production in APRIL-Tg mice during CIA appears to be crucial, as arthritis induced by administration of anti-collagen antibodies developed similar in APRIL-Tg and control mice, thus demonstrating that the downstream effector pathways induced by anti-collagen antibodies remain intact in APRIL-Tg mice. This protective effect was specifically mediated by APRIL, as adenoviral delivery of APRIL decreased CIA in a therapeutic setting. CONCLUSIONS: Collectively, our data identify APRIL as a negative regulator of CIA by regulating autoantibody production. These findings are of important clinical relevance, as the therapeutic potential of transmembrane activator and cyclophilin ligand interactor-Fc (atacicept) is presently evaluated in clinical trials.

The two directions of TNF-related apoptosis-inducing ligand in rheumatoid arthritis.

The TNF-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor (TNF) superfamily that has been recognized for its specific pro-apoptotic effect on cancer cells and has been therefore proposed as a treatment in cancer. Studies on animal models have shown that TRAIL could also have a beneficial effect in rheumatoid arthritis (RA). This includes reports suggesting that TRAIL could be used to control the synovial hyperplasia and hyperactivation of immune cells observed in RA, but recent reports suggest a disease promoting role of TRAIL in RA. Indeed, adverse effects and mechanism of resistance could counteract beneficial effect of TRAIL. This review focuses on the role of TRAIL in immune regulation, synovial hyperplasia and joint remodeling in RA. We will also discuss the potential use of TRAIL in RA treatment.

Pancreatic beta-cell specific BAG3 knockout results in chronic hyperinsulinemia inducing insulin resistance.

BACKGROUND: Insulin, secreted from pancreatic islets of Langerhans, is of critical importance in regulating glucose homeostasis. Defective insulin secretion and/or the inability of tissues to respond to insulin results in insulin resistance and to several metabolic and organ alterations. We have previously demonstrated that BAG3 regulates insulin secretion. Herein we explored the consequences of beta-cells specific BAG3 deficiency in an animal model. METHODS: We generated a beta-cells specific BAG3 knockout mouse model. Glucose and insulin tolerance tests, proteomics, metabolomics, and immunohistochemical analysis were used to investigate the role of BAG3 in regulating insulin secretion and the effects of chronic exposure to excessive insulin release in vivo. RESULTS: Beta-cells specific BAG3 knockout results in primary hyperinsulinism due to excessive insulin exocytosis finally leading to insulin resistance. We demonstrate that resistance is mainly muscle-dependent while the liver remains insulin sensitive. The chronically altered metabolic condition leads in time to histopathological alterations in different organs. We observe elevated glycogen and lipid accumulation in the liver reminiscent of non-alcoholic fatty liver disease as well as mesangial matrix expansion and thickening of the glomerular basement membrane, resembling the histology of chronic kidney disease. CONCLUSION: Altogether, this study shows that BAG3 plays a role in insulin secretion and provides a model for the study of hyperinsulinemia and insulin resistance.

Mechanisms and clinical relevance of TRAIL-triggered responses in the synovial fibroblasts of patients with rheumatoid arthritis.

OBJECTIVE: Results of studies in mice suggest a protective role for TRAIL in arthritis. The aim of this study was to investigate the role of TRAIL in patients with rheumatoid arthritis (RA). METHODS: In the present study, we compared RA fibroblast-like synoviocytes (FLS) that were resistant or sensitive to TRAIL-induced apoptosis and the expression of TRAIL receptors in these cells, and also investigated the clinical features of the patients from whom the FLS were derived. Furthermore, we evaluated the levels of TRAIL and its soluble decoy receptor osteoprotegerin (OPG) in patients with RA, patients with osteoarthritis (OA), and patients with spondylarthritis (SpA). RESULTS: Sensitivity to TRAIL-induced apoptosis varied in FLS from different patients, and the severity of disease in patients with RA was inversely correlated with the susceptibility of their FLS to TRAIL-induced apoptosis. TRAIL-sensitive cells expressed significantly lower levels of TRAILR-1, and silencing of TRAILR-1 increased TRAIL-induced apoptosis in RA FLS. TRAIL levels were elevated in the arthritic joints of patients with established RA, and TRAIL levels in the synovial fluid of these patients were elevated compared with levels in the synovial fluid of patients with OA or SpA. At baseline, a low OPG-to-TRAIL ratio in the sera of patients with early RA was associated with a better evolution of disease activity, but high serum levels of TRAIL at followup were associated with joint damage. CONCLUSION: These findings suggest that TRAIL has a dual role in RA, and that the resistance of RA FLS to TRAIL-induced apoptosis is associated with a disease-promoting activity of TRAIL in RA.

