IL-1ß Induces the Rapid Secretion of the Antimicrobial Protein IL-26 from Th17 Cells.

Th17 cells play a critical role in the adaptive immune response against extracellular bacteria, and the possible mechanisms by which they can protect against infection are of particular interest. In this study, we describe, to our knowledge, a novel IL-1ß dependent pathway for secretion of the antimicrobial peptide IL-26 from human Th17 cells that is independent of and more rapid than classical TCR activation. We find that IL-26 is secreted 3 hours after treating PBMCs with Mycobacterium leprae as compared with 48 hours for IFN-γ and IL-17A. IL-1ß was required for microbial ligand induction of IL-26 and was sufficient to stimulate IL-26 release from Th17 cells. Only IL-1RI+ Th17 cells responded to IL-1ß, inducing an NF-κB-regulated transcriptome. Finally, supernatants from IL-1ß-treated memory T cells killed Escherichia coli in an IL-26-dependent manner. These results identify a mechanism by which human IL-1RI+ "antimicrobial Th17 cells" can be rapidly activated by IL-1ß as part of the innate immune response to produce IL-26 to kill extracellular bacteria.

Mycoplasma-induced pustulosis with perifollicular involvement.

Mycoplasma pneumoniae-induced rash and mucositis (MIRM) is a disease characterized by mucosal involvement with variable cutaneous manifestations induced by M. pneumoniae infection. Previously reported rash morphologies include vesiculobullous, targetoid, papular, macular, and morbilliform lesions. Pustulosis is a rare presentation of MIRM that has been described only once before in the literature to our knowledge. We report a case of a 13-year-old boy presenting with a pustular skin eruption induced by Mycoplasma infection. Ours' is the second report of MIRM, to our knowledge, presenting with pustulosis and the first, to our knowledge, to first to describe the histopathologic finding of perifollicular neutrophilic infiltration in MIRM.

The rate of mutation of a single gene.

The rate of mutation refers to the probability that a unit length of DNA (generally a base pair) mutates with time. Fluctuation analysis or mutant accumulation assays applied to phenotypic changes measure mutation rates of cells. However, only a few phenotypic changes indicative of mutations are known thus limiting the analysis to those rare genes. Direct sequencing overcomes the limitations imposed by phenotypic analysis but is limited by the extensive number of clones or cells that have to be analyzed in fluctuation or mutant accumulation assays. We propose a strategy to determine the rate of mutation of a gene by limited direct sequencing of a few single cells of a defined lineage. To accomplish this, we determined the average number of mutations per position in each DNA length sequenced from the proportion of the non-mutated positions, according to the Poisson process and/or the Taylor series. Measuring the rate of mutation by direct sequencing of genes does not require ascertaining a phenotype and can be applied to any area of the genome in a cell. The approach avoids fluctuation errors.

Defining Transcriptional Signatures of Human Hair Follicle Cell States.

The epidermis and its appendage, the hair follicle, represent an elegant developmental system in which cells are replenished with regularity because of controlled proliferation, lineage specification, and terminal differentiation. Although transcriptome data exists for human epidermal and dermal cells, the hair follicle remains poorly characterized. Through single-cell resolution profiling of the epidermis and anagen hair follicle, we characterized the anatomical, transcriptional, functional, and pathological profiles of distinct epidermal, hair follicle, and hair follicle-associated cell subpopulations including melanocytes, endothelial cells, and immune cells. We additionally traced the differentiation trajectory of interfollicular and matrix cell progenitors and explored the association of specific cell subpopulations to known molecular signatures of common skin conditions. These data simultaneously corroborate prior murine and human studies while offering new insights into epidermal and hair follicle differentiation and pathogenesis.

New insights into the functions of B cells.

Organ transplants between genetically different individuals elicit powerful immune responses that invariably cause rejection in the absence of immune suppression. Among the immune responses elicited by organ allografts, B-cell responses causing antibody-mediated rejection are one of the most vexing. However, recent advances in the field indicate that B cells and antibodies' contribution to immunity extends well beyond the traditional functions ascribed to antibodies. Here we review "non-humoral" functions of B cells and the implications of these functions to transplantation.

Human antimicrobial cytotoxic T lymphocytes, defined by NK receptors and antimicrobial proteins, kill intracellular bacteria.

Human CD8+ cytotoxic T lymphocytes (CTLs) contribute to antimicrobial defense against intracellular pathogens through secretion of cytotoxic granule proteins granzyme B, perforin, and granulysin. However, CTLs are heterogeneous in the expression of these proteins, and the subset(s) responsible for antimicrobial activity is unclear. Studying human leprosy, we found that the subset of CTLs coexpressing all three cytotoxic molecules is increased in the resistant form of the disease, can be expanded by interleukin-15 (IL-15), and is differentiated from naïve CD8+ T cells by Langerhans cells. RNA sequencing analysis identified that these CTLs express a gene signature that includes an array of surface receptors typically expressed by natural killer (NK) cells. We determined that CD8+ CTLs expressing granzyme B, perforin, and granulysin, as well as the activating NK receptor NKG2C, represent a population of "antimicrobial CTLs" (amCTLs) capable of T cell receptor (TCR)-dependent and TCR-independent release of cytotoxic granule proteins that mediate antimicrobial activity.

