Graft-versus-host disease is locally maintained in target tissues by resident progenitor-like T cells

In allogeneic hematopoietic stem cell transplantation, donor αβ T cells attack recipient tissues, causing graft-versus-host disease (GVHD), a major cause of morbidity and mortality. A central question has been how GVHD is sustained despite T cell exhaustion from chronic antigen stimulation. The current model for GVHD holds that disease is maintained through the continued recruitment of alloreactive effectors from blood into affected tissues. Here, we show, using multiple approaches including parabiosis of mice with GVHD, that GVHD is instead primarily maintained locally within diseased tissues. By tracking 1,203 alloreactive T cell clones, we fitted a mathematical model predicting that within each tissue a small number of progenitor T cells maintain a larger effector pool. Consistent with this, we identified a tissue-resident TCF-1+ subpopulation that preferentially engrafted, expanded, and differentiated into effectors upon adoptive transfer. These results suggest that therapies targeting affected tissues and progenitor T cells within them would be effective.

979 FACTORS THAT INFLUENCE OLDER ADULTS’ PARTICIPATION IN PHYSICAL ACTIVITY: A SYSTEMATIC REVIEW OF QUALITATIVE STUDIES

Introduction

Despite the myriad advantages associated with physical activity (PA), older adults are often insufficiently active to maximise health benefits. Understanding factors that influence engagement in PA will support practitioners in providing well-designed interventions for older people. Our aim was to review the qualitative evidence exploring the factors affecting older adult’s engagement in PA.

Method

Four electronic databases were searched: CINAHL, Embase, MEDLINE and PsycINFO. Inclusion criteria were community-dwelling older adults (≥70 years), and studies including qualitative method. Exclusion criteria were studies examining a single disease group, individuals with cognitive impairment, care home residents, and PA interventions. The Critical Appraisal Skills Programme (CASP) checklist was used to assess methodological rigour. Framework synthesis using the COM-B model was applied to analyse data, and the GRADE-CERQual approach was used to assess confidence in findings. (PROSPERO: CRD42021160503).

Results

Twenty-one studies were included in the review. Participants (N = 3,955; mean age 78.9 years) included 64% female and 36% male older adults. Most studies were methodologically rigorous (17/21 scored ≥8 CASP). We identified 32 themes mapped against the COM-B framework (16 high confidence). Older adult’s perceived capability was influenced by their functional capacity, illness symptoms and perceived risk of injury from PA. PA was motivated by identifying as an ‘exerciser’, health gains and positive emotions (e.g. enjoyment), while negative sensations reduced motivation (e.g. pain). Opportunity was impacted by the weather, the environment ‘fit’, and the availability of social interaction during PA. Moreover, social opportunity was impacted by socio-cultural ageing stereotypes and discourses, influencing older adults’ PA through media outlets, social norms, and self-stigma.

Conclusion

The review found a complex web of interacting factors that influenced older people’s PA between the sub-domains of capability, motivation, and opportunity. Future initiatives to increase PA in older adults should focus on social influences, environmental barriers, and physical limitations.

Malignant T Cell Activation by a Bacillus Species Isolated from Cutaneous T-Cell Lymphoma Lesions

Cutaneous T-cell lymphoma (CTCL) is a life-debilitating malignancy of lymphocytes homing to the skin. Although CTCL is thought to arise from a combination of genetic, epigenetic, and environmental factors, specific triggers are unclear. The skin is colonized by a unique microbiota and is heavily influenced by its interactions. We hypothesized that adaptive immune responses to skin commensals lead to clonal T-cell proliferation and transformation in the appropriate genetic background. We therefore collected lesional and nonlesional skin microbiota from patients with CTCL to study T cell interactions using skin T cell explants and peripheral, skin-homing CD4+ T cells. By various methods, we identified Bacillus safensis in CTCL lesions, a rare human commensal in healthy skin, and showed that it can induce malignant T cell activation and cytokine secretion. Taken together, our data suggest microbial triggers in the skin microbiota of patients with CTCL as potential instigators of tumorigenesis.

