Hydrogen sulfide dysregulates the immune response by suppressing central carbon metabolism to promote tuberculosis.

The ubiquitous gasotransmitter hydrogen sulfide (H2S) has been recognized to play a crucial role in human health. Using cystathionine γ-lyase (CSE)-deficient mice, we demonstrate an unexpected role of H2S in Mycobacterium tuberculosis (Mtb) pathogenesis. We showed that Mtb-infected CSE-/- mice survive longer than WT mice, and support reduced pathology and lower bacterial burdens in the lung, spleen, and liver. Similarly, in vitro Mtb infection of macrophages resulted in reduced colony forming units in CSE-/- cells. Chemical complementation of infected WT and CSE-/- macrophages using the slow H2S releaser GYY3147 and the CSE inhibitor DL-propargylglycine demonstrated that H2S is the effector molecule regulating Mtb survival in macrophages. Furthermore, we demonstrate that CSE promotes an excessive innate immune response, suppresses the adaptive immune response, and reduces circulating IL-1ß, IL-6, TNF-α, and IFN-γ levels in response to Mtb infection. Notably, Mtb infected CSE-/- macrophages show increased flux through glycolysis and the pentose phosphate pathway, thereby establishing a critical link between H2S and central metabolism. Our data suggest that excessive H2S produced by the infected WT mice reduce HIF-1α levels, thereby suppressing glycolysis and production of IL-1ß, IL-6, and IL-12, and increasing bacterial burden. Clinical relevance was demonstrated by the spatial distribution of H2S-producing enzymes in human necrotic, nonnecrotic, and cavitary pulmonary tuberculosis (TB) lesions. In summary, CSE exacerbates TB pathogenesis by altering immunometabolism in mice and inhibiting CSE or modulating glycolysis are potential targets for host-directed TB control.

Prevalence and characteristics of celiac disease in South African patients with type 1 diabetes mellitus: Results from the Durban Diabetes and Celiac Disease Study.

BACKGROUND AND AIM: The aim of this study was to assess the prevalence and characteristics of celiac disease (CD) in all patients with type 1 diabetes mellitus attending a tertiary adult diabetes clinic in Durban, South Africa. METHODS: This was a cross-sectional observational study that screened 202 patients; of these, 56.4% were African (Black), 31.7% Asian Indian, 4.5% White, and 7.4% mixed race. Demographic data, symptoms, and anthropometry were documented. Blood tests included anti-tissue transglutaminase antibody (tTG), anti-endomysial antibody (EMA), and anti-gliadin antibody (AGA). Endoscopy and duodenal biopsy were performed in patients with celiac antibodies. Diagnosis of CD was based on the modified Marsh classification. RESULTS: Mean age and mean duration of diabetes were 26.4 ± 11.4 and 10.7 ± 9.1 years, respectively. Celiac antibodies were found in 65 (32.2%) patients: EMA 7.4%, tTG immunoglobulin A (IgA) 8.4%, tTG immunoglobulin G 1.9%, AGA IgA 18.3%, and AGA immunoglobulin G 21.8%. Histological evidence of CD was found in 5.9% (n = 12/202): 2.5% were classed as definite CD (Marsh 3) and 3.4% as potential CD (Marsh 1). None of the patients with CD were symptomatic. The sensitivity of AGA IgA, EMA, and tTG IgA antibodies for detecting histologically proven CD was 66.7%, 50.0%, and 41.7%, respectively. CONCLUSION: The prevalence of CD was similar to reports from western countries. No ethnic specific differences were noted. CD was silent in all patients in this study. The sensitivity of EMA and tTG antibodies was poor and merits further evaluation as screening tools for CD in South African patients with type 1 diabetes mellitus.

Microanatomic Distribution of Myeloid Heme Oxygenase-1 Protects against Free Radical-Mediated Immunopathology in Human Tuberculosis.