The mutable vaccine for mutable viruses.

Mutable viruses, such as HIV, pose difficult obstacles to prevention and/or control by vaccination. Mutable viruses rapidly diversify in populations and in individuals, impeding development of effective vaccines. We devised the 'mutable vaccine' to appropriate the properties of mutable viruses that undermine conventional strategies. The vaccine consists of a DNA construct encoding viral antigen and regulatory sequences that upon delivery to B cells target the enzymatic apparatus of 'somatic hypermutation' causing the construct to mutate one million-times baseline rates and allowing production and presentation of antigen variants. We postulate the mutable vaccine might thus anticipate diversification of mutable viruses, allowing direct control or slowing of evolution. Initial work presented here should encourage consideration of this novel approach.

C3d regulates immune checkpoint blockade and enhances antitumor immunity.

Despite expression of immunogenic polypeptides, tumors escape immune surveillance by engaging T cell checkpoint regulators and expanding Tregs, among other mechanisms. What orchestrates these controls is unknown. We report that free C3d, a fragment of the third component of complement, inside tumor cells - or associated with irradiated tumor cells and unattached to antigen - recruits, accelerates, and amplifies antitumor T cell responses, allowing immunity to reverse or even to prevent tumor growth. C3d enhances antitumor immunity independently of B cells, NK cells, or antibodies, but it does so by increasing tumor infiltrating CD8+ lymphocytes, by depleting Tregs, and by suppressing expression of programmed cell death protein 1 (PD-1) by T cells. These properties of C3d appear specific for the tumor and dependent on complement receptor 2, and they incur no obvious systemic toxicity. The heretofore unrecognized properties of free C3d suggest that protein might determine the effectiveness of immune surveillance and that increasing availability of the protein might prove advantageous in the treatment or prevention of cancer and premalignant conditions.

Loss of EPC-1/PEDF expression during skin aging in vivo.

EPC-1/PEDF (early population doubling level cDNA-1/retinal pigmented epithelium-derived factor) is a single-copy, quiescence-specific gene that is transcribed into a 1.5 kb mRNA and then translated into a 50 kDa secreted protein that is a potent inhibitor of angiogenesis. EPC-1 expression has been detected in a number of cultured cell lines, including lung and skin fibroblasts, retinal pigmented epithelial cells, and endometrial stromal fibroblasts. Furthermore, its expression has been shown to decline during replicative aging of these cells in culture. In this report, we describe our examination of the age-related changes in EPC-1 expression in situ in skin sections from donors of different ages. EPC-1 mRNA is detected primarily in the dermal layer of the skin and its expression declines with increasing donor age. This decline is statistically significant between young (less than 31 years old) and middle-aged (between 30 and 60 years old) donors, with the decline becoming less dramatic at older ages. This age-related decline in the expression of an angiogenic inhibitor contributes to the imbalance of angiogenic modulators that is observed during aging. In fact, this decline may reflect a compensatory change to help reverse the decline of angiogenesis marked by reduced abundance of microvessels. This downregulation of an angiogenesis inhibitor may, in turn, play a critical role in the development of diseases caused by abnormal vascularization. The potential role of the age-associated decline in EPC-1 expression in tissue remodeling and in the development of skin diseases with excessive angiogenesis may provide new insights into disease prevention.

Calcinosis cutis occurring in association with autoimmune connective tissue disease: the Mayo Clinic experience with 78 patients, 1996-2009.

OBJECTIVE: To describe characteristics and treatment of patients with calcinosis cutis in the clinical setting of autoimmune connective tissue disease (ACTD). DESIGN: Retrospective study. SETTING: Tertiary referral center. PATIENTS: Seventy-eight patients with calcinosis cutis and ACTD between 1996 and 2009. MAIN OUTCOME MEASURES: Clinical features, treatments, and outcomes of patients with calcinosis cutis in the clinical setting of ACTD. RESULTS: Of 78 patients (mean age at onset of calcinosis cutis, 40.1 years), 64 (82%) were female. The following diseases were associated with calcinosis cutis: dermatomyositis (n = 30) with classic (n = 15), juvenile (n = 14), and amyopathic (n = 1) subtypes; systemic sclerosis with limited cutaneous scleroderma (n = 24); lupus panniculitis (n = 4); systemic lupus erythematosus (n = 2); mixed connective tissue disease (n = 4); overlap connective tissue disease (n = 6); undifferentiated connective tissue disease (n = 6); polymyositis (n = 1); and rheumatoid arthritis (n = 1). Therapy for calcinosis cutis consisted of medical treatment alone (n = 19), surgical therapy alone (n = 11), combined medical and surgical treatment (n = 17), no treatment (n = 30), and unknown (n = 1). Diltiazem hydrochloride was the most commonly used medical therapy, with 9 of 17 patients having a partial response. Twenty-eight patients had surgical excision of 1 or more lesions of calcinosis cutis: 22 had a complete response, 5 had a partial response, and 1 had no response. CONCLUSIONS: Dermatomyositis and systemic sclerosis were the most common ACTDs associated with calcinosis cutis. Although no treatment was uniformly effective, surgical excision of symptomatic lesions and medical treatment with diltiazem provided benefit for some patients.

