Complex Tissue Regeneration in Mammals Is Associated With Reduced Inflammatory Cytokines and an Influx of T Cells.

While mammals tend to repair injuries, other adult vertebrates like salamanders and fish regenerate damaged tissue. One prominent hypothesis offered to explain an inability to regenerate complex tissue in mammals is a bias during healing toward strong adaptive immunity and inflammatory responses. Here we directly test this hypothesis by characterizing part of the immune response during regeneration in spiny mice (Acomys cahirinus and Acomys percivali) vs. fibrotic repair in Mus musculus. By directly quantifying cytokines during tissue healing, we found that fibrotic repair was associated with a greater release of pro-inflammatory cytokines (i.e., IL-6, CCL2, and CXCL1) during acute inflammation in the wound microenvironment. However, reducing inflammation via COX-2 inhibition was not sufficient to reduce fibrosis or induce a regenerative response, suggesting that inflammatory strength does not control how an injury heals. Although regeneration was associated with lower concentrations of many inflammatory markers, we measured a comparatively larger influx of T cells into regenerating ear tissue and detected a local increase in the T cell associated cytokines IL-12 and IL-17 during the proliferative phase of regeneration. Taken together, our data demonstrate that a strong adaptive immune response is not antagonistic to regeneration and that other mechanisms likely explain the distribution of regenerative ability in vertebrates.

Regeneration-Competent and -Incompetent Murids Differ in Neutrophil Quantity and Function.

Regeneration is rare in mammals, but spiny mice (Acomys spp.) naturally regenerate skin and ear holes. Inflammation is thought to inhibit regeneration during wound healing, but aspects of inflammation contribute to both regeneration and pathogen defense. We compared neutrophil traits among uninjured, regeneration-competent (Acomys: A. cahirinus, A. kempi, A. percivali) and -incompetent (Mus musculus: Swiss Webster, wild-caught strains) murids to test for constitutive differences in neutrophil quantity and function between these groups. Neutrophil quantity differed significantly among species. In blood, Acomys had lower percentages of circulating neutrophils than Mus; and in bone marrow, Acomys had higher percentages of band neutrophils and lower percentages of segmented neutrophils. Functionally, Acomys and Mus neutrophils did not differ in their ability to migrate or produce reactive oxygen species, but Acomys neutrophils phagocytosed more fungal zymosan. Despite this enhanced phagocytosis activity, Acomys neutrophils were not more effective than Mus neutrophils at killing Escherichia coli. Interestingly, whole blood bacteria killing was dominated by serum in Acomys versus neutrophils only or neutrophils and serum in Mus, suggesting that Acomys primarily rely on serum to kill bacteria whereas Mus do not. These subtle differences in neutrophil traits may allow regeneration-competent species to offset damaging effects of inflammation without compromising pathogen defense.