Epidermotropic metastasis of squamous cell carcinoma of the tonsil: A case report with molecular confirmation

Metastasis of oropharyngeal squamous cell carcinoma (SCC) to skin is uncommon and portends a poor prognosis. Clinical history and histopathology are key to discerning between metastatic disease vs de novo SCC of the skin. We describe a case of an HPV+ tonsillar SCC in a 77-year-old male, with metastasis to the neck skin. This case is unique because of prominent in situ epidermal involvement on skin biopsy specimen, complicating the distinction between primary and secondary disease. The nature of the lesion was resolved using next-generation sequencing of both the primary oropharyngeal SCC and skin lesion biopsy specimens. Both tumors showed identical ATR D1639G somatic mutations, while the skin lesion contained an additional POLE F1366L mutation. Clonal evolution of metastatic lesions is a well-described phenomenon; comparing the genetic profiles of primary and metastatic specimens can be useful in evaluating the tumor origin as well as identifying targetable genetic aberrations.

Waves in hyperbolic and double negative metamaterials including rogues and solitons

The topics here deal with some current progress in electromagnetic wave propagation in a family of substances known as metamaterials. To begin with, it is discussed how a pulse can develop a leading edge that steepens and it is emphasised that such self-steepening is an important inclusion within a metamaterial environment together with Raman scattering and third-order dispersion whenever very short pulses are being investigated. It is emphasised that the self-steepening parameter is highly metamaterial-driven compared to Raman scattering, which is associated with a coefficient of the same form whether a normal positive phase, or a metamaterial waveguide is the vehicle for any soliton propagation. It is also shown that the influence of magnetooptics provides a beautiful and important control mechanism for metamaterial devices and that, in the future, this feature will have a significant impact upon the design of data control systems for optical computing. A major objective is fulfiled by the investigations of the fascinating properties of hyperbolic media that exhibit asymmetry of supported modes due to the tilt of optical axes. This is a topic that really merits elaboration because structural and optical asymmetry in optical components that end up manipulating electromagnetic waves is now the foundation of how to operate some of the most successful devices in photonics and electronics. It is pointed out, in this context, that graphene is one of the most famous plasmonic media with very low losses. It is a two-dimensional material that makes the implementation of an effective-medium approximation more feasible. Nonlinear non-stationary diffraction in active planar anisotropic hyperbolic metamaterials is discussed in detail and two approaches are compared. One of them is based on the averaging over a unit cell, while the other one does not include sort of averaging. The formation and propagation of optical spatial solitons in hyperbolic metamaterials is also considered with a model of the response of hyperbolic metamaterials in terms of the homogenisation ('effective medium') approach. The model has a macroscopic dielectric tensor encompassing at least one negative eigenvalue. It is shown that light propagating in the presence of hyperbolic dispersion undergoes negative (anomalous) diffraction. The theory is ten broadened out to include the influence of the orientation of the optical axis with respect to the propagation wave vector. Optical rogue waves are discussed in terms of how they are influenced, but not suppressed, by a metamaterial background. It is strongly discussed that metamaterials and optical rogue waves have both been making headlines in recent years and that they are, separately, large areas of research to study. A brief background of the inevitable linkage of them is considered and important new possibilities are discussed. After this background is revealed some new rogue wave configurations combining the two areas are presented alongside a discussion of the way forward for the future.

An independent validation of a gene expression signature to differentiate malignant melanoma from benign melanocytic nevi

BACKGROUND

Recently, a 23-gene signature was developed to produce a melanoma diagnostic score capable of differentiating malignant and benign melanocytic lesions. The primary objective of this study was to independently assess the ability of the gene signature to differentiate melanoma from benign nevi in clinically relevant lesions.

METHODS

A set of 1400 melanocytic lesions was selected from samples prospectively submitted for gene expression testing at a clinical laboratory. Each sample was tested and subjected to an independent histopathologic evaluation by 3 experienced dermatopathologists. A primary diagnosis (benign or malignant) was assigned to each sample, and diagnostic concordance among the 3 dermatopathologists was required for inclusion in analyses. The sensitivity and specificity of the score in differentiating benign and malignant melanocytic lesions were calculated to assess the association between the score and the pathologic diagnosis.

RESULTS

The gene expression signature differentiated benign nevi from malignant melanoma with a sensitivity of 91.5% and a specificity of 92.5%.

CONCLUSIONS

These results reflect the performance of the gene signature in a diverse array of samples encountered in routine clinical practice. Cancer 2017;123:617-628. © 2016 American Cancer Society.