Heme oxygenase-1 (HO-1) is a cytoprotective enzyme that controls inflammatory responses and redox homeostasis; however, its role during pulmonary tuberculosis (TB) remains unclear. Using freshly resected human TB lung tissue, we examined the role of HO-1 within the cellular and pathological spectrum of TB. Flow cytometry and histopathological analysis of human TB lung tissues showed that HO-1 is expressed primarily in myeloid cells and that HO-1 levels in these cells were directly proportional to cytoprotection. HO-1 mitigates TB pathophysiology by diminishing myeloid cell-mediated oxidative damage caused by reactive oxygen and/or nitrogen intermediates, which control granulocytic karyorrhexis to generate a zonal HO-1 response. Using whole-body or myeloid-specific HO-1-deficient mice, we demonstrate that HO-1 is required to control myeloid cell infiltration and inflammation to protect against TB progression. Overall, this study reveals that zonation of HO-1 in myeloid cells modulates free-radical-mediated stress, which regulates human TB immunopathology.

Ferritin H Deficiency in Myeloid Compartments Dysregulates Host Energy Metabolism and Increases Susceptibility to Mycobacterium tuberculosis Infection.

Iron is an essential factor for the growth and virulence of Mycobacterium tuberculosis (Mtb). However, little is known about the mechanisms by which the host controls iron availability during infection. Since ferritin heavy chain (FtH) is a major intracellular source of reserve iron in the host, we hypothesized that the lack of FtH would cause dysregulated iron homeostasis to exacerbate TB disease. Therefore, we used knockout mice lacking FtH in myeloid-derived cell populations to study Mtb disease progression. We found that FtH plays a critical role in protecting mice against Mtb, as evidenced by increased organ burden, extrapulmonary dissemination, and decreased survival in Fth-/- mice. Flow cytometry analysis showed that reduced levels of FtH contribute to an excessive inflammatory response to exacerbate disease. Extracellular flux analysis showed that FtH is essential for maintaining bioenergetic homeostasis through oxidative phosphorylation. In support of these findings, RNAseq and mass spectrometry analyses demonstrated an essential role for FtH in mitochondrial function and maintenance of central intermediary metabolism in vivo. Further, we show that FtH deficiency leads to iron dysregulation through the hepcidin-ferroportin axis during infection. To assess the clinical significance of our animal studies, we performed a clinicopathological analysis of iron distribution within human TB lung tissue and showed that Mtb severely disrupts iron homeostasis in distinct microanatomic locations of the human lung. We identified hemorrhage as a major source of metabolically inert iron deposition. Importantly, we observed increased iron levels in human TB lung tissue compared to healthy tissue. Overall, these findings advance our understanding of the link between iron-dependent energy metabolism and immunity and provide new insight into iron distribution within the spectrum of human pulmonary TB. These metabolic mechanisms could serve as the foundation for novel host-directed strategies.

High prevalence of antithyroid peroxidase and antiparietal cell antibodies among patients with type 1 diabetes mellitus attending a tertiary diabetes centre in South Africa.

OBJECTIVE: Data on the prevalence of autoimmune thyroid disease (AITD) and gastric autoimmunity in type 1 diabetes mellitus (T1DM) in Africa are limited. The aim of this study was to assess the prevalence of antithyroid peroxidase (TPO-A) and antiparietal cell antibody (PCA) in patients with T1DM at a tertiary diabetes clinic in Durban, South Africa. RESEARCH DESIGN AND METHODS: This was a cross-sectional observational study among subjects attending the adult T1DM clinic at Inkosi Albert Luthuli Hospital. Information about history and clinical examination was collected. Blood tests included glutamic acid decarboxylase antibody (GADA), TPO-A, PCA, vitamin B12, folate, ferritin, thyroid stimulating hormone (TSH), free thyroxine, lipids and HbA1c. RESULTS: A total of 202 (M:F, 90:112) patients were recruited. The ethnic composition was African (black) (56.4%; n=114), Indian (31.7%; n=64), white (4.5%; n=9) and coloured (mixed race) (7.4%; n=15). Mean age and mean duration of diabetes were 26.4±11.4 and 10.7±9.1 years, respectively. Mean body mass index was 21.6±6.3 kg/m2. GADA was positive in 63.37% (n=128). The prevalence of TPO-A was 18.9% (n=39) and PCA 8.9% (n=17). The prevalence of overt hypothyroidism, subclinical hypothyroidism and Graves' disease was 10.9%, 2.5% and 1.5%, respectively; vitamin B12 deficiency was noted in 3.5% (n=7) and iron deficiency in 19.3% (n=39). CONCLUSIONS: Among patients with T1DM in this study, there was a high prevalence of coexistent AITD and gastric autoimmunity. Screening for hypothyroidism and thyroid autoimmunity should be undertaken in all patients at initial presentation. However, to assess the feasibility and optimal timing of subsequent testing in the African setting with limited resources, more collaborative research with longitudinal studies is required.