Cytotoxic activity of medicinal plants of the Kakamega County (Kenya) against drug-sensitive and multidrug-resistant cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: The geographical location of Kakamega County proximal to the Kakamega Rain Forest in Kenya and its rich flora represents an interesting resource of traditional medicinal plants. The medicinal plants in the present study are traditionally used to treat cancer in Kakamega County as recorded in published literature. AIM OF THE STUDY: Due to multidrug resistance (MDR) and severe side effects of currently used drugs in clinical oncology, new candidate compounds are urgently required to improve treatment outcome. The present study explored the in vitro cytotoxic potential of 34 organic and 19 aqueous extracts of Kakamega medicinal plants towards sensitive and multidrug-resistant cancer cell lines. METHODS AND RESULTS: The cytotoxicity was determined using the resazurin assay. Eight organic and two aqueous plant extracts inhibited the growth of CCRF-CEM leukemia cells by more than 50%. The organic extracts were Harungana madagascariensis Lam. ex poir (6.6% of untreated control), Prunus africana (Hook.f.) Kalkman (19.4%), Entada abyssinica Steud. ex A. Rich (38.6%), Phyllanthus fischeri Pax (40.7%), Shirakiopsis elliptica (Hochst.) Esser Synonym: Sapium ellipticum (Hochst. kraus) Pax (41.8%), Bridelia micrantha (Hochst.) Baill (45.4%) and Futumia africana Benth. (45.8%) and Microglossa pyrifolia (Lam.) Kuntze (48%). The aqueous extracts were Bridelia micrantha (Hochst.) Baill (31.3%) and Shirakiopsis elliptica (Hochst.) Esser Synonym: Sapium ellipticum (Hochst. Kraus) Pax (48.2%). In addition to P-glycoprotein-expressing tumor cells, we also investigated other mechanisms of drug resistance, i.e. BCRP- or EGFR-transfected and TP53-knockout tumor cells. Some extracts also showed considerable cytotoxic activity against these drug-resistant cell lines. As demonstrated for selected examples, some extracts exhibited enhanced cytotoxicity towards cancer cells, if applied in combination with other extracts. DISCUSSION: The panel of medicinal plants used in the Kakamega County for cancer treatment revealed indeed cytotoxicity to various extent towards cancer cells in vitro. Hence, our results may at least in part substantiate the traditional use of these compounds to treat cancer. Even more interesting, several extracts inhibited otherwise drug-resistant tumor cell lines with similar or even better efficacy than their drug-sensitive counterparts. This provides an attractive perspective for further exploration of their anticancer potential to combat drug resistance of refractory tumors.

Seroepidemiological Survey of Rift Valley Fever Virus in Ruminants in Garissa, Kenya.

INTRODUCTION: Rift Valley fever (RVF) is a vector-borne zoonotic disease caused by phlebovirus in the family Bunyaviridae. In Kenya, major outbreaks occurred in 1997-1998 and 2006-2007 leading to human deaths, huge economic losses because of livestock morbidity, mortality, and restrictions on livestock trade. AIM: This study was conducted to determine RVF seroprevalence in cattle, sheep, and goats during an interepidemic period in Garissa County in Kenya. METHODS: In July 2013, we performed a cross-sectional survey and sampled 370 ruminants from eight RVF-prone areas of Garissa County. Rift Valley fever virus (RVFV) antibodies were detected using a multispecies competitive enzyme-linked immunosorbent assay. Mixed effect logistic regression models were used to determine the association between RVF seropositivity and species, sex, age, and location of the animals. RESULTS: A total of 271 goats, 87 sheep, and 12 cattle were sampled and the overall immunoglobulin G seroprevalence was 27.6% (95% CI [23-32.1]). Sheep, cattle, and goats had seroprevalences of 32.2% (95% CI [20.6-31]), 33.3% (95% CI [6.7-60]), and 25.8% (95% CI [22.4-42]), respectively. Seropositivity in males was 31.8% (95% CI [22.2-31.8]), whereas that of females was 27% (95% CI [18.1-45.6]). CONCLUSIONS: The high seroprevalence suggests RVFV circulation in domestic ruminants in Garissa and may be indicative of a subclinal infection. These findings provide evidence of RVF disease status that will assist decision-makers to flag areas of high risk of RVF outbreaks and prioritize the implementation of timely and cost-effective vaccination programs.

Knowledge and demand for medicinal plants used in the treatment and management of diabetes in Nyeri County, Kenya.

ETHNOPHARMACOLOGICAL RELEVANCE: Non communicable diseases are currently a major health challenge facing humanity. Nyeri County has one of the highest diabetes prevalence in Kenya (12.6%), compared to the country's prevalence of 5.6%. The purpose of the study was to document; diabetes knowledge, medicinal plants and demand for the services of traditional medicine practitioners, in the management and treatment of diabetes. METHODS: A cross-sectional study was carried out in the six constituencies in Nyeri, using pre-tested semi-structured questionnaires. Thirty practicing traditional medicine practitioners were purposively selected for the study. Field observation and identification was carried out on all plants that were cited during the interview. Plant samples were collected and voucher specimen deposited in the University of Nairobi Herbarium in the - School of Biological Sciences. RESULTS: The study revealed 30 plant species in 28 genera and 23 families that are used by the traditional medicine practitioners to treat and manage diabetes. Demand for traditional medicine practitioners' services in the treatment of diabetes is low and often occurs when conventional drugs fail. CONCLUSION: Interaction with the TMPs unveiled significant diversity of potential anti diabetic medicinal plants and in-depth ethnobotanical knowledge that they possessed. Preference for traditional herbal medicine was low despite wide ethnobotanical knowledge in the face of high prevalence of diabetes in the locality. The findings form the basis of pharmacological studies for standardization of the documented ethnomedicine used in the treatment and management of diabetes in the study area.