GNA14 Somatic Mutation Causes Congenital and Sporadic Vascular Tumors by MAPK Activation

Vascular tumors are among the most common neoplasms in infants and children; 5%-10% of newborns present with or develop lesions within the first 3 months of life. Most are benign infantile hemangiomas that typically regress by 5 years of age; other vascular tumors include congenital tufted angiomas (TAs), kaposiform hemangioendotheliomas (KHEs), and childhood lobular capillary hemangiomas (LCHs). Some of these lesions can become locally invasive and unresponsive to pharmacologic intervention, leading to significant complications. Recent investigation has revealed that activating mutations in HRAS, KRAS, NRAS, GNAQ, and GNA11 can cause certain types of rare childhood vascular tumors, and we have now identified causal recurrent somatic activating mutations in GNA14 by whole-exome and targeted sequencing. We found somatic activating GNA14 c.614A>T (p.Gln205Leu) mutations in one KHE, one TA, and one LCH and a GNA11 c.547C>T (p.Arg183Cys) mutation in two LCH lesions. We examined mutation pathobiology via expression of mutant GNA14 or GNA11 in primary human endothelial cells and melanocytes. GNA14 and GNA11 mutations induced changes in cellular morphology and rendered cells growth-factor independent by upregulating the MAPK pathway. Our findings identify GNA14 mutations as a cause of childhood vascular tumors, offer insight into mechanisms of oncogenic transformation by mutations affecting Gaq family members, and identify potential targets for therapeutic intervention.

Perineural granulomas in cutaneous sarcoidosis may be associated with sarcoidosis small-fiber neuropathy

Perineural granulomas in cutaneous sarcoidosis have been rarely reported and their clinical significance has yet to be evaluated. Recently, a 27-year-old male presented with multiple pink papules on the flank and lower back, accompanied by a painful, burning sensation. Biopsies revealed well-defined granulomas, consistent with sarcoidosis, in the dermis and involving small cutaneous nerves. We hypothesized that perineural granulomas may be an under-recognized feature of cutaneous sarcoidosis and may be responsible for sensory disturbances. We reviewed cases from 29 consecutive patients with cutaneous sarcoidosis. Perineural granulomas were identified in 18/29 (62%) patients and in 22/40 (55%) biopsies. Perineural granulomas were identified in 7/9 biopsies from the proximal upper extremity, 1/3 from the distal upper extremity, 7/12 from the head and the neck, including 4/4 from the nose, 5/9 from the back, 1/2 from the flank and 1/1 from the proximal lower extremity and 0/4 from the distal lower extremity. The anatomical distribution is similar to sarcoidosis small-fiber neuropathy (SSFN), in which sarcoidosis patients without evident skin lesions experience sensory disturbances of unknown etiology involving the face, the proximal extremities and the trunk. Our results indicate perineural granulomas in cutaneous sarcoidosis are more common than previously appreciated, primarily involve the head, the proximal upper extremities and the back, and may be responsible for neurological manifestations.

Profound depletion of host conventional dendritic cells, plasmacytoid dendritic cells, and B cells does not prevent graft-versus-host disease induction

The efficacy of allogeneic hematopoietic stem cell transplantation is limited by graft-versus-host disease (GVHD). Host hematopoietic APCs are important initiators of GVHD, making them logical targets for GVHD prevention. Conventional dendritic cells (DCs) are key APCs for T cell responses in other models of T cell immunity, and they are sufficient for GVHD induction. However, we report in this article that in two polyclonal GVHD models in which host hematopoietic APCs are essential, GVHD was not decreased when recipient conventional DCs were inducibly or constitutively deleted. Additional profound depletion of plasmacytoid DCs and B cells, with or without partial depletion of CD11b(+) cells, also did not ameliorate GVHD. These data indicate that, in contrast with pathogen models, there is a surprising redundancy as to which host cells can initiate GVHD. Alternatively, very low numbers of targeted APCs were sufficient. We hypothesize the difference in APC requirements in pathogen and GVHD models relates to the availability of target Ags. In antipathogen responses, specialized APCs are uniquely equipped to acquire and present exogenous Ags, whereas in GVHD, all host cells directly present alloantigens. These studies make it unlikely that reagent-based host APC depletion will prevent GVHD in the clinic.