Challenges in the management of disseminated progressive histoplasmosis in human immunodeficiency virus-infected patients in resource-limited settings.

The diagnosis of histoplasmosis in patients with human immunodeficiency virus in southern Africa is complicated by the nonspecific presentation of the disease in this patient group and the unavailability of sensitive diagnostics including antigen assays. Treatment options are also limited due to the unavailability of liposomal amphotericin and itraconazole, and the inability to perform therapeutic drug monitoring further confounds management. We present 3 clinical cases to illustrate the limits of diagnosis and management in the southern African context, and we highlight the need for additional diagnostic tools and treatment options in resource-limited settings.

HIV-associated large-vessel vasculopathy: a review of the current and emerging clinicopathological spectrum in vascular surgical practice.

An established relationship exists between human immunodeficiency virus (HIV) and the vascular system, which is characterised by clinical expressions of aneurysmal and occlusive disease that emanate from a common pathological process. The exact pathogenesis is currently unknown; attempts to implicate opportunistic pathogens have been futile. Theories converge on leucocytoclastic vasculitis with the vaso vasora as the vasculopathic epicentre. It is thought that the virus itself or viral proteins trigger the release of inflammatory mediators that cause endothelial dysfunction and smooth muscle proliferation leading to vascular injury and thrombosis. The beneficial effects of highly active anti-retroviral therapy alter the natural history of the disease profile and promote longevity but are negated by cardiovascular complications. Atherosclerosis is an emerging challenge. Presently patients are managed by standard surgical protocols because of non-existent universal surgical interventional guidelines. Clinical response to treatment is variable and often compounded by complications of graft occlusion, sepsis and poor wound healing. The clinical, imaging and pathological observations position HIV-associated large-vessel vasculopathy as a unique entity. This review highlights the spectrum of HIV-associated large-vessel aneurysmal, occlusive and atherosclerotic disease in vascular surgical practice.

Cytokeratin expression in gastrointestinal stromal tumors: morphology, meaning, and mimicry.

BACKGROUND: Gastrointestinal stromal tumors (GISTs) are biologically distinctive neoplasms harboring KIT and PDGFRA mutations. Cytokeratin expression in GISTs is an under-recognized diagnostic pitfall, especially in high grade GISTs with limited biopsy material and from metastatic sites. MATERIALS AND METHODS: We evaluated the histomorphology and expression of four 'broad-spectrum' cytokeratin markers, AE1-AE3, CAM 5.2, MNF-116, and 34ßE12 in 64 GISTs diagnosed over a 68-month period. Individual cytokeratins 5, 6, 7, 8, 14, 17, 18, 19, and 20 were investigated in the 'broad-spectrum' cytokeratin-positive GISTs. RESULTS: Of 64 GISTs, 10 (15%) demonstrated cytokeratin immunopositivity. All 10, considered high risk by the National Institutes of Health consensus approach, were immunopositive for CAM 5.2 and MNF-116. Seven were AE1-AE3 immunopositive. Cytokeratins 8 and 18 were confirmed in 10 and 9 GISTs, respectively. One GIST demonstrated biphasic morphology with cytokeratin immunonegativity in low-grade spindle and immunopositivity in high-grade epithelioid foci. KIT and PDGFRA mutational analysis, undertaken in 5/10 cytokeratin-positive GISTs, harbored KIT exon 11 mutations. CONCLUSION: We hypothesize that cytokeratin expression exclusively in high risk GISTs is a consequence of tumor progression. Given the increasing number of commercially available broad-spectrum cytokeratin immunomarkers, including those reacting with cytokeratins 8 and 18, cytokeratin-positive GISTs must be differentiated from carcinomas, melanomas, and a range of cytokeratin-positive sarcomas to ensure optimal patient management and prognostication.

Pediatric plasmablastic lymphoma: a clinicopathologic study.