Comparative analysis of ear-hole closure identifies epimorphic regeneration as a discrete trait in mammals.

Why mammals have poor regenerative ability has remained a long-standing question in biology. In regenerating vertebrates, injury can induce a process known as epimorphic regeneration to replace damaged structures. Using a 4-mm ear punch assay across multiple mammalian species, here we show that several Acomys spp. (spiny mice) and Oryctolagus cuniculus completely regenerate tissue, whereas other rodents including MRL/MpJ 'healer' mice heal similar injuries by scarring. We demonstrate ear-hole closure is independent of ear size, and closure rate can be modelled with a cubic function. Cellular and genetic analyses reveal that injury induces blastema formation in Acomys cahirinus. Despite cell cycle re-entry in Mus musculus and A. cahirinus, efficient cell cycle progression and proliferation only occurs in spiny mice. Together, our data unite blastema-mediated regeneration in spiny mice with regeneration in other vertebrates such as salamanders, newts and zebrafish, where all healthy adults regenerate in response to injury.

Evaluation of the use of Ocimum suave Willd. (Lamiaceae), Plectranthus barbatus Andrews (Lamiaceae) and Zanthoxylum chalybeum Engl. (Rutaceae) as antimalarial remedies in Kenyan folk medicine.

ETHNOPHARMACOLOGICAL RELEVANCE: Crude extracts from the leaves of Ocimum suave Willd (Lamiaceae) and the root barks of Plectranthus barbatus Andrews (Lamiaceae) and Zanthoxylum chalybeum Engl. (Rutaceae) were studied to ascertain the ethnopharmacological standing of their antimalarial usage in Kenyan folk medicine. MATERIALS AND METHODS: Aqueous and Chloroform: Methanol (1:1) extracts of the plants were used in this study. Toxicity of the extracts was investigated by using brine shrimp lethality test and acute oral toxicity in mice. The antimalarial activity at a dose of 100 mg/kg was screened in Swiss albino mice against chloroquine sensitive Plasmodium berghei (D6) using Peters 4-day suppressive test. Chloroquine, at a dosage rate of 20 mg/kg was used as a reference drug. RESULTS: The extracts showed some signs of acute toxicity in the brine shrimp lethality test. However, no signs of toxicity were observed in the mice at a dose of 2000 mg/kg of the crude extracts. The results revealed that all the tested crude extracts were safe. Z. chalybeum aqueous extract and P. barbatus organic extract showed chemosuppressive activities of 81.45% and 78.69%, respectively. This antimalarial activity was not significantly different from that of chloroquine (P<0.05). CONCLUSION: The findings suggest that the Kenyan folkloric medicinal application of these plants has a pharmacological basis. Bioactivity guided fractionation and isolation of bioactive molecules from the two species could lead to new hits against Plasmodium falciparum malaria.

A systematic review of Rift Valley Fever epidemiology 1931-2014.