Profound depletion of host conventional dendritic cells, plasmacytoid dendritic cells, and B cells does not prevent graft-versus-host disease induction

The efficacy of allogeneic hematopoietic stem cell transplantation is limited by graft-versus-host disease (GVHD). Host hematopoietic APCs are important initiators of GVHD, making them logical targets for GVHD prevention. Conventional dendritic cells (DCs) are key APCs for T cell responses in other models of T cell immunity, and they are sufficient for GVHD induction. However, we report in this article that in two polyclonal GVHD models in which host hematopoietic APCs are essential, GVHD was not decreased when recipient conventional DCs were inducibly or constitutively deleted. Additional profound depletion of plasmacytoid DCs and B cells, with or without partial depletion of CD11b(+) cells, also did not ameliorate GVHD. These data indicate that, in contrast with pathogen models, there is a surprising redundancy as to which host cells can initiate GVHD. Alternatively, very low numbers of targeted APCs were sufficient. We hypothesize the difference in APC requirements in pathogen and GVHD models relates to the availability of target Ags. In antipathogen responses, specialized APCs are uniquely equipped to acquire and present exogenous Ags, whereas in GVHD, all host cells directly present alloantigens. These studies make it unlikely that reagent-based host APC depletion will prevent GVHD in the clinic.

A repertoire independent and cell intrinsic defect in murine GVHD induction by effector memory T cells (169.6)

Graft versus host disease (GVHD) is a major complication of allogeneic stem cell transplantation (alloSCT). In murine models of alloSCT, naïve T cells (TN) cause GVHD, while effector memory T cells (TEM) do not. Why TEM fail to cause GVHD is unknown and whether central memory T cells (TCM) are also unable to cause GVHD is controversial. It has been proposed that a more-restricted T cell receptor repertoire within the memory T cell (TM) pool may limit the ability of TM to recognize alloantigens. To address the role of repertoire, we developed a novel T cell receptor transgenic (Tg) GVHD model in which naive CD4+ TS1 Tg T cells, which recognize an epitope of influenza hemagglutinin (HA), are transferred, along with syngeneic bone marrow, into irradiated transgenic recipients that ubiquitously express HA. We then converted TS1 TN to TM and tested these for GVHD induction. TEM caused minimal, transient GVHD whereas TN and TCM caused potent GVHD. TEM engrafted and accumulated in the spleen to the same extent as TN, but failed to accumulate in the colon. Within the colon, TEM were dividing less actively than TN, and in co-transfer experiments TN out-competed TEM. TEM induced GVHD in recipients that lack expression of PD-L1 and PD-L2, indicating that PD-1, which is unregulated on TS1 cells post transplant, limits the ability of TEM to induce GVHD. Thus, cell intrinsic properties independent of repertoire explain the impairment of TEM while TCM clearly can cause GVHD.

Graft-versus-host disease is independent of innate signaling pathways triggered by pathogens in host hematopoietic cells

Graft-versus-host disease (GVHD) is initiated by APCs that prime alloreactive donor T cells. In antipathogen responses, Ag-bearing APCs receive signals through pattern-recognition receptors, including TLRs, which induce the expression of costimulatory molecules and production of inflammatory cytokines, which in turn mold the adaptive T cell response. However, in allogeneic hematopoietic stem cell transplantation (alloSCT), there is no specific pathogen, alloantigen is ubiquitous, and signals that induce APC maturation are undefined. To investigate APC activation in GVHD, we used recipient mice with hematopoietic cells genetically deficient in pathways critical for APC maturation in models in which host APCs are absolutely required. Strikingly, CD8-mediated and CD4-mediated GVHD were similar whether host APCs were wild-type or deficient in MyD88, TRIF, or MyD88 and TRIF, which excludes essential roles for TLRs and IL-1β, the key product of inflammasome activation. Th1 differentiation was if anything augmented when APCs were MyD88/TRIF(-/-), and T cell production of IFN-γ did not require host IL-12. GVHD was also intact when APCs lacked the type I IFNR, which amplifies APC activation pathways that induce type I IFNs. Thus in GVHD, alloreactive T cells can be activated when pathways critical for antipathogen T cell responses are impaired.