Plasmablastic lymphoma (PBL) is reported rarely in children. To date, 10 cases are documented in the English-language literature. This study, based on 13 biopsies from 11 HIV-positive children (9 males, 2 females), documents the clinicopathologic features of PBL. The CD4 count ranged from 9 to 800 cells/mm(3). All biopsies demonstrated exclusive plasmablastic morphology; CD20 immunonegativity; and VS38c, EMA, CD31, MUM-1, CD45, and CD79a immunopositivity. B-cell monoclonality was confirmed in all biopsies. Of 3 biopsies subjected to FISH investigation, 2 had a t(8,14) translocation. Nine patients with follow-up details were treated exclusively with HAART (highly active antiretroviral therapy) or with combinations of HAART, chemotherapy, and radiotherapy. Seven patients died. PBL histomorphology, disease stage, and treatment modalities employed were not predictive of outcome. The survival of 2 stage 4 patients for 3 and 8 years each, managed on HAART, chemotherapy, and radiotherapy, however, may justify a role for combined therapeutic modalities for PBL.

Mycophenolate mofetil therapy in children with idiopathic membranous nephropathy.

BACKGROUND: Idiopathic membranous nephropathy (IMN) is a rare form of childhood nephropathy. To date there are no standardized protocols of management for this condition in children. The aim of this study is to report on 4 children with IMN who were treated with mycophenolate mofetil (MMF). METHODS: MMF was given in combination with low dose steroids and angiotensin converting enzyme antagonists in a dose of 1,200 mg/m2 body surface area in two divided doses for a minimum of 6 months. RESULTS: All children had histopathological findings in keeping with Stage III membranous nephropathy. At the last hospital visit, 3 children had achieved a > 50% reduction of proteinuria with preservation of renal function. One patient who failed to respond progressed to Stage III chronic kidney disease. None of the children who were treated with MMF experienced any major side effects of the drug. CONCLUSIONS: MMF, administered over a limited period, served as a safe and effective immunosuppressive agent in the treatment of this condition, in conjunction with low dose steroids and angiotensin converting enzyme inhibitors. Large multicenter randomized studies of children with IMN are necessary to assess the efficacy and long term safety of MMF.

Infantile donovanosis presenting as external auditory canal polyps: a diagnostic trap.

Two infants, 6 months and 4 months of age, presented with bilateral or unilateral external auditory canal polyps and otorrhea, respectively. Additional findings on examination included otitis media and mastoiditis. Tympanic membrane perforation was noted in one patient and a postauricular abscess in the other. Incisional biopsies of the polyps and abscess were reported as nonspecific mixed inflammation and abscess wall, respectively. There was a limited response to an empirical 5-day course of trimethoprim sulfamethoxazole. The children were referred to the academic hospital, and excision of the polyps and biopsies of the middle ear, mastoid, and postauricular abscess was undertaken. All the biopsies demonstrated donovanosis. Reappraisal of the initial incisional biopsies also confirmed donovanosis. Trimethoprim sulfamethoxazole was administered to both patients for 3 weeks, with resolution of the lesions. Subsequent investigations confirmed genital tract donovanosis, human immunodeficiency virus seropositivity, acquired immunodeficiency syndrome, and pulmonary tuberculosis in both mothers. Heightened awareness of the occurrence of donovanosis at unusual sites and improved recognition of the histomorphological features of the disease, especially in small and superficial biopsies, are pivotal not only for its correct diagnosis in extragenital cutaneous and extracutaneous locations but also for timely and adequate therapy and an improved infant and maternal outcome.

Bartonella quintana-induced vulval bacillary angiomatosis.

Bacillary angiomatosis (BA) is an increasingly reported infection, mainly in patients with acquired immunodeficiency syndrome. Different epidemiological risk factors are associated with the transmission of the causative agents, Bartonella henselae and B. quintana. Vulval BA is described rarely. Two patients presented with a vulval mass (Patient 1) and a verrucous vulval growth (Patient 2), which were diagnosed clinically as tuberculosis and carcinoma, respectively. Patient 1 also had pulmonary tuberculosis and Kaposi sarcoma. Biopsy of the vulval lesions confirmed BA, characterized by a multilobular proliferation of blood vessels that were lined by epithelioid endothelial cells. There were prominent intervascular neutrophils, karyorrhectic debris, and clumps of paravascular argyrophilic organisms. The biopsy from Patient 1 was deep dermal/subcutaneous in location and displayed foci of confluent suppuration. There was florid pseudoepitheliomatous hyperplasia in the biopsy from Patient 2. Molecular investigations confirmed intralesional B. quintana, hitherto unreported in vulval BA, as the causative agent in both biopsies. On follow-up, Patient 2 had developed additional lesions in the vulva and thigh, but all her lesions and the vulval mass (Patient 1) responded to erythromycin treatment. Patient 1 succumbed to tuberculosis. Heightened recognition of BA underpins rapid and optimal clinicopathological diagnosis, even in uncommon locations. Identification of the causative Bartonella species is important for appropriate, interventive social management.