BACKGROUND: Rift Valley Fever (RVF) is a mosquito-borne viral zoonosis that was first isolated and characterized in 1931 in Kenya. RVF outbreaks have resulted in significant losses through human illness and deaths, high livestock abortions and deaths. This report provides an overview on epidemiology of RVF including ecology, molecular diversity spatiotemporal analysis, and predictive risk modeling. METHODOLOGY: Using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, we systematically searched for relevant RVF publications in repositories of the World Health Organization Library and Information Networks for Knowledge (WHOLIS), U.S Centers for Disease Control and Prevention (CDC), and Food and Agricultural Organization (FAO). Detailed searches were performed in Google Scholar, SpringerLink, and PubMed databases and included conference proceedings and books published from 1931 up to 31st January 2015. RESULTS AND DISCUSSION: A total of 84 studies were included in this review; majority (50%) reported on common human and animal risk factors that included consumption of animal products, contact with infected animals and residing in low altitude areas associated with favorable climatic and ecological conditions for vector emergence. A total of 14 (16%) of the publications described RVF progressive spatial and temporal distribution and the use of risk modeling for timely prediction of imminent outbreaks. Using distribution maps, we illustrated the gradual spread and geographical extent of disease; we also estimated the disease burden using aggregate human mortalities and cumulative outbreak periods for endemic regions. CONCLUSION: This review outlines common risk factors for RVF infections over wider geographical areas; it also emphasizes the role of spatial models in predicting RVF enzootics. It, therefore, explains RVF epidemiological status that may be used for design of targeted surveillance and control programs in endemic countries.

Effects of anticancer drug docetaxel on the structure and function of the rabbit olfactory mucosa.

Docetaxel (DCT) is an anticancer drug which acts by disrupting microtubule dynamics in the highly mitotic cancer cells. Thus, this drug has a potential to affect function and organization of tissues exhibiting high cellular turnover. We investigated, in the rabbit, the effects of a single human equivalent dose (6.26 mg/kg, i.v.) of DCT on the olfactory mucosa (OM) through light and electron microscopy, morphometry, Ki-67 immunostaining, TUNEL assay and the buried food test for olfactory sensitivity. On post-exposure days (PED) 5 and 10, there was disarrangement of the normal cell layering in the olfactory epithelium (OE), apoptotic death of cells of the OE, Bowman's glands and axon bundles, and the presence (including on PED 3) of blood vessels in the bundle cores. A decrease in bundle diameters, olfactory cell densities and cilia numbers, which was most significant on PED 10 (49.3%, 63.4% and 50%, respectively), was also evident. Surprisingly by PED 15, the OM regained normal morphology. Furthermore, olfactory sensitivity decreased progressively until PED 10 when olfaction was markedly impaired, and with recovery from the impairment by PED 15. These observations show that DCT transiently alters the structure and function of the OM suggesting a high regenerative potential for this tissue.

Medicinal plants used in treatment and management of cancer in Kakamega County, Kenya.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional medicine plays a critical role in treatment of chronic debilitating and life threatening conditions and diseases. Cancer is one such condition whose therapeutic intervention is commonly through inexpensive traditional herbal remedies. Increasingly industrialised societies are developing drugs and chemotherapeutics from these traditional herbal plants. Plant biogeography determines the abundance and availability of medicinal plants which in turn determine their use by local communities. The present study was carried out in Kakamega County of Kenya to identify and document medicinal plants used for treatment and management of cancer states by communities living adjacent to Kakamega Tropical rainforest of Kakamega County, Kenya. MATERIALS AND METHODS: An ethnobotanical survey was done using semi-structured questionnaires administered to 32 randomly selected herbalists from Kakamega County. RESULTS AND DISCUSSION: Sixty five (65) plants of 59 genera and 32 families were identified as candidates in therapeutic intervention against cancer states. Most commonly cited plant species were Spathodea campanulata P. Beauv. ssp. nilotica (Seem), Microglossa pyrifolia (Lam.) Kuntze, Harungana madagascariensis Lam. ex poir, Prunus africana (Hook. f.) kalkman, Cyphostemma serpens (A. Rich), Catharanthus roseus (L.) G. Don and Aloe volkensii Engl. The following were documented for the first time; Aeschynomene abyssinica (A. Rich.) Vatke, Synsepalum cerasiferum (welw.) T. D penn., Albizia coriaria Welw. ex Oliv., Aloe volkensii Engl. Bridelia micrantha (Hochst.) Baill, Croton macrostachyus Delile, Cyphostemma serpens (A. Rich), Dicliptera laxata C.B. Clarke, Ekebergia capensis Sparrm., Gardenia volkensii K. schum. ssp. volkensii, Glycine wightii (wight & Arn.), Ocimum gratissimum Suave, Olea hotcsh spp. hochstetteri, Pavetta abyssinica Fresen., Phyllanthus fischeri Pax, Psydrax schimperiana (A. Rich), Rhus vulgaris Meikle, Senna didymobotyra (Fresen.) Irwin and Barneby, Solanecio nandensis (S. Moore) C. Jeffrey, Solanum mauritianum Scop, Spathodea campanulata P. Beauv. ssp. nilotica (Seem), Spermacoce princea (K. Schum.) Verdc., Tabernaemontana stapfiana Britten, Tragia brevipes Pax and Zanthoxylum gilletii (De Wild.) P.G.Waterman. The most frequently used plant parts were fresh or dried leaves and stem barks. Administration to patients was almost exclusively oral, with the exceptions being topical application especially for breast cancer and skin sarcomas. CONCLUSIONS: This study identified diverse medicinal plants used in therapeutic and management intervention against cancer by communities living adjacent to Kakamega Tropical Rainforest. The primary mode of administration was oral.