Recipient B cells are not required for graft-versus-host disease induction

Recipient antigen presenting cells (APCs) are required for CD8-mediated graft-versus-host disease (GVHD), and have an important and nonredundant role in CD4-mediated GVHD in mouse major histocompatibility complex-matched allogeneic bone marrow transplantation (alloBMT). However, the precise roles of specific recipient APCs-dendritic cells, macrophages, and B cells-are not well defined. If recipient B cells are important APCs they could be depleted with rituximab, an anti-CD20 monoclonal antibody. On the other hand, B cells can downregulate T cell responses, and consequently, B cell depletion could exacerbate GVHD. Patients with B cell lymphomas undergo allogeneic hematopoietic stem cell transplantation (alloSCT) and many are B-cell-deficient because of prior rituximab. We therefore studied the role of recipient B cells in major histocompatibility complex-matched murine models of CD8- and CD4-mediated GVHD by using recipients genetically deficient in B cells and with antibody-mediated depletion of host B cells. In both CD4- and CD8-dependent models, B cell-deficient recipients developed clinical and pathologic GVHD. However, although CD8-mediated GVHD was clinically less severe in hosts genetically deficient in B cells, it was unaffected in anti-CD20-treated recipients. These data indicate that recipient B cells are not important initiators of GVHD, and that efforts to prevent GVHD by APC depletion should focus on other APC subsets.

Central memory CD8+ T cells induce graft-versus-host disease and mediate graft-versus-leukemia

In allogeneic hemopoietic stem cell transplantation, mature donor alphabeta T cells in the allograft promote T cell reconstitution in the recipient and mediate the graft-vs-leukemia (GVL) effect. Unfortunately, donor T cells can attack nonmalignant host tissues and cause graft-vs-host disease (GVHD). It has previously been shown that effector memory T cells not primed to alloantigen do not cause GVHD yet transfer functional T cell memory and mediate GVL. Recently, central memory T cells (T(CM)) have also been reported to not cause GVHD. In contrast, in this study, we demonstrate that purified CD8(+) T(CM) not specifically primed to alloantigens mediate GVHD in the MHC-mismatched C57BL/6 (B6)-->BALB/c and the MHC-matched, multiple minor histocompatibility Ag-mismatched C3H.SW-->B6 strain pairings. CD8(+) T(CM) and naive T cells (T(N)) caused similar histological disease in liver, skin, and bowel. B6 CD8(+) T(CM) and T(N) similarly expanded in BALB/c recipients, and the majority of their progeny produced IFN-gamma upon restimulation. However, in both models, CD8(+) T(CM) induced milder clinical GVHD than did CD8(+) T(N). Nonetheless, CD8(+) T(CM) and T(N) were similarly potent mediators of GVL against a mouse model of chronic-phase chronic myelogenous leukemia. Thus, in contrast to what was previously thought, CD8(+) T(CM) are capable of inducing GVHD and are substantially different from T(EM) but only subtly so from T(N).

Palifermin-associated papular eruption

BACKGROUND

Palifermin is a recombinant human keratinocyte growth factor that is used to reduce the duration and severity of oral mucositis in patients undergoing hematopoietic stem cell transplantation after myelotoxic therapy. Cutaneous adverse reactions associated with keratinocyte growth factor are reported to be rash, pruritus, and erythema.

OBSERVATIONS

After receiving palifermin following autologous hematopoietic stem cell transplantation and treatment with melphalan, a patient developed erythema and lichenoid papules that were distributed primarily in intertriginous areas. A biopsy specimen of the papules showed a striking resemblance to verrucae, but in situ hybridization studies were negative for human papillomavirus. Immunohistochemical staining with antibodies to Ki-67 and cytokeratin 5/6 showed increased keratinocyte proliferation in lesional skin.

CONCLUSIONS

After treatment with palifermin, a papular eruption clinically resembling lichen planus or plane warts, with histologic features of verruca plana, and intertriginous erythema may occur. In this case, neither eruption required treatment, and spontaneous resolution was observed over days to weeks. Histopathologic staining patterns of Ki-67 and cytokeratin 5/6 may be useful in identifying adverse reactions to palifermin therapy.

The characteristic histopathologic features of nevi on and around the ear

BACKGROUND

Nevi on certain areas of the body such as the acral, genital, and flexural regions may exhibit uncommon but characteristic histopathologic features. The purpose of this study was to characterize the distinctive features of nevi with a junctional component located on and around the ear.

MATERIALS AND METHODS

A total of 101 compound and junctional nevi of the ear received at the Yale Dermatopathology Laboratory during a 10-year period were examined in this study. The most characteristic feature of the majority of these nevi was irregularity of nesting pattern, with nests, which varied in size and shape and which were sometimes located between rete ridges.

RESULTS

Forty-two (42%) of nevi on and around the ear showed poor circumscription, lateral extension of the junctional component beyond the dermal component, and elongation of rete ridges with bridging between them. A subset of these nevi (26 cases) showed uniformly large melanocytes with large vesicular nuclei without prominent nucleoli, and abundant pale, finely granular cytoplasm. These lesions did not show a tendency to recur.