Myelodysplastic syndrome presenting as generalized granulomatous dermatitis.

BACKGROUND: Granulomatous dermatitis has rarely been reported as a manifestation of leukemia or myelodysplastic syndrome (MDS). We describe a case of widespread granulomatous dermatitis that preceded the diagnosis of MDS by 2 years. OBSERVATIONS: A 71-year-old man developed a generalized, mildly pruritic eruption that slowly progressed over a 2-year period. Punch biopsy specimens demonstrated interstitial dermal granulomatous inflammation. A complete blood cell count with differential showed marked monocytosis, and the findings of a subsequent biopsy of the bone marrow confirmed MDS. Lenalidomide therapy was initiated, and the patient's skin condition improved after 6 weeks of treatment; however, his MDS progressed to acute myeloid leukemia, and he died shortly thereafter. CONCLUSIONS: There is a paucity of literature documenting the occurrence of granulomatous dermatitis as a manifestation of an underlying hematologic disorder. This case illustrates a striking example of widespread granulomatous dermatitis heralding the onset of MDS. It is imperative that the dermatologic community recognize the rare association of granulomatous dermatitis with myelodysplasia, because the cutaneous manifestations may be the presenting finding and can precede the development of leukemia by several years.

Noncognate function of B cells in transplantation.

How B cells affect the outcome of transplants is a question of enduring interest. Initial efforts to answer that question suggested, wrongly, that B cells have no impact on transplantation. Now, however, B cells are known to influence not only the outcome of vascularized grafts through the production of anti-donor antibodies but also the competence of cellular immunity through a number of physiologic functions. In this study, we explain why the importance of B cells was overlooked in the past and consider the range of noncognate functions of B cells that may determine the outcome of transplants.

HIV genes diversify in B cells.

Mutation of the human immunodeficiency virus by host cells inhibits viral dissemination by creating non-functional variants. However, viral mutation does not always eliminate the ability of the virus to disseminate and, in fact, is thought to promote persistence by generating functional mutants that evade immunity or drugs. How and where HIV mutates is not known. Accordingly, where and to what extent variants emerge may be determined by the cell type with optimal mutation apparatus as well as by the properties of the viral genomic sequence itself. Here we considered that HIV, which can infect B cells, may co-opt the Ig somatic hypermutation machinery to generate functional variants and asked whether the HIV envelope coding sequence can diversify in B cells. We show that an HIV envelope coding sequence transfected into B cells mutates in a manner consistent with somatic hypermutation, causing the production of viral protein variants. This result demonstrates that B cells can express and diversify HIV proteins. Thus, B cells may contribute to viral evasion and to the development of multi-drug resistance.

Transplantation tolerance in NF-kappaB-impaired mice is not due to regulation but is prevented by transgenic expression of Bcl-xL.

NF-kappaB is a key regulator of transcription after TCR and costimulatory receptor ligation. To determine the role of T cell-intrinsic NF-kappaB activation in acute allograft rejection, we used IkappaBalphaDeltaN-Tg mice (H-2b) that express an inhibitor of NF-kappaB restricted to the T cell compartment. We have previously shown that these mice permanently accept fully allogeneic (H-2d) cardiac grafts and secondary donor skin grafts, and that splenocytes from these tolerant mice have reduced alloreactivity when restimulated in vitro. These results were compatible with either deletion or suppression of allospecific T cells as possible mechanisms of tolerance. The aim of this study was to investigate the mechanism of transplant tolerance in these mice. IkappaBalphaDeltaN-Tg mice did not have increased numbers or function of CD4+ CD25+ regulatory T cells either before or after cardiac transplantation. In addition, tolerance could not be transferred to fresh NF-kappaB-competent T cells and was not permissive for linked suppression to skin grafts sharing donor and third-party alloantigens, suggesting that dominant suppression is not the mechanism by which IkappaBalphaDeltaN-Tg mice achieve tolerance. In contrast, overexpression of the antiapoptotic protein Bcl-xL in T cells from IkappaBalphaDeltaN-Tg mice resulted in effective rejection of cardiac allografts and correlated with an increased frequency of splenocytes producing IFN-gamma in response to alloantigen. Together, these results suggest that the death of alloreactive T cells may be partly responsible for the transplantation tolerance observed in mice with defective T cell-intrinsic NF-kappaB activation.