Skin shedding and tissue regeneration in African spiny mice (Acomys).

Evolutionary modification has produced a spectrum of animal defence traits to escape predation, including the ability to autotomize body parts to elude capture. After autotomy, the missing part is either replaced through regeneration (for example, in urodeles, lizards, arthropods and crustaceans) or permanently lost (such as in mammals). Although most autotomy involves the loss of appendages (legs, chelipeds, antennae or tails, for example), skin autotomy can occur in certain taxa of scincid and gekkonid lizards. Here we report the first demonstration of skin autotomy in Mammalia (African spiny mice, Acomys). Mechanical testing showed a propensity for skin to tear under very low tension and the absence of a fracture plane. After skin loss, rapid wound contraction was followed by hair follicle regeneration in dorsal skin wounds. Notably, we found that regenerative capacity in Acomys was extended to ear holes, where the mice exhibited complete regeneration of hair follicles, sebaceous glands, dermis and cartilage. Salamanders capable of limb regeneration form a blastema (a mass of lineage-restricted progenitor cells) after limb loss, and our findings suggest that ear tissue regeneration in Acomys may proceed through the assembly of a similar structure. This study underscores the importance of investigating regenerative phenomena outside of conventional model organisms, and suggests that mammals may retain a higher capacity for regeneration than was previously believed. As re-emergent interest in regenerative medicine seeks to isolate molecular pathways controlling tissue regeneration in mammals, Acomys may prove useful in identifying mechanisms to promote regeneration in lieu of fibrosis and scarring.

Morphofunctional adaptations of the olfactory mucosa in postnatally developing rabbits.

Rabbits are born blind and deaf and receive unusually limited maternal care. Consequently, their suckling young heavily rely on the olfactory cue for nipple attachment. However, the postnatal morphofunctional adaptations of olfactory mucosa (OM) are not fully elucidated. To clarify on the extent and the pattern of refinement of the OM following birth in the rabbit, morphologic and morphometric analysis of the mucosa were done at neonatal (0-1 days), suckling (2 weeks), weanling (4 weeks), and adult (6-8 months) stages of postnatal development. In all the age groups, the basic components of the OM were present. However, proliferative activity of cells of the mucosal epithelium decreased with increasing age as revealed by Ki-67 immunostaining. Diameters of axon bundles, packing densities of olfactory cells, and cilia numbers per olfactory cell knob increased progressively with age being 5.5, 2.1, and 2.6 times, respectively, in the adult as compared with the neonate. Volume fraction values for the bundles increased by 5.3% from birth to suckling age and by 7.4% from weaning to adulthood and the bundle cores were infiltrated with blood capillaries in all ages except in the adult where such vessels were lacking. The pattern of cilia projection from olfactory cell knobs also showed age-related variations, that is, arose as a tuft from the tips of the knobs in neonates and sucklings and in a radial pattern from the knob bases in weanlings and adults. These morphological changes may be attributed to the high olfactory functional demand associated with postnatal development in the rabbit.