APRIL promotes B-1 cell-associated neoplasm.

A tumor-supporting role for the TNF-like ligand APRIL has been suggested. Here we describe that 9- to 12-month-old APRIL transgenic mice develop lymphoid tumors that originate from expansion of the peritoneal B-1 B cell population. Aging APRIL transgenic mice develop progressive hyperplasia in mesenteric lymph nodes and Peyer's patches, disorganization of affected lymphoid tissues, mucosal and capsular infiltration, and eventual tumor cell infiltration into nonlymphoid tissues such as kidney and liver. We detected significantly increased APRIL levels in sera of B cell chronic lymphoid leukemia (B-CLL) patients, indicating that APRIL promotes onset of B-1-associated neoplasms and that APRIL antagonism may provide a therapeutic strategy to treat B-CLL patients.

Lymphotoxin α stimulates proliferation and pro-inflammatory cytokine secretion of rheumatoid arthritis synovial fibroblasts.

OBJECTIVE: TNFα plays a crucial role in rheumatoid arthritis (RA) by stimulating fibroblast-like synoviocytes (FLS). Lymphotoxin α (LTα) is a pro-inflammatory cytokine with significant homology to TNFα. We compared the effects of both cytokines on cultured RA FLS. METHODS: Receptor expression on RA FLS was analyzed by FACS. Cells were stimulated with LTα or TNFα and proliferation was measured by [3H]thymidine incorporation and secretion of inflammatory cytokines and metalloproteinase 3 by ELISA. Activation of MAP kinases and Akt was analyzed by Western blotting. Nuclear translocation of NFκB was visualized by immunofluorescence. RESULTS: 60-80% and 30-50% of the RA FLS tested expressed TNF receptors I and II, respectively, and 70-75% expressed HVEM. LTα induced RA FLS proliferation at the same level of TNFα, which was blocked by etanercept. Both LTα and TNFα induced activation of MAP kinases ERK1/2 and p38 as well as Akt. 95-98% of FLS showed nuclear translocation of NFκB after stimulation with either cytokines. LTα and TNFα were potent to induce secretion of IL-6, IL-8 and metalloproteinase 3 in FLS. CONCLUSION: LTα is as effective as TNFα in stimulating RA FLS. Blocking both cytokines might allow a better control of inflammation and synovial proliferation in RA.

The Role of Cancer-Associated Fibroblasts in Cancer Invasion and Metastasis.

Cancer-associated fibroblasts (CAFs) play a key role in cancer progression by contributing to extracellular matrix (ECM) deposition and remodeling, extensive crosstalk with cancer cells, epithelial-to-mesenchymal transition (EMT), invasion, metastasis, and therapy resistance. As metastasis is a main reason for cancer-related deaths, it is crucial to understand the role of CAFs in this process. Colorectal cancer (CRC) is a heterogeneous disease and lethality is especially common in a subtype of CRC with high stromal infiltration. A key component of stroma is cancer-associated fibroblasts (CAFs). To provide new perspectives for research on CAFs and CAF-targeted therapeutics, especially in CRC, we discuss the mechanisms, crosstalk, and functions involved in CAF-mediated cancer invasion, metastasis, and protection. This summary can serve as a framework for future studies elucidating these roles of CAFs.

Effects of Different Housing Systems during Suckling and Rearing Period on Skin and Tail Lesions, Tail Losses and Performance of Growing and Finishing Pigs.

Feasible alternatives to stressful weaning and tail-docking are needed to inhibit tail biting. Therefore, we investigated the effects of housing systems for 1106 pigs that were weaned from: (1) conventional farrowing crates (FC), (2) free-farrowing pens (FF), or (3) group housing of lactating sows (GH) into (1) conventional rearing pens (Conv) or (2) piglets remained in their farrowing pens for rearing (Reaf). Tails were docked or left undocked batchwise. All pigs were regrouped for the fattening period. Pigs were scored for skin lesions, tail lesions and losses. After weaning, Conv-GH pigs had significantly less skin lesions than Conv-FC and Conv-FF pigs. After regrouping for fattening, Reaf-GH pigs had significantly less skin lesions than Conv pigs, Reaf-FC and Reaf-FF. The frequency of tail lesions of undocked Conv pigs peaked in week 4 (66.8%). Two weeks later, Reaf undocked pigs reached their maximum (36.2%). At the end of fattening, 99.3% of undocked Conv pigs and 43.1% of undocked Reaf pigs lost parts of their tail. In conclusion, the co-mingling of piglets during suckling reduced the incidence of skin lesions. Rearing in the farrowing pen significantly reduced the incidence of tail lesions and losses for undocked pigs. No housing system negatively affected the performance.