The spectrum of HIV-related nephropathy in children.

BACKGROUND: Despite the burden of human immunodeficiency virus (HIV) disease in Southern Africa, there have been few reports of HIV-related nephropathy in children. This study outlines the spectrum of HIV-1-related kidney diseases of children in KwaZulu-Natal, South Africa. METHODS: A review of the clinical presentation, laboratory and histopathological findings of children diagnosed with HIV-related nephropathy. RESULTS: Forty-nine out of 71 children (1-16 years old) with HIV-1 related nephropathy underwent kidney biopsy. The most common histopathological finding was focal segmental glomerulosclerosis (FSGS), which was present in 32 (65.3%) children; 13 (26.5%) having collapsing glomerulopathy and 19 (38.8%) classic FSGS. The majority of patients showed haematological (86.4%) and electrolyte abnormalities (69.4%). Renal impairment was present in 41% of patients on initial presentation. However, end-stage kidney disease was present in only 4% of these patients. All patients were treated with highly active anti-retroviral therapy (HAART), the majority (79.6%) showed decreased proteinuria with 38.8% having complete remission. CONCLUSIONS: This study, one of the largest series of children reported from Africa, demonstrates that nephrotic syndrome due to HIV-associated nephropathy (HIVAN) is the commonest presentation of HIV-related nephropathy in childhood. Highly active anti-retroviral therapy in combination with angiotensin-converting enzyme antagonists is highly effective in decreasing proteinuria and preserving renal function.

Extra-uterine myoid tumours in patients with acquired immunodeficiency syndrome: a clinicopathological reappraisal.

AIMS: AIDS-associated myoid tumours (AIDS-MTs), often Epstein-Barr virus (EBV)-associated (EBV-positive MTs), include smooth muscle tumors (SMTs) and the relatively recently recognized myopericytomas (MPCTs). The myoid immunophenotype of AIDS-MTs has been documented inconsistently. The aim of this study was to reappraise the phenotypic and immunophenotypic features of extra-uterine AIDS-MTs and the clinical profile of afflicted patients. METHODS AND RESULTS: EBV early RNA in-situ hybridization testing on 27 AIDS-MTs from 25 patients identified 19 of 27 (70.4%) EBV-positive MTs and eight of 27 (29.6%) EBV-negative MTs. EBV-positive MTs comprised 12 of 19 EBV-positive SMTs [six leiomyomas, one smooth muscle tumour of uncertain malignant potential (STUMP), five leiomyosarcomas] and seven of 19 EBV-positive MPCTs [benign (five), malignant (two)]. The EBV-negative MTs, made up exclusively of EBV-negative SMTs, included angioleiomyoma (one), leiomyoma (one), STUMP (one) and leiomyosarcomas (five). Malignant AIDS-MTs demonstrated hypercellularity, pleomorphism, increased mitoses and necrosis. EBV-positive leiomyosarcomas retained a conspicuous fascicular architecture. Four of five EBV-negative leiomyosarcomas demonstrated marked pleomorphism. All EBV-positive MPCTs and two EBV-positive leiomyosarcomas contained aggregates of desmin-negative round and oval cells. Seventeen of 25 patients died, mainly from comorbid diseases. CONCLUSION: While the reappraised spectrum of AIDS-MTs does not demonstrate divergent subtype-determined clinical behaviour, heightened awareness/recognition of this expanded spectrum will not only promote improved diagnosis of pleomorphic and myopericytic variants, which may be the sentinel clue to AIDS and its comorbidity, but will also facilitate distinction from histopathological mimics in specific anatomic locations.

Periampullary Epstein-Barr virus-associated myopericytoma.