CONCLUSIONS

This study supports the existence of a subset of nevi on or near the ear that, like certain nevi located on other special sites, exhibit unusual but characteristic features, which may be misinterpreted as atypical or malignant.

Human herpesvirus-8 is not associated with angiolymphoid hyperplasia with eosinophilia

BACKGROUND

Angiolymphoid hyperplasia with eosinophilia (ALHE) is an angioproliferative lesion, typically consisting of single or multiple red papules or nodules in the head and neck region. The etiology of ALHE, whether reactive or neoplastic, is unclear. It has been well documented in the literature that human herpesvirus-8 (HHV-8) DNA is present in the majority of cases of Kaposi's sarcoma; however, there is contradictory data regarding the association of this virus with ALHE.

METHODS

We performed immunohistochemical studies for HHV-8 on paraffin-embedded tissue from 23 cases of histologically confirmed ALHE. Polymerase chain reaction (PCR) analysis for HHV-8 DNA was performed on 14 of the 23 cases that had adequate remaining tissue for the procedure. The results of the immunohistochemical studies and PCR analysis were compared.

RESULTS

HHV-8 immunohistochemical studies were negative in all 23 cases of ALHE. PCR-based analysis on 14 cases failed to identify HHV-8 DNA.

CONCLUSIONS

Combined data from several, small published studies are equivocal for an association between HHV-8 and ALHE. The results of our large study show no association between HHV-8 and ALHE.

Differential Expression of HMGA1 and HMGA2 in Dermatofibroma and Dermatofibrosarcoma Protuberans: Potential Diagnostic Applications, and Comparison with Histologic Findings, CD34, and Factor XIIIa Immunoreactivity

The histologic distinction of dermatofibrosarcoma protuberans (DFSP) and dermatofibroma (DF) may be difficult, especially in the case of DF extending into the subcutaneous fat (deep DF). CD34 and Factor XIIIa staining is commonly used in separating DF from DFSP, but is not always helpful. HMGA1 and HMGA2 genes, members of the high mobility group protein family genes, encode proteins that act as architectural transcription factors and are frequently dysregulated in a variety of benign or locally aggressive mesenchymal tumors. In this study, we evaluated the immunoreactivity of HMGA1 and HMGA2 in a series of DF and DFSP to determine the possible utility for these markers in the differential diagnosis of these two entities. Immunohistochemical stains were performed on paraffin-embedded tissues from 22 cases of DF, including 14 cases of deep DF and 14 cases of DFSP, using antibodies against HMGA1 and HMGA2. CD34 and Factor XIIIa immunoreactivity was also evaluated in these lesions and compared with the results of HMGA immunostaining. Immunopositivity for both HMGA1 and HMGA2 was seen in 21of 22 (96%) DFs, but in only 3 (21%) and 1 (7%) of 14 DFSPs, respectively. While 100% of DFSP stained for CD34, 36% of DF also labeled for CD34. The immunoreactivity of HMGA1 and HMGA2 in DF was generally strong and diffuse, in contrast to weak and focal staining seen in DFSP. The proportion of cases with positive immunoreactivity for both markers was significantly higher in DF and in deep DF than in DFSP (P < 0.001). We conclude that HMGA1 and HMGA2 expression can be used to distinguish DF from DFSP with a degree of accuracy that is fully equivalent to that of Factor XIIIa and CD34.

Donor APCs are required for maximal GVHD but not for GVL

Graft-versus-host disease (GVHD) is a major source of morbidity in allogenic stem cell transplantation. We previously showed that recipient antigen-presenting cells (APCs) are required for CD8-dependent GVHD in a mouse model across only minor histocompatibility antigens (minor H antigens). However, these studies did not address the function of donor-derived APCs after GVHD is initiated. Here we show that GVHD develops in recipients of donor major histocompatibility complex class I-deficient (MHC I(-)) bone marrow. Thus, after initial priming, CD8 cells caused GVHD without a further requirement for hematopoietic APCs, indicating that host APCs are necessary and sufficient for GHVD. Nonetheless, GVHD was less severe in recipients of MHC I(-) bone marrow. Therefore, once initiated, GVHD is intensified by donor-derived cells, most probably donor APCs cross-priming alloreactive CD8 cells. Nevertheless, donor APCs were not required for CD8-mediated graft-versus-leukemia (GVL) against a mouse model of chronic-phase chronic myelogenous leukemia. These studies identify donor APCs as a new target for treating GVHD, which may preserve GVL.