Medicinal plants used in the management of chronic joint pains in Machakos and Makueni counties, Kenya.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional medicines play an important role in the management of chronically painful and debilitating joint conditions, particularly in the rural Africa. However, their potential use as sources of medicines has not been fully exploited. The present study was carried to find the medicinal plants traditionally used to manage chronic joint pains in Machakos and Makueni counties in Kenya. MATERIALS AND METHODS: To obtain this ethnobotanical information, 30 consenting traditional herbal medical practitioners were interviewed exclusively on medicinal plant use in the management of chronic joint pains, in a pre-planned workshop. RESULTS AND DISCUSSION: In this survey, a total of 37 plants belonging to 32 genera and 23 families were cited as being important for treatment of chronic joint pains. The most commonly cited plant species were Pavetta crassipes K. Schum, Strychnos henningsii Gilg., Carissa spinarum L., Fagaropsis hildebrandtii (Engl.) Milve-Redh. and Zanthoxylum chalybeum Engl. Acacia mellifera (Vahl) Benth., Amaranthus albus L., Balanites glabra Mildbr. & Schltr., Grewia fallax K. Schum., Lactuca capensis, Launaea cornuta (Oliv. & Hiern) O. Jeffrey, Lippia kituiensis Vatke, Pappea capensis Eckl. & Zeyh. and Pennisetum glaucum (L.) R. Br. are documented for the first time as being important in the management of chronic joint pains. CONCLUSIONS: The findings of this study show that a variety of medicinal plants are used in the management of chronic joint pains and the main mode of administration is oral.

A three-dimensional cellular model of the human respiratory tract to study the interaction with particles.

A novel triple co-culture model of the human airway barrier was designed to simulate the cellular part of the air-blood barrier of the respiratory tract represented by macrophages, epithelial cells, and dendritic cells. When epithelial cells (A549 cells) were grown on filter inserts with pores of 3.0 mum in diameter in a two-chamber system, they formed monolayers with polarization into apical and basolateral domains. The epithelial cell cultures were then supplemented with human blood monocyte-derived macrophages and dendritic cells on the apical and basal aspect, respectively. The single-cell cultures as well as the triple co-cultures were characterized in terms of a number of typical features, for example, morphology of cell types, integrity of epithelial layer, and expression of specific cell surface markers (CD14 for macrophages and CD86 for dendritic cells). The interplay of epithelial cells with macrophages and dendritic cells during the uptake of polystyrene particles (1 mum in diameter) was investigated with confocal laser scanning and conventional transmission electron microscopy. Particles were found in all three cell types, although dendritic cells were not directly exposed to the particles. More investigations are needed to understand the translocation pathway.

Salmonella virulence factor SipB induces activation and release of IL-18 in human dendritic cells.

Interleukin-18 (IL-18) plays an important role in innate and acquired immunity, in particular against intracellular pathogens. However, little is known about the microbial factors that trigger IL-18 secretion by dendritic cells (DCs). To determine the influence of bacterial virulence factors on the activation and release of IL-18, we infected human monocyte-derived DCs with virulence mutants of the facultative intracellular pathogen Salmonella typhimurium. Our results show that infection by S. typhimurium causes caspase-1-dependent activation of IL-18 and triggers the release of IL-18 in human DCs. The secretion of IL-18 by the DCs was closely correlated with the ability of the S. typhimurium strains to induce apoptosis. We demonstrate that activation and release of IL-18 are blocked by mutations in the Salmonella sipB gene, which encodes a virulence factor that activates caspase-1 to induce apoptosis. These findings indicate that the activation and release of IL-18 induced by bacterial virulence factors may represent one component of innate immunity against the intracellular bacteria.