Although myopericytoma occurs predominantly in the extremities, a wider anatomical distribution, malignant variant, and association with Epstein-Barr virus have been recognized recently. However, benign, malignant, or Epstein-Barr virus-myopericytoma has not been documented in the gastrointestinal tract to date. We report a periampullary Epstein-Barr virus-myopericytoma in a patient with AIDS who presented with obstructive jaundice. The tumor contained round, oval, and plump spindle cells arranged around and between slit-like, dilated, and staghorn vessels. A malignant variant was favored based on the presence of cellular pleomorphism, 23 mitoses per 10 high-power fields, necrosis, and lymphovascular involvement. Immunohistochemistry confirmed a myoid immunophenotype with h-Caldesmon positivity and desmin negativity. Epstein-Barr virus-encoded RNA was demonstrated by in situ hybridization. Heightened awareness of Epstein-Barr virus-myopericytoma and occurrence in the periampullary location are critical to diagnostic workup and differentiation of myopericytoma from other mesenchymal tumors and pseudotumors especially in small biopsies and in patients with AIDS.

T-cell-rich angiomatoid polypoid pseudolymphoma of the skin: a clinicopathologic study of 17 cases and a proposed nomenclature.

BACKGROUND: We describe a series of previously unreported, distinctive, polypoid solitary T-cell-rich cutaneous pseudolymphomas. METHODS: The clinicopathologic features were examined in 17 cases. RESULTS: Patient ages ranged from 16 to 71 years (mean = 38.5) with a female predominance (female : male = 14 : 3). All lesions, clinically diagnosed most often as pyogenic granuloma, presented as a solitary, polypoid, erythematous, papule ranging in size from 2.5 to 7.5 mm (mean = 5.8). Most occurred on the head and neck (7) and trunk (6) with other sites including the thigh (1), shoulder (1) and knee (1). A dense dermal infiltrate composed of mildly atypical lymphocytes with variable numbers of admixed plasma cells and histiocytes was prototypical. Commonly, there was an associated epidermal collarette (16/17), Grenz zone (11/17) or admixed eosinophils (8/17). Prominent vessels lined by plump endothelial cells, reminiscent of high endothelial venules of lymph nodes, were universal and some degree of telangiectasia was also common (12/17). CD3-positive T-cells consisted of an admixture of CD4-positive and CD8-positive forms (15/16). Multiple studies suggested polyclonality (seven cases). No recurrences after lesional excision were noted in the 17 patients with a follow-up range from 24 to 120 months (mean = 46.6). CONCLUSION: Although these lesions share histopathologic features of the so-called acral pseudolymphomatous angiokeratoma of children (APACHE), they occur in a completely different clinical setting, present in solitary and polypoid fashion and are T-cell rich. We propose the diagnostic label T-cell-rich angiomatoid polypoid pseudolymphoma for this distinctive but presumably reactive lesion.

Langerhans cells in anaplastic Kaposi sarcoma with a paucivascular phenotype: a potential diagnostic pitfall.

Anaplastic Kaposi sarcoma (AKS), a rare variant of Kaposi sarcoma, has a poorly recognized histomorphologic spectrum, including a paucivascular phenotype, that mimics a range of undifferentiated malignancies. This study, that highlights the hitherto undocumented phenomenon of S100-protein-positive Langerhans cells (SLCs) as a potential diagnostic pitfall in paucivascular AKS, involved review of nine such AKS that required diagnostic immunohistochemical (IHC) work-up. All biopsies had a predominant or exclusive spindle or epithelioid cell infiltrate. The first three tumors were diagnosed as malignant peripheral nerve sheath tumor (2) and metastatic melanoma (1), based on S100-protein immunopositivity. Biopsy of a co-existent pigmented sole lesion (patient 3) demonstrated nodular KS. Subsequent IHC investigation of these three tumors demonstrated an endothelial phenotype and HHV8 immunopositivity, confirming AKS. CD1a and langerin staining of the S100-protein-positive cells confirmed Langerhans cells as the cause of the diagnostic pitfall. Subsequently, six further paucivascular AKS with intratumoral SLCs were recognized on histomorphological and IHC appraisal. In conclusion, heightened awareness of the histomorphologic spectrum, appropriate IHC investigation, and informed appraisal thereof, are critical to the diagnosis of AKS with an undifferentiated phenotype, and the avoidance of IHC pitfalls, such as those caused by under-recognition and misinterpretation of bystander SLCs in AKS.