Early delayed-type hypersensitivity eosinophil infiltrates depend on T helper 2 cytokines and interferon-gamma via CXCR3 chemokines

We investigated the role of T helper (Th)1- and Th2-type cytokines in delayed-type hypersensitivity to soluble protein antigens elicited early postimmunization. Mice were sensitized by intradermal injection without adjuvants, or subcutaneously with complete Freund's adjuvant, and subsequently ear challenged intradermally. As soon as day 3, antigen-specific eosinophil-rich responses were elicited in wild-type mice, but not in T-cell receptor-alpha-/- mice without adjuvant. Draining lymph node T cells stimulated with antigen secreted interleukin (IL)-4, IL-5 and interferon-gamma (IFN-gamma). IFN-gamma-dependent specific immunoglobulin G (IgG)2a and IL-4-dependent IgG1 were also generated. Delayed-type hypersensitivity ear swelling and local eosinophil recruitment were decreased in IL-5-/-, IL-4-/- and signal transducer and activator of transcription-6 (STAT-6)-/- mice, and with anti-IL-4 treatment of wild-type mice, suggesting Th2 mechanisms. Interestingly, responses were also decreased in IFN-gamma-/- mice, and IFN-gamma protein and the IFN-gamma-inducible CXC chemokine, IP-10, were present in 24-hr ear tissue extracts, suggesting Th1 effects. Finally, ear swelling, total histology and eosinophils were decreased in mice deficient in CXCR3, the chemokine receptor for IP-10. These results suggest that both a Th2-like (IL-5, IL-4 and STAT-6) and a Th1-like (IFN-gamma, IP-10, CXCR3) pathway contribute to eosinophil recruitment in early delayed-type hypersensitivity.

Memory CD4+ T cells do not induce graft-versus-host disease

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality in allogeneic stem cell transplantation (alloSCT). Donor T cells that accompany stem cell grafts cause GVHD by attacking recipient tissues; therefore, all patients receive GVHD prophylaxis by depletion of T cells from the allograft or through immunosuppressant drugs. In addition to providing a graft-versus-leukemia effect, donor T cells are critical for reconstituting T cell-mediated immunity. Ideally, immunity to infectious agents would be transferred from donor to host without GVHD. Most donors have been exposed to common pathogens and have an increased precursor frequency of memory T cells against pathogenic antigens. We therefore asked whether memory CD62L-CD44+ CD4+ T cells would induce less GVHD than unfractionated or naive CD4+ T cells. Strikingly, we found that memory CD4 cells induced neither clinical nor histologic GVHD. This effect was not due to the increased number of CD4+CD25+ regulatory T cells found in the CD62L-CD44+ fraction because memory T cells depletion of these cells did not cause GVHD. Memory CD4 cells engrafted and responded to antigen both in vivo and in vitro. If these murine results are applicable to human alloSCT, selective administration of memory T cells could greatly improve post-transplant immune reconstitution.

IL-10 regulates murine lupus

MRL/MpJ-Tnfrsf6(lpr) (MRL/MpJ-Fas(lpr); MRL-Fas(lpr)) mice develop a spontaneous lupus syndrome closely resembling human systemic lupus erythematosus. To define the role of IL-10 in the regulation of murine lupus, IL-10 gene-deficient (IL-10(-/-)) MRL-Fas(lpr) (MRL-Fas(lpr) IL-10(-/-)) mice were generated and their disease phenotype was compared with littermates with one or two copies of an intact IL-10 locus (MRL-Fas(lpr) IL-10(+/-) and MRL-Fas(lpr) IL-10(+/+) mice, respectively). MRL-Fas(lpr) IL-10(-/-) mice developed severe lupus, with earlier appearance of skin lesions, increased lymphadenopathy, more severe glomerulonephritis, and higher mortality than their IL-10-intact littermate controls. The increased severity of lupus in MRL-Fas(lpr) IL-10(-/-) mice was closely associated with enhanced IFN-gamma production by both CD4(+) and CD8(+) cells and increased serum concentration of IgG2a anti-dsDNA autoantibodies. The protective effect of IL-10 in this lupus model was further supported by the observation that administration of rIL-10 reduced IgG2a anti-dsDNA autoantibody production in wild-type MRL-Fas(lpr) animals. In summary, our results provide evidence that IL-10 can down-modulate murine lupus through inhibition of pathogenic Th1 cytokine responses. Modulation of the level of IL-10 may be of potential therapeutic benefit for human lupus.

Novel inactivating mutations of transforming growth factor-beta type I receptor gene in head-and-neck cancer metastases

Carcinoma cell lines are frequently refractory to transforming growth factor-beta (TGF beta)-mediated cell cycle arrest. Whether and how TGF beta signaling is disrupted in the majority of human tumors, however, remains unclear. To investigate whether TGF beta signaling might be disrupted by inactivation of the key signaling molecule, the TGF beta type I (T beta R-I) receptor, and whether or not T beta R-I inactivation is associated with late stage disease, we conducted a comprehensive structural analysis of the T beta R-I gene in fine-needle aspirates of 23 head-&-neck cancer metastases. We encountered 4 different mutations of T beta R-I, 3 of which have not been previously identified. In 1 case, we found a somatic intragenic 4-bp deletion predicting for a truncation of the receptor protein. This is the first example of a true loss-of-function mutation of T beta R-I in a human epithelial neoplasm. In 2 other cases, we identified missense mutations located between the juxtamembrane- and serine-threonine kinase domains. One of these resulted in an alanine-to-threonine substitution (A230T), which disrupts receptor signaling activity by causing rapid protein degradation within the endoplasmatic reticulum. This represents a novel mechanism of inactivation of a TGF beta signaling intermediate. Finally, we identified a serine-to-tyrosine substitution at codon 387 (S387Y) in a metastasis but not in the corresponding primary tumor. We had previously shown this S387Y mutant to be predominantly associated with breast cancer metastases and to have a diminished ability to mediate TGF beta-dependent signaling. In aggregate, these findings provide further support for the hypothesis that inactivation of the TGF beta signaling pathway occurs in a significant subset of human cancers.

Prevention of graft versus host disease by inactivation of host antigen-presenting cells

Graft versus host disease, an alloimmune attack on host tissues mounted by donor T cells, is the most important toxicity of allogeneic bone marrow transplantation. The mechanism by which allogeneic T cells are initially stimulated is unknown. In a murine allogeneic bone marrow transplantation model it was found that, despite the presence of numerous donor antigen-presenting cells, only host-derived antigen-presenting cells initiated graft versus host disease. Thus, strategies for preventing graft versus host disease could be developed that are based on inactivating host antigen-presenting cells. Such strategies could expand the safety and application of allogeneic bone marrow transplantation in treatment of common genetic and neoplastic diseases.

Ultrastructural changes of the canine gastric mucosa after topical application of graded concentrations of ethanol

Changes in the fine structure of the gastric mucosa following exposure to graded concentrations of ethanol were studied in dogs. 300 ml of 12.5, 20, and 40%, vol/vol, were instilled intragastrically for 30 min. Mucosa from the midbody and midantrum along the greater curvature was examined by light and electron microscopy. Ethanol produced a gradation of changes in the surface epithelial cells and in the lamina propria without affecting the parietal cells and chief cells. 12.5% ethanol produced widened and irregular intercellular spaces while 20 and 40% disrupted the apical cell membrane with concomitant exudation of mucin into the gastric lumen. These changes were more severe after 40% ethanol. The tight junction between cells remained intact following exposure to the lower concentrations of ethanol, but focal separation of cell junctions was observed in severely damaged areas. Quantitation of protein, sodium, and potassium concentrations in the gastric contents revealed marked increases following exposure to ethanol which correlated with the concentration. These studies provide additional morphological data on the relationship between structural changes and functional abnormalities induced by agents which break the gastric mucosal barrier.

Acute ischemic changes in intestinal muscularis

A chronologic study of ischemic changes in the mouse intestinal muscularis was done to delineate the morphologic alterations occurring within 24 hours of ischemia. The muscle cells initially contracted with segmental condensation of myofilaments. Subsequently, increasing degeneration and lysis of myofilaments resulted in the formation of dense degenerative bands and nodules alternating with clear segments in the muscle cells. Eventually, the myofilaments disintegrated. Mitochondria were initially swollen and subsequently condensed, shrunken, and fragmented. The plasma membrane showed progressive dissolution and eventually disappeared. These ultrastructural changes were represented by discernible changes in the histologic sections.